7500 Series Flowmeter Technical Reference Manual

7500 Series Flowmeter Technical Reference Manual
7500MA0199 REV B4
7500 Series Flowmeter
Technical Reference Manual
Accusonic Technologies, Inc.
28 Patterson Brook Road
West Wareham, MA 02576
Tel: +1-508-273-9600
Fax: +1-508-273-9699
Copyright  by Accusonic Technologies.
All Rights Reserved
Division of ADS LLC
A Nova Technologies Company
Table of Contents
CHAPTER ONE
TABLE OF CONTENTS _______________________________________________________________ i
INTRODUCTION __________________________________________________________________ 1-1
OVERVIEW OF THE MANUAL ______________________________________________________ 1-1
THE ACCUSONIC MODEL 7500 __________________________________________________ 1-2
Transducers _________________________________________________________________ 1-3
Cables______________________________________________________________________ 1-4
Flowmeter Console ___________________________________________________________ 1-4
Display and System Input/Output (I/O) Options _____________________________________ 1-4
System Parameters and Setup ___________________________________________________ 1-4
Self Test and System Diagnostics ________________________________________________ 1-4
CHAPTER TWO
FLOWMETER DESCRIPTION ________________________________________________________ 2-1
COMPONENT OVERVIEW _________________________________________________________ 2-1
BASIC FLOWMETER CONSOLE _____________________________________________________ 2-1
RACK-MOUNT CONSOLE__________________________________________________________ 2-4
REMOTE FLOW TRANSMITTER UNIT ________________________________________________ 2-5
SYSTEM OVERVIEW _____________________________________________________________ 2-6
Measuring Fluid Stage _________________________________________________________ 2-6
System Expansion ____________________________________________________________ 2-7
System Processor Technical Details ______________________________________________ 2-7
Flow Transmitter Technical Details _______________________________________________ 2-9
CHAPTER THREE
ACOUSTIC FLOWMETER PRINCIPLES ________________________________________________ 3-1
MEASUREMENT SECTION CONFIGURATION ___________________________________________ 3-1
PLACEMENT OF ACOUSTIC PATHS IN ROUND PIPE _____________________________________ 3-2
PLACEMENT OF ACOUSTIC PATHS IN AN OPEN CHANNEL OR COMPOUND SECTION ___________ 3-2
TRAPEZOIDAL EXTRAPOLATION/INTERPOLATION STRATEGIES ____________________________ 3-4
Top and Bottom Clearance Considerations in an Open Channel Meter ___________________ 3-6
CROSSED PATHS ________________________________________________________________ 3-7
FLOWMETER MEASUREMENT CYCLE ________________________________________________ 3-8
Reading System Inputs _______________________________________________________ 3-11
Measuring Travel Times ______________________________________________________ 3-12
Signal Detection ___________________________________________________________ 3-13
Calculating Path Velocities ____________________________________________________ 3-14
MEASURING STAGE ____________________________________________________________ 3-16
CALCULATING FLOW ___________________________________________________________ 3-17
Integration Methods __________________________________________________________ 3-18
Flow Calculation Formulas for Full Pipes or Surcharged Conduits _____________________ 3-19
ACCUSONIC MODEL 7500
i
Table of Contents
Flow Calculation Formulas for Non-Surcharged Conduits ____________________________ 3-21
Updating Volume Totals ______________________________________________________ 3-25
Volume totalizer after Outage __________________________________________________ 3-25
Updating System Outputs _____________________________________________________ 3-26
ACOUSTIC FLOWMETER ACCURACY _______________________________________________ 3-26
Sources of Measurement Uncertainty ____________________________________________ 3-26
Sample Error Analysis (Round Pipe) _____________________________________________ 3-28
CHAPTER FOUR
UNPACKING AND INSTALLATION ____________________________________________________ 4-1
PHYSICAL INSTALLATION_________________________________________________________ 4-1
ELECTRICAL INSTALLATION ______________________________________________________ 4-2
AC Wiring __________________________________________________________________ 4-2
Transducer Wiring ____________________________________________________________ 4-3
Transducer and Cabling Checkout ________________________________________________ 4-5
Connecting Transducer Cabling__________________________________________________ 4-5
Connecting a Printer __________________________________________________________ 4-6
Level Sensor Setup ___________________________________________________________ 4-7
RS-232 PORT CONNECTION _______________________________________________________ 4-9
RS-485 INTERCONNECTION ______________________________________________________ 4-11
Cable Specifications__________________________________________________________ 4-11
CHAPTER FIVE
INITIAL SETUP, GENERAL OPERATIONS ______________________________________________ 5-1
CONTROL PANEL, PARAMETERS AND VARIABLES ______________________________________ 5-1
MENUS _______________________________________________________________________ 5-1
Stepping Through Menus _______________________________________________________ 5-3
ON LINE HELP _________________________________________________________________ 5-4
ENTERING PARAMETER VALUES ___________________________________________________ 5-8
AutoStart ___________________________________________________________________ 5-8
Using a Password _____________________________________________________________ 5-8
Using an External Keyboard ____________________________________________________ 5-9
Selecting Menu Access ________________________________________________________ 5-9
GENERAL PARAMETERS _________________________________________________________ 5-10
SECTION PARAMETERS __________________________________________________________ 5-11
PATH PARAMETERS ____________________________________________________________ 5-14
SAVING AND LOADING PARAMETERS ______________________________________________ 5-15
FIRST TIME POWER UP __________________________________________________________ 5-16
Initial checks _______________________________________________________________ 5-16
Adjusting Display Contrast ____________________________________________________ 5-16
First Time Diagnostics ________________________________________________________ 5-17
Initial Flowmeter Setup _______________________________________________________ 5-20
Procedure #1 - Set up General Parameters _______________________________________ 5-22
Procedure #2 - Setting up Section Parameters ____________________________________ 5-23
Procedure #3 - Setting up Path Parameters ______________________________________ 5-25
Procedure #4 - Setting the Password (optional) ___________________________________ 5-26
ii
ACCUSONIC MODEL 7500
Table of Contents
Procedure #5 - Save Configuration ____________________________________________ 5-27
Procedure #6 - Print Parameters_______________________________________________ 5-29
Measuring Flow _____________________________________________________________ 5-30
Interrupting Measurements ____________________________________________________ 5-30
DISPLAY SCREENS _____________________________________________________________ 5-31
SPECIAL CONFIGURATIONS _______________________________________________________5-34
Using Layer Boundary Parameters to Simulate a Round Pipe _________________________5-34
CHAPTER SIX
MAINTENANCE AND REPAIRS ______________________________________________________ 6-1
MAINTENANCE _________________________________________________________________ 6-1
Diagnostics __________________________________________________________________ 6-1
REPAIRS ______________________________________________________________________ 6-6
Review of Anti-static Procedures ________________________________________________ 6-6
REPLACEMENT PROCEDURES FOR NEMA CABINETS ___________________________________ 6-7
Replacing System Processor Circuit Boards ________________________________________ 6-7
Replacing Transceiver Card Set __________________________________________________ 6-8
Removing the Connector Panel __________________________________________________ 6-8
Replacing Path or Stage Cards ___________________________________________________ 6-9
Replacing the Pulse Transmitter _________________________________________________ 6-9
Replacing the High Voltage Power Module ________________________________________ 6-9
Replacing the Display Card ____________________________________________________ 6-10
Replacing the Keypad Card ____________________________________________________ 6-11
Replacing the Membrane Keypad and LCD Panel __________________________________ 6-11
Replacing the Diskette Drive ___________________________________________________ 6-12
Replacing the Power Supply ___________________________________________________ 6-12
REPLACEMENT PROCEDURE FOR FLOWMETERS IN RACK-MOUNT CABINET _________________ 6-13
Replacing System Processor Circuit Boards _______________________________________ 6-13
Replacing Transceiver Card Set _________________________________________________ 6-14
Removing the Connector Panel _________________________________________________ 6-14
Replacing Path or Stage Cards __________________________________________________ 6-14
Replacing the Pulse Transmitter ________________________________________________ 6-14
Replacing the High Voltage Power Module _______________________________________ 6-14
Releasing the Front Panel _____________________________________________________ 6-15
Replacing the Display Card ____________________________________________________ 6-15
Replacing the Keypad Card ____________________________________________________ 6-16
Replacing the Membrane Keypad and LCD Panel __________________________________ 6-16
Replacing the Diskette Drive ___________________________________________________ 6-16
CHAPTER SEVEN
PARAMETERS AND VARIABLES _____________________________________________________ 7-1
PARAMETER LIST _______________________________________________________________ 7-1
Always display plant totals _____________________________________________________ 7-1
Autostart switch ______________________________________________________________ 7-1
Available velocity enabled ______________________________________________________ 7-2
Average cable length per path ___________________________________________________ 7-2
ACCUSONIC MODEL 7500
iii
Table of Contents
Average stage cable length _____________________________________________________ 7-2
Averaging queue length ________________________________________________________ 7-2
Bidirectional flow ____________________________________________________________ 7-3
Bottom channel width _________________________________________________________ 7-3
Bottom velocity ratio __________________________________________________________ 7-3
Channel bottom height _________________________________________________________ 7-3
Cross sectional area ___________________________________________________________ 7-4
Current date _________________________________________________________________ 7-4
Current time _________________________________________________________________ 7-4
Data logging _________________________________________________________________ 7-4
Data log start ________________________________________________________________ 7-5
Delay time of other ducer_______________________________________________________ 7-5
Differential alarm threshold _____________________________________________________ 7-5
Differential flow averaging size __________________________________________________ 7-5
Differential warning threshold ___________________________________________________ 7-5
Display contrast ______________________________________________________________ 7-5
Display mode ________________________________________________________________ 7-6
Display totals line ____________________________________________________________ 7-6
Ducer connection _____________________________________________________________ 7-6
Ducer type (7600, 7601, 7605, 7612 ...) ___________________________________________ 7-6
End label character ____________________________________________________________ 7-6
End starting number ___________________________________________________________ 7-7
Error Reporting ______________________________________________________________ 7-7
Flowrate scale factor __________________________________________________________ 7-7
Format _____________________________________________________________________ 7-8
Frequency of other ducer _______________________________________________________ 7-8
Full Pipe ____________________________________________________________________ 7-8
Inactivity Timeout ____________________________________________________________ 7-9
K__________________________________________________________________________ 7-9
Layer boundary elevation 1 - n __________________________________________________ 7-9
Layer boundary width 1 - n ____________________________________________________ 7-10
Leak detection switch_________________________________________________________ 7-10
Log data to _________________________________________________________________ 7-10
Log interval ________________________________________________________________ 7-11
Log negative volume data _____________________________________________________ 7-11
Log velocity data ____________________________________________________________ 7-11
Manning coefficient of roughness _______________________________________________ 7-11
Manual gain ________________________________________________________________ 7-12
Manual stage (1 or 2) value ____________________________________________________ 7-12
Maximum bad measurements __________________________________________________ 7-12
Maximum change in flowrate __________________________________________________ 7-12
Maximum change in stage _____________________________________________________ 7-13
Maximum change in velocity ___________________________________________________ 7-13
Maximum expected flowrate ___________________________________________________ 7-13
Maximum expected velocity ___________________________________________________ 7-13
Maximum stage _____________________________________________________________ 7-14
Maximum stage difference 1 and 2 ______________________________________________ 7-14
Menu access ________________________________________________________________ 7-14
Minimum flowrate ___________________________________________________________ 7-14
Minimum good paths _________________________________________________________ 7-15
iv
ACCUSONIC MODEL 7500
Table of Contents
Minimum path submersion ____________________________________________________ 7-15
Minimum stage _____________________________________________________________ 7-15
Negative over velocity alarm threshold ___________________________________________ 7-16
Negative over velocity warning threshold _________________________________________ 7-16
Non-surcharged integration method______________________________________________ 7-16
Number of channel layers _____________________________________________________ 7-16
Over velocity alarm count _____________________________________________________ 7-16
Over velocity warning count ___________________________________________________ 7-16
Password control ____________________________________________________________ 7-17
Path angle __________________________________________________________________ 7-17
Path elevation _______________________________________________________________ 7-17
Path length _________________________________________________________________ 7-17
Path percent active ___________________________________________________________ 7-18
Path position________________________________________________________________ 7-18
Path simulation______________________________________________________________ 7-18
Path switch _________________________________________________________________ 7-19
Penstock label character _______________________________________________________ 7-19
Penstock starting number ______________________________________________________ 7-19
Pipe height _________________________________________________________________ 7-19
Pipe integration _____________________________________________________________ 7-20
Pipe shape _________________________________________________________________ 7-20
Pipe slope __________________________________________________________________ 7-20
Positive over velocity alarm threshold ____________________________________________ 7-20
Positive over velocity warning threshold __________________________________________ 7-20
Protrusion of other ducer ______________________________________________________ 7-21
Q FWD 1 - n _______________________________________________________________ 7-21
Q REV 1 - n ________________________________________________________________ 7-21
Radius ____________________________________________________________________ 7-21
Receiver gain _______________________________________________________________ 7-22
Repetition time ______________________________________________________________ 7-22
Section label character ________________________________________________________ 7-22
Section starting number _______________________________________________________ 7-22
Section switch ______________________________________________________________ 7-22
Section type ________________________________________________________________ 7-23
Self test interval _____________________________________________________________ 7-23
Shape factor ________________________________________________________________ 7-23
Signal detection method _______________________________________________________ 7-23
Simulation forward time ______________________________________________________ 7-24
Simulation reverse time _______________________________________________________ 7-24
Simulation source____________________________________________________________ 7-24
Simulation velocity __________________________________________________________ 7-24
Simulation velocity ramp scale _________________________________________________ 7-25
Single coefficient (1 - 5) ______________________________________________________ 7-25
Single integration ____________________________________________________________ 7-25
Speed of sound in fluid _______________________________________________________ 7-26
SQM ______________________________________________________________________ 7-26
Stage averaging size __________________________________________________________ 7-26
Stage ducer type _____________________________________________________________ 7-26
Stage interval _______________________________________________________________ 7-27
Stage mode _________________________________________________________________ 7-27
ACCUSONIC MODEL 7500
v
Table of Contents
Stage (1 or 2) offset __________________________________________________________ 7-27
Stage (1 or 2) range maximum __________________________________________________ 7-27
Stage (1 or 2) range minimum __________________________________________________ 7-28
Stage source ________________________________________________________________ 7-28
Surcharged integration method _________________________________________________ 7-28
Temperature coefficient _______________________________________________________ 7-29
Temperature coefficients for 7500: ______________________________________________ 7-29
Top weight _________________________________________________________________ 7-30
Totalizer cutoff time__________________________________________________________ 7-31
Travel time tolerance _________________________________________________________ 7-31
Units ______________________________________________________________________ 7-31
Velocity Substitution _________________________________________________________ 7-31
Velocity Substitution Ratio ____________________________________________________ 7-32
V FWD 1 - n _______________________________________________________________ 7-34
V REV 1 - n ________________________________________________________________ 7-34
Volume scale factor __________________________________________________________ 7-34
Weight ____________________________________________________________________ 7-35
Which Section ______________________________________________________________ 7-35
Width at path elevation _______________________________________________________ 7-35
Zero flow offset _____________________________________________________________ 7-35
VARIABLE LIST _______________________________________________________________ 7-37
Averaged stage ______________________________________________________________ 7-37
Average velocity of sound _____________________________________________________ 7-37
Average temperature _________________________________________________________ 7-37
Delta flow__________________________________________________________________ 7-37
Delta flow average ___________________________________________________________ 7-37
Differential flow warning______________________________________________________ 7-37
Differential flow alarm________________________________________________________ 7-37
Flow average _______________________________________________________________ 7-37
Flow error count _____________________________________________________________ 7-37
Flowrate ___________________________________________________________________ 7-37
Forward gain _______________________________________________________________ 7-38
Forward time _______________________________________________________________ 7-38
Negative volume ____________________________________________________________ 7-38
Positive volume _____________________________________________________________ 7-39
Reverse gain ________________________________________________________________ 7-39
Reverse time________________________________________________________________ 7-39
Section status _______________________________________________________________ 7-39
Signal delay ________________________________________________________________ 7-39
Stage 1 ____________________________________________________________________ 7-39
Stage 1 signal delay __________________________________________________________ 7-40
Total average flow ___________________________________________________________ 7-40
Total Flow _________________________________________________________________ 7-40
Total negative volume ________________________________________________________ 7-40
Total positive volume ________________________________________________________ 7-40
Total volume _______________________________________________________________ 7-40
Velocity ___________________________________________________________________ 7-40
Velocity error count __________________________________________________________ 7-41
Velocity of sound ____________________________________________________________ 7-41
Volume ____________________________________________________________________ 7-41
vi
ACCUSONIC MODEL 7500
Table of Contents
GENERAL VARIABLES __________________________________________________________ 7-42
SECTION AND END VARIABLES ___________________________________________________ 7-42
PATH VARIABLES ______________________________________________________________ 7-42
LEAK VARIABLES ______________________________________________________________ 7-42
CHAPTER EIGHT
OUTPUTS AND REPORTS ___________________________________________________________ 8-1
OUTPUTS _____________________________________________________________________ 8-1
Suggestion for Testing Outputs __________________________________________________ 8-1
Analog Outputs ______________________________________________________________ 8-1
Setting Up Analog Outputs ___________________________________________________ 8-1
Verify Analog, Relay and Totalizer Outputs ________________________________________ 8-4
Field Adjustment Procedure for 2-Channel 4-20 mA Output ___________________________ 8-4
Relay and Totalizer Outputs ____________________________________________________ 8-6
General purpose relays _______________________________________________________ 8-6
Leak Detection (Refer to Leak Detection - Chapter 12) _______________________________ 8-7
Totalizer Output ______________________________________________________________ 8-9
System Failure or Watchdog relay ________________________________________________ 8-9
Setting Up the General Purpose Relays ___________________________________________ 8-10
Setting Up the Totalizer Outputs ________________________________________________ 8-11
Verify Relay and Totalizer Outputs ______________________________________________ 8-11
SUMMARY OF DATA STORAGE OPTIONS ____________________________________________ 8-12
RS-232 Output ______________________________________________________________ 8-12
Reports ____________________________________________________________________ 8-13
Datalogging ________________________________________________________________ 8-13
Listings____________________________________________________________________ 8-14
Parameter load/save __________________________________________________________ 8-15
Error Reporting _____________________________________________________________ 8-15
RS-232 OUTPUTS ______________________________________________________________ 8-16
Setting up the RS-232 Outputs _________________________________________________ 8-19
Verifying RS-232 Output ______________________________________________________ 8-20
FLOWMETER REPORTS __________________________________________________________ 8-21
Setting Up Reports ___________________________________________________________ 8-23
DATA LOGGING _______________________________________________________________ 8-26
Data log file description _______________________________________________________ 8-27
Error Reporting _____________________________________________________________ 8-28
CHAPTER NINE
ADVANCED TROUBLESHOOTING ____________________________________________________ 9-1
WHAT TO DO FIRST: _____________________________________________________________ 9-1
STATUS LIGHTS ________________________________________________________________ 9-1
STATUS MESSAGES _____________________________________________________________ 9-2
ERROR CODES _________________________________________________________________ 9-3
Path, Section and Self-test Status Codes ___________________________________________ 9-3
MONITORING RAW PATH SIGNALS WITH OSCILLOSCOPE _______________________________ 9-12
VERIFYING AND ADJUSTING POWER SUPPLIES _______________________________________ 9-13
ACCUSONIC MODEL 7500
vii
Table of Contents
Checking the system voltages __________________________________________________ 9-14
Adjusting the power supply - rack-mount cabinet ___________________________________ 9-14
Adjusting the power supply - NEMA cabinet ______________________________________ 9-15
CHAPTER TEN
TRANSDUCER MAINTENANCE _____________________________________________________ 10-1
SIGNAL DETERIORATION ________________________________________________________ 10-1
7601 SERIES TRANSDUCERS ______________________________________________________ 10-3
Tools Required ______________________________________________________________ 10-4
7600 SERIES TRANSDUCERS ______________________________________________________ 10-9
Tools Required ______________________________________________________________ 10-9
CHAPTER ELEVEN
MISCELLANEOUS TECHNICAL INFO ________________________________________________ 11-1
ENTERING SPECIAL KEYS________________________________________________________ 11-1
FLOW TRANSMITTER ADDRESSING ________________________________________________ 11-2
SYSTEM SPECIFICATIONS ________________________________________________________ 11-4
ACCUSONIC MODEL 7500 Console ____________________________________________ 11-4
Power Requirement ________________________________________________________ 11-4
Enclosure Dimensions ______________________________________________________ 11-4
Environmental Requirements _________________________________________________ 11-4
Miscellaneous ____________________________________________________________ 11-4
Model 7520 Remote Flowmeter Transmitter _______________________________________ 11-4
Power Requirement ________________________________________________________ 11-4
Enclosure Dimensions ______________________________________________________ 11-4
Environmental Requirements _________________________________________________ 11-5
Miscellaneous ____________________________________________________________ 11-5
REMOTE OPERATION VIA MODEM _________________________________________________ 11-6
Modem Hookup Procedure ____________________________________________________ 11-6
Remote Operation ___________________________________________________________ 11-6
Calling up the 7500 __________________________________________________________ 11-6
Downloading Data Files_______________________________________________________ 11-7
Re-entering Measurement Mode and Exiting the Remote2 Program _____________________ 11-7
ELECTRICAL SURGE PROTECTION FOR ACCUSONIC FLOWMETERS ________________________ 11-8
Overview - Surges and Transients _______________________________________________ 11-8
The Case for an External Surge-Protection Enclosure________________________________ 11-9
Protection Components _______________________________________________________ 11-9
Application of Protection Devises to Accusonic Flowmeters _________________________ 11-10
Summary of Standard and Optional Equipment ___________________________________ 11-11
CHAPTER TWELVE
LEAK DETECTION SYSTEM _______________________________________________________ 12-1
SYSTEM COMPONENTS __________________________________________________________ 12-1
SYSTEM OPERATION____________________________________________________________ 12-3
viii
ACCUSONIC MODEL 7500
Table of Contents
Differential Flow Determination ________________________________________________ 12-3
Over Velocity Detection ______________________________________________________ 12-3
GENERAL SYSTEM OPERATION ___________________________________________________ 12-5
LEAK DETECTION PARAMETER LIST _______________________________________________ 12-7
Always Display Plant Totals ___________________________________________________ 12-7
Differential alarm threshold ____________________________________________________ 12-7
Differential flow average size __________________________________________________ 12-7
Differential warning threshold __________________________________________________ 12-8
Leak detection switch_________________________________________________________ 12-8
Negative over velocity alarm threshold ___________________________________________ 12-8
Negative over velocity warning threshold _________________________________________ 12-8
Over velocity alarm count _____________________________________________________ 12-9
Over velocity warning count ___________________________________________________ 12-9
Positive over velocity alarm threshold ____________________________________________ 12-9
Positive over velocity warning threshold __________________________________________ 12-9
GLOSSARY OF TERMS ______________________________________________________________ 1
A Glossary of Terms and an Index are included at the rear of this manual.
TABLE OF TABLES
Table 1-1 Accusonic Transducers ____________________________________________________________ 1-3
Table 3-1 Data Verification and Substitution __________________________________________________ 3-10
Table 5-1 Flowmeter Menu Hierarchy ________________________________________________________ 5-5
Table 5-2 List of General Parameters ________________________________________________________ 5-10
Table 5-3 List of Section Parameters _________________________________________________________ 5-11
Table 5-4 List of Path Parameters ___________________________________________________________ 5-14
Table 5-5 Checklist of Initial Setup Parameters ________________________________________________ 5-21
Table 6-1 System Diagnostic Error Messages ___________________________________________________ 6-4
Table 6-2 Status Light Error Definitions ______________________________________________________ 6-6
Table 8-1 General Purpose Relay Specifications ________________________________________________ 8-8
Table 8-2 Watchdog Relay Specifications ______________________________________________________ 8-9
Table 8-3 Variables Available via RS-232 _____________________________________________________ 8-17
Table 9-1 Status Messages __________________________________________________________________ 9-2
Table 9-2 Path Status Codes _________________________________________________________________ 9-4
Table 9-3 Section Status Codes ______________________________________________________________ 9-7
Table 9-4 Self-test Status Codes ______________________________________________________________ 9-9
Table 9-5 Stage Status Codes _______________________________________________________________ 9-10
Table 9-6 Standard DC Wiring Colors _______________________________________________________ 9-14
Table 11-1 Jumper positions________________________________________________________________ 11-3
Table 12-1 Checklist of Initial Setup Parameters for Leak Detection System _______________________ 12-10
TABLE OF FIGURES
Figure 1-1
Figure 2-1
Figure 2-2
Figure 2-3
Figure 2-4
Figure 2-5
Figure 2-6
Figure 2-7
ACCUSONIC MODEL 7500 _______________________________________________________ 1-2
Flowmeter Cabinets, Front Panels __________________________________________________ 2-2
NEMA-4 Flowmeter Enclosure, Inside View __________________________________________ 2-3
Rack-mount Flowmeter Enclosure, Inside and Rear Views ______________________________ 2-4
Remote Flow Transmitter, NEMA Enclosure _________________________________________ 2-5
System Overview _________________________________________________________________ 2-6
Larger Configurations ____________________________________________________________ 2-7
System Processor Group __________________________________________________________ 2-9
ACCUSONIC MODEL 7500
ix
Table of Contents
Figure 2-8 Block diagram of Flow Transmitter ________________________________________________ 2-10
Figure 3-1 Placement of Paths in Straight Round Pipe ___________________________________________ 3-1
Figure 3-2 Placement of Paths in an Open Channel ______________________________________________ 3-2
Figure 3-3 Five-path Open Channel Configuration ______________________________________________ 3-5
Figure 3-4 Variation of Uncertainty with Stage for Five-path Open Channel Meter ___________________ 3-5
Figure 3-5 Multipath Reflection ______________________________________________________________ 3-6
Figure 3-6 Crossed Path Configuration________________________________________________________ 3-7
Figure 3-7 Measurement Cycle ______________________________________________________________ 3-9
Figure 3-8 Layout of an Acoustic Path _______________________________________________________ 3-12
Figure 3-9 Predicted-arrival Signal Pass Gates ________________________________________________ 3-14
Figure 3-10 Waveform Features Used for Signal Detection ______________________________________ 3-14
Figure 3-11 Calculation of Path Velocities ____________________________________________________ 3-15
Figure 3-12 Calculate and Validate Flow _____________________________________________________ 3-17
Figure 4-1 Location of AC Power Connections, NEMA Cabinets __________________________________ 4-2
Figure 4-2 Transducer Numbering - Simple Pipe _______________________________________________ 4-3
Figure 4-3 Transducer Numbering - Open Channel _____________________________________________ 4-3
Figure 4-4 Transducer Numbering - Crossed Paths _____________________________________________ 4-4
Figure 4-5 Stripping and Terminating the Transducer Cable _____________________________________ 4-4
Figure 4-6 Transducer Wiring Connections ____________________________________________________ 4-6
Figure 4-7 Location of Printer Connector ______________________________________________________ 4-6
Figure 5-1 Control Panel____________________________________________________________________ 5-2
Figure 5-2 Two Examples of Menus __________________________________________________________ 5-3
Figure 5-3 Tree organization of the parameters _________________________________________________ 5-7
Figure 6-1 Card Retainters __________________________________________________________________ 6-8
Figure 6-2 Rear View of Connector Panel in Lowered Position ____________________________________ 6-9
Figure 6-3 High Voltage Module Replacement _________________________________________________ 6-10
Figure 6-4 Diskette Drive Removal __________________________________________________________ 6-12
Figure 6-5 Releasing the Front Panel ________________________________________________________ 6-15
Figure 7-1 Open Channel and Compound System Parameters ___________________________________ 7-36
Figure 8-1 Hourly Report __________________________________________________________________ 8-25
Figure 9-1 Raw Receive Signal ______________________________________________________________ 9-12
Figure 9-2 Received Signal _________________________________________________________________ 9-13
Figure 9-3 Power Supply Adjustment Locations _______________________________________________ 9-16
Figure 9-4 Power Supply Adjustment Locations _______________________________________________ 9-17
Figure 10-1 Use of Transducer Installation Gauge ____________________________________________ 10-14
Figure 10-2 7601 Transducer Extraction Tool (uninstalled) _____________________________________ 10-15
Figure 10-3 Connection to 7601 Transducer __________________________________________________ 10-16
Figure 10-4 Extracting 7601 Transducer using Withdrawal Tool ________________________________ 10-17
Figure 10-5 Connection to 7600 Transducer __________________________________________________ 10-18
Figure 10-6 7600 Transducer/Valve Assembly ________________________________________________ 10-19
Figure 10-7 7600 Transducer Assembly with Extraction Tool Installed ___________________________ 10-20
Figure 10-8 Model 7605 Stainless Steel Transducer ____________________________________________ 10-21
Figure 10-9 Model 7625 PVC Transducer ___________________________________________________ 10-22
Figure 10-10 Model 7630/34 Internal Mount Transducer _______________________________________ 10-23
Figure 11-1 Address 1, the default address ____________________________________________________ 11-2
Figure 11-2 Address 3 _____________________________________________________________________ 11-2
Figure 12-1 Typical Section/End/Penstock Configuration _______________________________________ 12-2
x
ACCUSONIC MODEL 7500
Table of Contents
CUSTOMER SPECIFIC DRAWINGS - FP
ACCUSONIC MODEL 7500
xi
Accusonic 7500 Series Flowmeter
i
Chapter 1
Introduction
Accusonic manufactures a wide variety of acoustic flowmeters for pipelines and open channels. Its
products have been in service since the early 1970's in a variety of hydroelectric, water delivery and waste
industries. The ACCUSONIC MODEL 7500 provides customers with the finest flow measurement
solutions for a wide range of today's applications.
Overview of the Manual
This manual is designed for technicians and engineers responsible for the installation, setup and operation
of the ACCUSONIC MODEL 7500. It provides both an overview and detailed description of the
instrument and the procedures used to control it and to diagnose problems. Note that this manual covers
all the options available in this equipment series, and may describe functions and features not included in
your system.
Chapter One introduces the equipment and summarizes the manual.
Chapter Two identifies the components of the system, describes its functional organization, and
describes the measurement cycle.
Chapter Three describes the principles of acoustic flowmeters and describes the algorithms used in the
calculation of flow.
Chapter Four describes how to install the flowmeter console and how to connect the transducer cables to
the console.
Chapter Five describes how to turn on and operate the system and includes the step-by-step procedure
for starting up the instrument and initializing parameters.
Chapter Six describes the diagnostic system and explains how to replace subassemblies.
Chapter Seven is a dictionary of all system parameters and variables.
Chapter Eight describes how to set up outputs and reports.
Chapter Nine includes information for interpreting status errors reported by the system.
Chapter Ten describes how to care for the transducers.
Chapter Eleven describes miscellaneous technical information.
Chapter Twelve describes the leak detection system (optional).
A glossary of terms and an index are included at the rear of this manual.
ACCUSONIC MODEL 7500
1-1
Introduction
The 7500 Series Flowmeter
The ACCUSONIC MODEL 7500 accurately and reliably measures fluid flow in large pipes, open
channels, and rivers. It can be used to measure flow in virtually any enclosed conduit, whether partially
full or surcharged, and also in open channels and rivers.
The flowmeter employs an ultrasonic technique to measure average fluid velocity along several parallel
paths, and then calculates total flow from these values. The equipment can be configured to meet the
accuracy required in a specific application.
When used as a four or eight parallel path flowmeter on pressurized pipes, the instrument measures flow
to within ± 0.5% of actual flow rate. 1 Flow in pipes one foot to sixty feet in diameter can be measured
economically with the system.
When used as an open channel flowmeter, the instrument is capable of measuring flow to within ± 1.5%
of actual flow rate. 1 The instrument collects a stage (water level) measurement from one or two integral
up-looking acoustic transducer(s) or from an external stage device.
In closed conduits that are sometimes partially filled and at other times are surcharged, the instrument
changes its method of computing flow in response to changes in stage.
A flowmeter consists of a minimum of three groups of elements, as shown in Figure 1-1. They include
transducers, cables and the flowmeter console.
Figure 1-1 7500 Series Flowmeter System
1
When installing according to Accusonic specifications.
1-2
ACCUSONIC MODEL 7500
Introduction
Transducers
Transducers are available in a variety of styles for a variety of applications, including:
♦
♦
♦
♦
♦
♦
♦
Exposed steel pipe
Concrete pipe
Buried or encased pipe
Pipe with external access only
Pipe that cannot be dewatered for installation
Open channels
Rivers
Table 1-1 lists the transducers supplied by Accusonic.
Table 1-1 Accusonic Transducers
Fully Removable Transducers
7600
High pressure, penetrating (align by oscilloscope) (1 Mhz)
7601
Low pressure, penetrating (1 Mhz)
7620
Pencil transducer for spool pieces (1 Mhz)
7655
Hazardous Locations, penetrating. Certified for Class 1,
Division 1, Groups C & D. (500 kHz)
Externally Accessible Transducers
7625
Penetrating, with plexiglass window that remains in place
7605
Stainless steel version of above, for high pressure
applications
Internal Mount Transducers
7630
Internal mount with redundant elements (1 Mhz)
7634
Internal mount with redundant elements (500 kHz)
intended for long paths or use in dirty water
7616
Array mount for rectangular conduit (500 kHz)
7617
Hazardous Locations, array mount for retangular conduit.
Certified for Class 1, Division 1, Group D. (500 kHz)
7656
Hazardous Locations, internal mount. Certified for Class 1,
Division 1, Groups C & D. (500 kHz)
Open Channel Transducers
7616
Array mount, for smaller channels (500 kHz)
7612
Open channel, for wider channels (200 kHz)
7615
Open channel, (500 kHz)
7611
Open channel, for channels up to 1500 feet wide (100 kHz)
Up-Looking Acoustic Stage Transducers
7632
200 kHz
7612
200 kHz
7615
500 kHz
7616
500 kHz, array mounted
ACCUSONIC MODEL 7500
1-3
Introduction
Cables
Cables are coaxial or twin-axial cable according to the transducers in use. Cable runs are typically
restricted to 1000 feet, but in some applications may be longer.
Flowmeter Console
The flowmeter console is an industrial-hardened, microprocessor-based control system which can
be configured to simultaneously measure flow in several pipes or channels. Furthermore, it can be
expanded using add-on units to meet the needs of installations where there are many pipes or channels to
measure.
Display and System Input/Output (I/O) Options
The instrument offers a variety of display and system I/O options to meet specific requirements.
The instrument is equipped with a four-line by 40-character liquid crystal display (LCD). It is also
available with a two-line by 40-character alphanumeric LCD, a 25-line by 80-character CRT display or a
25-line by 80-character electroluminescent (EL) display.
System output options may include scalable analog current and voltage, digital RS-232, and binary BCD,
programmable relays for alarm and totalizer pulses, as well as other specialized outputs. All process
outputs are continuously updated after each measurement.
Process input options may include Binary, Binary Coded Decimal (BCD), and analog current and voltage.
There is also a printer option that allows specialized reports to be printed at preselected time intervals.
The report can list a variety of measurements and conditions, such as average flow rate, accumulated total
flow, and the number of measurements and percentage of measurement errors that occurred over the
reporting interval.
The instrument may be equipped with a 3.5 inch or 5.25 inch diskette drive for parameter and data storage
and data logging.
System Parameters and Setup
The system is pre-configured at the factory for the number of sections and the number of paths in each
section. At startup, site-specific information is entered using the control panel keypad or an optional
keyboard. Once configured, the system parameters are stored in battery-backed memory and may
optionally be stored on diskette. System parameters can also be changed on site at any time.
Self Test and System Diagnostics
The instrument has built-in self-test routines and continually monitors the reasonableness of all measured
data to ensure that the flowmeter is operating properly. If error conditions exist, the system displays the
type and location of the fault in easy-to-understand messages.
1-4
ACCUSONIC MODEL 7500
Introduction
FORCED PAGE BREAK TO GET PAGE NUMBERS TO WORK - REMOVE FROM MANUAL.
ACCUSONIC MODEL 7500
1-5
ACCUSONIC MODEL 7500
1-1
Chapter 2
Flowmeter Description
This chapter describes the principal electronic components which make up the flowmeter. It describes the
hardware in detail and explains how the system monitors signal quality and maintains measurement
integrity.
Component Overview
The ACCUSONIC MODEL 7500 includes a microprocessor system with keypad and display, process
input and output interfaces, transducers, and cabling. The instrument is housed in a single enclosure
called the flowmeter console or the system console. In larger installations, remote units, also called remote
flow transmitters, may be located some distance away from the system console.
Units are housed in wall-mounted NEMA enclosures or in 19-inch relay racks. The basic console is also
available in custom configurations that contain heating or cooling apparatus for operation in extreme
temperatures.
Basic Flowmeter Console
The accompanying Figure 2-1(see page 2-2) is a front view of the basic console, shown in both the
NEMA-4 and the rack-mount enclosures. Figure 2-2 (see page 2-3) is an internal view of the NEMA-4
package, showing its principal electronic subassemblies. Internal views of the rack-mount cabinet and the
remote unit are shown later in the chapter (see pages 2-4 and 2-5, respectively).
NEMA-4 Enclosure - A steel cabinet houses the system processor for one or more flowmeters and
controls a maximum of sixteen transducers (eight paths). In an open channel or compound flowmeter, the
cabinet may also house two integral 1 stage sensors. In larger configurations, remote cabinets may contain
remote flow transmitters and stage sensors.
Hinged Front Panel - Front panel swings open to the left to allow access to all components.
Fastener/Lock - Enclosure may be fitted with a padlock for security.
Keypad - Twenty-four position membrane keypad is used for setup, control and fault diagnosis.
Display - Backlit, alphanumeric liquid crystal display (LCD) shows four lines of information, 40
characters per line, standard. When the instrument is on-line and measuring flow, the display shows
calculated flow data through the measured section(s) except when configured to show flowmeter
variables or diagnostic data.
1
Stage detectors may be integral or external. The difference lies in how they attach to the flowmeter.
Integral refers to an acoustic uplooker, external can be any other type of sensor, connected via a 420mA current loop input.
ACCUSONIC MODEL 7500
2-1
Flowmeter Description
Figure 2-1 Flowmeter Cabinets, Front Panels
The following display options are also available:
♦ Two-line x 40 characters LCD
♦ 25 lines x 80 characters electroluminescent (EL)
♦ 25 lines x 80 characters, external CRT display
Cabling - Cables for power, data communications and for the transceivers are routed through bulkhead
connectors at the bottom of the NEMA enclosure, and at the rear of the rack-mount cabinet.
Figure 2-2 (see page2-3) shows an inside view of the flowmeter cabinet. The components include:
Processor Group - Four basic cards and up to four option cards make up the system processor. The
system processor stores system parameters, initiates all measurements, and calculates the flow results.
♦ Processor card - Complete microprocessor system with memory and a real time clock and
calendar. The card interfaces to a standard AT bus.
♦ Memory card - Stores the flowmeter program and algorithm constants in non-volatile
storage; stores site-specific parameters and intermediate results in battery-backed RAM.
♦ Basic I/O card - Watchdog timer-controlled alarm relays and LCD display driver.
♦ System communications card - Provides serial data communications between the system
processor and the flow transmitters. An additional RS-232 port and parallel ports may be
configured for various uses.
♦ Options include:
· Diskette controller
· Current or voltage analog output interfaces
· Additional programmable relays
· Supplemental data communications
· Binary I/O interfaces (Gray code, BCD)
· Pulse output interfaces
· Analog stage inputs
2-2
ACCUSONIC MODEL 7500
Flowmeter Description
Figure 2-2 NEMA-4 Flowmeter Enclosure, Inside View
Keyboard connector - DIN-style connector located on the keypad card to which a standard autoswitching
P.C. keyboard may be attached. The external keyboard is enabled by a switch on the keypad card.
Chapter 5 (page 20, Using an External Keyboard) describes how to enable and disable an external
keyboard.
Diskette drive - 3.5 inch or 5.25 inch diskette drive for data logging and backup of flowmeter
configuration and control parameters.
Power connector - Terminal strip connection for AC power source.
Flow Transmitter Group - Controls all the functions necessary to measure travel time on the acoustic
paths and fluid stage. Cards in the flow transmitter are:
♦ Transceiver card set - Two-card set: the larger card includes precision timing circuits, pulse detector
circuits, and the Accusonic patented Signal Quality Monitor to ensure precise measurement of the
pulse travel time on each path. The smaller card provides serial data communications between the
flow transmitter and the system processor.
♦ Pulse transmitter card - Produces the high voltage pulse to drive a transducer.
♦ Path selector cards - Select path and direction in a travel time measurement. A card controls two
paths (four transducers), up to a maximum of four cards in each cabinet.
♦ Integral stage cards - Connects an up-looking stage transducer to monitor fluid level. Maximum two
stage cards in a cabinet, similar to path selector card.
ACCUSONIC MODEL 7500
2-3
Flowmeter Description
Connector panel - Removable panel contains terminal strips for connecting transducers, communication
ports, alarms and all process input and output lines. Slots for mounting the pulse transmitter, path selector
cards and stage cards are on the rear of the panel.
Power supply - Power line input is 90-250 VAC, 47-63 Hz. Primary power supply provides
±5 VDC, ±12 VDC.
In addition to the primary power supply, other regulators and batteries located in the system are:
♦ High voltage power module converts 5 VDC to 180 VDC for the pulse transmitter.
♦ Lithium battery on the processor card provides power for the real time clock and
calendar.
♦ NiCad battery on the memory card backs up RAM on that card.
♦ Voltage regulator on the Basic I/O card provides 5 VDC for the display.
Rack-mount Console
Figure 2-3 shows an inside view of the rack-mount enclosure.
Figure 2-3 Rack-mount Flowmeter Enclosure, Inside and Rear Views
2-4
ACCUSONIC MODEL 7500
Flowmeter Description
Remote Flow Transmitter Unit
Figure 2-4 shows an inside view of the remote flow transmitter in a NEMA enclosure. The rack-mount
remote flow transmitter is very similar to the basic console as previously shown in Figure 2-3.
Figure 2-4 Remote Flow Transmitter, NEMA Enclosure
ACCUSONIC MODEL 7500
2-5
Flowmeter Description
System Overview
The functional organization of the ACCUSONIC MODEL 7500 is shown in the block diagram of Figure
2-5. Two functional groups, the flowmeter processor group and the flow transmitter group are connected
by a communications link.
The flowmeter processor group:
♦ Manages the overall operation of the system
♦ Interacts with an operator through the keypad and display
♦ Calculates flow
♦ Manages all system inputs and outputs
♦ Initiates system diagnostic procedures
The flow transmitter group:
♦ Drives the path and stage transducers
♦ Performs signal processing on the incoming signal
♦ Measures travel time for a pulse on each acoustic path
♦ Reports the results to the system processor
Figure 2-5 System Overview
Measuring Fluid Stage
The flowmeter accommodates a variety of fluid stage measurement equipment, including up- or downlooking acoustic devices, float wheels and pressure monitors. The flowmeter supports integral devices
supplied by Accusonic as well as stand-alone stage measuring subsystems from other suppliers.
The Accusonic 7500 series compatible up-looking acoustic transducer is installed as an integral part of
the instrument and shares the travel measurement and pulse transmitting and receiving facilities of the
flow transmitter. Stage information from the integral up-looking device is returned to the system
processor via the communications link.
2-6
ACCUSONIC MODEL 7500
Flowmeter Description
External stage equipment is self-contained, and includes its own control and measurement circuits which
output stage information via a digital or analog interface. In the ACCUSONIC MODEL 7500 external
stage equipment connects directly to the system processor through the appropriate process input card.
System Expansion
The maximum capacity of the standard flowmeter console is eight acoustic paths and two integral stage
inputs. The system can be expanded by adding remote flow transmitters, each housed in a separate
cabinet. Remote flow transmitters connect to a single system processor using a serial communications
link.
Figure 2-6 shows the block diagram of a larger configuration with additional flow transmitters.
Figure 2-6 Larger Configurations
System Processor Technical Details
The system processor group is the overall control center of the instrument and directs the performance of
all measurements and diagnostics. It occupies the top half of a NEMA-4 cabinet or the front section of the
rack-mount cabinet.
ACCUSONIC MODEL 7500
2-7
Flowmeter Description
System processor group functions include:
♦ Perform power-up self test, control the watchdog timer, and perform periodic system checks
♦ Manage operator console display and keypad
♦ Provide battery-backed storage of all system parameters
♦ Direct the operation of all flow transmitters
♦ Execute the flowmeter algorithms to compute total flow
♦ Perform reasonability checks on all velocity and flow data as it is computed
♦ Interpolate missing data caused by loss of signal or power interruption
♦ Respond to all process inputs; drive all process outputs and alarms
♦ Control the system diagnostics
Figure 2-7 (see page 2-9) shows a detailed block diagram of the system processor group. The principal
components are:
♦ Processor card - Single board computer with local memory, battery-backed real time clock,
calendar, and keypad interface. Attaches to AT bus. Battery lifetime on the real time clock
is 10 years, nominal.
♦ Memory card - The memory is divided into two sections:
-NiCad battery-backed memory for storing parameters and non-volatile data.
Battery lifetime during power loss or shutdown is one month. 2
-Non-volatile storage containing the operating system and flowmeter control
program.
♦ Basic I/O card - Contains hardware interface for the LCD display, watchdog timercontrolled alarm relay, and optional programmable relays. The watchdog timer indicates
a system failure by closing an alarm relay if the system fails to complete a flow
measurement cycle within a defined time period.
♦ Communication card - Contains line drivers and receivers for serial communications with
the flow transmitter (s). The card also contains an additional serial port and a parallel port.
♦ Diskette system - Consists of a controller card and a drive unit that is available in 3.5 inch
and 5.25 inch diskette size.
Primary interaction with the system is via the front panel display and keypad. During initial setup, it is
useful to add a PC-compatible keyboard to simplify data entry. The external keyboard can be detached
from the unit for routine operations. If a keyboard is not supplied, either use an autoswitching type or
check with Accusonic to see which type is compatible.
During initial setup, the operator enters control parameters defining the type of transducers, units of
measurement, and the meter section configuration. As-built locations of transducers in each section are
also entered. Once these parameters have been entered, they can be transferred to battery-backed RAM on
the memory card and, optionally, to diskette. During subsequent startups, the parameters are
automatically loaded into the system memory from the battery-backed RAM.
The operating system, device drivers, diagnostic programs, and the flowmeter program are stored in nonvolatile storage. The operating system is transferred into processor memory at power up. Status
information and interim results are stored in a battery-backed RAM so that after a power interruption, the
data can be restored and the system can continue without loss of data.
2
Data may also be copied to diskette for more permanent storage.
2-8
ACCUSONIC MODEL 7500
Flowmeter Description
Figure 2-7 System Processor Group
Flow Transmitter Technical Details
The flow transmitter group manages the operation of the transducers under the direction of the system
processor. It measures the travel time in each direction 3 on all active acoustic paths and operates any uplooking acoustic stage transducers. The flow transmitter operates independently of and asynchronously to
the flowmeter processor. It receives measurement instructions, carries them out and returns the results.
The flow transmitter occupies the lower half of a NEMA-4 or the rear of a rack-mount cabinet.
Flow transmitter functions are:
♦ Provide a transmitter signal to a transducer
♦ Process and detect the signal from a receiving transducer and discriminate the first
negative-going pulse
♦ Adjust automatic gain control (agc) setting for each direction and stage
♦ Perform signal integrity checking on each measurement
♦ Update status information on the viability of each measurement
♦ Compute travel time on a path or group of paths, or average several consecutive readings
as directed by the system processor
♦ Compute travel time for stage transducers (open channel or compound meter only)
♦ Return travel times and status of each measurement back to the system processor
♦ Perform periodic closed-loop self tests to verify subsystem accuracy and precision
3
From the viewpoint of the flow transmitter (and from the flowmeter algorithms), there are two
travel time measurements for each acoustic path. In this section, the term direction is used
wherever it seems appropriate to emphasize this fact.
ACCUSONIC MODEL 7500
2-9
Flowmeter Description
Figure 2-8 shows a detailed block diagram of the flow transmitter. Principal components are:
♦ Transceiver (two-card set) - Contains microprocessors, local memory and control ROM,
precision time base generator, travel time counter, and receiver. The receiver has the
Accusonic-patented agc and Signal Quality Monitor that ensure precise pulse waveform
detection and discrimination. Also contains line drivers and receivers for communication
with the system processor, and contains an array of indicator lights that show the status
of the flow transmitter.
♦ Transmitter card - Generates an 800 volt pulse that drives the selected transducer and starts the
travel time counter.
♦ Transducer bus - Connects transmitter and receiver circuits to path and stage cards. It
includes addressing information which activates a single path or stage card and specifies
the transducer(s) to be used in the current measurement. When a path travel time is being
measured, the bus address also specifies direction by designating which transducer in the
selected pair is the transmitter and which is the receiver.
♦ Path selector card - Contains relays which connect the sending transducer to the transmit
bus, and connects the listening transducer to the receive bus. A single path selector card
controls the four transducers which form two acoustic paths. Cabling between the path card
and a transducer should not exceed 1000 feet without the approval of Accusonic.
♦ Stage card - Interfaces a single up-looking acoustic transducer for monitoring fluid stage
or elevation; used only with open channel or compound conduit meter sections. A single
stage card controls a single stage transducer.
The flow transmitter operates asynchronously to the system processor. It receives and queues commands
via the communication link. Each command is processed in order of arrival and, upon completion, returns
the requested data. Depending on the application, the system processor may issue a command and simply
wait for the results or continue with other work.
Figure 2-8 Block diagram of Flow Transmitter
2-10
ACCUSONIC MODEL 7500
Flowmeter Description
The primary function of the flow transmitter is to measure travel times on the acoustic paths. The
subsystem may take a single measurement on one direction or collect a set of measurements over several
directions. Alternatively, it may take several consecutive sets of measurements and return the average
travel time for each direction. The subsystem performs a number of data consistency and signal quality
checks during a measurement and returns detailed status information along with each measurement
reported.
The subsystem periodically performs a self test to verify the operation of critical circuits in the subsystem.
It continually updates an array of status flags that may be tested by the system processor or displayed via
the status lights on the transceiver card.
ACCUSONIC MODEL 7500
2-11
ACCUSONIC MODEL 7500
12
Chapter 3
Acoustic Flowmeter Principles
Accusonic acoustic flowmeters measure the transit time of ultrasonic pulses traveling along several
diagonal paths through a moving fluid and derive the average downstream component of velocity across
each path. The number and placement of acoustic paths and the mathematical formula used to compute
flow depend on the shape and dimensions of the fluid conduit and the required accuracy of the
measurement. The measurement method is based on the geometry of the conduit, the accuracy desired,
and the behavior of the fluid. Under most conditions, the flowmeter does not require calibration by
comparison to other flow measurements.
This chapter describes the principles of acoustic flowmeter operation and examines the underlying
methods of analysis and real-world configurations. The measurement cycle is described in detail. Sources
of error that affect the overall uncertainty of the measurements are also analyzed. Formulas are presented
without derivation.
Measurement Section Configuration
Converting velocity to flow rate is done by multiplying the cross-sectional area by the area-averaged
section velocity. Because a velocity profile is rarely accurately known, it is necessary to estimate the
effect of the unknown velocity profile. This is best done by using multiple acoustic paths. The four-path
configuration, shown in Figure 3-1, exhibits very uniform response over a wide range of velocity profiles.
Figure 3-1 Placement of Paths in Straight Round Pipe
The spacing of paths depends on the shape of the section and the accuracy required. For closed pipes
flowing full, transducer placement depends on the numerical integration technique employed for
computing flow. For open channels or for pipes not filled, numerical techniques are not generally used;
placement depends on variation in fluid level and on the accuracy desired.
In typical multiple-path configuration, four pairs of transducers are placed in the fluid stream to define
parallel paths at selected elevations -- in a straight pipeline as shown in Figure 3-1 and in an open channel
as shown in Figure 3-2 (see page 3-2).
ACCUSONIC MODEL 7500
3-1
Acoustic Flowmeter Principles
Placement of Acoustic Paths in Round Pipe
For a four-path flowmeter in round pipe flowing full, the paths are usually parallel diagonal chords that
intersect the pipe at elevations 18 and 54 degrees above and below the axis of the pipe. As a rule, paths
are horizontally oriented. If there if an upstream bend in the pipe, the paths are usually rotated to a plane
perpendicular to the plane of the bend. This reduces the effect of cross flow that is not parallel to the
center axis of the pipe.
When paths are located within five diameters of a bend, additional measures should be taken as described
in the section on crossed paths (see page 3-7). Consult Accusonic for recommended installation
configurations.
Placement of Acoustic Paths in an Open Channel or Compound
Section
An open channel is defined as a conduit, whether open or closed, in which water flows with a free
surface. A compound installation is a closed conduit which can flow partially full as well as surcharged,
thereby exhibiting the characteristics of both an open channel and a full pipe.
Because a compound installation contains the characteristics of an open channel at times, many of the
same parameters are used for both types of installation. When entering parameters for an open channel,
Section parameter Surcharged integration is irrelevant, and the Section parameter Full pipe should be set
higher than the maximum water level, to ensure that the meter never thinks there is a surcharged
condition.
Transducer placement in an open channel or compound conduit is more complex than in a pipe, since the
level of the fluid may vary over a large range.
Trapezoidal integration is generally considered to be the method of choice in an open channel. It can be
extremely accurate (Accusonic normally guarantees an uncertainty of 2% of flowrate in a well-defined
channel, but can be 1% under ideal conditions), and can be tolerant of wide ranges of stage and number of
operating paths.
The issue is one of balancing the desired accuracy over the entire range of operating conditions against
cost. The system designer must consider the impact of degraded operation or worst case water levels
which may result in increased integration errors.
Figure 3-2 Placement of Paths in an Open Channel
3-2
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
Following is a generic strategy for choosing number of paths and path placement (If there is cross flow
additional paths may be required):
1. Identify the lowest fluid stage for which accurate measurements are required. Normally, the lowest
path is placed as low in the channel as possible. Refer to the following section, “Top and Bottom
Clearance considerations in an Open Channel Meter”, for determination of minimum distance from
the bottom.
2. Place another path at the minimum allowable distance below the lowest expected stage.
3. Additional paths may be placed at intermediate elevations if higher accuracy is required. The added
paths are spaced in such a manner that the overall measurement uncertainty never exceeds the
specified limit for any level of fluid.
Often, only two paths are used to measure low stage flow, but in installations where high accuracy is
required at low stage, there may be as many as four paths below the minimum water level. In general,
four paths are required for best accuracy in any given cross section. This is because the smallest
errors are in the layers bounded by paths, whereas the bottom and surface layers require the use of
estimated velocity profiles in order to estimate their contribution to the total flow.
Of course, things get more complicated and accuracy will be reduced further if the lowest path must
be placed at an elevation higher than minimum to avoid signal interference from sand and/or debris in
the channel bottom. This silting effect also changes the cross section area, further impacting accuracy.
4. Additional paths must be placed above these if the stage varies significantly. Usually, if the stage
increases by more than the vertical distance between the two highest paths already in place, then an
additional path should be incorporated to maintain accuracy. However, because the accuracy of path
bounded layers is very high compared to the bottom and surface layers, the path spacing can usually
be increased as their elevation increases because the total flowmeter error is reduced as the top and
bottom layer flows becomes a smaller fraction of the total flow. This may not be true in all cases,
however, as in the case of a trapezoidal cross section (like the California Aqueduct), where the area is
increasing rapidly as the stage increases, or in some well manicured rivers in the UK where there is a
narrow channel for low flows and an artificial flood plain for high flows.
5. Consideration should also be given to the accuracy requirements which may change as the flow or
level varies, and also the percent of the time that these conditions may exist. These conditions affect
the cost vs. accuracy tradeoff for a portion of the time that the meter is in use. For example, the
accuracy requirement during a flood may not be as high as for minimum flow, where the water must
be distributed evenly among many demanding users. As another example, it may not be worth
designing the meter to handle a 100-year flood. On the other hand, this may be what the user wants to
measure most.
ACCUSONIC MODEL 7500
3-3
Acoustic Flowmeter Principles
Trapezoidal extrapolation/interpolation strategies
In open channel trapezoidal integration, the flow bounded by two paths (or one path and the top or
bottom) is calculated by averaging the upper and lower velocities and multiplying by the area enclosed.
This is very accurate, even under conditions of unusual velocity profiles, particularly when several layers
are present, because errors in one layer tend to cancel errors in the adjacent layers.
Figure 3-3 shows an open channel section built with five paths. Figure 3-4 illustrates how extrapolation
error affects flowmeter uncertainty as a function of fluid levels. Accuracy deteriorates as fluid level rises
above a particular path until the fluid level reaches the next path, where accuracy again improves. As the
fluid level rises further, the accuracy falls off again until it passes the next path, and so on.
Since with trapezoidal integration the error in the layer flows can be made small by increasing the number
of acoustic paths, the main metering uncertainty is the flow in the lowest and highest areas.
Estimating the flow in the bottom layer requires a guess as to what the ratio of the average velocity in that
layer is to the measured velocity at the lowest path. A quick look at the theoretical velocity profiles near a
smooth/rough bottom surface will show that the bottom flow is about .75 times the lowest velocity times
the bottom layer area. Setting the parameter “Bottom Velocity Ratio” to 0.5 (default) accomplishes this.
The most significant error in the lower layer comes from changes in cross-sectional area due to silt level,
which is unknown.
The total contribution of the bottom layer flow to the total flow will be small if the above installation
suggestions are followed, so the total error will be minimal.
The same cannot be said about the surface velocity and the surface layer (above the top path). The errors
are more significant for the following reasons:
1. The top layer will usually have a greater area than the bottom. The distance from the top path to the
surface is relatively large because channels are generally wider at the top and the minimum distance
necessary to avoid multipath problems is greater. The surface level is almost always further than the
minimum distance in any event due to the unwillingness of the customer to buy additional paths.
2. The surface layer velocity is very difficult to estimate. Unlike the bottom, there is no boundary
condition, so the actual velocity at the surface is unknown, and can be affected by wind, ice, floating
debris, temperature layering or unusual upstream conditions (such as control structures or tethered
boats). Therefore, it is virtually impossible to generate a theoretical model of this velocity profile. In
operation, the flowmeter estimates the surface velocity from the two highest working path velocities.
This can be anywhere from a good to a terrible guess depending mostly on how close the paths are to
the surface. The meter linearly extrapolates the two highest path velocities to the following extent:
If the extrapolation distance is greater than the vertical distance between two paths used for
extrapolation, then the extrapolation is only carried out to the path separation distance, and that value
is used as the surface velocity.
Because the value as extrapolated may not be very accurate, this estimated surface velocity is
weighted before averaging it with the highest operating path velocity to determine the flow in the top
layer. This “confidence factor” is entered as the parameter “Top Weight”.
Note that if the highest usable path is not working, then the accuracy of this procedure is significantly
reduced.
3-4
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
Figure 3-3 Five-path Open Channel Configuration
Figure 3-4 Variation of Uncertainty with Stage for Five-path Open Channel Meter
ACCUSONIC MODEL 7500
3-5
Acoustic Flowmeter Principles
Top and Bottom Clearance Considerations in an Open Channel Meter
There are limits as to how near the bottom of the channel the lowest path can be placed, and how near the
top surface of the fluid path can be reliably used. This limitation stems from a multipath reflection, as
shown in Figure 3-5.
Figure 3-5 Multipath Reflection
When the acoustic path is sufficiently close to a reflector, the reflected signal arrives at the detector before
the electronics can discriminate the arrival of the direct signal. In the ACCUSONIC MODEL 7500
detector circuits are set to discriminate an incoming pulse within its first full period.
The following formula shows that the minimum clearance H depends on operating frequency and path
length.
H ≅
where:
Lv s
2f
H
L
vs
f
= Minimum clearance required
= Path length between transducers
= Velocity of sound in fluid
= Carrier frequency of acoustic pulse, Hz
The resultant value H is entered into the flowmeter as “Minimum Path Submersion”. This is used to
prevent reflections from the fluid surface. Note that this value is only entered once for all paths.
Therefore, it is best to use the longest path in the section to calculate ‘H’.
3-6
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
Crossed Paths
Under certain conditions, two planes of acoustic paths may be installed at opposite angles to improve the
flow measurement accuracy. This is done when there is cross flow, caused by bends in a pipe, or in
situations where the geometry of the conduit cannot be measured accurately.
♦ Cross flow - Where the streamlines of flow are not parallel to the conduit centerline as a
result of an upstream obstruction or a transition in conduit shape or dimensions. The effect is
especially pronounced when there is a bend in the conduit upstream of the measurement
section.
♦ Survey uncertainty - Where the walls of the conduit are irregular, asymmetric, or (as is often
the case in a river) cannot be surveyed exactly or permanently.
Figure 3-6 shows crossed paths installed in a pipe with bends. Crossed paths are typically installed at the
same elevations.
Figure 3-6 Crossed Path Configuration
Depending on the acoustic path angle θ, cross flow of 1° introduces a velocity error ranging from 1.7%
for a 45° path to 3.8% for a 65° path.
When crossed paths are used, the meter treats each plane of acoustic paths as a separate “subsection” and
averages the flowrates calculated for each plane to determine the flowrate through the metering section.
Flowrates for the separate planes can be assigned different weights before averaging if the acoustic path
angles or number of paths are not the same for each plane.
ACCUSONIC MODEL 7500
3-7
Acoustic Flowmeter Principles
Flowmeter Measurement Cycle
For every measurement, the following six steps are performed. These six steps make up a measurement
cycle:
♦ Sample process inputs - Collect data from external inputs, such as analog level
measurement.
Measure Acoustic Stage (if present).
♦ Travel time measurement - Measure the acoustic travel times along one or more linear paths
through the moving fluid.
♦ Velocity calculation - Calculate velocities on each path based on asbuilt information and
measured travel times.
♦ Flow Calculation - Integrate the measured velocities over the entire cross-sectional area of
the fluid to determine total volumetric flow.
♦ Update volume totals - Calculate totalized flow (volume) based on average flowrate and
elapsed time.
♦ Update process outputs - Transmit results of measurement via such devices as RS-232,
contact closures, or current loop outputs.
The sequence of the flowmeter measurement cycle is shown in Figure 3-7.
3-8
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
Figure 3-7 Measurement Cycle
As it proceeds through a cycle, the instrument assesses whether or not each measurement is reasonable,
based on values entered during instrument setup. The instrument may reject a questionable result and
substitute a value using data from the previous cycle. Table 3-1 shows which data is verified at each step
in the cycle and lists the substitute values that may be used in each case. At the end of the cycle, the
instrument pauses until it is time to perform the next measurement. The topics that follow the table
describe the six steps of the measurement cycle in detail.
ACCUSONIC MODEL 7500
3-9
Acoustic Flowmeter Principles
Table 3-1 Data Verification and Substitution
Step
1. Sample inputs
2. Collect travel times
Error condition
No stage input
Bad stage measurement
Stage exceeds
maximum
Stage below minimum
Stage below path
elevation (s)
Stage error counter
exceeds limit
No response from flow
transmitter
No received signal on a
path (forward or reverse
direction)
Noise was detected
Flow transmitter
parameter was not set
Action
Set error codes,
increment stage
error counter
“
“
“
Turn off any paths out
of water
Bypass travel time
data collection
Set error code and
increment an error
counter
“
“
Set error code and
increment an error
counter
“
Value repeated with...
Reading from previous
cycle1
“
“
“
n/a
n/a
Readings from previous
cycle1
“
“
Readings from previous
cycle
Unknown flow
“
transmitter error
Gain error
Set Warning Code
No Substitution,use data
1
Previous readings is only used when the error counter has not exceeded the parameter Maximum Bad
readings, otherwise an error flag is set.
3-10
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
Table 3-1 Data Verification and Substitution (continued)
Step
3. Calculate velocities
4. Calculate flow
5. Update volume totals
6. Update outputs
Error condition
Travel time out of
expected range
Velocity exceeds max.
Velocity changed too
quickly
Error counter exceeds
max.
Not enough good paths
Flow exceeds max.
Flow changed too
quickly
Flow error counter
exceeds max.
If any flow error counter
is exceeded
Action
Set error code and
increment an error
counter
“
“
Clear velocity output
attribute
Set an error code and
increment an error
counter
“
“
Clear flow output
attribute
Clear the total flow
output attribute for that
section
For any value intended
Set the output
for output that is marked representation for the
in error
failed section according
to the rules shown to the
right
Value replaced with...
Use velocity from
previous cycle
“
“
n/a
Use flow from previous
cycle
“
“
“
n/a
On the display or RS232 port, output “-----”
for the error value.
Set analog and digital
representation of error
value to maximum high
or low or no change as
specified during
instrument setup
1
Previous reading is only used when the error counter has not exceeded the parameter Maximum Bad
readings, otherwise an error flag is set.
Reading System Inputs
At the beginning of the cycle the instrument reads all system inputs and integral stage monitors and
automatically tailors the measurement cycle. For example, changes in stage may affect the number of
active paths or may require that the flowmeter shift to a different flow calculation algorithm.
ACCUSONIC MODEL 7500
3-11
Acoustic Flowmeter Principles
Measuring Travel Times
The propagation velocity of an acoustic signal in a moving liquid changes when there is a velocity
component of the moving fluid parallel to the direction of sound propagation. A sound pulse traveling
diagonally downstream across a river will be accelerated by the moving fluid; a pulse traveling diagonally
upstream will be decelerated. As a result, acoustic transit times are shortened or lengthened, respectively.
Figure 3-8 shows a model conduit.
Figure 3-8 Layout of an Acoustic Path
The transit time effect is measured by placing acoustic transducers A and B at the sides of the conduit so
they define a diagonal path across a section of the moving fluid. Transducers are bi-directional devices
that, depending on the attached electronics, can function both as transmitters and as receivers of ultrasonic
pulses.
When an acoustic pulse propagates from B to A in the downstream direction along the diagonal, the pulse
of acoustic energy is carried along by the moving fluid and arrives at A sooner than if the fluid was
motionless. Similarly, when the pulse propagates in the upstream direction from A to B, it arrives later.
The system processor directs the flow transmitter to initiate travel time measurements. Forward and
reverse travel times are measured for each path. For a stage transducer, the round-trip travel time is
measured. Measurements proceed as follows:
♦ Microprocessor sets up path and direction via path selector cards
♦ Clears the travel time counter
♦ Enables pulse transmitter
♦ Transmitter emits a high voltage pulse to drive (ping) the sending transducer, and at precisely the
same time, it starts the travel time counter
♦ Adjusts receiver gain, based on the level stored at the end of the last measurement made on that
direction1
♦ Enables receiver circuits shortly before the earliest possible arrival time, as estimated from the
current path length
♦ Checks for electrical noise on the incoming signal, sets a status flag if noise is detected
1 During the first cycle following a cold start, receiver gain is set to a level based on the length of the path being
measured and the transducer type.
3-12
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
♦ Listening transducer converts the received acoustic pulse to an electrical signal and couples the
incoming signal to the receiver
♦ Receiver waits for the incoming signal to exceed the detection threshold on the first negative-going
edge
♦ Verifies that the correct signal features were detected
♦ Stops the travel time counter upon signal reception
♦ Signals an overflow if no signal is detected shortly after the latest possible arrival time as estimated
from the current path length. This terminates the measurement on that path
♦ Adjusts agc level depending on the signal strength of the pulse just received; stores the new value
for use in the next measurement in this direction or stage
Signal Detection
The ability to correctly detect the incoming signal pulse and to precisely discriminate the target threshold
crossing on the first negative-going edge of the incoming waveform is critical to the accuracy of the
flowmeter.
Factors affecting the process are:
♦ Flowmeter may be installed in an environment that is electrically noisy
♦ Debris, entrained gas, marine life and silt may cause the signal strength of the received pulse to vary
over a wide range
♦ Active face transducers may become fouled over time
The ACCUSONIC MODEL 7500 correctly identifies the first negative-going pulse due to automatic gain
control (agc), predicted-arrival signal pass gates, and the Signal Quality Monitor (SQM).
Automatic gain control adjusts the gain of the receiver according to the signal strength of a received
pulse. The gain on each direction is controlled independently. At the end of each measurement, the agc
adjusts up or down in response to the signal strength of the pulse just processed. The agc adjusts down if
noise is detected or if the incoming signal is too strong, up if the incoming signal is weak and the noise
level is low. The instrument stores the new agc setting and automatically sets up the receiver to the new
level the next time a measurement is taken on the same direction.
If forward and reverse signal levels differ by more than 6dB, a path status warning is issued. This is not a
critical error; it may indicate that a transducer is misaligned or failing and that it should be checked.
After power up or after a path has been inactive, the agc sets the initial gain at a level proportional to the
length of the path being measured - the longer the path, the higher the gain.
Predicted-arrival gates are used to limit the time over which the pulse receiver will accept an incoming
pulse. The instrument predicts the earliest arrival time and the latest arrival time for each direction based
on path length and the range of possible flow through the meter section. The earliest arrival time
predictions are used to define three gates: Noise gate, Range gate and Overflow gate, as shown in Figure
3-9.
ACCUSONIC MODEL 7500
3-13
Acoustic Flowmeter Principles
Signal Quality Monitor (SQM) verifies that the incoming pulse is sufficient for reliable use and
confirms that the first negative pulse of the waveform goes through the detection point at a high enough
rate. It also prevents detection on the second negative-going pulse.
Figure 3-10 shows a detailed view of an incoming pulse waveform, and identifies the features used by
SQM to validate the data.
Figure 3-9 Predicted-arrival Signal Pass Gates
Figure 3-10 Waveform Features Used for Signal Detection
Calculating Path Velocities
The instrument calculates a fluid velocity for each acoustic path using the following formula. The key
parameters are path length, angle, and forward and reverse transit times. Validity checks are performed on
the data as shown in the flowchart on page 3-15 (Figure 3-11). If any data is missing or if the calculation
results in a questionable value, data is flagged and a substitute value is used as shown previously in Table
3-1 (begins on page 3-10).
3-14
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
v=
(T1 − T2 )
L
*
T1 T2
2 cos θ
where:
v
T1
T2
L
θ
= Average velocity of the fluid across the path
= Travel time between transducers in the upstream direction
= Travel time between transducers in the downstream direction
= Distance between transducers (acoustic path length)
= Angle between acoustic path and direction of fluid flow
Figure 3-11 Calculation of Path Velocities
ACCUSONIC MODEL 7500
3-15
Acoustic Flowmeter Principles
Measuring Stage
In open-channel and compound systems, the fluid level (stage) varies, and must be measured. The meter
uses this level measurement to determine the cross sectional area of the fluid for calculating flowrate, and
to determine which acoustic paths will be activated as they become submerged. The meter can accept
level input from various types of stage sensors, including uplookers, downlookers, pressure sensors, or
manual (keypad) input.
An “Uplooker” is a transducer mounted near the bottom of the channel, below the lowest expected level.
The uplooker transmit an acoustic signal upward to reflect off of the surface. The electronics for the
uplooker are integral to the flowmeter. When using an Accusonic uplooking transducer, AGC is used as
in velocity measurement, with the same considerations. The Predicted Arrival Gates are set based on the
parameters Minimum Stage and Maximum Stage. The total travel time is divided by two and corrected for
temperature using the calculated speed-of-sound from the previous velocity measurement. Speed-ofsound is calculated based on “Good” paths that are below fluid level. If there are no “Good” paths, the
stage calculation will use the default speed-of-sound from the general parameters list.
An “External” stage device is typically either an acoustic downlooker or a pressure transducer, containing
its own electronic control system. The level information from these devices is accepted into the meter as a
4-20 milliamp current loop.
Normally, only one stage sensor is used, although each measurement section can be configured for
redundant level data from two sensors, which need not be of the same type. For example, a sewer system
could be configured with an uplooking acoustic transducer mounted off the bottom of the channel to
avoid “silting”, and a downlooking mounted at the top of the channel. When the channel is nearly empty,
the fluid level is below the uplooker, and the downlooker is used. When the channel is full, the
downlooker is submerged, and the uplooker is used.
When using redundant stage sensors, operation is as follows:
When both sensors are operating, the stage values are compared. If the difference between them is less
than the parameter Maximum stage difference 1 and 2, then
Stage = (STAGE 1 + STAGE 2) / 2
If the difference between them is greater than Maximum stage difference 1 and 2, STAGE 1 is used and
an error is flagged for STAGE 2. Therefore, the sensor with the greatest chance of being “right” should
always be assigned to STAGE 1.
If either STAGE 1 or STAGE 2 is not working, an error is flagged and the other is used. If neither stage
sensor is working, all paths will be deactivated and operation will cease until a stage measurement can be
made.
3-16
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
Calculating Flow
To calculate flow, the instrument integrates the velocities using an integration method appropriate to the
configuration of the meter and the nature of the fluid. It performs validity checks on the data as shown in
the flowchart of Figure 3-12. If any data is missing or if the calculation results in a questionable value, it
is flagged and a substitute value is used as shown previously in Table 3-1 (beginning on page 3-10).
Figure 3-12 Calculate and Validate Flow
ACCUSONIC MODEL 7500
3-17
Acoustic Flowmeter Principles
Integration Methods
The Flowmeter is designed to cater for a very wide range of possible conduit shapes, including pipes
which always flow full, and conduits where the fluid sometimes fills the conduit and sometimes does not.
The flowmeter operates in one of two basic modes, which the user has to choose:
♦ Pipe mode - for conduits which always flow full.
♦ Compound mode - for all other conduits, including rivers, open channels and conduits which
may surcharge. For this mode, an input of fluid depth or Stage is required.
In “Pipe” mode, one of the following integration methods may be selected by the user:
♦ Chebyshev integration - for round pipes flowing full.
♦ Gaussian integration - for rectangular pipes or closed conduits of defined shape flowing
full.
For either of these methods, if paths fail, the path substitution routine may be selected.
In “Compound” mode, for conduits which may surcharge, the user should first select the integration
method to be used under surcharged conditions from the following:
♦ Chebyshev integration - for round pipes.
♦ Gaussian integration - for rectangular pipes or closed conduits of defined shape.
♦ Area integration - for conduits where the path locations are chosen from non-surcharged
design considerations.
For any of these three methods, if paths fail, either the “Path Substitution” routine, or the
“Available Velocity” routine may be selected.
♦ Trapezoidal integration - for conduits where the path locations are chosen from nonsurcharged design considerations. If paths fail, the method’s own special routines apply, as
long as at least two paths are good.
Normally, for the non-surcharged state, in “Compound” mode, the user should select either:
♦ Auto - which enables the flowmeter to choose automatically the integration method,
depending on the Stage and the number of good paths yielding velocity data. The possible
choices are:
Manning
Single-path Trapezoidal
Multi-path Trapezoidal
the user selected surcharged integration method.
♦ Trap - as for “Auto”, but omitting “Manning”.
However, the following alternative, very restricted methods, are available if required, for the nonsurcharged state:
♦ Manning formula - for use where there are no acoustic paths installed.
♦ Single path integration - for use when only one path is installed (Path #1), the user may
slect either “USGS”, “Polynomial” or “Trapezoidal” methods. If the path fails, the flow
computation fails.
For open channels which cannot surcharge, the surcharged condition may be avoided by setting the
parameter which defines the “full pipe” condition to a value above the maximum possible Stage value.
If one of the surcharged options available under the “Compound” mode is desired for use in a conduit
which is always flowing full, this can be arranged by setting a manually entered value for Stage which
forces the surcharged condition.
3-18
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
Flow Calculation Formulas for Full Pipes or Surcharged Conduits
Chebyshev integration is normally the best method for a round pipe flowing full. The formula is shown
below.
n
Q = 2 R 2 ∑ wi v i
i =1
where:
Q
R
wi
vi
n
i
= Flow
= Pipe radius
= Integration weighting factor for the i’th path
= Average velocity as measured along the i’th path
= Number of acoustic paths
= Acoustic path number
Gaussian integration is normally the best method for rectangular pipes or other conduits of a regular
cross section flowing full. The formula is shown below.
Q=
D n
∑ wi v i Li
2 i =1
where:
Q
D
Li
wi
vi
n
i
= Flow
= Pipe diameter
= Width of pipe at the elevation of the i’th path
= Integration weighting factor for the i’th path
= Average velocity as measured along the i’th path
= Number of acoustic paths
= Acoustic path number
Area integration used in surcharged conduits which have path spacing resulting from non-surcharged
design considerations. An example would be a horseshoe-shaped tunnel.
n
Q = A∑ Vi K i Wi
i =1
where:
Q
A
Vi
Ki
Wi
n
i
ACCUSONIC MODEL 7500
= Flowrate
= Area of the pipe set by the Parameter Cross sectional area
= Velocity as measured along the i’th path
= Integration adjustment factor, normally set to 1.000
= Weighting constant for the i’th path. Note that the W’s for all paths
should add up to unity.
= Number of acoustic paths
= Acoustic path number
3-19
Acoustic Flowmeter Principles
Surcharged trapezoidal integration used in any shape of conduit in which the flow can be best
visualized as being made up from the sum of a number of physical panels, each bounded by paths or the
conduit top and bottom.
The flow is computed from the path velocities and the cross-section geometry. The cross section is
described by the layer parameters and the Full pipe parameter.
The computation is similar to that for non-surcharged trapezoidal integration, except that the flow in the
panel between the uppermost good path (or pair of crossed paths) and the conduit soffit is:
Q Top = Area between uppermost good path and soffit * Velocity * (1 + Bottom Velocity Ratio)/2.
The other elements of the calculation are as described under “Multi-path Trapezoidal Integration” below.
Path substitution is a “fallback” method available only in “Pipe” mode and in the Gauss, Chebyshev and
Area surcharged methods under “Compound” mode. It is designed to keep the flowmeter operating when
the flow conditions are such that paths fail. The method has to be enabled by the user, and the parameter
“Minimum good paths” set. When the number of good paths is less than the number installed, but more
than or equal to the parameter Minimum good paths, substitute values for velocity are inserted for those
paths which have failed. The substitute values are derived from user calculated path velocity ratios and
current velocity readings from good paths pre-assigned from a fixed table.
Available Velocity integration is a “fallback” method available only in the Gauss, Chebyshev and Area
surcharged methods under “Compound” mode. It is designed to keep the flowmeter operating when the
flow conditions are such that paths fail. The method has to be enabled by the user. The flowmeter
automatically selects the method when at least one path has failed. This method is inhibited if the
“Velocity Substitution” routine is in operation, but will take over when the number of good paths falls
below the parameter “Minimum good paths”.
The Flowrate is calculated from:
Q = A * V avg
where:
Q
= Flowrate
A
= Area of the pipe set by the parameter “Cross sectional area”
V avg
= the arithmetic mean of all good path velocities.
3-20
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
Flow Calculation Formulas for Non-Surcharged Conduits
Path Velocities - each path is characterized by parameters describing Length, Angle and Elevation. In
“Compound” mode, the paths must be numbered in order of elevation, with the lower path numbers
having lower elevations. It is possible for pairs of paths in a section to be configured as “Crossed Paths”,
and these are indicated by having the same elevation.
Paths are energized and measurements taken only if they are submerged by an amount greater than a
minimum submersion parameter.
If a path fails to provide a good velocity value, because the signal is not found or the data fail to pass
acceptability tests, then the last good velocity value is used for all flow calculations until the number of
consecutive failures exceeds the maximum bad measurements parameter. If the value is exceeded, the
path is declared to have failed, and its data are then not used for flow computation, unless and until new
valid data are obtained.
Instantaneous values for velocity are averaged for paths having identical elevations, and the averaged
velocity used as the velocity at that elevation. If one of the paths fails for more than the maximum bad
measurements parameter, the good path will be used alone for providing the velocity at that elevation.
The velocities displayed will be the path velocities for non-crossed paths, and the individuul nonaveraged velocities for crossed paths. Paths which do no have identical elevations will be treated as
separate paths in the Trapezoidal Integration.
Conduit Cross-section - the conduit cross-section is defined in terms of up to 16 “Layers”, each layer
being described by an elevation and a width. The width of the conduit at any elevation is computed by
linear interpolation between the layer widths above and below. The elevation and width of the channel
bottom are defined separately. The layer elevations are independant of the path elevations. For a
rectangular or trapezoidal conduit, only one layer needs to be defined, describing the top of the channel.
For a closed conduit, the top-most layer elevation must be equal to or greater than the elevation of the
soffit (or the Full Pipe parameter). For an open channel, the top-most layer elevation must be set above
the highest possible stage.
Manning formula - used when there are no good paths operating, either because the Stage is low or
because of path failure. The flow is computed from the Stage and fixed parameters of channel roughness,
channel slope, and the layer parameters. The formula is only appropriate if the flow is non-critical, and if
there is no “back-water”effect.
It is programmed to fail if the Stage exceeds 0.3 * Full Pipe parameter.
Q = A * C * n −1 * R 0.667 * S
where: Q
A
C
n
R
S
= Flowrate
= the cross-section area of fluid at the current Stage, computed using layer data
= Manning constant 1.49 if English units and 1.00 if Metric units are selected
= the Manning coefficient of roughness
= Hydraulic radius, which is the Area/Wetted Perimeter
= Slope of the energy line. For a long pipe, the pipe slope.
ACCUSONIC MODEL 7500
3-21
Acoustic Flowmeter Principles
Single path USGS Integration - This method is typically used after a stage-area relationship has been
determined for a particular site by some comparative flow measurement method, such as current meters.
Using this stage-area information, the USGS coefficients are obtained by matrix algebra and are used in
the following formula to determine spatial average channel velocity:
ACVEL = VEL * (VFWD1 + (VFWD2 * S) + (VFWD3 * S 2 ))
where:
ACVEL
VEL
VFWD
S
= Average channel velocity
= Velocity as measured along the acoustic path
= Coefficients entered as General parameters V FWD
= Stage (water depth)
Note that if velocities are less than 0, coefficients entered as General parameters V REV are used.
Flowrate is calculated as:
Q = ACVEL *[(QFWD1 + QFWD2 * S) + (QFWD3 * S 2 )) * (QFWD4 + QFWD5 * S QFWD6 ))]
Where QFWD are integration constants entered as General parameters Q FWD.
Note that if velocities are less than 0, coefficients entered as General parameters Q REV are used.
For additional information, contact Accusonic.
Single path Polynomial integration - If only one path is operating, the meter uses the coefficients
entered in Section parameter Single coefficient, which represents a fifth-order polynomial relationship
between stage (level) and area for the particular site. Flowrate is calculated as follows:
Q = AV
where:
V
= Velocity at the lowest path divided by a coefficient from a
table providing velocity-head coefficients in open channels.
A
= Area calculated as a + bs + cs2 + ds3 + es4
where a, b, c, d, and e are entered as Section parameters Single Coefficient.
s = stage (water depth)
For further information, contact Accusonic or see the Publication Velocity-Head Coefficients in Open
Channels. 2
2
H. Hulsing et al, Velocity-Head Coefficients in Open Channels, Geological Survey Water-Supply Paper 1869-C,
(Washington: United States Government Printing Office, 1966),C7.
3-22
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
Single-Path Trapezoidal Integration -used when only one path (or pair of crossed paths) is good, either
because the Stage is low or because of path failure. The flow is computed from the variables Stage and
Water Velocity, and fixed layer parameters describing the conduit dimensions.
Q = A * V/Path position coefficient
where: Q
= Flowrate
A
= the cross-section area of fluid at the current Stage, computed using layer data
V
= the fluid velocity from the one path or pair of crossed paths
Path position coefficient is obtained from the look-up table below 3.
Ratio of path depth below surface
to depth of water above bottom
Ratio of point velocity to
mean velocity in the vertical
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0.95
1.160
1.149
1.130
1.108
1.067
1.020
0.953
0.871
0.746
0.648
The coefficient for the depth nearest to the actual depth is selected.
3
H. Hulsing et al, Velocity-Head Coefficients in Open Channels, Geological Survey Water-Supply Paper 1869-C,
(Washington: United States Government Printing Office, 1966),C7.
ACCUSONIC MODEL 7500
3-23
Acoustic Flowmeter Principles
Multi-path Trapezoidal Integration - used when two or more paths (or pairs of crossed paths) at
different elevations are good. The flow is computed from the variables of Stage and all good path
velocities, and the fixed parameters of Layer data, Path elevations, Bottom Velocity Ratio and Top
weight.
The total Flow in a Section is made up of the sum of the flows in various panels. The lowest panel is
bounded by the conduit walls (as defined by the layer data), conduit bottom and the lowest good path.
Each intermediate panel is bounded by the conduit walls and good acoustic paths at the top and bottom.
The top panel is bounded by the conduit walls, the uppermost good path and the water surface.
The flow in the lowest panel is:
Q Bottom = A Bottom * V A * (1 + Bottom Velocity Ratio)/2
where: A Bottom = conduit area between the bottom and the lowest good path or pair of crossed paths
VA
= water velocity as computed from the lowest good path or pair of crossed paths
The flow in the intermediate panel above the bottom panel is:
Q Int
= A Int * (V A + V B )/2
where: A Int
= conduit area between good path A and the next good path B
VB
= water velocity as computed from the next good path or pair of crossed paths
The flows in any other intermediate panels is computed similarly.
The flow in the uppermost panel bounded by the surface is:
Q Top = A Top * (V N +Top Weight * V Surface )/(1 + Top Weight)
where: A Top = conduit area between the uppermost good path (or pair of crossed paths)
and the water surface.
VN
= Water velocity computed from the uppermost good path or pair of crossed paths
V Surface = an estimated water velocity at the surface from a limited algebraic extrapolation of the
velocities from the uppermost good path (or pair of crossed paths) and the next good
path (or pair of crossed paths) below it.
If the difference in elevation between the water surface and the uppermost good path is less than the
difference in elevations between the uppermost and next lower good paths, then:
V Surface = V N + (V N - V M ) * (Stage - E N )/(E N - E M )
where: E N and E M
are the elevations of the uppermost good path and of the next lower good path
and
V N and V M
are the water velocities from the uppermost good path (or pair of crossed paths)
and of the next lower good path (or pair of crossed paths)
If the difference in elevation between the water surface and the uppermost good path is greater than the
difference in elevations between the uppermost and the next lower good paths, then:
V Surface =V N + (V N - V M )
The total Flow in the conduit = Q Bottom + Q Int + Q Top
3-24
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
Updating Volume Totals
The flowmeter calculates flow rate as described above. Using the rate, it calculates total fluid volume
passing through the meter since the previous cycle. It does so by:
♦ Averaging the flow measurement from the current cycle with a user-defined number of previous
readings, and
♦ Computing total volume through the meter during the current cycle. This computation uses the
following formula:
Vi =
qi + qi −1
* (t i − t i −1 )
2
where:
Vi
qi
= Total volume through meter during i’th cycle
= Flow rate measured for current cycle
(after averaging with previous measurements)
q i-1
= Flow rate measured at the end of the previous cycle
(after averaging with previous measurements)
ti
= Time at the end of the i’th cycle
t i-1
= Time at the start of the i’th cycle
Fluid volume for the current cycle is then added to the previous totalizer volume to determine the total
fluid volume which has passed through the section.
For measurements taken just after power up, after an interruption in measurement cycles, or after certain
kinds of error conditions, there may be fewer than the site-specified number of previous values available
to use for averaging. Under this condition, the instrument uses whatever number of values are available
(possibly none). This means that the first few flow readings on the meter after startup may show a
variation in flow rate until the averaging effect takes over.
The instrument maintains three separate values of total volume: total forward volume, total reverse
volume, and net total volume.
All totals are stated in site-specified aggregate units that are defined during unit setup. For example, the
system might be set up such that one volume unit equals 1000 acre-feet, or one unit equals 3 million
gallons.
Volume totalizer after Outage
When the steady state cycle of measurements is interrupted - either through a power failure, temporary
loss of signal due to noise, or when the unit is taken off line by an operator to change parameters - the
duration of the interruption determines how the instrument will estimate total volume through the meter
during the period of interruption.
If the interruption is shorter than a site-specified limit (Totalizer Cutoff Time), the instrument uses the
formula given above for updating the totalizer. If the interruption exceeds the specified time limit, the
instrument does not attempt to update the totalizer for the period of the outage.
ACCUSONIC MODEL 7500
3-25
Acoustic Flowmeter Principles
Updating System Outputs
During the last step of the cycle, the instrument updates system outputs. For example, if there is an analog
output corresponding to flow, the signal is now set to the new or updated level. If a relay has been
programmed to output a totalizer pulse each time one of the volume totals increments, this event will be
triggered at the same time.
Acoustic Flowmeter Accuracy
This section of the chapter describes the kinds of error which generally can occur in acoustic flowmeter
measurements. Later in this section, a sample analysis of system error for a round pipe is given (pg 3-28).
If you would like to review a case study and error analysis of open channel installations, consult
Accusonic for available literature.
Sources of Measurement Uncertainty
There are several sources of uncertainty in the acoustic method of measuring fluid flow. Each is described
below. We characterize the importance of the error and describe what steps are taken in Accusonic
instrument design and installation practices to minimize the effect.
Path Length - Error in measuring length will appear in the velocity since these parameters are
proportional, as shown in velocity equation described at the start of this chapter and repeated below. This
error usually can be kept below 0.1% by using a steel tape measure, calipers, or a micrometer to measure
the distance between transducers in every path.
v=
(T1 − T2 )
L
*
T1 T2
2 cos θ
Path Angle - Error in measuring the angle will appear in the velocity, since velocity is inversely
proportional to the cosine of the angle, as shown in the velocity formula above. For a 45° path angle, and
assuming fluid flow is parallel to the centerline of the conduit, a 1° measurement error in the as-built path
angle produces a 1.7% velocity error. In order to minimize this error, Accusonic specifies an installation
and survey technique that produces measurement accuracy of the path angle to 6 minutes of arc, yielding
an error less than 0.17%.
Radius Measurement Error - Error in measuring the radius of a round pipe appears in the flow since
radius is a term in the integration formula for pipe. Assuming the pipe is round, a measurement error of
0.1% in the radius produces a 0.2% flow error. In order to minimize this error, Accusonic specifies an
installation and survey technique that produces measurement accuracy of pipe radius to within 1/8 inch.
In a ten-foot-diameter pipe, this is less than a 0.1% measurement uncertainty, which yields less than a
0.2% flow uncertainty.
Cross Flow Error - When there are streamline components that are not parallel to the axis of the meter
section, an error analogous to path angle measurement will appear in the velocity. This effect, called cross
flow, is usually caused by upstream bends, transitions in conduit shape or size or obstruction located too
close to the meter section.
3-26
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
Cross flow cannot be easily measured. When it exists, it typically changes as a function of flow rate and
fluid stage, so simple compensation cannot be used to correct the measurements. Cross flow errors can be
substantially reduced by the use of crossed paths, described earlier in this chapter. When crossed paths are
used, velocity measurement error is inversely proportional to the cosine of the difference between the two
path angle errors, an error value near zero. For crossed paths, even several degrees of cross flow yield
negligible velocity measurement error.
Crossed paths are also useful for correcting installation errors where the conduit is out of round or not
straight, preventing accurate determination of centerline.
Non-liquid Propagation Delays - Transit time measured on an acoustic path which is not part of the
moving fluid introduces velocity error. This includes cable, logic and detector delays, acoustic delays
associated with the transducer windows, and the stationary liquid delays which occur when the
transducers are separated from the moving fluid (e.g. recessed into the walls of the conduit).
Accusonic has measured all transducer, logic and detector circuit, and cable delays. Stationary fluid
effects, if present, can be measured from the geometry and predicted. The flowmeter software uses
parameters defined during instrument setup to compensate for non-liquid propagation delays.
Variable Acoustic Signal Strength - Velocity measurement error can be produced by spurious signal loss
(apart from normal spreading loss) caused by fouling of the transducer faces, silt, entrained gas, marine
life or debris. Furthermore, acoustic signals may be distorted by multipath reflections from debris. The
most serious effect on flowmeter accuracy occurs if the receiver circuitry is unable to consistently
recognize the same point (e.g. first leading edge) on every incoming pulse. The instrument employs a
Signal Quality Monitor that eliminates this type of error in the path velocity measurement by rejecting
unacceptable signals.
Time Base - Velocity measurement error can be produced by jitter and drift in the oscillator used to
control the transit time counters. The instrument uses a precision crystal oscillator having high stability
and accuracy within 0.005%.
Quantization - There is a true random error of ± one counting period made on every transit time
measurement. The instrument uses a very high counting period (equivalent to 160 Mhz) and further
reduces error by averaging over a user-selectable period. Normally, this is not a significant source of
error.
Differential Detector Errors - Caused when different circuits are used for the forward and reverse
measurements along each path. Accusonic uses one detector circuit for both forward and reverse path
measurement by sequentially connecting first to one receiving transducer and then to the other.
Level Measurement Error (open channel and compound meters only) - Has a direct effect on the overall
meter accuracy which cannot be directly compensated. However, it is fairly simple to calculate the effects
on accuracy for all fluid stages - this typically influences the instrument’s overall specified accuracy for a
given installation.
ACCUSONIC MODEL 7500
3-27
Acoustic Flowmeter Principles
Integration Error - Defined as the difference between the flow rate calculated by integrating over the
exact velocity profile and that obtained by integrating a discrete number of velocities measured on an
acoustic flowmeter.
In a straight circular pipe, using four-path integration, the error is typically less than 0.1%. This level of
accuracy can also be achieved under less favorable conditions by using crossed paths. Consult Accusonic
for applications assistance.
In an open channel, the integration error can be significant and may be the principal component affecting
overall instrument accuracy. It is convenient to evaluate the uncertainty of an open channel meter by
separately considering three layers.
♦ Middle layers - Those bounded by active paths are a relatively small contribution to overall
error. Integration accuracy is comparable to that for a closed pipe.
♦ Top layer - The flow between the topmost active acoustic path and the free surface of the
fluid is uncertain to the extent that the velocity profile over that region is uncertain. A path
cannot be placed arbitrarily close to the surface because of multipath effects described
previously. As a result, the instrument estimates the velocity distribution by extrapolating
surface velocity from measurements taken at the top two paths below the surface. This
extrapolated velocity can be adjusted to account for strong winds likely to affect the surface
velocity, either in or against the direction of flow. The uncertainty in extrapolated velocity
distribution increases with the thickness of the layer above the topmost active path. For most
meters, this uncertainty is the most significant contribution to overall device error.
♦ Bottom layer - The flow between the lowest active acoustic path and the bottom surface of
the fluid is uncertain in the same way. The error contribution here may be smaller than that of
the top layer because: The boundary condition is known, because fluid velocity at the bottom
surface is zero. Furthermore, total flow of the bottom layer is usually a small proportion of
total flow. Typically, this uncertainty is minimized by placing an acoustic path as close to the
bottom surface as possible, consistent with the limits of reflected signals as discussed earlier
in this chapter.
Sample Error Analysis (Round Pipe)
This sample summarizes the errors in a flowmeter installed in a round pipe. Details of this analysis may
be found in Acoustic Flowmeters for Pipelines 4 and The Application of Acoustic Flowmeters to Pipeline
Flow Rate Measurement 5. Reprints of both papers are available from Accusonic.
Four-path flowmeters are typically specified to an accuracy ±0.5% of flow for velocity ranges from 1
foot/second up to the maximum flow. To achieve these accuracy’s the flowmeter must be installed
according to Accusonic specifications in a section of pipe with a minimum of ten diameters of upstream
straight pipe. For installations having less than ten diameters of straight pipe upstream of the meter
section, eight crossed paths (four paths in two crossed planes) may be required to maintain an accuracy of
±0.5% of flow. Consult Accusonic for critical applications.
4
5
Francis C. Lowell Jr., and Fritz Hirschfeld. Mechanical Engineering, Vol. 101, Number 10, Ocotber 1979.
Francis C. Lowell Jr., Unpublished, presented to the Cooling Tower Institute Symposium, 1978.
3-28
ACCUSONIC MODEL 7500
Acoustic Flowmeter Principles
Path Length Measurement Uncertainty - Path length measurement is usually done with the pipe
dewatered. Using steel tape measures in larger pipes and calipers or micrometers in smaller pipes,
individual path length uncertainty is less than 0.15%. For example, a 1/16 inch error in a 4-foot path
produces 0.13% error in the velocity calculation. However, since there are four paths and the error is
random, overall flow measurement uncertainty due to path length measurement error is:
EL =
(0.0013)
= 0.00065
4
or
0.065%
Path Angle Measurement Uncertainty - Path angle measurement is done with the pipe dewatered using a
theodolite accurate to within ±12 seconds of arc. The primary source of error is the ability to set the
theodolite up on the pipe centerline. Careful setup according to Accusonic procedures will ensure that the
theodolite is within ±6 minutes of arc of true centerline. For 45° paths, the error in flow measurement due
to path angle measurement error is:
Eθ = 1 −
cos( 4510
. )
= 0.0017
cos( 45.00)
or
0.17%
The error is systematic and is not reduced by adding more paths. In a crossed path installation, however,
the error is negligible.
Radius Measurement Uncertainty - Pipe radius is measured from the inside with the pipe dewatered. The
radius is measured at several locations and is averaged to account for normal tolerance in pipe roundness.
When done according to Accusonic procedures, the radius measurement is accurate to ±0.1%, which is
equivalent to 1/8 inch in a ten-foot diameter pipe.
The flow measurement uncertainty due to radius measurement error is:
ER = 1 − (
1 2
) = 0.002
1.001
or
0.2%
Integration Uncertainty - Velocity profile error has been estimated using extensive computer simulation
for a wide variety of symmetrical velocity profiles. The uncertainty due to profile integration error in this
instrument is typically less than 0.1% assuming there is no cross flow and a smooth symmetrical profile.
Calculating Total Bias - System accuracy is defined as the square root of the sum of the squared values
of the individual errors. Therefore, the total flow measurement uncertainty for a four-path flowmeter is:
E B EL2 + Eθ2 + E R2 + E12 = (0.065) 2 + (0.17) 2 + (0.2) 2 + (0.1) 2 = 0.25%
The random error is minimized by taking an average of many readings (typically ≈ 100). This results in a
random component of E R ≈ 0.3%.
Calculating Total Uncertainty - The total uncertainty is calculated by taking the square root of the sum of
the total bias and random error:
ET = E B2 + E R2 = 0.4%
ACCUSONIC MODEL 7500
3-29
ACCUSONIC MODEL 7500
3-30
Chapter 4
Unpacking and Installation
When the flowmeter arrives, inspect the packaging for signs of damage. If there is obvious external
damage to the shipping container, request that the carrier's agent be present when the unit is unpacked. Be
particularly careful not to destroy the shipping container during opening so that it may be used for future
shipment of the unit.
Warning
Do not apply power to damaged components. Injury or further damage may occur.
Remove the flowmeter from the package and verify all parts against the packing list. Examine each of the
components for physical damage. If a component is damaged, notify the carrier and follow the
instructions for damage claims. Report any shipping problems immediately to Accusonic.
Physical Installation
The flowmeter should be mounted on a location so the cable run from the transducers to the main unit or
to a remote flow transmitter does not exceed 1000 feet without the approval of Accusonic. In addition, the
unit requires an AC connection, as well as connections to alarms or to the site process control system. If a
printer is connected to the system, it will be desirable to locate it near the flowmeter during setup.
If the flowmeter is supplied in a wall-mounted cabinet, determine a suitable location with sufficient
clearance so that the front panel of the unit can swing fully open without interference. Although the
NEMA cabinet is sealed, it is good practice to mount the unit in a location that provides protection from
the elements. The instrument should be mounted vertically and should be attached to a wall or mounting
panel capable of safely supporting 100 pounds. Use 3/8 inch lag screws or carriage bolts.
If the flowmeter is supplied as a rack-mounted unit, select a rack or table location with enough clearance
to allow removal of the top portion of the cabinet. The rack-mounted unit must be mounted indoors. The
instrument is normally supplied with rack slides, so when a unit is mounted in a relay frame, service
clearance above the unit is not necessary.
The height at which the unit is mounted must allow for easy access to the keypad and easy viewing of the
display. If an external display or keyboard is used, provide a suitable table or shelf.
ACCUSONIC MODEL 7500
4-1
Unpacking and Installation
Electrical Installation
All wiring is brought into the unit through customer-supplied conduit connectors. Holes for the cableconduit connectors must be drilled through the cabinet on site. The preferred location for all connectors is
the bottom surface of the unit. Use separate conduit and connectors for:
♦
♦
♦
♦
AC power supply mains
Transducer cabling (may require more than one feedthrough)
Alarms and low voltage relay connections
Digital I/O, printer connections, and analog I/O
Caution
When drilling conduit holes, remove the circuit cards from the unit and drape the front
panel of the device. Give particular attention to protecting the diskette drive.
AC Wiring
AC power consumption is less than 175 VA. Use #16 AWG or #14 AWG for power connections.
Rack-mount units have a standard power cord connector located on the rear of the cabinet. The connector
contains 2 Amp Slo-Blo fuses located under a removable access cover. Simply attach the power cord and
plug the unit into a mains outlet.
The NEMA enclosures require direct mains wiring and should be installed with a separate main power
cutoff switch near the instrument.
Route AC power mains wiring into the NEMA cabinet through the appropriate feedthrough to the AC
mains terminal block and connect as shown in Figure 4-1. Be sure to follow appropriate local codes and
practices, and to attach a proper earth ground to the instrument.
Figure 4-1 Location of AC Power Connections, NEMA Cabinets
4-2
ACCUSONIC MODEL 7500
Unpacking and Installation
Transducer Wiring
Pull transducer cabling through the appropriate feedthrough and trim each line, leaving enough cable to
reach the transducer terminal blocks at the bottom of the flowmeter console. Tag each cable with a path
number and transducer letter according to the Accusonic numbering convention as shown in Figures 4-2
through 4-4. Trim the cables, strip back 6 inches of outer sheathing from each, pull inner conductors back
from inside the outer braid, solder spade lugs to the conductor and shield of each cable as shown in Figure
4-5 on page 4-4.
Do not connect the cables to the flowmeter yet. Leave the ends of the cables so that the conductors are not
in contact with one another or with any metal parts on the flowmeter console.
Caution
Double-check the cable numbering and verify sufficient reach before trimming.
Figure 4-2 Transducer Numbering - Simple Pipe
Figure 4-3 Transducer Numbering - Open Channel
ACCUSONIC MODEL 7500
4-3
Unpacking and Installation
Figure 4-4 Transducer Numbering - Crossed Paths
1. Strip outer sheath back 6 inches, exposing braided shield.
2. Pierce the braid, snake inner conductor(s) and insulation out.
3. Twist braid tightly, trim to 3 inches, attach forked lug, crimp and sol
4. Trim inner conductor to 4 inches, strip 3/8 inch of insulation, attach
5. Attach, lug, crimp and solder.
Figure 4-5 Stripping and Terminating the Transducer Cable
4-4
ACCUSONIC MODEL 7500
Unpacking and Installation
Transducer and Cabling Checkout
There are three steps to verify the transducer cabling and transducers:
1. Verify that there is infinite resistance across each transducer.
2. Verify that there are no internal shorts in any cable.
3. Verify continuity in the cabling.
Step 1 - Verify infinite resistance across each transducer
Measure the resistance across the transducer cable terminals using a Megohmmeter (high voltage
ohmmeter) set to the highest resistance range. Each transducer should measure infinite resistance. Contact
Accusonic if any transducer measures less than 20 MΩ resistance.
Test transducer resistance at the unit, with the cabling detached, if possible. This can usually be
performed easily when the transducers are pipe-mounted, where the outside of the pipe is accessible, and
when the transducers are fitted with E/O connectors. Use a short test cable attached to an E/O connector.
When the transducer is not accessible, or when the cable is permanently attached to the unit, do the best
you can. Test the resistance at a wiring junction located as near as possible to the transducers. If it is not
possible to detach the cabling back to the flowmeter console, be sure the console ends of the cables are
detached from the unit and that they are not accidentally shorted together.
Step 2 - Verify that there are no internal shorts in any cable
With the free ends of all cables detached and isolated, test that the resistance across each cable is infinite.
For coaxial cable, test conductor to shield, conductor to ground and shield to ground. For twin-axial
cable, test conductor to conductor, each conductor to shield, each conductor to ground, and shield to
ground.
Step 3 - Verify Continuity
Work from either end of the cable and use a partner to connect pairs together, one at a time, at the far end
of the cable. For each coaxial cable, short the connector to shield and measure continuity. For each twinaxial cable, short each connector to shield and measure continuity.
Connecting Transducer Cabling
After verifying that all transducer cabling is sound, connect each line to the appropriate terminal on the
flowmeter console, as shown in Figure 4-6.
ACCUSONIC MODEL 7500
4-5
Unpacking and Installation
Figure 4-6 Transducer Wiring Connections
Connecting a Printer
Any PC-compatible printer with a parallel interface may be connected to the flowmeter. Even if a printer
is not needed for routine operations, it is good practice to attach one to the instrument during instrument
setup. The data cable between the flowmeter and the printer should not exceed 20 feet.
The printer connects via standard D-shell connector located on the connector panel as shown in
Figure 4-7.
If the printer is to be used temporarily, simply route the data cable out the door of the flowmeter, and take
care not to crush it by trying to shut the door. For more permanent installation, route the cable through a
cable feedthrough in the bottom of the enclosure.
Figure 4-7 Location of Printer Connector
4-6
ACCUSONIC MODEL 7500
Unpacking and Installation
Level Sensor Setup
Acoustic Uplooking Transducer - If supplied by Accusonic, the acoustic uplooking transducer will be
supplied with twin-axial, shielded cable. Connect the cable to the Stage 1 or Stage 2 terminal strip located
to the right of the path selector cards in the Flow Transmitter section of the console. Connect + to +, (copper tracer) and shield to -. Connect - to ground with a jumper wire.
External Stage (Level) Sensor - Any stage sensor providing a 4-20 mA process loop signal can be used
by the flowmeter. The loop signal is read and converted by an analog input board mounted in the PC bus.
This board utilizes a dual-slope analog-to-digital converter, which requires no calibration.
After installing the external stage sensor according to the manufacturer’s instructions, use a twin-axial,
shielded cable to connect the input to the terminal strip located at either TB1 or TB2 in the 7500. Refer to
customer-specific drawings at the end of the 7500 manual for terminal strip locations. Connections are as
follows:
Pin 1
Pin 2
Pin 3
Stage 1 shield
Stage 1 loop input
Stage 1 loop return
Pin 4
Pin 5
Pin 6
Stage 2 shield
Stage 2 loop input
Stage 2 loop return
Input impedance for each channel is 100 ohms. Both the loop input and loop return terminals must be
between 0 and +4 volts relative to ground.
Once connected, the easiest way to verify proper connection and test for the presence of loop noise is to
enter the diagnostic menu. The recommended procedure follows. Familiarity with proper grounding
techniques is useful in determining proper shield connections to reduce loop noise pickup.
From the main menu, select [DIAGNOSE], then select [HARDWARE], then [INPUTS]. From this point,
menu choices will be shown for the available inputs. Select either IN1 or IN2 and press the Enter key to
accept the choice. A number will be displayed after the input data. This number is the raw, unscaled input
value direct from the analog input board. The range is 0-6000 bits, with 0 bits representing 4 mA and
6000 bits representing 20 mA. Both the upper and the lower ends of the range should be checked while in
the diagnostic menu to verify proper connection. It may also be helpful to monitor a steady-state level
near midrange, to check for the presence of loop noise. Any “jitter” in the readings with a steady-state
signal is an indication of noise. This can be used to determine the best grounding scheme.
When proper operation is verified, the following procedure is used to set the software to use the input. In
the SECTION parameters menu, find the parameter STAGE SOURCE. Select [EXTERN], to use the
analog input. Choosing this will lead to two more choices, STAGE RANGE MAX and STAGE RANGE
MIN. At these prompts, enter the range at the calibrated ends of the level sensor. The 7500 will calculate
the correct offset and scale factors.
ACCUSONIC MODEL 7500
4-7
Unpacking and Installation
Example: The level sensor is an acoustic downlooker. It is calibrated to output 4 mA at two feet of depth,
and 20 mA at 25 feet. Set STAGE RANGE MIN to 2, and STAGE RANGE MAX to 25. For multiplesection meters, this setup must be done for each section.
In some cases, such as cross-path installations, it may be desirable to run two sections from a single
external stage sensor. This can be done by connecting both analog inputs in the level sensor’s output loop
and setting identical ranges for both sections, or by setting the Stage Source for the second section to
Section, then choosing the section to use as the source.
4-8
ACCUSONIC MODEL 7500
Unpacking and Installation
RS-232 Port Connection
The serial port of the 7500 complies fully with the RS-232C standard with respect to signal level and
hardware handshake. The port is configured as a DTE (Data Terminal Equipment) device. Therefore,
connection to an external device requires a fully-pinned cable for proper operation. If correct connections
are not made, the output may be erratic or may not work at all. With early versions of flowmeter software,
the system may "lock up", causing a watchdog timer reset. Common cables for connection to DCE and
DTE devices are shown below.
Frame Ground
1
Transmit Data
2
Receive Data
3
Request to Send
4
Clear to Send
5
Data Set Ready
6
Data Terminal Ready
20
Carrier Detect
8
Signal Ground
7
1
2
3
4
5
6
20
8
7
For connection to DCE devices (modems, etc.)
Frame Ground
1
2
Transmit Data
Receive Data
1
3
3
2
4
4
5
5
6
6
20
20
8
8
7
Signal Ground
7
For connection to DTE devices (computers, terminals, etc.) with no hardware flow control. This is
the most common arrangement
ACCUSONIC MODEL 7500
4-9
Unpacking and Installation
Frame Ground
1
1
Transmit Data
2
3
Receive Data
3
2
Request to Send
4
Clear to Send
5
5
4
6
8
20
20
8
6
Signal Ground
7
7
For connection to DTE devices (computers, terminals, etc.) with full hardware flow control.
3
Transmit Data
Receive Data
3
2
2
8
5
7
4
1
8
4
20
6
6
Signal Ground
5
Frame Ground
7
1
For connection to DTE devices with 9-pin serial cable (laptop cable).
4-10
ACCUSONIC MODEL 7500
Unpacking and Installation
RS-485 Interconnection
When assembling systems with a 7500 and 7520 remote flow transmitters, it may be necessary to build
the interconnecting cables at the site. Following are specifications and guidelines to help you.
Cable Specifications
•
•
•
•
•
•
•
Cable Type:
Wire Gauge:
Shunt Capacitance:
Rise Time:
Max Transmission Distance:
Maximum Loss:
Recommended Cable Types:
ACCUSONIC MODEL 7500
Shielded, twisted pairs
24 AWG or larger
16pf/ft or less
Signal rise and fall time equal to or less than 13µs.
4,000 Feet
6db max between 7500 and last 7520
Belden #8729
Alpha # 2254/4
4-11
ACCUSONIC MODEL 7500
12
Chapter 5
Initial Setup, General Operations
This chapter describes setup and operation of the flowmeter using the standard front panel keypad and
display. Operating differences introduced by using an external keyboard or display are also discussed.
You cannot damage the instrument by entering incorrect parameters or otherwise manipulating the control
panel.
Control Panel, Parameters and Variables
The control panel, which consists of a display and a keypad as shown in Figure 5-1 (see page 5-2), is used
to set up the flowmeter, start measurements and perform diagnostics. Once the instrument starts taking
measurements, it will continue to do so at a rate defined during setup. Flow measurements can be
interrupted or halted from the front panel.
Set up the flowmeter by entering appropriate values for various parameters, or by accepting default
values. Parameters define the geometry of each meter section and govern the operating modes of the
instrument. All parameters are listed in this chapter. Chapter 7 contains a dictionary that defines each
parameter (beginning on page 7-1) in detail and lists its default value and range of allowed values.
Variables provide a view of measurements of calculations when the unit is on line. Chapter 7 describes
flowmeter variables (beginning on page 7-40) in detail.
An optional password can be used to lock the control panel and prevent change in instrument setup or an
interruption in flow measurement.
Menus
Commands and control parameters are entered into the instrument using menus shown on the display. A
menu appears on the control panel within a few seconds after system power up, unless the instrument has
been previously set up to begin measuring flow automatically.
Most menus display the available options and you simply choose among them; in a few cases, you need to
enter data. The menus are arranged in a multi-level fashion, with related options grouped together. There
are numerous parameters and variables, and the hierarchy makes it possible to move among the choices
with ease and to select or change one quickly.
The top line of every menu shows the currently available options, with the selected or active option
shown enclosed by brackets and displayed in capital letters. If there are more options than fit on the top
line, the instrument displays two arrows at the beginning or at the end of the line (<< or >>) to indicate
that additional options are available. The next section, Stepping Through Menus, describes how to access
these options.
ACCUSONIC MODEL 7500
5-1
Initial Setup, General Operations
Figure 5-1 Control Panel
The second line of a menu shows a list of submenu options that correspond to the selected item. If there
are no additional options, it describes the bracketed selection more fully.
Figure 5-2 (page 5-3) shows two examples of menus.
The first example shows the main menu, which has three options displayed on the top line. Configure is
selected. The second line shows that the Configure function has four additional options, Parameter,
Variable, Outputs and Reports.
The second example shows the submenu that appears after the Configure function in the main menu has
been invoked by pressing Enter. The Reports function from this submenu has been selected, and another
submenu appears offering two choices--List and Report. The second line in this example describes the
List function.
5-2
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Figure 5-2 Two Examples of Menus
Stepping Through Menus
Six keys are used to navigate through the various menu options and to move through lists of parameters
or variables. They include the four cursor keys (←↑→↓) plus Enter and Esc.
The left and right cursor keys (← and →) choose among different functions within a menu. In the main
menu example shown previously, these two keys select a new option from the choices: configure,
operate, reset, and diagnose. Selection wraps from one end of a line to the other.
Once you step through the menus and access a set of parameters and variables, the set is displayed one at
a time on the second line of the display. The up and down cursor keys (↑ and ↓) choose among items
within such a list.
• Pressing ↓ displays the next item in the list
• Pressing ↑ displays the previous item
These cursor keys do not wrap around from the top and bottom of the list. Pressing ↑ when the instrument
is displaying the first item in a list brings up the menu which invoked the list in the first place; pressing ↓
from the last item in the list brings up the message Press Esc to return to previous menu.
Many parameters display a short list of available options (e.g. On, Off). The left and right cursor keys (←
and →) choose among items in such a list.
If there are too many options to display on one line, arrows (<< or >>) indicate that additional options are
available. The left and right cursor keys are used to bring up the options not shown.
The Enter key invokes the currently active selection. If the active selection has additional options, the
submenu displays them. Otherwise, the instrument carries out the function invoked.
The Esc key steps you back to the previous menu - the reverse of Enter. Refer again to Figure 5-2.
Pressing Esc in the first example has no effect, since the main menu is at the highest level of the system.
Pressing Esc twice in the second example returns to the main menu. It is possible to return to the main
menu at any time by repeatedly pressing Esc.
ACCUSONIC MODEL 7500
5-3
Initial Setup, General Operations
Note
The Esc key is also used to suspend flow measurement and activate the control panel menus.
Pressing the CTRL and Esc keys together will exit any configuration menu, automatically save
parameters, and start measurement.
Table 5-1 shows the organization of menus, Tables 5-2 through 5-4 (beginning on page 5-10) list all
parameters and variables. Chapter 7 defines each parameter and variable in detail.
Although the sheer quantity of parameters may seem intimidating at first, they have been assigned
different “access levels” so that you only see what you need to see. At the top of the general parameters
menu is the choice for access level. When access level is set to SETUP, the user will only see the
minimum parameters required to get the flowmeter operational. Stepping through the menus becomes a
simple matter of entering information where necessary (most have reasonable defaults, no entry is
required) and going down through the menus. When you arrive at the bottom of a particular menu, you
will automatically increment to the top of the next menu. Keep in mind that an explanation is available for
any parameter by pressing the “HELP” key.
On Line Help
You may request more information about a selected option by pressing the Help key at any time. Help
messages display information about the active menu. When using an external keyboard, help is available by
pressing and holding the shift key and pressing the question mark key.
5-4
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Table 5-1 Flowmeter Menu Hierarchy
CONFIGURE
PARAMETER
Section
Section 1, Section 2, etc.
(see Table 5-3 on page 5-11)
Path 1, Path 2, etc.
(see Table 5-4 on page 5-14)
General
General System Parameters (see Table 5-2 on page 5-10)
Leak
Leak Detection Parameters (see page 12-7)
Files
Save
Load
Password
Change Password
VARIABLE
Section
Section and path variables
End
End variables
Leak
Leak detection variables
General
General system variables
OUTPUTS
RS-232
Analog
Digital
Relay
Totals
REPORTS
List
List parameters and variables to a file or printer
ACCUSONIC MODEL 7500
5-5
Initial Setup, General Operations
Report
Define printer reports
OPERATE
Measure flow rate
RESET
Reset volumes and return to operate mode
DIAGNOSE
SYSTEM
Keypad
Test keypad
Display
Test display
Serial
Transmit
Data transmit test
Input
Data input test
Output
Output driver test
TRANSCEIVER
Self test
Run transceiver self test
Measurement
Locate measurement failure
Stage
Locate stage failure
Tattler
Investigate tattler LEDs
HARDWARE
Inputs
Installed inputs test
Outputs
Installed outputs test
5-6
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Here is the general organization of the parameters:
Figure 5-3 Tree organization of the parameters
ACCUSONIC MODEL 7500
5-7
Initial Setup, General Operations
Entering Parameter Values
To enter a numerical value, simply press the appropriate digit keys, including the decimal point if needed.
For very large or very small numbers, use scientific notation. Enter the whole number first, followed by
the letter E and then the power of ten (positive or negative). For example, enter 6.023 x 10-23 as 6.023E23 or enter 4.35 x 104 by typing 4.35E4.
To enter text, first press and hold one of the two shift keys and then press the appropriate letter. Use the
left shift key for letters whose legend on the key is in the top left corner; for letters marked on the top
right of the key, use the right shift key. The colon (:) is used to specify the floppy disk as the target for
data logging or parameter backup. It is entered by pressing Ctrl-1.
On Line Help
You may request more information about a selected option by pressing the Help key at any time.
Help messages display information about the active menu. When using an external keyboard, help
is available by pressing and holding the shift key and pressing the question mark key.
AutoStart
The parameter Autostart defines the action of the flowmeter upon power up. When Autostart is on, the
flowmeter will bypass the menu system and proceed directly to measuring flow. When the parameter is
off, the system starts up with the menus, and will await operator intervention before taking measurements.
It is good practice to turn this parameter off during instrument setup.
Using a Password
A password is used to lock out the control panel and prevent changing the setup of the instrument.
Password protection is in effect only when the parameter Password control is on, and the instrument is
measuring flow.
However, if Password control is on and Autostart is off, when the instrument powers up it displays the
system menu, where password control is NOT in effect. To prevent unauthorized tampering with the
instrument setup, always turn on both Password control and Autostart.
If you forget the password, contact Accusonic.
5-8
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Using an External Keyboard
The following conditions apply to the operation of the control panel when using an external keyboard:
♦The keyboard type must match the CPU type (XT or AT). 7500’s can be equipped with either
type, if you are unsure of which type is installed, use an autoswitching keyboard, which
configures itself to be the correct type when the system boots.
♦The Keypad/keyboard slide switch located on the keypad card (near the keyboard connector)
must be in the keyboard position.
♦If using an auto-switching keyboard, the system must be rebooted by turning the power switch
off and then on or by pressing Ctrl Alt Del.
♦Activate the keyboard before use by pressing Ctrl– (i.e., press and hold the control key, press
the minus key on the numeric keypad and then release both keys together.) If the keyboard is
not activated the display will appear to respond with the wrong characters as keys are pressed.
Pressing Ctrl– more than once will not cause any harm.
♦Deactivate the keyboard before unplugging it and switching back to the keypad by pressing
Ctrl+ (i.e., press and hold the control key, press the plus key on the numeric keypad and then
release both keys together.) If the keyboard is not deactivated, the display will appear to
respond with the wrong characters as keys on the keypad are pressed. The keyboard can be
deactivated only using the keyboard; it cannot be deactivated from the keypad.
♦Enter numbers from the top row of the normal keypad, or, if using a 101-key keyboard, from
the numeric keypad with NumLock on. Do not use NumLock with 88-key keyboards.
♦On 101-key keyboards, use the normal cursor control keys located to the left of the numeric
keypad. On 88-key keyboards use the cursor control keys located on the numeric keypad and
be sure NumLock is off.
♦Access the help system from an external keyboard by pressing Shift? (shift question-mark).
♦Access the status screen during measurement from an external keyboard by pressing - (minus
key).
Selecting Menu Access
Depending on how the instrument is set up, certain parameters and variables may be hidden from the
menu displays. The purpose of this is to simplify the use of the menus. For example, certain parameters
usually need to be accessed once during instrument setup. Such initial setup parameters should be hidden
in the course of day-to-day operations.
Menu Access may be changed at any time; it is controlled in the General Parameters section of the
menus, as listed in Table 5-2 (page 5-10). Refer to Chapter 7 for details. There are three menu access
levels:
Set Up - Parameters used during instrument setup
Limited - Parameters used in day-to-day operation, data access, and reporting
Extended - All parameters
The tables that follow list all parameters and variables and indicate the availability of each as a function
of menu access. The instrument displays abbreviations for some parameters and variables. All variables
are accessible at all menu access levels.
Note that, due to system enhancements, your system's menu listings may be slightly different from those
set out in this chapter.
ACCUSONIC MODEL 7500
5-9
Initial Setup, General Operations
General Parameters
General parameters govern the overall operation of the instrument. They are listed in Table 5-2. Refer to
Chapter 7 for details about each parameter. Any change to a general parameter takes effect immediately as
it is entered.
Table 5-2 List of General Parameters
General Parameter
Description and Choices
Menu Access: (setup limited extended)
Repetition time (seconds)
Self test interval (sec.)
Stage interval (seconds)
Leak detection switch (off, on)
Stage mode (normal, fast)
Datalogging (off, on)
Log data to: (disk,printer,both)
Datalog Start Time
Datalog Interval
Menu Access Level
Set Up







Limited









Error reporting (off,on)
Autostart switch (off, on)
Inactivity timeout (min.)

Display mode (sections, ends, both)
Section label character
Section starting number
Units (English, metric)
Speed of sound in fluid
Password control (off, on)
Averaging queue length
Maximum bad measurements
Travel time tolerance
Display totals line (off, on)
Always display flow totals (off, on)
Display contrast (down, up)1
Current time (HH:MM:DD)
Current date (MM:DD:YY)








Extended








14
14

















1 Used for LCD displays only; this has no effect on full-screen electroluminescent (EL) or CRT screens.
5-10
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Section Parameters
Section parameters specify:
♦ Size of the section (i.e., pipe, channel, etc.)
♦ Operating limits (velocity, flow, etc.)
♦ Section-related operations
A change to a section parameter does not take effect immediately. After you finish changing section
parameters the instrument prompts you to confirm them all as a group. The new values take effect at that
time. The parameters are listed in Table 5-3. Refer to Chapter 7 for details about each parameter. Several
of the following parameters appear only if the Section type is compound, which includes open channels.
Table 5-3 List of Section Parameters (not necessarily in order)
Menu Access Level
Section Parameter Description
Set Up
Limited
Extended



Section switch (off, on)


Section type (pipe, compound)


Pipe integration (Cheb, Gauss)
2

2
Enter pipe shape (round, other)
1

1
Radius

2
Pipe height
2
Shape Factor


Surcharged integration method


Available velocity enabled (off, on)
3

3
Cross sectional area


Non-surcharged integration method

4
Manning coefficient of roughness
4

4
Pipe slope


Single integration
5

5
Single coefficient
6

6
Q FWD
6
6
Q REV
6

6
V FWD
6

6
V REV

Stage averaging size


Stage source (off, manual, external,
other)
7
7
Stage ducer type
8

8
Frequency of other transducer
8
8
Delay time of other transducer
9

9
Manual stage value
10

10
Stage (1 or 2) range maximum
10
10
Stage (1 or 2) range minimum
7

7
Stage (1 or 2) offset
ACCUSONIC MODEL 7500
5-11
Initial Setup, General Operations
Table 5-3 List of Section Parameters, Continued
Menu Access Level
Section Parameter Description
Set Up
Limited
Extended
7
7
Average stage cable length
11
11
Maximum stage difference 1 and 2


Channel bottom height


Minimum stage


Maximum stage


Maximum change in stage


Full pipe


Minimum path submersion


Bottom channel width


Number of channel layers



Layer boundary elevation



Layer boundary width
12

12
Bottom velocity ratio
12

12
Top weight


Average cable length per path


Ducer connection (balanced, single)

Signal detection method (1st Neg, zero
crossing)


Minimum good paths

Velocity substitution (off, ratio)



Maximum expected velocity


Maximum change in velocity


Positive over velocity warning threshold


Negative over velocity warning
threshold


Over velocity warning count


Positive over velocity alarm threshold


Negative over velocity alarm threshold


Over velocity alarm count


Flowrate scale factor


Volume scale factor

Simulation source (internal, external)

Totalizer cutoff time (minutes)



Maximum expected flowrate


Maximum change in flowrate



Minimum flowrate


Bidirectional Flow (on off)
5-12
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Table 5-3 List of Section Parameters, Continued
Menu Access Level
Section Parameter Description
Set Up
Limited
Extended


Data Logging (off, on)
Log flow data (off, on)


14
14
Log negative volume data
14

14
Log velocity data
Log stage data (off, on)



Temperature coefficient 1, 2 ... 5
Zero Flow Offset


1 If Pipe integration is set to Cheb.
2 If Pipe integration is set to Gauss.
3 If Available velocity enabled is On.
4 If Non-surcharged integration is Manning.
5 If Single integration is polynomial.
6 If Single integration is USGS.
7 If Stage source is acoustic.
8 If Stage ducer type is Other.
9 If Stage source is manual.
10 If Stage source is External.
11 If redundant stages are used.
12 If Non-surcharged integration is trapezoidal.
13
14 If Data logging is set to On.
ACCUSONIC MODEL 7500
5-13
Initial Setup, General Operations
Path Parameters
Path parameters specify:
♦ Path geometry
♦ Transducer type
♦ Path-related operations
They are listed in Table 5-4. Refer to Chapter 7 for details about each parameter. A change to a path
parameter does not take effect until all parameters for a path are confirmed as a group.
Table 5-4 List of Path Parameters
Menu Access Level
Path Parameter Description
Path switch (off, on)
Path angle
Weight
Path elevation
Width at path elevation
Path position
K
Transducer type (7600, 7601, 7605
...)
Frequency of other ducer
Delay time of other ducer
Protrusion of other ducer
Path length
Path percent active
Signal Quality Monitor (off, on)
Velocity substitution ratio
Path simulation (off, velocity,
times)
Simulation velocity
Simulation forward time
Simulation reverse time
Simulation velocity ramp scale
Receiver gain (auto, manual)
Manual gain (dB)
Set Up


1
1


2
2
2


Limited

Extended



1
1



2
2
2





3
4
4


5
1 If Pipe integration is set to Gaussian.
2 If Transducer type chosen is other.
3 If Path simulation is set to velocity.
4 If Path simulation is set to times.
5 If Receiver gain is set to manual.
5-14
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Saving and Loading Parameters
Unless newly entered parameters are saved to battery-backed memory or to the diskette, they will be lost
if the unit is turned off or if power is interrupted. The flowmeter offers a mechanism to save the
parameters so they won't be lost. Parameters can be reloaded from memory or disk.
Parameters are saved to and loaded from files. Files can exist in battery-backed memory or on floppy
diskette; the system will prompt you to choose the location. Files have names, which consist of one to
eight alphanumeric characters, without punctuation marks.
There may be more than one file of saved parameters in existence at any time. For example it may be
useful to have different setups with distinct operating configurations.
In most cases you will save parameters to the default file in battery-backed memory. Doing so is
particularly convenient for normal operations, because every time the system is turned on, it loads the
parameters stored in the default file, which is named SYSTEM. If you save more than one configuration,
be careful to use a different file name for each.
When you select a save or load operation, the system prompts you to specify the location of the file.
Flowmeter refers to battery-backed memory in the flowmeter console; Disk refers to the floppy disk drive.
If you choose to save to the flowmeter, you will be asked if the default file should be overwritten. Do not
overwrite the default files unless you want the system to use the new parameters each time it is turned on.
If you choose to save parameters to floppy disk, the system prompts you to enter a filename by displaying
the message Enter file name. When you enter the filename, it appears to the right of the message.
♦
To specify the default file (system), press Enter.
♦ To save parameters to a separate file, enter characters directly from the keypad using the left and
right shift keys to select the letter desired. For example, press left-shift-1 to enter an A, press rightshift-1 to enter a B. The letters Q and Z cannot be entered using this technique. When the filename
is complete, press Enter.
ACCUSONIC MODEL 7500
5-15
Initial Setup, General Operations
First Time Power Up
Be certain that all transducers, system inputs, and system outputs are connected before powering up the
unit. On the rack-mount unit, the power switch is located on the front panel. On the NEMA unit, the
power switch is located inside the cabinet.
Turn the flowmeter and all remote flow transmitters on. The green power-good indicators in all units
should light.
Close and latch the door of the NEMA unit. After a minute or so, the instrument will show various startup
messages and then display the main menu:
[CONFIGURE] operate reset diagnose
Parameter Variable Outputs Reports
Initial checks
The first time the instrument is turned on, you may wish to adjust the contrast of the display and run a
quick diagnostic checkout before performing the initial setup. Running diagnostics also serves as an
introduction to the menus.
Adjusting Display Contrast
If you wish to adjust the contrast on an LCD display, step through the following procedure. This
procedure begins from the main menu. Return to the main menu at any time by repeatedly pressing Esc
until the main menu appears. This procedure has no effect on a full-screen CRT or full-screen EL
(electroluminescent) display.
Top line of the display shows:
[CONFIGURE] operate reset diagnose
[PARAMETER] variable outputs reports
[SECTION] general files password
section [GENERAL] files password
User Level: [SETUP] limited extended
Repetition Time (seconds):
Bypass each successive option until
Display Contrast option is shown
Display Contrast: <-Down Up->
Display Contrast: <-Down Up->
[CONFIGURE] operate reset diagnose
5-16
Press
key(s)
Enter
Enter
→
Enter
↓
↓
↓↓
→
or
←
Esc Esc
Explanation
Accept Configure
Accept Parameter
Select General
Accept General
Bypass
Bypass
Bypass each
Increase contrast
or
Decrease contrast
Go to main menu
At main menu
ACCUSONIC MODEL 7500
Initial Setup, General Operations
First Time Diagnostics
To perform a basic checkout of the system, step through the following sample sequence. This procedure
begins from the main menu. The diagnostic tests are self explanatory, and can be terminated at any time
by repeatedly pressing Esc until the main menu appears. The following sequence details only those
diagnostics that are useful as a basic checkout at system start-up. Additional diagnostic procedures are
available if problems are encountered during system operation. These diagnostics are discussed in greater
detail in Chapter 6, Diagnostics, beginning on page 6-1.
Note
Many tests cannot be run until parameters are entered and the system is run.
This is true, for example, for path diagnostics because until the path length and
other parameters are defined, the system cannot operate the paths.
Top line of the display shows:
Press key(s)
Explanation
Select Diagnose
[CONFIGURE] operate reset diagnose
→→→
Accept Diagnose
configure operate reset [DIAGNOSE]
Enter
Accept System
[SYSTEM] transceiver hardware utils
Enter
Run diagnostic
[KEYPAD] display serial printer
Enter
Press every key on the keypad, including the arrow keys. The display should show each
key as it is pressed. Terminate the test by pressing Shift-E. The system will report
statistics about the number of keys pressed. Press any key to continue.
Select Display
[KEYPAD] display serial printer
→
Run diagnostic
keypad [DISPLAY] serial printer
Enter
The display will fill with the digit 0 in every location, and then proceed through every
digit and the entire alphabet. Terminate the test at any time by pressing any key.
Select Serial
keypad [DISPLAY] serial printer
→
Accept Serial
keypad display [SERIAL] printer
Enter
Accept Transmit
[TRANSMIT] input output
Enter
The instrument will transmit and attempt to read back characters on the serial port. A
loopback connector or computer should be attached to the serial port. If there is an error, a
message will be displayed. Also refer to Chapter 6 for information on diagnostics. Press any
key to return to the menu.
Select Input
[TRANSMIT] input output
→
Accept Input
transmit
[INPUT] output
Enter
The instrument will attempt to read any incoming characters on the serial port. This diagnostic
assumes that there is traffic on the port. If there is an error message, it will appear on the
display. Refer to Chapter 6 for additional information on Diagnostics. Return to the menu by
pressing any key.
Select Output
transmit [INPUT] output
→
Accept Output
transmit input
[OUTPUT]
Enter
This diagnostic tests the RS-232 device driver by continuously outputting a stream of data
(ASCII characters) until Escape is pressed.If there is an error message, it will appear on the
display. Refer to Chapter 6 for additional information on Diagnostics. Return to the menu by
pressing Escape..
Go to previous menu
transmit input [OUTPUT]
↑
ACCUSONIC MODEL 7500
5-17
Initial Setup, General Operations
Select Printer
[KEYPAD] display serial printer
→→→
Accept Printer
keypad display serial [PRINTER]
Enter
The system displays printer status. Status display is continuous, so that if there is a
problem, you can wiggle cables, turn printer on, etc. while watching the display for
a status change. See Chapter 6 for status messages. Press Escape to return to the
menu.
Go to previous menu
keypad display serial [PRINTER]
Esc
Select Transceiver
[SYSTEM] transceiver hardware utils
→
Accept Transceiver
system [TRANSCEIVER] hardware utils
Enter
Run self test
[TEST] run stage path align comm
Enter
The instrument will run a brief self test of the flow transmitter, and report the
results on the display. If there is an error message, continue testing by selecting
Diagnose and follow the instructions given on the screen. Also refer to Chapter 6
for information about flow transmitter diagnostics. Return to the above menu by
pressing Esc.
Select Run
[TEST] run stage path align comm
→
Measurement
Accept Run
test [RUN] stage path align comm
Enter
Measurement
The instrument performs further diagnostics on the flow transmitter. If errors appear in the
Operate mode, this test and the Stage diagnostic test may help isolate the problem. The type of
error will be displayed on the console display. Also refer to Chapter 6 for information about
flow transmitter diagnostics. Press Escape to return to the menu after either test.
Return to higher
Esc
menu level
Select Hardware
[SYSTEM] transceiver hardware utils
→→
Accept Hardware
system transceiver [HARDWARE] utils
Enter
Accept Outputs
[OUTPUTS] inputs
Enter
If the system has been configured for outputs, the first output and type of output will appear on
the display. Pressing the down or up arrows will toggle between installed outputs. Start with
the first output shown. The following procedure shows an analog (e.g., 0-10V or 4-20 mA)
output.
To show current
OUT1 Analog 8-bit channel 0
Enter
output level
To toggle to half or
OUT1 Analog 8-bit channel 0 = zero
Enter
full scale
Watch the external output device to see if it reads at the corresponding level (i.e., representing
zero, half-scale or full-scale) as the output is toggled. Relay outputs will toggle between On
and Off. Volume totalizers will increment each time Enter is pressed.
Pressing Escape once returns to the output listing. Use the down arrow to toggle through the
list and test each output. After testing all outputs, press Escape twice to return to the previous
menu. Remember to reset any volume totalizers that have been incremented during this
procedure.
Select Inputs
[OUTPUTS] inputs
→
Accept Inputs
outputs [INPUTS]
Enter
If the system is configured for inputs, the type and location of the first input will be displayed.
Pressing the down or up arrows will toggle through the list of inputs.
5-18
ACCUSONIC MODEL 7500
Initial Setup, General Operations
To show current
input level
Return to list of
IN1 Analog 8-bit channel 0 = 1032
Esc
inputs
Watch the external input device to see if it is reading at the corresponding value. Relay
outputs will toggle between On and Off.
Pressing Escape once returns to the input listing. Use the down arrow to toggle through the
list and test each input. After testing all inputs, press Escape twice to return to the previous
menu.
Go to main menu
outputs [INPUTS]
Esc Esc
At main menu
configure operate reset [DIAGNOSE]
IN1 Analog 8-bit channel 0
ACCUSONIC MODEL 7500
Enter
5-19
Initial Setup, General Operations
Initial Flowmeter Setup
There are four required and two optional procedures to setting up the instrument:
1. Set up general parameters
2. Set up each section
3. Set up each path in each section
4. Set up the password (optional)
5. Save the configuration
6. Print parameters (optional)
The flowmeter has been factory-configured with the number of pipes or channels and the number of paths
in each, as specified at time of purchase. After installation, there are a number of site-specific parameters
which must be input. During the process of entering setup parameters, the menu access level Setup is
recommended. See Chapter 7 for a detailed description of the setup parameters.
Site parameters are available from the site engineer who worked with Accusonic to define the application.
As-built parameters are determined by survey when transducers are installed in each section. If the
transducers were installed by Accusonic, the as-built parameters are on file at the Accusonic factory.
Table 5-5 is a checklist of parameters needed for initial setup.
5-20
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Table 5-5 Checklist of Initial Setup Parameters
Parameter
Value
Units (English or metric)
The following parameters are required for each section:
Radius (if conduit is pipe and integration is Chebyshev)
Pipe Height (if conduit is pipe and integration is
Gaussian)
Shape Factor (if conduit is pipe and integration is
Gaussian)
Average cable length per path
Minimum good paths
Maximum expected velocity (will be calculated based on
maximum expected flowrate)
Flowrate scale factor
Volume scale factor
Maximum expected flowrate
Maximum change in flowrate
Bidirectional flow
The following as-built parameters are required for each path in each
section.
Path angle
Path elevation (if integration is Gaussian or if open
channel)
Width at path elevation (if integration is Gaussian or if
open channel)
K (defaults to optimum value)
Path position (if integration is Gaussian or if open
channel)
Transducer type
Path length
Path percent active (defaults to 100%)
ACCUSONIC MODEL 7500
5-21
Initial Setup, General Operations
Procedure #1 - Set up General Parameters
This procedure includes:
♦Selecting the access level
♦Defining frequency of flow measurements
♦Specifying English or metric units
To set up general parameters, step through the following procedure. This procedure begins at the main
menu. Return to the main menu at any time by repeatedly pressing Esc until the main menu appears.
Top region of the display
[CONFIGURE] operate reset diagnose
[PARAMETER] variable outputs list
[SECTION] general files password
section [GENERAL] files password
User level: [SETUP] limited extended
Repetition Time (seconds)
Autostart [OFF] on
Autostart off [ON]
Units [ENGLISH] metric
System will beep, then display:
Press Esc to return to previous menu
section [GENERAL] files password
[SECTION] general files password
5-22
Press
key(s)
Enter
Explanation
Accept
Configure
Accept
Enter
Parameter
Select General
→
Accept General
Enter
Accept Setup
Enter
Enter number of seconds between
successive measurements.
Select On
→
Accept On
Enter
Accept English
Enter
or select and
or
accept metric
→ Enter
Return to
Esc
previous menu
Select Section
←
Ready for next
step
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Procedure #2 - Setting up Section Parameters
This procedure includes:
♦Selecting a section
♦Turning the section on
♦Specifying radius or conduit dimensions
♦Entering the average cable length
♦Specifying limits on flow rate and fluid velocity to be used for reasonability checks
♦Setup of the path parameters for each path in the section
To set up section parameters, repeat this procedure for each section, and perform the path setup as
described in Procedure #3. Be sure to set up every path in each section. This procedure does not begin at
the main menu; it begins where Procedure #1 left off. To run this procedure starting from the main menu,
select and accept Configure and then select Parameter.
As you enter path parameters, the software checks that the values entered for path length, elevation, and
angle are consistent with the radius entered for the meter section. If the values are not consistent, the
instrument will beep and display the message, Possible path length error. Double check the values
entered for an error, and if the reasonability test still fails, check with Accusonic for help. In the
meantime, it is possible to ignore the error and proceed with entering the remaining parameters. The flow
results for the section with the possible path error, of course, will be suspect.
For each path and section you will be asked by the software whether to use the newly entered data in the
current operation. This causes the set of parameters just entered to take effect as a group, but does not
back up the new parameters to battery-backed memory or to the diskette. Before leaving the Configure
submenus you will be asked whether to save the changes. If the changes are not saved at this time and if
the flowmeter is shut down or power is lost before the data is backed up to battery-backed memory or to
the diskette, the new parameters will be lost. If you wish to save the changes at this time, the system will
ask you to enter a file name. There are two ways to enter the filename:
♦Press the Enter key to select the default filename, SYSTEM.
♦Enter the characters directly from the keypad using the left and right shift keys to select the letter
desired. For example, press left-shift-1 to enter an A, press right-shift-1 to enter a B. The letters Q and
Z cannot be entered using this technique.
An alternative rapid way to return to the Operate mode from anywhere in the parameter menus is by
pressing <CTRL ESC>. This causes the parameter to be stored in the flowmeter under the default file
SYSTEM, and then download them to restart measurements.
Procedure number 5 (page 5-27) also shows how to back up the data at a later time so that it will not be
lost in the event of shutdown or power loss.
Section parameters are listed in Table 5-3 (beginning on page 5-11), and described in detail in Chapter 7.
ACCUSONIC MODEL 7500
5-23
Initial Setup, General Operations
The procedure for setting the section parameters is given below:
Top region of the display
Press key(s)
[SECTION] general files password
[SECTION 1] section 21 etc.
OFF
off
Enter
Enter
or
→ Enter
Section switch [OFF] on
Section switch off
[ON]
Enter each section parameter as it is displayed.
See list in Table 5-3; refer to Chapter 7 for details.
→
Enter
[PATH 1] path 22 etc.
OFF
off

...

Explanation
Accept Section
Accept selected
section or
select and accept
next section
Select On
Accept On
Go to
Procedure #3 to
set up all paths.
Then return here to
continue with the next
section.
To next section
[PATH 1] path 2 etc.
Esc
Now accept the newly entered parameters:
Use new section 1 changes:
no [YES]
Choose yes to accept the new section values, no to discard. Then press Enter.
Note: This operation accept the newly entered values and causes them to take effect.
It does not backup the new values to battery-backed memory or to diskette.
Until the values are backed up, they will be lost in the event the flowmeter is
powered down. You will be prompted to save these values to a file before leaving
the Configure submenus.
The instrument prompts for the next section. If there are additional sections to fill in,
repeat the steps above. Repeat until the parameters for all sections are entered.
After data is entered for the last section, the instrument prompts for section 1 again.
When all sections have been completed, continue with the following:
Go to main menu
[SECTION 1] section 2 etc.
Esc
Esc
Esc
(At main menu)
[CONFIGURE] operate reset diagnose
1 Section 2 (etc.) appears only if configured by the factory for more than one section.
2 Path 2 path 3 (etc.) appears according to the number of paths configured by the factory for the
current section of this meter.
5-24
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Procedure #3 - Setting up Path Parameters
This procedure includes:
♦Selecting a path
♦Turning the path on
♦Specifying geometry of the path (angle, position, length, percent active)
♦Entering the type of transducer
To set up path parameters, repeat the following procedure for each path. This procedure begins after
section parameters have been entered as in Procedure 2. Return to the main menu at any time by
repeatedly pressing Esc until the main menu appears.
Path parameters are listed in Table 5-4 (see page 5-14), and described in detail in Chapter 7.
Top region of the display
Press key(s)
Explanation
Accept selected path
[PATH 1] path 21 etc.
Enter
or
OFF
off
or
select and accept
→ Enter
next path
Select On
Path switch [OFF] on
→
Accept On
Path switch off
[ON]
Enter
Enter each parameter as it is displayed. (See list in Table 5-4; refer to Chapter 7 for details.)
After the last parameter is entered, the instrument beeps and displays:
To previous menu
Press Esc to return to previous menu
Esc
The instrument performs a check on the overall geometry of the path to be sure that path length
is consistent with the data entered for path angle and position. If the data is not consistent, the
instrument beeps and displays:
Possible path length error: [RETRY] ignore
Choose retry and press Enter to review all path parameters again, then adjust accordingly.
Otherwise, choose ignore and press Enter to skip to the next step.
Now confirm the newly entered parameters:
Use new path 1 changes: no [YES]
Choose yes to accept the new path values, choose no to discard them. Then press Enter.
Note: This operation accepts the newly entered values and causes them to take effect.
It does not backup the new values to battery-backed memory or to diskette.
Until the values are backed up, they will be lost in the event the flowmeter is
powered down. You will be prompted to save these values to a file before leaving
the Configure submenus.
Proceed to enter parameters for the next path, if any. To do so, go to the beginning of this
procedure and repeat all the steps above. Repeat until the parameters for all paths are entered.
After data is entered for the last path in the current section, the instrument prompts for
path 1 again. When all paths are complete for this section, continue with the following.
Return to
[PATH 1] path 2 etc.
procedure #2
1 Path 2 path 3 (etc.) appears according to the number of paths configured by the factory for
the current section of this meter.

ACCUSONIC MODEL 7500
5-25
Initial Setup, General Operations
Procedure #4 - Setting the Password (optional)
The instrument is shipped with a blank password. To enter a password or to change an existing password,
step through the following procedure:
Top of the display
[CONFIGURE] operate reset diagnose
[PARAMETER] variable outputs reports
[SECTION] general files password
section general files [PASSWORD]
Change password
section general files [PASSWORD]
Enter old password:
section general files [PASSWORD]
Enter new password:
section general files [PASSWORD]
Retype new password:
Password changed successfully
Strike any key to continue.
[CONFIGURE] operate reset diagnose
Press
key(s)
Enter
Enter
→→→
Enter
Type in
old
password,
then
Enter
Type in
new
password,
then
Enter
Type in
new
password,
then
Enter
Esc Esc
Esc
Explanation
Accept Configure
Accept Parameter
Select Password
Accept Password
If no password was
ever entered, just
press Enter
Enter new code
Repeat entry
Go to main menu
At main menu
For the password to be used, you must also enable password protection. This is done in the General
parameters list, under Extended menu access.
5-26
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Procedure #5 - Save Configuration
This procedure includes:
♦Specifying a file name
♦Saving the current configuration to that file
Note
If the flowmeter is equipped with a diskette unit and you wish to save
parameters to a diskette, be sure there is a blank DOS-formatted high density diskette
in the drive unit.
In this procedure, parameters are saved to a file in battery-backed memory and optionally to a diskette
file. Any filename will do; just bear in mind that to reload the parameters from diskette or from batterybacked memory, you must remember the name of the file in which you originally saved the data. If you
skip the filename, the system will store the parameters in a default file named SYSTEM.
When saving to a diskette file, the system prompts you to enter a filename by displaying the message
Enter file name on the display. As you enter the filename, it will appear to the right of the message on the
second line. There are two ways to enter the filename:
♦ Press the Enter key to select the default filename, SYSTEM.
♦ Enter the characters directly from the keypad using the left and right shift keys to select the letter
desired. For example, press left-shift-1 to enter an A, press right-shift-1 to enter a B. The letters Q
and Z cannot be entered using this technique.
To save the current parameter configuration, step through the following procedure. This procedure begins
at the main menu. Return to the main menu at any time by repeatedly pressing Esc until the main menu
appears.
ACCUSONIC MODEL 7500
5-27
Initial Setup, General Operations
The procedure for saving a configuration follows:
Top region of the display
Press key(s)
Explanation
Accept Configure
[CONFIGURE] operate reset diagnose
Enter
Accept Parameter
[PARAMETER] variable outputs reports
Enter
Select Files
[SECTION] general files password
→→
Accept Files
section general [FILES] password
Enter
Accept Save
[SAVE] load
Enter
Accept Flowmeter
Save to: [FLOWMETER] disk
Enter
Accept Yes
Overwrite default parameters? [YES] no
Enter
The system saves all parameters to battery-backed memory in files named SYSTEM.
Upon completion the Save/Load menu is displayed again. If the flowmeter is equipped
with a diskette unit, continue with the following steps, otherwise return to the main menu
by repeatedly pressing ESC until the display matches the last line in this procedure.
Accept Save
[SAVE] load
Enter
Select
Disk
Save to: [FLOWMETER] disk
→
Accept Disk
Save to: flowmeter [DISK]
Enter
Specify default file
Enter file name:
Enter
for Save operation
The system saves all parameters to diskette in files named B:SYSTEM.
Upon completion the Save/Load menu is displayed again.
Go to main menu
[SAVE] load
Esc Esc Esc
At main menu
[CONFIGURE] operate reset diagnose
5-28
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Procedure #6 - Print Parameters
After parameters are entered and saved, print a listing of the parameters for review purposes. The
procedure that follows assumes that a compatible printer and cable have been installed according to the
procedures given in Chapter 4, Connecting a Printer (page 4-6). The printer must be turned on and be on
line.
To print parameters, step through the following procedure:
Top region of the display
Press key(s)
Explanation
Accept Configure
[CONFIGURE] operate reset diagnose
Enter
Select Reports
[PARAMETER] variable outputs reports
→→→
Accept Reports
parameter variable outputs [REPORTS]
Enter
Accept List
[LIST] report
Enter
Accept All
[ALL] parameters variables
Enter
Accept Printer
List to: [PRINTER] file cancel
Enter
The system prints all parameters and variables. Upon completion, the previous menu is
displayed again.
parameter variable outputs [REPORTS]
[CONFIGURE] operate reset diagnose
Esc Esc
Go to main menu
At main menu
If a printer is not available, a listing should be made to floppy disk. The floppy disk listing will be in
standard text-file format, and will automatically be named LISTING.PRN. This can be printed later on
any DOS-based PC with a printer connected.
ACCUSONIC MODEL 7500
5-29
Initial Setup, General Operations
Measuring Flow
After parameters are entered, place the flowmeter on line by selecting and accepting the Operate option
from the main menu.
If Autostart switch is on, the instrument will automatically begin to measure flow immediately after the
system powers up (See Chapter 7, Parameter List on page 7-1).
Flow measurements are made at a rate set by the parameter Repetition time until the process is interrupted
via the control panel or the unit is shut down. Although not strictly necessary, it is good practice to take
the unit off line before powering it down. This can be done by pressing Esc, which returns control to the
main menu.
Interrupting Measurements
Flowmeter measurements may be interrupted at any time, thus returning control to the control panel
menus. This may be done to gain access to parameters or variables, to run a diagnostic, to modify data
logging or data reporting, or simply to shut down the unit.
After an interruption, no further measurements are taken. If the unit is left off line for a period exceeding
the totalizer cutoff time, flow totalization is also interrupted (described in Chapter 3, see Volume Totalizer
after Outage on page 3-25). While measurements are suspended, the watchdog timer is deactivated, all
system inputs are ignored, and all system outputs are held at the current values.
Note that measurements are also not performed while the meter is in a Configuration menu. The General
parameter Inactivity timeout (see page 7-10) is used to avoid loss of measurement data if the flowmeter is
accidentally left in a Configuration menu. The parameter should be set to the number of minutes of
measurement information that you can afford to lose. The flowmeter will automatically restart and return
to Operate mode after this period of time has elapsed.
When there is no password protection in effect, simply press Esc to take the unit off line and return to the
menu prompts. When password protection is in effect, pressing Esc while the instrument is making flow
measurements causes the prompt Enter Password to Abort to appear on the display. Enter the password
and then press the Enter key to activate the control panel menus. If the password is not entered within
fifteen seconds, the system resumes measurements.
5-30
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Display Screens
Several display screens are available, enabling the flowmeter operator to choose which variables will be
displayed. The same variable headings will appear on a 4-line x 40-character display, full-screen display,
or a separate CRT. The 4-line x 40-character display shows headings, and up to three lines of data (which
may be for 3 separate sections, ends, or totals). If there are more than 3 lines of data to be displayed, the
screens can be scrolled vertically using the ↑ and ↓ keys. Values from numerous measurement sections
and subtotals as well as a totals line can be displayed simultaneously on a full-screen display.
When shipped from the factory, the 7500 console is typically set to display the headings shown in Mode 1
below, with flowrate and total volumes for bi-directional flow. Section status (GOOD, ALERT, or BAD)
is displayed under the DATE heading.
Other display modes are available and can be activated while in measurement mode by pressing the
numbers 1 through 0 or the letter A, S, W, X, or Y on the keypad or external keyboard (capital A).
When viewing any of the screen modes, status codes can be viewed by pressing the “ECODE” key or the
± key on the keypad, (press the "-" (minus) key on an external keyboard). To return from status codes to
the last selected data display screen described above press BKSP, or the appropriate number or letter key.
Screen Display, Mode 1
#
S1
S2
T
FLOW POS-VOL
0.000
0
0.000
0
0.000
0
NEG-VOL
0
0
0
DATE
GOOD
GOOD
TIME
Screen Display, Mode 2-Open Channel/Compound Installations
This mode is used for open channel/compound installations. For each section, flowrate, fluid level
(stage), the integration method being used, and measurement status are displayed, as shown below.
#
S1
S2
T
FLOW STAGE
0.000
0.0
0.000
0.0
0.000
0.0
ACCUSONIC MODEL 7500
INTEG
TRAP
CHEB
DATE
GOOD
GOOD
TIME
5-31
Initial Setup, General Operations
Screen Display, Modes 3 and 4 - Individual Path Velocities
These screens show instantaneous velocities along acoustic paths 1-4 and 5-8, respectively, and are used
during system commissioning or troubleshooting, as well as during testing. The following example shows
the Mode 3 display (i.e., velocities, paths 1-4, for three measurement sections).
#
S1
S2
S3
VEL1
0.000
0.000
0.000
VEL2
0.000
0.000
0.000
VEL3
0.000
0.000
0.000
VEL4
0.000
0.000
0.000
Screen Display, Modes 5 and 6 -Leak Detection
These screens are used for displaying variables associated with Leak Detection functions and are
available only with the full-screen display or CRT options.
Mode 5
#
FLOW
POS VOL
NEG VOL
E1
E2
0.000
0.000
0
0
0
0
T
0.000
0
0
E3
E4
0.000
0.000
0
0
0
0
DATE
TIME
Mode 6
TOP
FLOW
0.000
0.000
#
E1
E2
BOT
FLOW
0.000 0
0.000 0
DIFF
FLOW
ALARM/
STATUS
GOOD
GOOD
Screen Display, Mode 7 - Positive Volume Only
This screen displays only positive volumes, rather than positive and negative totals, and is used at sites
where flow is unidirectional.
#
S1
S2
T
FLOW
0.0000
0.0000
0.0000
5-32
VOLUME
0
0
0
STATUS
GOOD
GOOD
DATE
TIME
ACCUSONIC MODEL 7500
Initial Setup, General Operations
Screen Display, Mode 8 - Leak Detection, Positive Volume Only
This screen displays only positive volume, as well as system status, date and time.
#
FLOW
VOLUME
STATUS
E1
E2
E3
0.000
0.000
0.000
0
0
0
GOOD
GOOD
GOOD
T
0.000
0
GOOD
E4
E5
0.000
0.000
0
0
GOOD
GOOD
DATE
TIME
Screen Display, Modes 9 and 0 - Transducer Gains
These screens display forward and reverse transducer gains for paths 1-4 and 5-8, respectively, and are
most useful when aligning or troubleshooting transducers.
# 1F 1R 2F 2R 3F 3R 4F 4R
S1 0
0 0 0 0 0 0 0
S2 0
0 0 0 0 0 0 0
TIME
Screen Display, Mode A - Temperature
Temperature is displayed on this screen. Press A on the keypad or capital A on a separate keyboard to
display this screen.
#
S1
S2
S3
FLOW
0.000
0.000
0.000
VOLUME
0
0
0
TEMP
33.7
33.5
33.5
DATE
GOOD
GOOD
GOOD
Screen Display, Mode S - Stage
This screen displays stage(s) for each section. Stage will not be displayed if stage status is ‘9’ (off) and
will be “dashed” if stage status is other than ‘1’ (Good), ‘8’ (alias warning) or ‘6’ (maximum difference in
stages exceeded).
#
STAGE1
STAGE2
STAGE3
STAGE4
S1
0.0000
0.0000
S2
0.0000
Screen Display, Modes W, X, and Y
These are custom screens set up at Accusonic. They can be programmed to display any combination of
variables and text, in any language. Bar graphs can also be displayed of any variable. When custom
programming has not been installed, these screens are defaulted to simple single-section displays. Contact
Accusonic for custom display programming.
ACCUSONIC MODEL 7500
5-33
Initial Setup, General Operations
Special Configurations
Occasionally, it may be necessary to configure the meter in a “non-standard” mode to meet a particular
requirement. This section contains special configurations.
Using Layer Boundary Parameters to Simulate a Round Pipe.
When a “compound flowmeter” is set up in a pipe, the shape of the pipe has to be described using the
Layer Boundary Parameters. If the pipe is round, a large number of possible ways of describing its shape
in terms of trapezoidal layers can be devised.
The table below gives one possibility, which has the merits of giving very close approximations to the
wetted area, with only 15 numbers to be calculated. The maximum errors occur when the stage is below
0.1 x Pipe Diameter. This is below the lowest layer and likely to be below the lowest path, and so of no
relevance. At a stage of 0.05 x Pipe Diameter, the error is 4.5% of actual area. For stages between 0.1 and
0.2 x Pipe Diameter, the errors are less than 0.2%. Above 0.2 x Pipe Diameter, the errors are small.
Layer Boundary Elevation
0.1 x Diameter
0.2 x Diameter
0.3 x Diameter
0.4 x Diameter
0.5 x Diameter
0.6 x Diameter
0.7 x Diameter
0.8 x Diameter
0.9 x Diameter
1.0 x Diameter
Layer Boundary Width
0.612 x Diameter
0.807 x Diameter
0.920 x Diameter
0.984 x Diameter
1.003 x Diameter
0.987 x Diameter
0.920 x Diameter
0.807 x Diameter
0.612 x Diameter
0.205 x Diameter
Other Parameters which have to be set as part of this scheme:
Bottom Channel Width:
0.205 x Diameter
Bottom Velocity Ratio:
0.5
Channel Bottom Height:
0.000
Top Weight:
0.0
All Path Elevations in terms of measured distance above the channel bottom.
5-34
ACCUSONIC MODEL 7500
Chapter 6
Maintenance and Repairs
Maintenance
Accusonic recommends biweekly inspection during the first two months of operation, and monthly
thereafter:
♦ Inspect transducers and remove built-up debris to ensure that performance is not degraded.
Inspect cables and other parts for wear and replace as necessary.
♦ Visually inspect inside the electronics cabinet for signs of damage and check that both fans in the
cabinet are operating.
♦ If the system has a chassis-style enclosure, clean the dust filter on the rear panel monthly. More
frequent cleaning may be required in dusty environments.
♦ If the system has a NEMA enclosure, brush away any accumulated dust or dirt. The system
maintains its temperature by transferring heat through the walls of the enclosure. Dirt buildup will
result in heat buildup and potential early failure.
♦ Recheck transducer cables for isolation and leakage, as described in Chapter 4, Transducer
Cabling and Checkout on page 4-5).
Diagnostics
Problems in the system processor group can be located using system diagnostics. Chapter 5 describes
First Time Diagnostics (beginning on page 28) procedures recommended at the time of initial system
setup and for use any time a problem occurs with one of these components. These include diagnostics of
the:
♦
♦
♦
♦
♦
♦
Keypad
Display
Serial inputs and outputs
Analog inputs and outputs
Printer
Transceiver Self-test
Additional diagnostic procedures are described below. These procedures are recommended if the section
status displays BAD during normal operation, indicating that good measurements are not being made by
the flowmeter. Section status is displayed by pressing the "ECODE" key or the +/- key on the keypad, or
by pressing the minus sign (-) on a separate keyboard. Press ESCape to toggle back to normal display
screen.
Information on the Error Codes is available by pressing the HELP key on the keypad, or by pressing
Shift? (Shift and question-mark keys) on a separate keyboard. Also see Chapter 9 for additional
information on the error codes, as well as possible causes, and suggested troubleshooting.
ACCUSONIC MODEL 7500
6-1
Maintenance and Repairs
System Reset (Procedure 1)
If the Section Status Error Code displays C or H during operation, perform the following procedure to
reset the transceiver. This procedure begins at the main menu.
Top line of the display
Press key(s)
Explanation
[CONFIGURE] operate reset diagnose
configure operate [DIAGNOSE]
[SYSTEM] transceiver hardware utils
system [TRANSCEIVER] hardware utils
[TEST] run stage path align comm
test run stage path align [COMM]
[RESET] statistics
→→→
Enter
→
Enter
→→→→→
Enter
Enter
RESET sent
EscEscEsc
Select Diagnose
Accept Diagnose
Select Transceiver
Accept Transceiver
Select Comm
Accept Comm
Perform software
reset of transceiver
Return to main menu
From main menu, select Operate mode and watch the meter for several minutes to see if Section Status
error codes reappear.
6-2
ACCUSONIC MODEL 7500
Maintenance and Repairs
Transceiver Diagnostics (Procedure 2)
If the transceiver has been reset and section error codes of C or H continue to appear in the Operate mode,
continue with transceiver diagnostics by performing the following procedure, which begins at the main
menu.
Top line of the display shows:
[CONFIGURE] operate reset diagnose
configure operate [DIAGNOSE]
[SYSTEM] transceiver hardware utils
system [TRANSCEIVER] hardware utils
[SELF-TEST] measure stage comm align
self-test [MEASURE] stage comm align
Press key(s)
→→→
Enter
→
Enter
→
Enter
Explanation
Select Diagnose
Accept Diagnose
Select Transceiver
Accept Transceiver
Select Measure
Accept Measure
The system performs diagnostics on the flow transmitter and displays messages to help isolate the
problem. These error messages are listed in Table 6-1 (see page 6-4). Note that some of these messages
are for informational purposes only and do not indicate an error. If any other messages are displayed, try
correcting the problem by replacing the transceiver card set, as described later in this chapter.
Table 6-1 (see page 6-4) also indicates other cards or cables which might be replaced in response to
specific diagnostic error messages, if replacing the transceiver card has not corrected the problem.
Procedures for replacing other cards are described later in this chapter.
ACCUSONIC MODEL 7500
6-3
Maintenance and Repairs
Table 6-1 System Diagnostic Error Messages
+10 Volt internal supply failure
+12 Volt external supply failure
+2.5 Volt internal reference failure
-12 Volt external supply failure
Active transmit (Information only)
AGC D/A A/D Linearity test failure
Background test failure
Bad input data string in past (Also try replacing the Communications board)
Believability test failure
Communication protocol error (Also try replacing the Communications board)
Continuous noise in past
Continuous noise now
Data rejected - bad SQM
Data rejected - noise
Differential gain 6 dB
Global fakes in use now (Informational only)
Hardware failed to reset
Hardware test function error
Impulse noise in past
Impulse noise now
Input buffer overflow
Invalid measurement (T 1/16 Tbar)
No receive - counter overflow
Oscillator test failure
Output buffer overflow
Passive transmit (Informational only)
Path enable bit not set (Also try replacing Communications board)
Path parameters not set (Also try replacing Communications board)
Path selector not connected (Also try replacing the Path Selector cards and cables)
Pcodes in use now (Informational only)
RAM in use test failure
Read Timeout! Any key to continue (No communication with COMM board/device driver)
(Also try replacing the Communications board)
Receiver detector level failure
Self test enable bit not set (Also try replacing Communications board)
Self test errors
Self test parameters not set
Stage errors. Time counter did not start
Time counter did not start
Transmitter did not charge (Also try replacing Transmitter board and cables)
Transmitter not connected (Also try replacing Transmitter board and cables)
Unidentified interrupt
Unknown background testing error
Write Timeout! Any key to continue (Could not write to the device driver - driver hung up)
6-4
ACCUSONIC MODEL 7500
Maintenance and Repairs
Stage (Level) Diagnostics (Procedure 3)
In Open Channel or Compound installations only, if the Stage Status Error Code displays 2, H or C
during operation, perform the following procedure, which begins at the main menu:
Note
This stage diagnostic is only valid when the stage device is an Acoustic uplooker.
If the stage device is connected via an analog input, use the hardware input
to diagnose the stage device.
Select Diagnose
[CONFIGURE] operate reset diagnose
→→→
Accept Diagnose
configure operate [DIAGNOSE]
Enter
Select Transceiver
[SYSTEM] transceiver hardware utils
→
Accept
system [TRANSCEIVER] hardware utils
Enter
Transceiver
Select Stage
[SELF-TEST] measure stage comm align
→→
Accept Stage
self-test measure [STAGE] comm align
Enter
Stage Diagnostic errors: following is a list of all possible errors you will encounter when using the stage
diagnostic module, and suggested courses of action:
No errors found - Normal operation
PARAMETER ERRORS: These generally occur because stage parameters have not been activated.
Note that stage parameters must be entered and downloaded for stage diagnostics to run. Download by
entering measurement mode.
Stage on/off mask not set
Stage parameters not set
Stage enable bit not set
Global fakes in use now
Pcodes in use now
HARDWARE ERRORS: The following indicate Transceiver board failures. If any of these errors
occur, the Transceiver board should be replaced, as it is not field repairable and requires recalibration if
parts are replaced.
Unknown Transceiver failure
Hardware failed to reset
Believability test failure
Time counter did not start
AGC D/A A/D Linearity test failure
-12 Volt external supply failure
Receiver detector level failure
Oscillator test failure
RAM in use test failure
Unknown background testing error
Other hardware errors, probably not on the Transceiver.
Transmitter did not charge - Check 180V light, if out, replace 180V supply. If lit, replace Transmitter
board.
Transmitter not connected - Reseat or replace transmitter, cabling to transceiver.
Stage selector not connected - Reseat or replace Stage board, cabling between transceiver and
Transmitter.
ACCUSONIC MODEL 7500
6-5
Maintenance and Repairs
COMMUNICATIONS ERRORS - These errors indicate a problem between the PC side and
communications board or between the communications board and the transceiver. Both the Transceiver
board and the Communications board should be replaced.
Table 6-2 Status Light Error Definitions
0
1
2
3
4
5
6
7
System has been reset since power up (normally on)
Unused
Unexpected interrupt (system problem, may be outside the flow transmitter section)
Initialization error
Serial communications problem
Communication hardware error
Transceiver error, run Transceiver Self Test and Diagnose procedures in Chapter 5
Transceiver group error; on when any of LEDs 2-6 (above) is on
Repairs
All repairs must be done with the instrument turned off. As a further precaution, turn off the electrical
supply to the flowmeter at the external circuit breaker.
Warning
If transducers are attached to the flowmeter, do not attempt
any repairs to the unit during an electrical storm.
Separate procedures are supplied for flowmeters mounted in NEMA and rack-mounted cabinets.
Review of Anti-static Procedures
The flowmeter contains CMOS integrated circuits which are susceptible to damage from static discharge.
Always use anti-static procedures when handling components inside the cabinet. The best procedure is to
wear a grounding wrist strap attached to a bare metal surface inside the cabinet. At the very least,
discharge any possible static buildup by touching a bare metal surface in the cabinet immediately before
handling any electronic assembly.
6-6
ACCUSONIC MODEL 7500
Maintenance and Repairs
Replacement Procedures for NEMA Cabinets
Replacing System Processor Circuit Boards
To replace system processor circuit cards (those located in the upper half of the cabinet), first remove the
card retainers, as shown in Figure 6-1 (see page 6-8). Both retainers must be removed to gain access. After
the retainers are out of the way, the cards pull out.
Depending on the instrument configuration, there may be slots for eight or ten cards in the processor
group. Except for the system processor card, there are no fixed slot locations. The flowmeter is shipped
with a configuration sheet detailing the actual location of circuit cards in your instrument. A copy of the
configuration sheet is kept on file at the factory.
Before removing a circuit card, always double check its identity by finding a connector or external
connection to that card, and then tracing it back to the unit. Alternatively, the cards are labeled in etch
along one edge, and most bear at least one identifying label from the manufacturer.
Before disconnecting any cables from a circuit card, be sure to note the location and orientation of the
connectors to ensure that they can be reinstalled correctly. Some cable connectors in the system are NOT
polarized; if installed backwards, they can cause damage.
Specific considerations:
♦ System processor card - Has two cables which must be detached before removing the card.
Refer to system As-built drawings in the rear of this manual for card locations.
♦ Basic I/O card - Has three cables which must be removed.
♦ System communications card - Has at least one and possibly four cables plugged into it.
Furthermore, if the flowmeter is attached to remote flow transmitters, there will be additional
components on the card. Be sure to replace the card with the proper type. See configuration sheet
for details.
♦ Diskette controller card and System I/O cards - All have at least one cable. Be sure to note the
configuration and reattach the cables correctly to the replacement card. These connectors are not
keyed and will cause damage if installed backwards.
ACCUSONIC MODEL 7500
6-7
Maintenance and Repairs
Figure 6-1 Card Retainters
Replacing Transceiver Card Set
The transceiver card set is held in place by the left card retainer. Remove the retainer and remove the two
cards together after removing the cable attached to the upper right hand side of the two-card set. In most
cases the cards are replaced as a pair. If necessary, remove the two ribbon cables to separate the cards.
Removing the Connector Panel
Remove the connector panel (Figure 6-2 on page 6-9) to gain access to the path and stage cards, the pulse
transmitter and the high voltage power module.
Remove the panel by loosening four captive thumbscrews marked with arrows and located approximately
in the corners of the panel.
Gently pull the panel forward and let it rest on the lower surface of the cabinet. The cables mounted on
the rear panel will prevent it from dropping completely out of the way.
Depending on the configuration of the instrument, there will be one or two narrow ribbon cables which
obstruct access into the area behind the connector panel.
Unplug the cables at the far end of any cables. Note the location of the mating connectors to ensure
correct reassembly.
6-8
ACCUSONIC MODEL 7500
Maintenance and Repairs
Replacing Path or Stage Cards
Path and stage cards are mounted on the back of the connector panel, as shown below in Figure 6-2. They
are exposed and accessible after the connector panel is removed. The cards simply unplug from the panel
for replacement. Be sure to install a replacement card in the same slot.
Figure 6-2 Rear View of Connector Panel in Lowered Position
Replacing the Pulse Transmitter
The pulse transmitter is located on the back of the connector panel as shown above in Figure 6-2. Remove
the ribbon cable before pulling the card from its socket.
Reverse the procedure to reassemble.
Replacing the High Voltage Power Module
The high voltage power module is attached to the left end of the plate supporting the connector panel as
shown below in Figure 6-3.
ACCUSONIC MODEL 7500
6-9
Maintenance and Repairs
Figure 6-3 High Voltage Module Replacement
First detach the connector panel from the cabinet by releasing four captive fasteners marked with white
arrows.
To remove the module, first disconnect the two cables to gain clearance. Then remove four screws and
unplug the entire module. Reverse the procedure to reassemble.
Replacing the Display Card
The display card is located inside the cabinet on the back side of the hinged front panel, at the top.
To replace the display card, unplug the pigtail wiring connection at the left of the card.
Disconnect the flex-circuit cable from the right side of the card - be careful not to tug on the cable or bend
or twist it. Remove four nuts to detach and remove the card.
Reverse the procedure to reassemble.
6-10
ACCUSONIC MODEL 7500
Maintenance and Repairs
Replacing the Keypad Card
The keypad card is located inside the cabinet centered on the back side of the hinged front panel.
To replace the keypad card, disconnect two cables from the right side of the card. If there is an external
keyboard connected to the left side of the card, disconnect it. Remove four screws to detach the card and
remove it.
Reverse the procedure to reassemble.
Replacing the Membrane Keypad and LCD Panel
The membrane keypad and the LCD panel are removed and replaced as a single assembly.
To replace the assembly, first remove the display card and the keypad card as described above.
Loosen ten bolts holding the retaining flange that secures the assembly in place. Be careful in removing
the last few bolts so that the unit doesn't fall out of the front panel. If the sealing gasket has stuck to the
assembly, remove it gently.
Clean the gasket and mating surfaces with isopropyl alcohol.
Reverse the procedure to reassemble.
ACCUSONIC MODEL 7500
6-11
Maintenance and Repairs
Replacing the Diskette Drive
The diskette drive is located inside the cabinet on the back side of the hinged front panel, at the bottom.
Refer to Figure 6-4.
Figure 6-4 Diskette Drive Removal
To remove the diskette drive, unplug the two cables at the back (right side) of the drive. Remove four
screws - two on the top and two on the bottom surfaces of the drive enclosure. Do not remove the four
screws that attach the drive enclosure to the front panel of the cabinet.
Cock the diskette drive slightly by holding the front (left side) of the unit away from the front panel, and
push the rear of the unit (right side) away from you. This allows the disk drive to slide out to the left.
Reverse the procedure to reassemble.
Replacing the Power Supply
Replacement of the power supply requires substantial disassembly of the flowmeter. Contact Accusonic
for details before attempting this procedure.
6-12
ACCUSONIC MODEL 7500
Maintenance and Repairs
Replacement Procedure for Flowmeters in Rack-mount Cabinet
The rack-mount is available in two configurations, one for table top use, and the other for mounting in a
standard NEMA relay rack or cabinet. Replacement procedures are identical in both cases. Unless
otherwise noted, directions left and right are as viewed from the front of the cabinet.
When the cabinet is mounted in a NEMA rack, perform replacement procedures with the unit pulled fully
forward on its slides. The only exception is when releasing the rear connector panel - that procedure is
easier when the unit is pushed all the way back into the rack.
Replacing System Processor Circuit Boards
To replace system processor circuit cards (those located in the front half of the cabinet), first remove the
top cover of the unit, and then remove the card retainer located along the left edge of the cards. Release
the retainer by loosening two screws. After the retainers are out of the way, the cards pull out.
Depending on the instrument configuration, there may be slots for eight or ten cards in the processor
group. Except for the system processor card, there is no fixed slot location for any of the cards. The
flowmeter is shipped with a configuration sheet detailing the actual location of circuit cards in your
instrument. A copy of the configuration sheet is kept on file at the factory.
Before removing a circuit card, always double check its identity by locating a connector or external
connection to that card, and then tracing it back to the unit. Alternatively, the cards are labeled in etch
along one edge, and most bear at least one identifying label from the manufacturer.
Before disconnecting any cables from a circuit card, be sure to note the location and orientation of the
connectors to ensure that they can be reinstalled correctly. Some cable connectors in the system are NOT
polarized; if installed backwards, they can cause damage.
Specific considerations:
♦ System processor card - Has two cables which must be detached before removing the card.
Refer to system As-built drawings in the rear of this manual for card locations.
♦ Basic I/O card - Has three cables which must be removed.
♦ System communications card - Has at least one and possible four cables plugged into it.
Furthermore, if the flowmeter is attached to remote flow transmitters, there will be additional
components on the card. Be sure to replace the card with the proper type. See configuration sheet
for details.
♦ Diskette controller card and System I/O cards - All have at least one cable. Be sure to note the
configuration and reattach the cables correctly to the replacement card. These connectors are not
keyed and will cause damage if installed backwards.
ACCUSONIC MODEL 7500
6-13
Maintenance and Repairs
Replacing Transceiver Card Set
To remove the transceiver card set first remove the top cover of the unit. Detach the cable plugged into
the back lower right-hand corner of the larger card. Remove both cards together; in most cases the cards
are replaced as a pair. If necessary, remove the two ribbon cables to separate the cards.
Removing the Connector Panel
This procedure is performed to gain access to the path and stage cards, and the pulse transmitter.
To remove the rear connector panel from a rack-mount cabinet used on a table top, it is necessary to first
remove the side panels to gain access to the screws that secure the connector panel to the unit. When the
cabinet is located in a rack, the screws remain accessible even when the side panels are in place.
Remove the panel by loosening four screws located along the sides of the back panel.
Gently pull the panel away from the unit and let it rest on the attached cables which will keep the panel
from dropping completely out of the way.
Depending on the configuration of the instrument, there will be one or two narrow ribbon cables which
might obstruct access into the area behind the connector panel.
Unplug the cables at their far end. Note the location of the mating connectors to ensure correct
reassembly.
Replacing Path or Stage Cards
Path and stage cards are mounted on the back of the connector panel, as previously shown in Figure 6-2
(page 6-9). They are exposed and accessible after the connector panel is removed. The cards simply
unplug from the panel for replacement. Be sure to install a replacement card in the same slot.
Replacing the Pulse Transmitter
The pulse transmitter is located on the back of the connector panel as previously shown in Figure 6-2
(page 6-9). Remove the ribbon cable before pulling the card from its socket.
Reverse the procedure to reassemble.
Replacing the High Voltage Power Module
The high voltage power module is accessible from below the unit.
To remove the module, remove the bottom panel and disconnect two cables from the module. Then
remove four screws and unplug the entire unit. Reverse the procedure for reassemble.
6-14
ACCUSONIC MODEL 7500
Maintenance and Repairs
Releasing the Front Panel
The front panel holds the display and keypad and their respective control cards. It must be released from
the unit to service these components. Remove the top panel of the unit to gain access to two slide-lock
bars which hold the front panel in place.
To release the panel, lightly push the front panel into the unit to release the pressure on the slide-lock bars
and use a screwdriver to slide each bar as shown in Figure 6-5. The slide-lock bars are not captive.
Figure 6-5 Releasing the Front Panel
To reassemble, hold the panel in place and lightly press it toward the rear of the unit. Reach into the unit
and reattach the slide-locking bars, one on each side of the panel. Slide the slide-lock bar over the tangs
on the bolts from the front panel handles and then press each bar downward to lock the assembly in place.
Replacing the Display Card
The display card is located inside the cabinet on the back side of the front panel, at the top.
To replace the display card, first release the front panel as described above and then unplug the pigtail
wiring connection at the left of the card.
Disconnect the flex-circuit cable from the right side of the card - be careful not to tug on the cable or bend
or twist it. Remove four nuts to detach and remove the card.
Reverse the procedure to reassemble.
ACCUSONIC MODEL 7500
6-15
Maintenance and Repairs
Replacing the Keypad Card
The keypad card is centered on the back side of the front panel.
To replace the keypad card, first release the front panel as described above and then disconnect two cables
from the right side of the card. If there is an external keyboard connected to the left side of the card,
disconnect it. Remove four screws to detach and remove the card.
Reverse the procedure to reassemble.
Replacing the Membrane Keypad and LCD Panel
The membrane keypad and the LCD panel are an integral unit that is replaced as a single assembly.
To replace the assembly, first release the front panel and then remove the display card and the keypad
card as described above.
Reverse the procedure to reassemble.
Replacing the Diskette Drive
The screws that hold the diskette drive in place are accessible from the bottom of the unit. Remove four
screws - two on each side of the drive as shown in Figure 6-4(see page 6-12).Do not remove the four
screws that attach the drive bracket to the unit. After releasing the screws, the drive slides out through the
front panel.
6-16
ACCUSONIC MODEL 7500
Maintenance and Repairs
FORCED PAGE BREAK FOR PAGE NUMBERING REASONS - REMOVE FROM MANUAL.
ACCUSONIC MODEL 7500
6-17
ACCUSONIC MODEL 7500
18
Chapter 7
Parameters and Variables
Parameters and variables are listed in alphabetic order. Each entry lists the parameter type, the menu
access levels in which the parameter is displayed, the range of allowed values and the default value.
When the symbol # appears for range, it means that an integer, a whole number, or a number in scientific
notation in the range 10-38 to 1 x 1038 may be entered.
Table 5-1 on page 16 summarizes the flowmeter menu hierarchy.
Refer to Figure 7-1 on page 36 for a diagram of an open-channel parameters application.
Parameter List
Always display plant totals
Specifies what to do with “Total Flowrate” if one or more measurement sections are “BAD”. In the OFF position
any bad section will prevent the calculation of total plant flow. In the ON position total plant flow will be displayed
and will indicate valid even if a section is bad (the section may be bad because it is dewatered). The flowrate for the
bad section(s) will not be added to the total. WARNING! Set this to OFF on leak-detection systems! Setting it to
ON may cause false detection of leaks if there is a flowmeter failure.
Autostart switch
Specifies whether the flowmeter bypasses the menu system upon power up and automatically begins flow
measurement. On bypasses the menus and is recommended in case of power failure while the system is
unattended.
Type:
General parameter
Menu levels:
Setup, Extended
Range:
Off, On
Default:
ACCUSONIC MODEL 7500
On
7-1
Parameters
Available velocity enabled
In compound installations when the metering section is surcharged, the meter can be enabled to use the
velocities from all operating paths to determine a flowrate if the number of working paths is less than the
number required for the other method chosen. This enables the meter to continue operating if one or
more paths temporarily drop out. Accuracy will be somewhat less than if all paths are operating. See
Chapter 3, Flow Calculation Formulas, beginning on page 3-18, for further information.
Type:
Section
Menu levels:
Setup, Extended
Range:
Off, On
Default:
On
Average cable length per path
The average length in system units of the transducer cables measured from the path selector card to the
transducers. Averaged for all paths in the meter section.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
#
Default:
0
Note
Practical operating range is 0-1000 feet, 350 meters.
Average stage cable length
The average length in system units of the acoustic stage transducer cable or cables measured from the
stage card to the transducer(s).
Type:
Section
Menu levels:
Setup, Extended
Range:
#
Default:
0
Averaging queue length
The maximum number of flow rate measurement samples used in calculating an average flow rate. This
represents the size of a queue in which flow rate measurements are stored for averaging. As each
measurement is made, an entry is added to the averaging queue until the number of entries equals this
setting. Once the queue is filled, each new entry replaces the oldest entry in the queue. Upon first startup
or any time flow measurements are interrupted for a length of time exceeding Totalizer cutoff time, the
averaging queue is flushed.
Type:
General parameter
Menu levels:
Extended
Range:
0 to 2000
Default:
7-2
10
ACCUSONIC MODEL 7500
Parameters
Bidirectional flow
Defines whether the flowmeter accounts for reverse flow through the section. If On, reverse flow will be
calculated and subtracted from totalizer output. If Off, reverse flow is set to zero and has no effect on the
totalizer.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
Off, On
Default:
Off
Bottom channel width
In open channel and compound installations, one of the parameters required to define the channel or
conduit cross section. The value is expressed in feet or meters, according to the general parameter Units.
Other parameters are Number of channel layers, Channel layer height, and Channel layer width.
Type:
Section
Menu levels:
Setup, Extended
Range:
0 - 5000
Default:
0
Bottom velocity ratio
In open channel and compound installations, a coefficient of friction is used to extrapolate velocity
between the bottom acoustic path and the conduit bottom and between the top path and the conduit top
when the conduit is surcharged. .
Type:
Section
Menu levels:
Setup, Extended
Range:
0-1
Default:
.5
Channel bottom height
Height of the channel or conduit bottom above a datum, such as sea level.
Type:
Section
Menu levels:
Setup, Extended
Range:
-100 to 15,000
Default:
ACCUSONIC MODEL 7500
0
7-3
Parameters
Cross sectional area
The area to be used by the meter in calculating flowrate if the area method of integration, or the available
velocity method of integration is being used under surcharged conditions. See Section parameter
Available velocity enabled (page 2).
Type:
Section
Menu levels:
Setup, Extended
Range:
#
Default:
0
Current date
The current date is displayed in format MM.DD.YY
Type:
General
Menu levels:
Setup, Limited, Extended
Range:
01.01.80 to 12.31.99
Default:
Current date
Current time
The current time is displayed in format HH.MM.SS.
Type:
General
Menu levels:
Setup, Limited, Extended
Range:
00.00.00 to 23.59.59
Default:
Current time
Data logging
Allows various types of data to be averaged and printed or stored on diskette. When the Section
parameter is set to On, enables logging of flow and positive volume and allows selective logging of
negative volumes and individual path velocities. Log files on disk are organized by meter section. See
section parameter Log data to (page 10) for how to specify the destination for printing or for diskette
backup. When the General parameter is set to On, system totals for flowrate and volumes will be logged.
Type:
General and Section parameter
Menu levels:
General parameter--Setup, Extended
Section parameter--Limited, Extended
Range:
Default:
7-4
Off, On
Off
ACCUSONIC MODEL 7500
Parameters
Data log start
Defines the time, in 24-hour format (hh:mm:ss) when data logging is to begin. 00:00:00 is midnight,
12:00:00 is noon. Data logging continues at the interval set for the parameter Log interval until the
parameter Data logging is turned Off.
Type:
General parameter
Menu levels:
Limited, Extended
Range:
00:00:00 to 23:59:59
Default:
00:00:00
Delay time of other ducer
In Section parameter Stage source, if Acoustic and Other are chosen in successive menu levels, enter the
signal delay of the transducer, in seconds. This is also required if Other is chosen in Path parameter Ducer
type. The value entered should include transit time through both ducer windows (2 x thickness/speed of
sound) plus 1/2 of wave period (1µs for 500kHz ducer) plus 0.2µs for electronic delays.
Type:
Section and Path parameter
Menu levels:
Setup, Extended
Range:
# (in seconds)
Default:
0
Differential alarm threshold
See Chapter 12, Leak Detection System, page 12-7.
Differential flow averaging size
See Chapter 12, Leak Detection System, page 12-7.
Differential warning threshold
See Chapter 12, Leak Detection System, page 12-7.
Display contrast
Used to increase or decrease contrast of an LCD display. This parameter has no effect when a CRT or
full-screen electroluminescent (EL) display is in use.
Type:
General parameter
Menu levels:
Setup, Limited, Extended
Range:
Down, Up
Default:
ACCUSONIC MODEL 7500
n/a
7-5
Parameters
Display mode
Selects whether data will be displayed on screens 1 & 2, by individual sections, ends (which are factory
configured combinations of sections) or both.
Type:
General parameter
Menu levels:
Extended
Range:
Sections, Ends, Both
Default:
Sections
Display totals line
Allows the operator to turn off the Totals line at the bottom of the display.
Type:
General parameter
Menu levels:
Extended
Range:
Off, On
Default:
On
Ducer connection
The 7500 is configured at the factory for the type of transducer cable connection, usually single line.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
Balanced, Single
Default:
Single
Ducer type (7600, 7601, 7605, 7612 ...)
Specifies the model of the Accusonic transducers in the section. Since each model transducer has a
different internal signal delay, correct specification of this parameter is critical to the accuracy of flow
calculations.
Type:
Path parameter
Menu levels:
Setup, Extended
Range:
7600, 7601 etc.
Default:
7600
End label character
A single character used to identify a factory-configured combination of sections on the console display.
Typically used in leak detection systems.
Type:
General parameter
Menu levels:
Extended
Range:
Alphanumeric
Default:
7-6
E
ACCUSONIC MODEL 7500
Parameters
End starting number
The number to label the first end in the series of ends attached to this flowmeter. See General parameter
End label character above.
Type:
General parameter
Menu levels:
Extended
Range:
#
Default:
1
Error Reporting
Error reporting is a diagnostic tool. When enabled, status information will be stored on a floppy disk
when data status is bad (other than 1,9, or x) for more than Maximum Bad Measurements. Stored
information will consist of date, time and status codes. Additional menu choices will enable storage of
flowrate, stage, velocities and gains. Information will be stored on every measurement cycle. Error
reporting requires that a blank, formatted disk be in the floppy drive.
Type:
General
Menu levels:
Extended
Range:
On or Off
Default:
Off
Flowrate scale factor
The flowmeter calculates flow rate in cubic feet per second (cfs) or cubic meters per second (cms),
depending on whether English or metric units have been chosen in the General parameters list. These
flow rates can be scaled by the Flowrate scale factor to reflect other flow units. Common flow rate scale
values are:
If units are in
Desired flow rate in
Flowrate scale factor
Feet
million gallons/day (mgd)
0.646272
gallons/minute (g/m)
448.8
gallons/second (g/s)
7.48
liters/second (l/s)
1,000.0
cubic meters/hour (cm/h)
3600.0
megaliters/day (mld)
86.40
Meters
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
#
Default:
ACCUSONIC MODEL 7500
1
7-7
Parameters
Format
Format is used with digital outputs. It allows the user to choose the part of the selected variable to be sent
to the output. Enter as:
<total number of digits to output>.<number of decimal places>
For example:
A BCD output of stage is desired. 16 bits of output are available, which will provide four BCD digits. The
range of stage is 310.25 to 336.51 feet. Format could be set to 4.1, which would cause the BCD output to
range from 3102 to 3365 (decimal point is not output). For better resolution, format could be set to 4.2.
The BCD output would then range from 1025 to 3651. In this case, the most-significant digit is always a
‘3’, so there is no need to output it. The input can be strapped to ‘3’ at the receiving device.
Type:
Output parameter
Menu Levels: Setup, Limited, Extended
Range:
#
Default:
0.0
Note
Practical operating range depends on output hardware installed.
Frequency of other ducer
In Section parameter Stage source, if Acoustic and Other are chosen in successive menu levels, enter the
frequency of the acoustic transducer being used. This is also required if Other is chosen in Path
parameter Ducer type.
Type:
Section and Path parameter
Menu levels:
Setup, Extended
Range:
#
Default:
0.0
Full Pipe
In compound installations, the stage (level) value which indicates a surcharged conduit for purposes of
changing to the integration method chosen in the section parameter Surcharged integration.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
0 - 100
Default:
7-8
0
ACCUSONIC MODEL 7500
Parameters
Inactivity Timeout
The length of time (in minutes) the system can be left unattended and out of measurement mode. If no
keys are pressed for this length of time, the system will reset and begin measurement automatically. This
feature will only work if the General parameter Autostart has been set to On. Setting the inactivity
timeout period to 0 deactivates the feature.
Type:
General parameter
Menu levels:
Extended
Range:
#
Default:
10
K
An integration factor for the specified path according to the type of installation. For example, for a fourpath section in round pipe, K should be set to 1 for each path.
Type:
Path parameter
Menu levels:
Setup, Extended
Range:
Default:
#
1 - for sections with 1 or 4 paths
0.996 for sections with 2 paths
0.5 - for sections with eight crossed paths
Layer boundary elevation 1 - n
In open channel and compound installations, the elevation of the particular layer above the site datum.
They are used for defining the channel cross section. The layer elevations need not correspond to
acoustic path heights. Elevations of each layer is expressed in feet or meters, according to the general
parameter Units. Channel layer elevations are taken from the as-built survey sheet and should not be
changed after setup. The number of channel layers to be defined is determined by the section parameter
Number of channel layers. The value for the top layer must be greater than or equal to the parameter Pipe
Full in a Compound meter, and Maximum Stage in an open channel.
Type:
Section
Menu levels:
Setup, Extended
Range:
0 - 100
Default:
ACCUSONIC MODEL 7500
0
7-9
Parameters
Layer boundary width 1 - n
In open channel and compound installations, the width of the particular layer as measured at the top of the
layer for defining the channel cross section. Width of each layer is expressed in feet or meters, according
to the general parameter Units. Channel layer widths are taken from the as-built survey sheet and should
not be changed after setup. The number of channel layer widths to be defined is determined by the
section parameter Number of channel layers. Side slope of each layer is calculated based on this width,
the width of the layer beneath it (or bottom channel width) and the layer height.
Type:
Section
Menu levels:
Setup, Extended
Range:
0 - 5000
Default:
0
Leak detection switch
Enables the leak detection system algorithms. Note that this parameter appears twice on the flowmeter
menu--once as a General parameter and again under the specific Leak detection option. The switch must
be turned on in the General parameter list in order to enable the system to perform the calculations
required for leak detection. It must also be enabled under the Leak detection option for each
pipeline/penstock for which leak detection functions should be performed.
Type:
General and Leak detection parameter
Menu levels:
Setup, Limited, Extended
Range:
Off , On
Default:
Off
Log data to
Specifies the destination for data logging. Data logging will occur only if the section parameter Data
Logging is On. If disk is selected, there must be a formatted diskette in the diskette drive unit. If printer is
selected, data is sent to the parallel printer port.
Type:
General parameter
Menu levels:
Limited, Extended
Range:
disk, printer, both
Default:
n/a
Note
When a logging diskette is more than 80% full, the flowmeter displays
a warning message on the control panel.
7-10
ACCUSONIC MODEL 7500
Parameters
Log interval
Defines the interval over which data is averaged. At the end of each interval, data is recorded on whatever
device or devices have been selected with the section parameter Log data to. Expressed in 24 hour format
(hh:mm:ss). This parameter appears in the menus only if the section parameter Data Logging is On.
Type:
General parameter
Menu levels:
Limited, Extended
Range:
00:00:00 to 24:00:00
Default:
00:10:00 (ten minutes)
Log negative volume data
Specifies whether reverse flow is to be logged. Data logging will occur only if the Section or General
parameter Data Logging is On.
Type:
Section parameter
Menu levels:
Limited, Extended
Range:
Off, On
Default:
Off
Log velocity data
Specifies whether velocity measurements are included in the log report. If this parameter is Off and the
section parameter Data logging is On, flowrate and positive volume are logged..
Type:
Section parameter
Menu levels:
Limited, Extended
Range:
Off, On
Default:
Off
Manning coefficient of roughness
In open channel and compound installations, the coefficient of roughness to be used in the Manning
formula for calculating flow based on level measurement alone. The Manning formula is appropriate
only in sites where a stage/discharge relationship is applicable and where no acoustic paths are submerged
and/or operating. The coefficient of roughness is usually between 0.010 and 0.030. See Chapter 3
description of Manning Equation on page 3-21.
Type:
Path parameter
Menu levels:
Extended
Range:
#
Default:
ACCUSONIC MODEL 7500
None
7-11
Parameters
Manual gain
Specifies the path receiver gain in decibel (dB) units. This parameter has no effect unless the path
parameter Receiver gain is set to Manual. Should be used only for troubleshooting; see parameter
Receiver gain (page 21).
Type:
Path parameter
Menu levels:
Extended
Range:
#
Default:
None
Manual stage (1 or 2) value
In open channel or compound installations, if Manual is chosen in Section parameter Stage source, the
meter will use a fixed value as the fluid level in the channel or conduit. This value will override all other
stage inputs and is used only if no level variation is expected or for testing purposes.
Type:
Section
Menu levels:
Setup, Extended
Range:
#
Default:
0
Maximum bad measurements
The maximum number of consecutive measurements failing a reasonability test before the flowmeter
signals an alarm. When a bad measurement is detected and the number of bad measurements does not
exceed this value, the last good value is substituted for the bad value. When the number of bad
measurements is exceeded, the flow may be computed using an alternative or modified integration
method.
Type:
General parameter
Menu levels:
Extended
Range:
#
Default:
10
Note
Bad measurements are not used in flow rate averaging.
Maximum change in flowrate
Maximum allowable rate of change in flow rate between consecutive measurements, expressed in cubic
feet/second2 or cubic meters/second2 according to the general parameter Units. If a measurement exceeds
this limit, the consecutive bad counter for the section is incremented. The new value will be the last good
value plus or minus the maximum change parameter value. If the new reading does not “catch up” to the
present reading within “MAXIMUM BAD MEASUREMENTS”, the section will fail.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
#
Default:
7-12
Calculated: 10% of the value specified for Maximum expected flowrate
ACCUSONIC MODEL 7500
Parameters
Maximum change in stage
Maximum allowable rate of change in stage (level) per second, expressed in feet or meters, according to
the general parameter Units. If a measurement exceeds this limit, the consecutive bad counter for the
section is incremented, and the measured value is not used for flow calculation. This parameter is used to
filter out bad stage measurements which may be caused by submerged debris.
Type:
Section
Menu levels:
Setup, Extended
Range:
0 - 100
Default:
0.5
Maximum change in velocity
Maximum allowable rate of change in velocity between consecutive measurements, expressed in
feet/second2 or meters/second2 according to the general parameter Units. If a measurement exceeds this
limit, the consecutive bad counter for the path is incremented. The new value will be the last good value
plus or minus the maximum change parameter value. If the new reading does not “catch up” to the present
reading within “MAXIMUM BAD MEASUREMENTS”, the path will fail.
Type:
Section parameter
Menu levels:
Extended
Range:
#
Default:
20
Maximum expected flowrate
Maximum allowable flow measurement, expressed in cubic feet/second or cubic meters/second according
to the general parameter Units. If a measurement exceeds 1.5 times this value, the consecutive bad
counter for the section is incremented, and the measured value is not used for flow calculation. Enter the
actual maximum flow rate expected. The flowmeter adds the appropriate safety factor.
Type:
Section parameter
Menu levels:
Setup, Limited, Extended
Range:
#
Default:
Calculated: (Velocity =100) times area of the section
Maximum expected velocity
Maximum allowable velocity measurement, expressed in feet/second or meters/second according to the
value of the general parameter Units. If a measurement exceeds 1.5 times this value, the consecutive bad
counter for the path is incremented, and the measured value is not used for flow calculation.
Type:
Section parameter
Menu levels:
Setup, Limited, Extended
Range:
#
Default:
ACCUSONIC MODEL 7500
Calculated: Maximum expected flowrate/area of section
7-13
Parameters
Maximum stage
Defines the maximum value of stage (level) that the flowmeter will use. Expressed in feet or meters,
according to the general parameter Units, above the reference datum (see parameter Channel bottom
height page 3). In a compound installation this value is usually set equal to or above the value set in
parameter Full pipe.
Type:
Section
Menu levels:
Setup, Extended
Range:
0 - 1000
Default:
0
Maximum stage difference 1 and 2
The maximum acceptable difference in feet or meters between redundant stage measurements. If this
parameter is exceeded, the value from the Stage 1 sensor only is used. If only one sensor is working, its
value is used.
Type:
Section
Menu levels:
Setup, Extended
Range:
0 - 100
Default:
0
Menu access
Specifies which parameters and variables will be displayed while navigating the menus.
Type:
General parameter
Menu levels:
Setup, Limited, Extended
Range:
Setup, Limited, Extended
Default:
Setup
Minimum flowrate
Defines the minimum absolute value of flow rate that the flowmeter will display. Expressed in cubic
feet/second or cubic meters/second according to the value of the general parameter Units. Flow measured
in either direction that is less than this limit displays as zero flow rate and is not totalized.
Type:
Section parameter
Menu levels:
Setup, Limited, Extended
Range:
#
Default:
7-14
0
ACCUSONIC MODEL 7500
Parameters
Minimum good paths
In a pipe installation, the minimum number of paths which must show valid measurements before a flow
rate calculation will be made. When fewer than this number of valid paths are operating, the flowmeter
signals a section error and flow calculation stops. To ensure measurement integrity, this parameter must
be set to the number of paths in the section. If the parameter is set to three for a four-path section, the
failure of a single path will not be signaled, and the last good value for velocity for the failed path will be
used forever, unless new valid data are obtained. If path substitution is enabled, a value for failed paths
will be provided from other good paths.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
#
Default:
Total number of paths in section
Minimum path submersion
The minimum distance above each acoustic path that the stage (level) measurement must indicate before
the acoustic path is activated, as calculated by the minimum clearance required to avoid multipath
reflections. The value depends on operating frequency and path length. (See Chapter 3, page 3-6 for
formula.)
Type:
Section
Menu levels:
Setup, Extended
Range:
0 - 20
Default:
0
Minimum stage
Defines the minimum value of stage (level) that the flowmeter will use. Expressed in feet or meters,
according to the general parameter Units, above the reference datum (see parameter Channel bottom
height on page 3). If the stage measurement is below this value, the consecutive bad counter for the
section is incremented, and the measured value is not used for flow calculation.
If an Acoustic uplooker is used, 6” (0.15m) above the face of the stage transducer is suggested. Add stage
offset to 6” to get minimum stage. For other stage measurement devices, minimum stage is dependent on device
limits and/or channel limits.
Type:
Section
Menu levels:
Setup, Extended
Range:
0 - 1000
Default:
ACCUSONIC MODEL 7500
0
7-15
Parameters
Negative over velocity alarm threshold
See Chapter 12, Leak Detection System page 12-8.
Negative over velocity warning threshold
See Chapter 12, Leak Detection System page 12-8.
Non-surcharged integration method
In open channels and in compound installations when the conduit is not surcharged, this specifies the
integration method to be used by the meter. The default choice, Auto, will set the meter to automatically
select Manning, single path trapezoidal or multi-path trapezoidal depending on stage and the number of
good paths. If Trapezoidal is chosen the Manning option is inhibited. Choice of any of the other methods
will lock the meter into that method regardless of the number of paths submerged, as long as the conduit
is not surcharged. The choice of integration is determined based on requirements established at the time
of system configuration and should not be changed without consulting Accusonic. See Chapter 3, Flow
Calculation Formulas, beginning on page 3-18, for further information.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
Auto, Trapezoidal, Single path, Manning
Default:
Auto
Number of channel layers
In open channel and compound installations, the number of layers used in defining the channel or conduit
cross section. For regularly shaped trapezoidal channels, only one layer may need to be defined,
including the parameters Bottom channel width, Channel layer height 1, and Channel layer width 1. For
irregularly shaped channels, up to 16 separate layers, each with separate height and width, may be
defined.
Type:
Section
Menu levels:
Setup, Extended
Range:
1 - 16
Default:
8
Over velocity alarm count
See Chapter 12, Leak Detection System, page 12-8.
Over velocity warning count
See Chapter 12, Leak Detection System, page 12-9.
7-16
ACCUSONIC MODEL 7500
Parameters
Password control
Specifies whether a password protection is in effect. Password protection prevents unauthorized users
from interrupting measurements or changing parameters on the instrument. See Chapter 5 (pages 19 and
37) for information on setting or changing a password.
Type:
General parameter
Menu levels:
Extended
Range:
Off, On
Default:
Off
Note
If Password control is On and Autostart switch is Off and the unit is powered
down for any reason, it will restart in the menu system, thereby allowing
parameters to be changed. For complete protection from tampering,
set both Password control and Autostart switch to On.
Path angle
Specifies the angle in degrees between an acoustic path and the centerline of the meter section. This is
obtained from the as-built survey data sheet and should not be changed after setup.
Type:
Path parameter
Menu levels:
Setup, Extended
Range:
#
Default:
45°
Path elevation
For Gaussian installations, the elevation of the path from the pipe center line. These are obtained from the
as-built survey data sheet, and should not be changed after setup.For Open or Compound channels, the
elevation is relative to the site datum. Paths must be numbered in order of elevation. Paths of identical
elevation are assumed to be crossed.
Type:
Path parameter
Menu levels:
Setup, Extended
Range:
#
Default:
0
Path length
Length of the path from transducer face to transducer face, expressed in meters or feet according to the
general parameter Units. This is obtained from the as-built survey data sheet and should not be changed
after setup.
Type:
Path parameter
Menu levels:
Setup, Extended
Range:
#
Default:
ACCUSONIC MODEL 7500
0
7-17
Parameters
Path percent active
Specifies the percent of the path that is within the moving fluid. For example, if both transducers forming
a 1 meter path are recessed into the conduit walls by 1 cm, the value for this parameter would be 98 (%).
This is obtained from the as-built survey data sheet and should not be changed after setup.
Type:
Path parameter
Menu levels:
Setup, Extended
Range:
0 to 100
Default:
100
Path position
Elevation in degrees of a path above the centerline of the conduit. This value is used to calculate constants
for pipe integration. Default values change according to integration method and the number of paths in
the section.
Type:
Path parameter
Menu levels:
Setup, Extended
Range:
#
Default:
For 2-path section: ±30°, according to path number
For 4-path section: Path 1, -54°; path 2, -18°; path 3, 18°; path 4, 54°
Path simulation
Used for system testing. Specifies the simulation parameter, Simulation forward time, Simulation reverse
time or Simulation velocity, used as the source of travel times for simulation. When set to Times, the
forward and reverse simulation times are used. When set to Velocity, the velocity is first converted to
travel times and these times are used. Normally Off. See parameters Simulation forward time, Simulation
reverse time, Simulation source, Simulation velocity, and Simulation velocity ramp. On the keypad,
pressing Ctrl - ↑ will ramp the velocity up by the simulation velocity ramp scale, pressing Ctrl - ↓ will
ramp down by this scale. On an external keyboard, the PG-UP key will ramp up, the PG-DN key will
ramp down. → resets all simulated velocities to the un-ramped value. ← sets all simulated velocities to 0.
Type:
Path parameter
Menu levels:
Extended
Range:
Off, Velocity, Times
Default:
Off
Note
Flow rate for the path is not measured when Path simulation
is set to Velocity or Times.
7-18
ACCUSONIC MODEL 7500
Parameters
Path switch
Specifies whether measurements are to be made along the path. If the path is turned Off, the last good
velocity from the path will continue to be used for flow calculation. Set On to activate path
measurements. To remove this path’s contribution from the flow calculation, enter a very small value for
K, e.g. 0.0000001.
Type:
Section parameter
Menu levels:
Setup, Limited, Extended
Range:
Off, On
Default:
Off
Penstock label character
A single character used to identify a section, penstock or unit line on the console display.
Type:
General parameter
Menu levels:
Extended
Range:
Alphanumeric
Default:
P
Penstock starting number
The number to label the first penstock in the series of penstocks attached to this flowmeter.
Type:
General parameter
Menu levels:
Extended
Range:
#
Default:
1
Pipe height
Distance, expressed in meters or feet according to the general parameter Units, from the bottom of the
pipe to the top of the pipe as measured at the center of the cross section. Only accessible if the section
parameter Pipe integration is set to Gauss.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
#
Default:
ACCUSONIC MODEL 7500
0
7-19
Parameters
Pipe integration
Specifies whether Chebyshev or Gaussian integration method will be used. The choice of integration
method is specified by Accusonic and should not be changed. See Chapter 3, Flow Calculation Formulas
beginning on page 3-18.
Type:
Section parameter
Menu levels:
Limited, Extended
Range:
Cheb, Gauss
Default:
Cheb
Pipe shape
Specifies the cross-sectional shape of the conduit at the meter section. Used only in Gauss integration.
Type:
Section parameter
Menu levels:
Limited, Extended
Range:
Round, Other
Default:
Round
Pipe slope
In open channel and compound installations, the slope to be used in the Manning formula for calculating
flow based on level measurement alone. The Manning formula is appropriate only in sites where a
stage/discharge relationship is applicable and where no acoustic paths are submerged and/or operating.
The value represents the slope of the pipe parallel to its centerline axis. Enter as Rise/Run.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
#
Default:
0
Positive over velocity alarm threshold
See Chapter 12, Leak Detection System, page 12-9.
Positive over velocity warning threshold
See Chapter 12, Leak Detection System, page 12-9.
7-20
ACCUSONIC MODEL 7500
Parameters
Protrusion of other ducer
If Other is chosen in Path parameter Ducer type, transducer protrusion must also be entered for each path.
Note that protrusion is path-specific--the value for inner paths will differ from that for outer paths.
Protrusion is always entered in inches, regardless of any other unit selected.
Type:
Path parameter
Menu levels:
Setup, Extended
Range:
# (in inches)
Default:
0.0
Q FWD 1 - n
In open channel and compound installations, the forward single path integration constant, used only when
the USGS single path integration method is chosen in section parameter Single path integration.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
#
Default:
0
Q REV 1 - n
In open channel and compound installations, the reverse single path integration constant, used only when
the USGS single path integration method is chosen in section parameter Single integration.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
#
Default:
0
Radius
Specifies the radius of the pipe at the center of the metering section in meters or feet according to the
general parameter Units. Only used when the section parameter Pipe Integration is set to Cheb. This is
obtained from the as-built survey data sheet and should not be changed after setup.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
#
Default:
ACCUSONIC MODEL 7500
0
7-21
Parameters
Receiver gain
Specifies whether the receiver gain for the path will be set automatically (i.e., automatic gain control, agc)
or manually. Normally set to auto, except during transducer alignment and troubleshooting. (See parameter
“Manual Gain”, page 12.)
Type:
Path parameter
Menu levels:
Extended
Range:
Auto, Manual
Default:
Auto
Repetition time
Specifies in seconds the time between flow measurements and display updates for all sections.
Type:
General parameter
Menu levels:
Limited, Extended
Range:
#
Default:
2
Section label character
A single character used to identify a section, penstock or unit line on the console display.
Type:
General parameter
Menu levels:
Extended
Range:
Alphanumeric
Default:
S
Section starting number
The number to label the first section in the series of sections attached to this flowmeter.
Type:
General parameter
Menu levels:
Extended
Range:
#
Default:
1
1
Section switch
Specifies whether a meter section is in use. When Off, section parameters for this section are not
displayed in the menus.
Type:
Section parameter
Menu levels:
Setup, Limited, Extended
Range:
Off, On
Default:
7-22
Off
ACCUSONIC MODEL 7500
Parameters
Section type
Specifies the type of flowmeter application. Choose compound for open channels and for conduits
flowing partially full at times and surcharged at others. Choose pipe only for conduits that are always
surcharged (flowing full).
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
Pipe, Compound
Default:
Pipe
Self test interval
Specifies the time in seconds between self-tests. When a bad self-test is detected, a follow-up test is
always performed and repeats to the limit specified in the general parameter Maximum bad self-tests.
When set to 0, self-testing is not performed.
Type:
General parameter
Menu levels:
Limited, Extended
Range:
#
Default:
100
Shape factor
Factor used with Gaussian integration to correct for irregularities in the conduit shape. The factor is
calculated from as-built parameters; it is site-specific and should not be changed after setup.
Type:
Section parameter
Menu levels:
Extended
Range:
0.995 to 1.005
Default:
1.0
Signal detection method
Specifies the signal detection method. Should only be changed under the direction of Accusonic.
Type:
Section parameter
Menu levels:
Extended
Range:
1st neg, Zero crossing
Default:
1st neg
ACCUSONIC MODEL 7500
7-23
Parameters
Simulation forward time
Forward travel time (in seconds) to be used by flow transmitter to simulate a path velocity. See path
parameter Path simulation on page 18.
Type:
Path parameter
Menu levels:
Extended
Range:
#
Default:
0
Simulation reverse time
Reverse travel time (in seconds) to be used by flow transmitter to simulate a path velocity. See path
parameter Path simulation on page 18.
Type:
Path parameter
Menu levels:
Extended
Range:
#
Default:
0
Simulation source
Used for system testing. Specifies the kind of simulation to be used if the path parameter Path simulation
is On. When set to Internal, the system processor uses a simulated value of velocity or travel time to
calculate section flow. When set to External, the flow transmitter uses a simulated value of velocity or
travel time to calculate path velocity. The path parameter Path simulation governs whether a velocity or a
travel time is used. This parameter does not turn simulation on. See parameter Path simulation (pg 18),
Simulation forward time (pg 23), Simulation reverse time (pg 24) and Simulation velocity (pg 24).
External is a better test of the complete system--it tests the flow transmitter and communications link as
well as the CPU.
Type:
Section parameter
Menu levels:
Extended
Range:
Internal, External
Default:
Internal
Simulation velocity
Value of velocity to be used by system processor to simulate section flow rate. See section parameter
Simulation source on page 24.
Type:
Path parameter
Menu levels:
Extended
Range:
#
Default:
7-24
8
ACCUSONIC MODEL 7500
Parameters
Simulation velocity ramp scale
Used for system testing. Specifies how much the simulated value of velocity currently in use increases or
decreases per second as the CTRL-up and CTRL-down-arrow keys on the control panel are pressed. As the
cursor keys are pressed, the new velocity value is determined by the following:
New velocity = previous velocity + (Simulation velocity * Ramp scale)
Type:
Path parameter
Menu levels:
Extended
Range:
#
Default:
n/a
See “Path Simulation” on page 18 for more information.
Single coefficient (1 - 5)
The straight single path polynomial coefficients used when the Polynomial integration method is chosen
in Section parameter Single integration. These coefficients are the terms of a fifth-order polynomial
equation for fitting a flow curve to a set of velocities. See Chapter 3, Flow Calculation Formulas,
beginning on page 3-18, for further information.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
#
Default:
0
Single integration
In open channel and compound installations when only one acoustic path is installed, this parameter
determines the method of single-path integration to be used by the meter. The choice of integration is
determined based on requirements established at the time of system configuration and should not be
changed without consulting Accusonic. See Chapter 3, Flow Calculation Formulas, beginning on page 318, for further information. The single path must be Path 1 of the section.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
USGS, Polynomial, Trapezoidal
Default:
ACCUSONIC MODEL 7500
Trapezoidal
7-25
Parameters
Speed of sound in fluid
Specifies the speed of sound in the fluid in meters/second or feet/second according to the general
parameter Units. Flowmeter accuracy does not depend on the accuracy of this value.
Type:
General parameter
Menu levels:
Extended
Range:
#
Default:
4800 (English units)
1450 (Metric units)
SQM
Specifies whether Signal Quality Monitor (SQM) is in use. During normal operations, this should always
be On. See Chapter 3 page 3-14 for details.
Type:
Path parameter
Menu levels:
Extended
Range:
Off, On
Default:
On
Stage averaging size
The maximum number of stage (level) measurement samples used in calculating an average stage for use
in flow measurement calculation. This represents the size of a queue in which stage measurements are
stored for averaging. As each measurement is made, an entry is added to the averaging queue until the
number of entries equals the setting. Once the queue is filled, each new entry replaces the oldest entry in
the queue. Upon first startup or any time stage measurements are interrupted for a length of time
exceeding Totalizer cutoff time, the averaging queue is flushed and restarted.
Type:
Section parameter
Menu levels:
Extended
Range:
1 - 1000
Default:
10
Stage ducer type
In open channel or compound installations, if an integral acoustic stage transducer is chosen in Section
parameter Stage source, the transducer model must be entered. If Other is chosen for this parameter,
additional parameters for Frequency and Delay must be entered.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
7612, 7615, 7616, 7632, other
Default:
7-26
0
ACCUSONIC MODEL 7500
Parameters
Stage interval
Stage measurement repetition rate in seconds. This is independent of the path measurement rate chosen in
General parameter Repetition time.
Type:
General parameter
Menu levels:
Setup, Extended
Range:
#
Default:
5
Stage mode
If Normal is selected, the meter will search at every Stage interval over the entire range for a reading until
it finds the current stage (level). If Fast is selected, the meter will remember the last stage value and will
start seeking the level in that range first. Normal mode can take up to 5 seconds to make a stage
measurement. If Fast mode is chosen, it will default to Normal mode briefly whenever the stage signal is
lost. Recommended setting is ‘FAST’.
Type:
General parameter
Menu levels:
Setup, Limited, Extended
Range:
Normal, Fast
Default:
Normal
Stage (1 or 2) offset
The height of the stage (level) source above a reference datum, such as the conduit bottom.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
-100 to 15,000
Default:
0
Stage (1 or 2) range maximum
In open channel and compound installations, sets the scale for values from an external stage (level) source
to be used by the meter. For example, if an acoustic downlooker is being used and is calibrated to output
4 to 20 mA from 1 to 5 feet, enter a maximum of 5. The meter will calculate scaling and offset
parameters based on the type of input hardware in use. See also Stage (1 or 2) range minimum.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
#
Default:
ACCUSONIC MODEL 7500
0.0
7-27
Parameters
Stage (1 or 2) range minimum
In open channel and compound installations, sets the scale for values from an external stage (level) source
to be used by the meter. For example, if an acoustic downlooker is being used and is calibrated to output
4 to 20 mA from 1 to 5 feet, enter a minimum range of 1. The meter will calculate scaling and offset
parameters based on the type of input hardware in use. See also Stage (1 or 2) range maximum.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
#
Default:
0.0
Stage source
In open channel or compound installations, the source of stage (level) measurements used in determining
the cross sectional area for use in calculating flowrate. Choose acoustic when stage measurement is being
done by an integral uplooking level sensor. Two different stage sources can be chosen for each section.
Manual allows entry of a fixed value, see parameter Manual stage value. External allows selection of an
alternate input such as a 4-20 mA current loop or a BCD source. Section selects the level measurement
from another flow measurement section for use.
Type:
Section
Menu levels:
Setup, Extended
Range:
Off, Manual, External, Section, Acoustic
Default:
Acoustic on Stage 1 source
Off on Stage 2 source
Surcharged integration method
In compound installations, this specifies the integration method to be used when the conduit is full. The
choice of method depends on the shape of the conduit, placement of transducers, and other operational
requirements, e.g., whether flow calculations should continue if one or more acoustic paths is not
operating. Generally, the choice of integration method is determined based on requirements established at
the time of system configuration and should not be changed without consulting Accusonic. In open
channels, set Section parameter Full pipe to some large value, so that the meter will never switch to a
surcharged integration method. See Chapter 3, Flow Calculation Formulas, beginning on page 3-18, for
further information.
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
Chebyshev, Gaussian, Trapezoidal, Area
Default:
7-28
Chebyshev
ACCUSONIC MODEL 7500
Parameters
Temperature coefficient
Temperature is calculated based on the derived velocity of sound in the fluid. These coefficients are the
terms of a fifth-order polynomial equation for fitting a temperature curve to a set of velocities.
Type:
Section parameter
Menu levels:
Extended
Range:
#
English Default:
Coefficients:
#1 -62502.5156
#2 39.90736
#3 -0.00851368
#4 6.072802E-007
#5 0
Metric Default: Coefficients:
#1 -32078.05
#2 67.25613
#3 -0.0471539
#4 1.105531E-005
#5 0
Temperature coefficients for 7500:
Enter these coefficients for operation in other than distilled water or if output in celsius units is desired.
Note
The figures displayed will be rounded to 6 significant figures but stored to 7 significant figures.
For Distilled water:
Metric units, output in degrees Celsius:
Temperature Coef. 1: -32078.05
Temperature Coef. 2: 67.25613
Temperature Coef. 3: -0.04715139
Temperature Coef. 4: 1.105531E-005
Temperature Coef. 5: 0
English units, output in degrees Fahrenheit:
Temperature Coef: 1: -62502.5156
Temperature Coef. 2: 39.90736
Temperature Coef. 3: -0.00851368
Temperature Coef. 4: 6.072802E-007
Temperature Coef. 5: 0
For Salt water (salinity= 35 ppt):
ACCUSONIC MODEL 7500
7-29
Parameters
Metric units, ouput in degrees Celsius:
Temperature Coef. 1: -68450.77
Temperature Coef. 2: 138.8034
Temperature Coef. 3: -0.0939744
Temperature Coef. 4: 2.124461E-005
Temperature Coef. 5: 0
English units, output in degrees Fahrenheit:
Temperature Coef. 1: -125797.61
Temperature Coef. 2: 77.7423
Temperature Coef. 3: -0.0160364
Temperature Coef. 4: 1.104515E-006
Temperature Coef. 5: 0
Top weight
In open channel and compound installations, the top weighting velocity coefficient is used to correct the
extrapolated surface velocity. This value is used only in multipath trapezoidal integration when the
conduit is not surcharged. When using trapezoidal integration in a surcharged conduit, the bottom
velocity ratio is used for calculating flow between the top path and the top of the conduit.
Note
The meter uses the velocities from the two top operating acoustic paths to extrapolate a velocity for the
panel above the top path. See Section 3 page 3-24, Multi-path Trapezoidal Integration.
Type:
Section
Menu levels:
Setup, Extended
Range:
#
Default:
7-30
0.1
ACCUSONIC MODEL 7500
Parameters
Totalizer cutoff time
Specifies the maximum time limit in minutes over which the flowmeter will interpolate flow if
measurements are suspended or interrupted. See Chapter 3, Section: Volume Totalizer After Outage, page
3-25.
Type:
Section parameter
Menu levels:
Extended
Range:
#
Default:
10
Travel time tolerance
The maximum allowable difference between measured travel time and the travel time calculated using
speed of sound in the fluid and the path length. Expressed as a percentage. If this value is exceeded, the
measurement is considered bad and the consecutive bad measurement counter is incremented.
Type:
General parameter
Menu levels:
Extended
Range:
#
Default:
10
Units
Specifies whether English or metric units are in use. When this parameter is set to English, linear
dimensions are expressed in feet, total volume in cubic feet, and flow in cubic feet/second. When set to
metric, values are given in meters, cubic meters, and cubic meters/second.
Type:
General parameter
Menu levels:
Setup, Extended
Range:
English, metric
Default:
English
Velocity Substitution
If an acoustic path stops making good measurements, a velocity can be substituted for that path in
calculating flowrate. In order for velocity substitution to take place, the Section parameter Minimum
number of good paths must be reduced by the number of paths whose velocities can be substituted. If Off
is chosen, no substitution will be performed. The last good measurement on the path will be used.
If Ratio is chosen, the velocity calculated for a mirror path will be used to calculate a velocity for the bad
path. Typically, outer paths (i.e., paths 1 and 4) serve as mirror paths for each other and inner paths (i.e.,
paths 2 and 3) serve as mirror paths for each other. If there is no mirror path or if the velocity along that
path is also bad, the meter will search for the first good path and will use that velocity in calculating a
substitute velocity. The substitute velocity is calculated using ratios determined and entered into the meter
at the time of system commissioning, when path velocities are logged at typical operating points and a
velocity profile is established. See Path parameter Velocity substitution ratio.
ACCUSONIC MODEL 7500
7-31
Parameters
The substitute velocity is calculated as:
Substitution velocity = good path’s velocity x (bad path’s velocity substitution ratio / good path’s
velocity substitution ratio)
The substituted velocity will not be used in logged data, and will not appear in RS-232 outputs (velocity
will be dashed).
Note
Velocity substitution cannot be used with leak-detection systems, compound systems when the pipe is not
full, or with trapezoidal integration.
Type:
Section parameter
Menu levels:
Extended
Range:
Off, Ratio
Default:
Ratio
Velocity Substitution Ratio
Ratios to be used in calculating substitute velocities for individual paths are determined during system
commissioning by measuring average velocities for all paths at normal operating flowrates. See Section
parameter Velocity Substitution. These velocities can be entered directly, if desired, or they can be normalized to
path 1 and the calculated value entered. Following are two examples of how to determine velocity
substitution ratios.
Example 1: The measurement section is installed in a turnout where the flowrate rarely changes. In this
case, the velocity profile is known. There is no need to take a range of data points, and no need to
normalize. Simply log velocities for long enough to get a good average, then enter the averaged velocities
directly as ratios.
Path
Velocity
1
8.59
2
12.34
3
13.73
4
10.85
If path 3 were to fail, the flowmeter would use the velocity from path 2 (the mirror path) and calculate a
substitute velocity using the formula:
Substitution velocity = good path’s velocity x (bad path’s velocity substitution ratio / good path’s
velocity substitution ratio)
13.73 = 12.34 X (13.73 / 12.34). In this example, 13.73 would be the substitute velocity. The accuracy of
the substitution is very good in this case, because the flowrate (and consequently the velocity profile)
doesn’t change.
7-32
ACCUSONIC MODEL 7500
Parameters
Example 2: The flowrate for the section usually ranges between 500 and 800 CFS. A set of velocities
would be taken for each path over the range of flows as follows:
Path
Velocity @ 500
Velocity @ 600
Velocity @ 700
Velocity @ 800
1
4.02
4.95
5.66
6.43
2
5.34
6.57
7.72
8.96
3
5.13
6.24
7.29
8.53
4
4.53
5.65
6.86
8.01
The velocities at each flowrate would then be normalized to path 1 so that they can be averaged over the
range of flows. To normalize, use the following calculation:
Path N ratio = Path N’s good velocity / Path 1’s good velocity
Path
Normalized
Velocity @ 500
Normalized
Velocity @ 600
Normalized
Velocity @ 700
Normalized
Velocity @ 800
Average
Normalized Vel
1
1.00
1.00
1.00
1.00
1.000
2
1.328
1.327
1.364
1.393
1.353
3
1.276
1.261
1.288
1.327
1.288
4
1.127
1.141
1.212
1.246
1.182
The Average Normalized Velocity would then be entered as each paths Velocity Substitution Ratio.
If path 1 were to fail and the flowrate were 700 CFS, the flowmeter would use the velocity from path 4
(the mirror path) and calculate a substitute velocity using the formula:
Substitution velocity = good path’s velocity x (bad path’s velocity substitution ratio / good path’s
velocity substitution ratio)
Plugging in actual numbers yields: 5.803 = 6.86 X (1.00 / 1.182). In this example, 5.803 would be
substituted for the original value of 5.66. The accuracy of the substitution will depend on the variation in
velocity profile over the range of flows.
If good velocities are not known at the time of system setup, set the ratios to 1.0.
Type:
Path parameter
Menu levels:
Extended
Range:
#
Default:
ACCUSONIC MODEL 7500
1.0
7-33
Parameters
V FWD 1 - n
In open channel and compound installations, the forward average channel velocity constant, used only
when the USGS single path integration method is chosen in section parameter Single path integration.
Type:
Section
Menu levels:
Setup, Extended
Range:
#
Default:
0
V REV 1 - n
In open channel and compound installations, the reverse average channel velocity constant, used only
when the USGS single path integration method is chosen in section parameter Single path integration.
Type:
Section
Menu levels:
Setup, Extended
Range:
#
Default:
0
Volume scale factor
The flowmeter calculates flow rate in units determined by the Flowrate scale factor. The totals based on
these flow rates are divided by the Volume scale factor to obtain volume in the desired units according to
the following formula:
Volume in desired units = Totalized measured units / Scale factor
Some common volume scale factors are:
If flow is scaled to
Desired volume in
Set volume scale to
Cubic feet/second
acre-feet
43,560.0
cubic feet
1.0
liters
0.0353356
gallons
0.13368984
mg
133,689.84
gallons
1.0
mg
1,000,000.0
mgd
mg
86,400.0
Cubic meters/second
gallons
0.00379
liters
0.001
cubic feet
0.02833
1000 cubic meters
3,600,000.0
Gallons/second
Cubic meters/hour
If a totalized pulse output circuit is used, each pulse represents an increment of one volume unit.
7-34
ACCUSONIC MODEL 7500
Parameters
Type:
Section parameter
Menu levels:
Setup, Extended
Range:
#
Default:
43,560 (English units)
1,000 (Metric units)
Weight
A weighting factor denoting the importance of the path. The path velocity is multiplied by the weight and
other factors to determine flow rate. Path weights are assigned based on conduit shape and integration method.
They should not be changed without consulting Accusonic. If 0 is entered the default value appropriate for the
number of paths and integration method will be returned.
Type:
Path parameter
Menu levels:
Extended
Range:
#
Default:
0.217079 (for outer paths of a 4-path section) using Chebyshev integration
0.568319 (for inner paths of a 4-path section) using Chebyshev integration
0.7854
(for both paths of a 2-path section) using Chebyshev integration
Which Section
Determine the source of stage (level) data, if a stage (level) value from another section is chosen for use
in determining the cross-sectional area for use in calculating flowrate.
Type:
Section parameter
Menu level:
Extended
Range:
Default:
Width at path elevation
Width of the conduit at the path height. Used with the Gaussian integration method and in open channel
installations. This value is from the as-built survey sheet prepared at the time of transducer installation
and should not be changed without consulting Accusonic.
Type:
Path parameter
Menu levels:
Setup, Extended
Range:
#
Default:
0
Zero flow offset
This value is added to the calculated flowrate to correct for zero flow offset. Example: If flowrate is
displayed as 2.1 CFS at zero actual flow, enter -2.1 to correct the offset.
ACCUSONIC MODEL 7500
7-35
Parameters
TYPICALINTEGRATIONMETHOD
(ALLPATHSGOOD)
FULLTRAPEZOIDAL (ABOVEFULLPIPE)
TRAPEZOIDAL
RISE
RUN
RUN
CHANNELBOTTOM
SIDEVIEW
MINIMUMSTAGE
MINIMUMPATHSUBMERSION
MINIMUMPATHSUBMERSION
MINIMUMPATHSUBMERSION
MINIMUMPATHSUBMERSION
IFCHANNELBOTTOMHEIGHTISZERO,
ALLPARAMETERSW
ITHDASHED
LINESTORIGHTAREREFERENCED
TOBOTTOM.
IFBOTTOMHEIGHTISOTHERTHAN
ZERO,THEYAREREFERENCEDTO
THISLEVEL.
(NOPATHSAVAILABLECAN'TMEASUREVELOCITIES)
SINGLE-PATHTRAPEZOIDAL (ONLYONEPATH'ON')
MANNING
NONE (NOSTAGEAVAILABLE)
CHANNELBOTTOMHEIGHT
RISE
PIPESLOPE=
STAGE
OFFSET
LAYERBOUNDARYW
IDTH3
LAYERBOUNDARYW
IDTH2
BOTTOMW
IDTH
UPLOOKERTRANSDUCER
LAYERBOUNDARYW
IDTH1
SEALEVEL
FIGURE7-1OPENCHANNELANDCOMPOUNDSYSTEMPARAMETERS
(LAYERSDEFINE
CHANNELSHAPE)
LAYERBOUNDARYELEVATION1
PATH1
PATH1ELEVATION
PATH3ELEVATION
PATH3
LAYERBOUNDARYELEVATION2
PATH2
PATH2ELEVATION
PATH4
PATH4ELEVATION
FULLPIPE
LAYERBOUNDARYELEVATION3
MAXIMUMSTAGE
ACCUSONIC MODEL 7500
7-36
Parameters
Variable List
Variables are listed in alphabetical order. All variables are available at all menu levels.
Any Volume Variable (positive, negative or total) can be reset by entering 0 while the variable is
displayed. All volumes in the system can be reset by selecting RESET from the top-level menu.
Averaged stage
The running average of stage measurements in the measurement section as calculated using the number of
measurements specified in the parameter Averaging size. This will be the average of Stage 1 and Stage 2
if both are being used and are within the parameter Maximum stage difference 1 and 2.
Type:
Section variable
Display Screen: 2
Average velocity of sound
Average of velocities of sound through the fluid in the measurement section or some combination of
sections, as calculated for the individual paths.
Type:
Section and End variable
Average temperature
Average temperature of fluid in the measurement section or some combination of sections, as calculated
using temperatures calculate for individual paths.
Type:
Section and End variable
Display Screen: A
Delta flow
The difference between instantaneous flowrates calculated at the two ends of a pipeline leak detection
system. This value is added to the differential flow averaging queue.
Type:
Leak detection variable
Display Screen: 6
Delta flow average
The running average of the difference between flowrates at two ends of a pipeline leak detection system.
Type:
Leak detection variable
Display Screen: 6
Differential flow warning
Reads "OFF" unless the differential flow average has exceeded the leak detection parameter Differential
warning threshold. If the threshold is exceeded, a warning relay closes as this variable changes to ON.
Type:
Leak detection variable
Display Screen: 6
ACCUSONIC MODEL 7500
7-37
Parameters
Differential flow alarm
Reads "OFF" unless the differential flow average has exceeded the leak detection parameter Differential
alarm threshold. If the threshold is exceeded, an alarm relay indicating a leak closes as this variable
changes to ON.
Type:
Leak detection variable
Display Screen: 6
Flow average
Average flow rate through the measurement section or some combination of sections, as calculated using
the number of flow rate measurements specified in the parameter Averaging queue length.
Type:
Section and End variable
Display Screen: 1,2,8,A
Flow error count
The number of consecutive errors in the flow error counter. When this count exceeds the parameter
Maximum bad measurements, an error is flagged. The error count is reset to 0 when flow is good.
Type:
Section variable
Flowrate
The flowrate calculated for the measurement section from individual path velocities.
Type:
Section and End variables
Forward gain
This gain level is adjusted in response to the single strength of the last acoustic pulse received in the
forward direction on this path. The receiver will be set at this gain level the next time a measurement is
taken in the same direction on this path.
Type:
Path variable
Display Screen: 9,0
Forward time
Forward travel time in seconds (in the downstream direction) for the individual path.
Type:
Path variable
Negative volume
Accumulated volume in the negative direction in the measurement section or some combination of
sections.
Type:
Section and End variable
Display Screen: 1
7-38
ACCUSONIC MODEL 7500
Parameters
Positive volume
Accumulated volume in the positive direction in the measurement section or some combination of
sections.
Type:
Section and End variable
Display Screen: 1,5
Reverse gain
This gain level is adjusted in response to the signal strength of the last acoustic pulse received in the
reverse direction on this path. The receiver will be set at this gain level the next time a measurement is
taken in the same direction on this path.
Type:
Path variable
Display Screen: 9,0
Reverse time
Reverse travel time in seconds (in the upstream direction) for the individual path.
Type:
Path variable
Section status
Status codes based on internal system diagnostics. The first set of 8 digits after the section number are
path status or error codes (PATH); the next set of two digits/characters represent stage or level (SG),
followed by overall section status (S) and two digits representing self-test (ST). See Chapter 9 for detailed
code explanations and recommended actions.
Type:
Section variable
Display Screen: 1,2,6,7,8,A
Signal delay
Total electronic signal delay in the system. The delay is calculated based on parameters entered for cable
length, transducer type, signal detection method, etc..
Type:
Path variable
Stage 1
The instantaneous elevation of the water surface relative to the site datum is computed from data from the
stage sensor, which may be an acoustic uplooking transducer, an acoustic downlooking transducer, or a
pressure sensor. If there are redundant stage sensors in one metering section, Stage 2 will appear as a
variable as well.
Type:
Section variable
ACCUSONIC MODEL 7500
7-39
Parameters
Stage 1 signal delay
The total electrical and mechanical signal delay, which is subtracted from the acoustic travel time. This
value includes cable, receiver, and transducer delays and is calculated by the system based on parameters
entered.
Type:
Section variable
Total average flow
The sum of the flow averages through all measurement sections.
Type:
General variable
Display Screen: 1,2,5,6,7,8,A
Total Flow
The sum of the instantaneous flow rates through all measurement sections.
Type:
General variable
Total negative volume
The sum of accumulated negative volumes of all measurement sections.
Type:
General variable
Display Screen: 1
Total positive volume
The sum of accumulated positive volume of all measurement sections.
Type:
General variable
Display Screen: 1
Total volume
The sum of all accumulated positive and negative volumes of all measurement sections.
Type:
General variable
Display Screen: 7,8,A
Velocity
The average velocity calculated for the individual path.
Type:
Path variable
Display Screen: 3,4
7-40
ACCUSONIC MODEL 7500
Parameters
Velocity error count
The number of consecutive errors in the velocity error counter. When this count exceeds the parameter
Maximum bad measurements, if the number of good paths is less than the parameter Minimum good
paths, flow calculation stops and an alarm is signaled. Otherwise, the last good velocity for the path is
used in calculating flowrate.
Type:
Path variable
Velocity of sound
Velocity of sound calculated for the individual path using measured travel times.
Type:
Path variable
Volume
The sum of accumulated positive and negative volumes through the measurement section or some
combination of sections.
Type:
Section and End variable
Display Screen: 7,8,A
ACCUSONIC MODEL 7500
7-41
Parameters
GENERAL VARIABLES
General variables reflect the overall operation of the flowmeter. They are listed below.
♦ Total average flow
♦ Total flow
♦ Total negative volume
♦ Total positive volume
♦ Total volume
SECTION AND END VARIABLES
Section variables monitor detailed operation of one section. End variables monitor the operation of one
end of a pipeline or penstock, which might be composed of a single section or of more than one section.
Section and End variables are listed below.
♦ Averaged stage1
♦ Average velocity of sound
♦ Average temperature
♦ Flow average
♦ Flow error count1
♦ Flowrate
♦ Negative volume2
♦ Positive volume2
♦ Section status1
♦ Stage 1 and/or 21
♦ Stage 1 and/or 2 signal delay1
♦ Volume2
PATH VARIABLES
Path variables monitor operation of individual paths. Path variables are listed below.
♦ Forward gain
♦ Forward time
♦ Reverse gain
♦ Reverse time
♦ Signal delay
♦ Velocity
♦ Velocity error count
♦ Velocity of sound
LEAK VARIABLES
Leak detection variables reflect the differential flowrates of more than one end. Leak detection variables
are listed below.
♦ Delta flow
♦ Delta flow average
♦ Differential flow warning
♦ Differential flow alarm
___________________________________________________________________________________________________________________________________
1 Section variable only
2 May be reset to zero by entering 0 via the control panel while the variable is displayed. Resetting these
variables has no effect on external totalizers.
7-42
ACCUSONIC MODEL 7500
Parameters
FORCED PAGE BREAK FOR PAGE NUMBERING REASONS. REMOVE FROM MANUAL.
ACCUSONIC MODEL 7500
7-43
Parameters
7-44
ACCUSONIC MODEL 7500
Chapter 8
Outputs and Reports
Outputs
The flowmeter can be tailored to output a variety of flowmeter variables in a format suitable for use by a
process controller (plc) or external computer. For example, the outputs may be used to drive a real time
data acquisition system or even a spreadsheet.
Data values can be output in analog or digital form; events and alarms may also appear as relay contact
closures. Analog outputs are typically 0-10 V or 4-20 mA; digital data is typically in ASCII format from
the RS-232 ports, although other specialized outputs are available.
Suggestion for Testing Outputs
Use simulated data as a simple way to test analog and digital output parameters. To exercise all settings,
run the system with simulated values at minimum and maximum output ranges, at one or more points in
range, and also at overflow and underflow values. This is usually easier than altering actual fluid flow to
test the outputs. For further information, refer to the descriptions of the path parameters Simulation
Velocity and Simulation Velocity Ramp Scale in Chapter 7 on page 7-25.
When connecting to outputs, operation of external equipment and correct connection can be easily
verified by the use of the I/O diagnostics. Verification routines for the various outputs are found under the
Diagnose menu choice. Procedures for following these routines are set out below. Menu choices will only
appear for installed hardware. Analog outputs can be set to zero, half-scale, or full-scale. Relay and
totalizer outputs can be toggled. This provides a quick way to verify hardware operation without
software/setup complications.
Analog Outputs
This section describes how to set up the analog outputs for a specified section variable. It also explains
how to scale each output and define its behavior during error conditions.
Setting Up Analog Outputs
To set up analog outputs, select Configure from the main menu, then select Output. From the Output
menu, select Analog. The menu shows a choice for every output installed at the factory. These are labeled
Analog1, Analog2, etc. Each analog output can be independently assigned to one of several variables.
More than one analog output may be assigned to the same variable.
ACCUSONIC MODEL 7500
8-1
Outputs and Reports
Determining Offsets and Scale Factors
Each output may be independently scaled. Once you have selected the desired variable, the menu prompts
for maximum and minimum. The maximum is the value of the variable for which a full scale analog output
is required, the minimum is the value of the variable for which a minimum output is required (typically
4mA for 4-20mA output or 0V for 0-10V output).
The lower limit of any output may be set to zero or to any value. The following two examples illustrate
how this is done.
Example 1:
Desired output value:
Desired output range:
Flowrate
0 to 450 CFS
Set the following parameters:
Example 2:
ANALOG1
MAXIMUM
MINIMUM
= FLOWAVG
= 450.0
=0
Desired output value:
Desired output range:
Flowrate
-100 to +300 CFS
Set the following parameters:
ANALOG1
MAXIMUM
MINIMUM
= FLOWAVG
= 300
= -100
The value going to the output is the same value as seen on the screen; i.e., it is scaled to CFS, MGD, etc.
8-2
ACCUSONIC MODEL 7500
Outputs and Reports
Selecting Action for Flowmeter Section Error Conditions
There are two possible error conditions which can occur with an analog output. The first and most
important is the behavior of the output on a system failure of some kind, for example, an insufficient
number of good paths. In this case, the example below illustrates the options for analog output behavior
under these conditions. Note that the flowrate display will be dashed.
The second error condition occurs when the flowmeter output variable is outside the dynamic range of the
analog output device. Under these conditions, the analog output clamps at the lowest output level if the
output variable underflows or at the highest output level if the output variable overflows. For example, if
the output range of the variable flowrate is defined to be 0-1,000 cfs, corresponding to 4 to 20 mA output,
a flowrate of 1,010 cfs or a negative flowrate drives the analog output to 20 mA or to 4 mA, respectively.
Voltage outputs behave in the same manner.
During analog output setup, the menu prompts for the Error Action to be taken by the output during a
system error condition. The two choices are Hold and Fixed.
Hold causes the output to remain at the same value as before the error.
Fixed prompts for the value you would like the output to go to under an error condition. The Fixed Value
entered is conditioned by the parameters maximum and minimum before it is output to the analog channel,
as shown in the following example.
Example 3:
Desire output value:
Desire output range:
Desired output on system error:
Set the following parameters:
ANALOG1
MAXIMUM
MINIMUM
ERROR ACTION
FIXED VAL
Flowrate
0 to 450 CFS
450 CFS
= FLOWAVG
=450.0
=0
= FIXED VALUE
= 450
With a small adjustment to the scaling and offset factors, the error action feature can be used to remotely
signal an error condition. In the example shown, the normal output will be from 2.2% to 100% of the
range. During an error event, the flowrate at the output will be 0% (-10 CFS, an impossible plant
condition), indicating an error. Note that a small part of the output range will be lost (in this case 2.2%),
causing a small loss in resolution.
Example 4:
Desire output value:
Desire output range:
Desired output on system error:
Set the following parameters:
ANALOG1
MAXIMUM
MINIMUM
ERROR ACTION
FIXED VAL
ACCUSONIC MODEL 7500
Flowrate
0 to 450 CFS
-10 CFS
= FLOWAVG
=450.0
= -10
= FIXED VALUE
= -10.0
8-3
Outputs and Reports
Verify Analog, Relay and Totalizer Outputs
The following procedure is used to verify that analog outputs (e.g., 0-10V or 4-20mA), relays, and
totalizers are operating correctly. The procedure begins at the main menu.
Top line of the display shows:
configure operate reset [DIAGNOSE]
Press key(s)
Enter
Explanation
Accept
Diagnose
Select
[SYSTEM] transceiver hardware utils
→→
Hardware
Accept
system transceiver [HARDWARE]
Enter
Hardware
utils
Accept Outputs
[OUTPUTS] inputs
Enter
If the system has been configured for outputs, the first output and type of
output will appear on the display. Pressing the down or up arrows will
toggle between installed outputs. Start with the first output shown. The
following procedure shows an analog (e.g., 0-10V or 4-20mA) output.
To show current
OUT1 Analog 8-bit channel 0
Enter
output level
To toggle to
OUT1 Analog 8-bit channel 0 = zero
Enter
half or full scale
Watch the external output device to see if it reads at the corresponding level
(i.e., representing zero, half-scale or full-scale) as the output is toggled.
Relay outputs will toggle between On and Off. Volume totalizers will
increment each time Enter is pressed.
Pressing Escape once returns to the output listing. Use the down arrow to
toggle through the list and test each output. After testing all outputs, press
Escape twice to return to the previous menu. Remember to reset the volume
totalizers that have been incremented during this procedure.
Field Adjustment Procedure
for 2-Channel 4-20 mA Output
Equipment required:
Misc screwdrivers
Small flat-bladed screwdriver
Calibrated Digital Ammeter
SPAN
R1
R5
ZERO
Procedure:
1. Turn off power to the flowmeter.
2. Locate the six-pin output terminal strip. This
will be mounted on the right-hand side of the
path-select panel in NEMA enclosures, and on
the rear panel in rack-mount enclosures. The
output driver board is located behind connector.
3. It may be necessary to disconnect the path
8-4
SPAN
CN1
R11
R15
ZERO
CR1
CR11
ACCUSONIC MODEL 7500
Outputs and Reports
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
cables to adjust the outputs in a NEMA enclosure. Do this only if required. There is usually enough service
loop in the cables to allow lowering the panel.
On NEMA units, there are four captive thumbscrews in the corners of the path-select panel. These allow the
panel to be lowered for access to the output converter boards.
For rack-mount units, the rear panel can be lowered by removing four flat-headed screws in the corners of the
rear panel. If the unit is being used as a portable, the rack ears (sides) of the unit may need to be removed first
(six #2 phillips screws each).
The output converter will be a small circuit board approximately 3 inches (75mm) square. It plugs into the sixpin output terminal strip.
The board should be calibrated while connected to the operating load. Disconnect one side of the output loop
and connect the Ammeter in series.
Disconnect the wire from pin 2 of the terminal strip and connect Ammeter positive lead to pin 2. Connect
ammeter minus lead to the wire removed from pin 2.
From main 7500 menu, choose [DIAGNOSE], then select [HARDWARE], then [OUTPUTS]. Scroll down
through the menu until you come to 12-bit Analog output channel 0. Press ENTER and the display will respond
with ‘-> zero’. The output is now set to 0 scale.
Set the channel 0 ZERO potentiomer (labelled R1 on the board) so that the ammeter reads 4.00 mA
Press ENTER twice more. The display will respond with ‘-> full’. The output is now set to full scale.
Set the channel 0 SPAN potentiomer (labelled R5) to read 20.00 mA.
Pressing ENTER will scroll through zero, half, and full-scale. Verify that zero is still 4.00 mA (tweak if
necessary), and that half-scale is 12.0 mA.
Disconnect the ammeter and reconnect the wire you removed from pin 2.
Disconnect the wire from pin 5 of the six-pin terminal strip and connect Ammeter positive lead to pin 5.
Connect ammeter minus lead to the wire removed from pin 5.
Press ESC to exit from testing channel 0. Press the down-arrow to go down to the second output, 12-bit Analog
output channel 1.
Press ENTER and the display will respond with ‘-> zero’.
Set the channel 1 ZERO potentiomer (labelled R11 on the board) so that the ammeter reads 4.00 mA
Press ENTER twice more. The display will respond with ‘-> full’. The output is now set to full scale.
Set the channel 1 SPAN potentiomer (labelled R15) to read 20.00 mA.
Pressing ENTER will scroll through zero, half, and full-scale. Verify that zero is still 4.00 mA (tweak if
necessary), and that half-scale is 12.0 mA.
Disconnect the ammeter and reconnect the wire you removed from pin 5.
Repeat for any additional output boards. If there are multiple boards, they can be unplugged from their output
connector to gain access to lower boards. There is no need to turn the power off when doing this, only the
output loop is being broken.
Press ESC to exit the current channel test. Press the down-arrow to scroll down to the next output. Repeat the
above steps for all outputs.
When calibration is complete, Turn off power and reverse the disassembly process. The calibration is complete.
ACCUSONIC MODEL 7500
8-5
Outputs and Reports
Relay and Totalizer Outputs
Flowmeter options include general purpose operator-assignable relays and a watchdog relay. Relays may
be wire-OR'd or diode-OR'd together to derive composite signals. Each relay has a separate user-set
software counter. The relay-activating condition must continue for the number of measurements
exceeding this counter value before the relay will activate.
General purpose relays
The flowmeter may be equipped with one or more general purpose relays. Each relay is a
2−Form C (DPDT) with both make and break contacts. When a relay activates, its make contacts close
and its break contacts open. The electrical specifications are given in Table 8-2 on page 8-8.
The function of each relay is set and can be reassigned from the menus on the control panel. An example
procedure is set out later in this Chapter. No relay functions are assigned at the factory unless specified by
the customer at the time the order is placed.
A relay can be assigned to one of several functions. Not all of the functions need to be assigned (there
may be fewer relays installed than there are functions), nor must every relay be assigned to a function - it
may be reserved for a future use. The following lists the name of each function, its shorthand notation
(which is what appears in the control panel menus) and how it operates:
Section Status - SSTAT - Activates when a path returns too many consecutive bad measurements and
there are no longer enough good paths to make a flow calculation for that section. Indicates that the
section variable Section Status does not equal 1 (good) or 9 (off) or S (path substitution in use) for a
number of consecutive bad measurements exceeding the general parameter Maximum bad measurements.
Self Test Failure - SELFTEST - Activates when the system detects too many bad self tests in a row on a
flow transmitter.
Indicates that the flow transmitter self test result is not equal to 1 (good) or 9 (off).
Loss of Signal - SIGLOSS - Activates if no signal is detected on one or more paths in the section.
Mismatched gain on two directions of one path - GAIN - Activates whenever the gain between the
forward and reverse directions on any path differs by more than 6 dB. This can be an early warning of
cable or transducer failure. This condition is not considered a bad measurement.
System Error - SYSTEM - Activates when any of the functions Section status, Stage status, Self test
failure or Loss of Signal activates. System relays can be assigned to an individual section or as a General
relay, in which case it will close on any of those conditions in any section.
8-6
ACCUSONIC MODEL 7500
Outputs and Reports
Flow measurements - FLOW - Activates when specified flow condition occurs (four options):
• Flow is Positive - FLOWPOS - Flow measured through a section is in the forward direction.
• Flow is Negative - FLOWNEG - Flow measured through a section is in the reverse direction.
• Flow Over Error - FLOWOVER 1 - Exceeds a specified value for a specified number of
consecutive measurements.
• Flow Under Error - FLOWUNDER1 - Flowrate is below a specified value for a specified
number of consecutive measurements.
Stage-Activates as follows:
•
•
•
Stage Over1 - Average stage (water level) measured is higher than a specified value.
Stage Under1 - Averaged stage (water level) measured is lower than a specified value.
Stage Error - No stage (water level) data is provided by any level sensor. If there are multiple stage
sources, relay will not activate until ALL are bad.
Leak Detection (Refer to Leak Detection - Chapter 12)
Differential Flow -The differential flow relay activates to indicate a leak in the pipeline. Each relay
corresponds to a differential flow threshold parameter, as follows:
• Differential flow warning - Differential warning threshold.
• Differential flow alarm - Differential alarm threshold.
Velocity measurements - VELOCITY - Activates when excessive velocities are measured in the forward
or reverse direction. This capability is designed to provide Leak Detection capability with only a singlepoint measurement. Therefore, because velocities may be very high, Signal Quality filtering is not used.
Each relay corresponds to an over-velocity threshold parameter, as follows:
•
•
•
•
1
Positive over-velocity warning - Positive over-velocity warning threshold.
Positive over-velocity alarm - Positive over-velocity alarm threshold.
Negative over-velocity warning - Negative over-velocity warning threshold.
Negative over-velocity alarm - Negative over-velocity alarm threshold.
For the Over and Under functions, the menu system prompts for both the
under/over limit and the number of consecutive bad measurements allowed before
the alarm activates.
ACCUSONIC MODEL 7500
8-7
Outputs and Reports
Table 8-1 General Purpose Relay Specifications
Relay Type
Contact material
Contact resistance (initial)
Contact resistance (end of life)
Max switched rating
Max switched voltage
Mechanical life, operations
Electrical life, operations
Dry circuit
30 VDC, 2A
125 VAC, 1A
30 VDC, 1A
125 VAC, 1/2A
Operate time, typ
Release time, typ
Contact bounce, NO side, typ
Contact bounce, NC side, typ
Contact to contact capacitance, typ
Contact to coil capacitance, typ
Insulation, 25°C,50% R.H., 500 VDC
8-8
2−Form C
Gold-clad silver alloy
50 mOhm
200 mOhm
60 W or 125 VA
50 V AC or DC
100,000,000
50,000,000
500,000
500,000
2,000,000
2,000,000
3 ms
2 ms
1.5 ms
2.5 ms
1.0 pF
2.0 pF
1000 MOhm, min
ACCUSONIC MODEL 7500
Outputs and Reports
Totalizer Output
A totalizing accumulator increments each time a specified volume is measured through one section or all
sections. The totalizer can be tailored to activate on the basis of the positive flow measurement or the
negative flow measurement.
A totalizer indicates that Total Volume (or Positive volume or Negative volume) has incremented. It is
important that the value of Volume scale factor be chosen so that no more than one increment can occur
during a single measurement period. The system can produce only one totalizer pulse per measurement.
An example of setting up the totalizer outputs is set on page 8-11 of this chapter.
System Failure or Watchdog relay
The watchdog relay activates if there is a hardware or a software error detected by the system controller.
This is a low-power relay.
Table 8-2 Watchdog Relay Specifications
ACCUSONIC MODEL 7500
Relay Type
1-Form C
Contact resistance, initial
Max switched rating
Max switched voltage
Max switched current
Electrical life, operations
Low levels
Rated load
Operated time, typ
Release time, typ
Contact bounce, NO side, typ
Contact bounce, NC side, typ
Insulation, 20°C
200 mOhm
3W
28 V
.25 A
100,000,000
10,000,000
0.25 ms
0.25 ms
0.5 ms
1.5 ms
1010 Ohms
8-9
Outputs and Reports
Setting Up the General Purpose Relays
In this example, relay number 2 is assigned the function SSTAT.
Top region of the display
Press key(s)
Explanation
Accept Configure
[CONFIGURE] operate reset diagnose
Enter
Select Outputs
[PARAMETER] variable outputs reports
→→
Accept Outputs
parameter variable [OUTPUTS] reports
Enter
Select relay
[RS232] analog digital relay totals
→→→
Accept Relay
rs232 analog digital [RELAY] totals
Enter
Select Relay 2
[RELAY 1] relay 2 ...1
→
Accept Relay 2
relay 1 [RELAY 2] ...
Enter
Turn relay on
RELAY 2
→ Enter
Output switch: [OFF] on
Accept Section
RELAY 2
Enter
Output type: general [SECTION] leak
Accept Section 1
[SECTION 1]
Enter
ON
RELAY 2 SECTION 1
Accept SSTAT
Enter
Output when [SSTAT] selftest >>
Define the relay counter
RELAY 2 SECTION 1
Type any value
value
Max. Bad Measurements: 0
and Enter
2
Return to main menu
RELAY 2
Esc Esc Esc
Press Esc...
At main menu
[CONFIGURE] operate reset diagnose
Before leaving the Outputs menu you will be asked whether to save the outputs you have
defined. Follow the procedure described in Chapter 5 for saving to battery-backed memory
or to a diskette.
1 Additional relays are listed if they are installed.
2
Pressing Esc once here returns you to the Relay 1, Relay 2... menu where you may assign
other relays.
8-10
ACCUSONIC MODEL 7500
Outputs and Reports
Setting Up the Totalizer Outputs
In this example, Totalizer number one is assigned to indicate an increment in positive volume in
flowmeter section 1.
Top region of the display
Press key(s)
Explanation
Accept Configure
[CONFIGURE] operate reset diagnose
Enter
Select Outputs
[PARAMETER] variable outputs reports
→→
Accept Outputs
parameter variable [OUTPUTS] reports
Enter
Select Totals
[RS232] analog digital relay totals
→→→→
Accept Totals
rs232 analog digital relay [TOTALS]
Enter
1
Accept Totalizer 1
[TOTALIZER 1] totalizer 2 ...
Enter
To turn totalizer relay on
TOTALIZER 1
Enter or
Output Switch: off [ON]
→ Enter
Accept Section
TOTALIZER 1
Enter
Output type: general [SECTION]
Accept Section 1
[SECTION 1]
Enter
ON
Accept PVolume
TOTALIZER 1 SECTION 1
Enter
Section variable: [PVOLUME] nvolume
Return to main menu
TOTALIZER 12 SECTION 1
Esc Esc Esc
Press Esc...
Before leaving the Outputs menu you will be asked whether to save the outputs you have
defined. Follow the procedure described in Chapter 5 for saving to battery-backed memory
or to a diskette.
At main menu
[CONFIGURE] operate reset diagnose
1 Additional totalizers are listed if they are installed.
2
Pressing Esc once here returns you to the Totalizer 1, Totalizer 2... menu where you may
assign other totalizers.
Verify Relay and Totalizer Outputs
The procedure for verifying general purpose relay and totalizer outputs is set out on page 8-4.
ACCUSONIC MODEL 7500
8-11
Outputs and Reports
Summary of Data Storage Options
The following describes the difference between Reports, Data logging, Listings, Parameter load/save, Error
Reporting, and RS-232 Output. Data Storage type is shown in BOLD. Samples are shown in Small Type.
RS-232 Output
• What is stored:
One output of each variable after measurement cycle.
If “averaged” outputs are selected, they are averaged over the selected averageing queue length.
• Format:
AXCII text, with Token identifiers before each variable.
• Destination device:
Serial Port - designed to go to a Terminal or PC for logging.
• Sample:
DATE: 12.01.94
TIME: 16.25.29
FLWA-1: 138.49765
VEL1-1: 2.8787517
VEL2-1: 3.2599885
VEL3-1: 3.2887631
VEL4-1: 3.1109835
FLWA-2: 138.95862
VEL1-2: 2.8566508
VEL2-2: 3.2461038
VEL3-2: 3.3234835
VEL4-2: 2.9337661
8-12
ACCUSONIC MODEL 7500
Outputs and Reports
Reports
• What is stored:
Averaged output of flow, stage, volumes, and totals (in a multi-section meter).
Time and Date are included.
Start time and report interval can be selected.
Text headers can be customized.
Note: The averaged output value of each variable = (sum of all measurements / number of
measurements during the report period).
• Format:
ASCII text, English language headers.
• Destination devices:
Printer, Floppy Disk
• Sample:
Karr Dam Power Plant
Quarterly Report
FLOW
STAGE P-VOL
======== ======== ========
Mon Mar 06 1995 13.00.20
321 measurements
END-1 (100% good)
1000.000 -------1900
END-2 (100% good)
1002.000 -------1870
END-3 (100% good)
2120.000 -------2100
======== ======== ========
totals:
4122.000
5870
Mon Mar 06 1995 14.00.30
323 measurements
END-1 (100% good)
1000.000 -------2100
END-2 (100% good)
1003.000 -------2070
END-3 (100% good)
2100.000 -------2532
======== ======== ========
totals:
4103.000
6702
Datalogging
• What is stored:
Averages of flowrate, Volume, Stage, and Velocities.
Start time and datalog interval can be selected.
Note: The averaged output value of each variable = (sum of all measurements / number of
measurements during the report period).
• Format:
Comma-delimited ASCII test with a quote-delimited time/date stamp. Designed to be read directly into popular
speadsheets.
• Destintation devices:
Floppy Disk, Printer (printer output is not very useful).
• Sample:
"950306132143",1000.300,0,,,100
"950306132155",1010.400,0,,,100
ACCUSONIC MODEL 7500
8-13
Outputs and Reports
Listings
• What is stored:
Textual representation of parameters and/or variables. Text only, cannot be loaded back into the flowmeter in this
format.
• Format:
ASCII text
• Destination devices:
Printer, Floppy Disk
• Sample:
7500 Software: REV 4.12
Customer: Ypsilanti Power
Job No.: FP12345
Parameter List
Gen. Parameters
Menu Access: extended
Repetition Time (sec.): 2
Self Test Interval (sec.): 100
Stage Interval (sec.): 5
Leak Detection Switch: off
Stage Mode: fast
Data Logging: off
Log Data To: disk
Data Log Start: 00.00.00
Log Interval: 00.10.00
Error Reporting: off
Auto Start Switch: off
Inactivity timeout (min): 0
Units: english
Speed of Sound in Fluid: 4800.0
Password Control: off
Averaging Queue Length: 10
Max. Bad Measurements: 10
Travel Time Tolerance:
20.0
Display mode: both
Display totals line: on
Current Time: 13.20.30
Current Date: 03.06.95
Section 1 Parameters
Section Switch: on
Section Type: pipe
Pipe Integration: cheb
Radius: 5.0000
Stage 1 Source: acoustic
Stage 2 Source: off
Average Cable Length Per Path:
Ducer Connection: single
Sig. Det. Method: 1st_neg
8-14
0.0
ACCUSONIC MODEL 7500
Outputs and Reports
Parameter load/save
• What is stored:
Binary representation of parameters. Used only to save parameters to disk.
• Format:
Binary
• Destination devices:
Flowmeter (battery-backed RAM), Floppy Disk.
• Sample:
Not available, not readable by eye.
Error Reporting
• What is stored:
Flowmeter results during error conditions. This is a log of variables recorded during periods when acoustic paths
have failed or flowrate cannot be measured, to be used as troubleshooting information.
Instantaneous values of Flowrate, Stage(s), Velocities, and Gains can be selected.
• Format:
ASCII text. Designed to be read on-site with a laptop computer equipped with any text editor.
• Destination device:
Floppy disk file with filename ERRLOG.HIS.
• Sample:
Nov 18 10:21:04
FLOW
STAGES
VELS
FWD GAINS
REV GAINS
1
21111111 1 B 1
702.062832
5.100000 0.000000 5.100000
1.400000 1.200000 1.300000 1.400000 1.500000 1.600000 1.700000 1.800000
45 3 3 6 4 3 6 6
48 3 4 5 3 4 8 6
ACCUSONIC MODEL 7500
8-15
Outputs and Reports
RS-232 Outputs
A single RS-232 port is available in the basic flowmeter; others are optional and must be configured at the
factory. Refer to page 4-9 for RS-232 Cable Configuration Information. Each available RS-232 port may
be independently configured to output one or more selected flowmeter variables.
Data is normally output at the conclusion of each measurement cycle.The output stream from each port is
a series of message segments in ASCII format delimited by carriage return/linefeed pairs (i.e., ASCII
OD/0A16 or 012/0158). An additional carriage return/linefeed pair terminates the output from each
measurement.
There is at least 2 one message segment in the stream for each variable. A message segment consists of the
(abbreviated) variable name followed by the colon character (ASCII value 03A16 or 0728) followed by its
value. The format of the value depends on the variable.
In addition to the usual RS-232 setup parameters (baud rate, start/stop bits, etc.), a menu choice is
provided for compatibility with Accusonic 7430-series controllers. This choice allows the user to select
several different protocols:
• STX ETX. When selected, a Start-of-Text character (ASCII 2) will be transmitted before the
measurement data packet. An End-of-Text character (ASCII 3) will be transmitted at the end of the
packet.
• POLL. The 7500 will not transmit any data until it receives a polling character (ASCII 0F 16 or 015 8 ).
• BOTH. The 7500 will wait for a polling character, then transmit a data packet framed by STX/ETX
characters. Select this option for operation with a 7430-series controller.
Table 8-1 (page 8-17) lists the flowmeter variables available via the RS-232 ports. It shows the
abbreviation for each as it appears in the message segment and details the format of the value reported.
Variables are listed in the order in which they appear in the setup menu and in which they will be output.
To configure the RS-232 outputs, refer to the procedure that follows the table.
2For
8-16
variables with multiple values (e.g. path velocities) there is a separate packet for each value.
ACCUSONIC MODEL 7500
Outputs and Reports
Table 8-3 Variables Available via RS-232
Variable Name
General Variables
Total flow
Total average flow
Total volume
Total positive volume
Total negative volume
Time:
Date:
Section Variables
Flowrate
Flow average
Volume
Positive volume
Negative volume
Averaged Stage
Section status
Integration method
Path velocities
Path travel times fwd
Path travel times rev
Path gains fwd
Path gains rev
Velocity of sound
Average velocity of sound
Average temperature
ACCUSONIC MODEL 7500
Data Format1 in Message Segment
TLFLOW: [-]nnn.nnnnn[e-rrr]<CR><LF>
TLFLWA: [-]nnn.nnnnn[e-rrr]<CR><LF>
TLVOLM: [-]nnn.nnnnn[e-rrr]<CR><LF>
TLPVOL: [-]nnn.nnnnn[e-rrr]<CR><LF>
TLNVOL: [-]nnn.nnnnn[e-rrr]<CR><LF>
TIME: hh.mm.ss<CR><LF>
DATE: mm.dd.yy<CR><LF>
FLOW-<s>: [-]nnn.nnnnn[e-rrr]<CR><LF>
FLWA-<s>: [-]nnn.nnnnn[e-rrr]<CR><LF>
VOLM-<s>: [-]nnn.nnnnn[e-rrr]<CR><LF>
PVOL-<s>: [-]nnn.nnnnn[e-rrr]<CR><LF>
NVOL-<s>: [-]nnn.nnnnn[e-rrr]<CR><LF>
STAG-<s>: [-]nnn.nnnnn[e-rrr]<CR><LF>
STAT-<s>:cccccccccccccccc<CR><LF>
INTG-<s>:iiii<CR><LF>
VEL<p>-<s>: [-]nnn.nnnnn[e-rrr]<CR><LF>
TMF<p>-<s>: [-]nnn.nnnnn[e-rrr]<CR><LF>
TMR<p>-<s>: [-]nnn.nnnnn[e-rrr]<CR><LF>
GNF<p>-<s>:gg<CR><LF>
GNR<p>-<s>:gg<CR><LF>
VSD<p>-<s>: [-]nnn.nnnnn[e-rrr]<CR><LF>
AVG<p>-<s>: [-]nnn.nnnnn[e-rrr]<CR><LF>
TEMP-<s>: [-]nnn.nnnnn[e-rrr]<CR><LF>
8-17
Outputs and Reports
Table 8-3 Variables Available via RS-232 (continued)
Leak Detection Variables
Delta flow
Delta flow avg.
End Variables
End flow
End average flow
End volume
End positive volume
End negative volume
End stage avg.
End velocity sound avg
End temperature
DFLW-1: [-]nnn.nnnnn[e-rrr]<CR><LF>
DFLA-l: [-]nnn.nnnnn[e-rrr]<CR><LF>
EFLW-<e>: [-]nnn.nnnnn[e-rrr]<CR><LF>
EFLA-<e>: [-]nnn.nnnnn[e-rrr]<CR><LF>
EVOL-<e>: [-]nnn.nnnnn[e-rrr]<CR><LF>
EPVL-<e>: [-]nnn.nnnnn[e-rrr]<CR><LF>
ENVL-<e>: [-]nnn.nnnnn[e-rrr]<CR><LF>
ESTG-<e>: [-]nnn.nnnnn[e-rrr]<CR><LF>
EVAG-<e>: [-]nnn.nnnnn[e-rrr]<CR><LF>
ETMP-<e>: [-]nnn.nnnnn[e-rrr]<CR><LF>
1 <p> path no.
<s> section no.
<e> end no.
[-]
optional minus sign
nn... up to 8 digits
[e-rrr] optional exponent (if < .000001)
cc... 16 character path status codes,
iiii
integration method
gg
path gain [-27..100]
<CR> carriage return
<LF> linefeed
<STX> optional start-of-text character
<ETX> optional end-of-text character
8-18
ACCUSONIC MODEL 7500
Outputs and Reports
Setting up the RS-232 Outputs
In this example we set up the RS-232 output.
Top region of the display
Press key(s)
Explanation
Accept Configure
Select Outputs
Accept Outputs
Accept RS232
Accept RS232 1
Select On
Accept On
Select Setup
Accept Setup
Accept 9600 or select and
accept another baud rate
Accept 8 or select and
Enter
accept 7.
Accept None or select and
Parity: [NONE] odd even
Enter
accept odd or even.
Accept 1 or select and
Stop bits: [1] 2
Enter
accept 2.
Accept None or select and
Protocol: [NONE] stx_etx poll both
Enter
accept another protocol.
Return to assign/setup
Esc
menu
Accept Assign
[ASSIGN] setup
Enter
Accept General
Output type: [GENERAL] sect end leak
Enter
Display scrolls through the list of variables shown in Table 8-2. Select and accept the option On
for any variable whose value you want output to the selected RS-232 port. After the last variable is
shown, the following menu is displayed:
Return to main menu
[ASSIGN] setup
Esc2 Esc Esc
Esc Esc
Before leaving the Outputs menu you will be asked whether to save the outputs you have defined.
Follow the procedure described in Chapter 5 for saving to battery-backed memory or to a diskette.
At main menu
[CONFIGURE] operate reset diagnose
1 Options RS232 2 RS232 3 ...etc. appear only if additional ports were installed at the factory.
[CONFIGURE] operate reset diagnose
[PARAMETER] variable outputs reports
parameter variable [OUTPUTS] reports
[RS232] Analog Digital Relay Totalizer
RS232 1 ... 1
[OFF] on
off
[ON]
[ASSIGN] setup
assign [SETUP]
Baud rate:
300 1200 2400 [9600] 19200 38400
Data bits: 7 [8]
2
Enter
→→
Enter
Enter
Enter
→
Enter
→
Enter
Enter
Press Esc once to return to the menu RS232 1 RS232 2. Repeat the procedure to define other
RS-232 outputs, if they are available on your system.
ACCUSONIC MODEL 7500
8-19
Outputs and Reports
Verifying RS-232 Output
The following procedure is used to verify that RS-232 outputs are operating correctly. The procedure
begins at the main menu.
Top line of the display shows:
Press key(s)
Explanation
Select Diagnose
[CONFIGURE] operate reset diagnose
→→→
Accept Diagnose
configure operate [DIAGNOSE]
Enter
Accept System
[SYSTEM] transceiver hardware utils
Enter
Select Serial
[KEYPAD] display serial printer
→→
Accept Serial
keypad display [SERIAL] printer
Enter
Select Output
[TRANSMIT] input output
→→
Accept Output
transmit input [OUTPUT]
Enter
This diagnostic tests the RS-232 device driver by continuously outputting a stream of
data (ASCII characters) until Escape is pressed. If there is an error message, it will
appear on the display. Refer to Chapter 6 for additional information on Diagnostics.
Return to the menu by pressing Escape.
8-20
ACCUSONIC MODEL 7500
Outputs and Reports
Flowmeter Reports
The instrument can be tailored to print summary reports at hourly, daily, monthly or any other interval. A
report can be set up to print at the designated interval without further operator intervention, or it can be
logged to disk for printing later. Up to three separate reports may be defined, with each report differing
either in reporting frequency, in the data which it presents, or in destination. There are two major types of
reports. A Flow report includes one or more of the following variables and reports data for individual
sections and ends.
♦
♦
♦
♦
♦
♦
Date, time
Flow rate - True average taken over the specified report interval
Positive volume - Total forward volume through the meter at the time of the report
Negative volume - Total reverse volume through the meter at the time of the report
Total volume - Net volume through the meter at the time of the report
Stage - True average of fluid level over the specified report interval
Information is reported and totalized for all meter sections turned on at the time of the report. In addition,
the overall percentage of good path readings is summarized by section. 3
A Leak Detection report includes the following information for each penstock or pipeline for which leak
detection is enabled and operating:
♦ Date, time
♦ Top Flow - Average flow rate through all sections at the top end taken over the specified
report interval
♦ Bottom Flow - Average flow rate through all sections at the bottom end taken over the
specified report interval
♦ Average Differential Flow - Average, over the report interval, of the difference between flow
rates measured at the top and bottom ends of the pipeline.
♦ Total Flow - The sum of the instantaneous flow rates through all sections at the bottom end
♦ Maximum Differential - The maximum difference between instantaneous flow rates
calculated
by the meter measured at the top and bottom ends of the pipeline during the report interval.
♦ Minimum Difference - The minimum difference calculated by the meter between
instantaneous flow rates measured at the top and bottom ends of the pipeline during the report
interval.
3
The percentage of good path readings is calculated in accordance with the general
parameter Maximum bad measurements. That is, if in a series of measurements
the number of consecutive bad measurements never exceeds the specified limit,
then the overall measurement report will show as 100% good, even though one or
more bad measurements may have actually occurred.
ACCUSONIC MODEL 7500
8-21
Outputs and Reports
The example on the following page describes setting up a total flow report and directing it to print every
other day at 7:00 am. A similar method is used to create other reports or to log a report to disk.
The procedure that follows assumes that a compatible printer and cable have been installed according to
the procedures given in Chapter 4, Connecting a Printer on page 4-6. The printer must be turned on and be
on line.
To set up the reports, step through the procedure shown on the following page.
A sample hourly report printout follows the procedure (Figure 8-1 on page 8-25).
8-22
ACCUSONIC MODEL 7500
Outputs and Reports
Setting Up Reports
[CONFIGURE] operate reset diagnose
[PARAMETER] variable outputs reports
parameter variable outputs [REPORTS]
[LIST] reports
list [REPORTS]
[REPORT 1] report 2 report 3
[OFF] on
off [ON]
Report data: [FLOW] leak
Report to: [PRINTER] disk both
Report header: Daily/hourly/other report
Report header:
Report header: Alternate Day Report:
Report title: Enter your name here
Report title:
Report title: XYZZY Corp
Enter
→→→
Enter
→
Enter
Enter
→
Enter
Enter
Enter
Ctrl - Bksp
and →
→→ ...
Alternate Day
Report
Enter ↓
Crtl - Bksp
...
XYZZY CORP
Enter ↓
Report type: [DAILY] hourly other
Report type: daily hourly [OTHER]
Report start date (MM.DD.YY):
→→
Enter
01.01.93
Enter ↓
Report start time (HH.MM.SS):
07.00.00
Enter ↓
ACCUSONIC MODEL 7500
Accept Configure
Select Reports
Accept Reports
Select Reports
Accept Reports
Accept Report 1
Select On
Accept On
Accept Flow data
Accept Printer
Delete the headings you
don't need; use the
cursor keys to move
across text that you
want to keep.
Type in a suitable
header such as
Alternate Day Report.
Up to 40 characters are
allowed. This will
appear as the top line of
the report.
Accept new header. Go
to next menu item.
Delete the existing text.
Type in suitable header
such as your company
name. Up to 40
characters are allowed.
Appears at the top line
of jump pages2.
Accept new title. Go to
next menu item.
Select Other
Accept Other
Enter suitable date;
accept it and go to next
menu item.
Enter a suitable time;
accept it and go to next
menu item.
8-23
Outputs and Reports
Setting Up Reports (continued)
Report interval (HH.MM.SS):3
Report interval days4:
00.00.00 Enter ↓
2
Enter ↓
Enter 0 hour interval; accept it
and go to next menu item.
Enter 2 day interval; accept it
and go to next menu item.
Flowrate: off [ON]
Select ON for each Variable that
Averaged stage: [OFF] on
→
you want included in the report.
Positive volume: [OFF] on
and
Enter to accept this choice.
Negative Volume: [OFF] on
Enter
Volume: [OFF] on
Totals: [OFF] on
Return to main menu
Report 1
Esc Esc Esc5
Press Esc...
Before leaving the Reports menu, you will be asked whether to save the reports you have defined.
Follow the procedure described in Chapter 5 for saving to battery-backed memory or to a diskette.
(As in earlier procedure)
At main menu
[CONFIGURE] operate reset diagnose
1 A new page is fed to the printer and Report type is printed on the top line if, during the
intervening period of a report, any other material was sent to the printer. This can happen
when both daily and hourly reports are defined.
2 A subsequent instance of a report prints on the same page as the previous instance if it fits
and if no other report was sent to the printer during the intervening period. When the new
instance will not fit, a new page is fed to the printer and Report title is printed on the top line.
3 Does not appear if report type is daily or hourly. If report interval will be greater than 24
hours, enter 00.00.00 or another time increment up to 24.00.00 here and proceed to report
interval days.
4 This value (in days) will be added to the number of hours, minutes, and seconds entered in
the previous parameter.
5 Pressing Esc once here returns you to the menu Report 1, Report 2 ... where you may define
up to three different reports.
8-24
ACCUSONIC MODEL 7500
Outputs and Reports
HOURLY REPORT
Mon Jan 04 1993 08.00.00
SECT-1 (100% good)
SECT-2 (100% good)
totals:
Mon Jan 04 1993 09.00.00
SECT-1 (100% good)
SECT-2 (100% good)
totals:
Mon Jan 04 1993 10.00.00
SECT-1 (100% good)
SECT-2 (100% good)
totals:
Mon Jan 04 1993 11.00.00
SECT-1 (100% good)
SECT-2 (100% good)
totals:
FLOW
P-VOL
=======
=======
1325
measurements
2.976
28
939.573 10557
=======
=======
943
10585
N-VOL
=======
T-VOL
======
0
28
0
10557
=======
======
0
10585
1382
measurements
3.006
28
939.573 10635
=======
=======
943
10663
0
28
0
10635
=======
======
0
10663
1386
measurements
3.078
29
939.573 10712
=======
=======
943
10741
0
29
0
10712
=======
======
0
10741
1382
measurements
3.146
29
939.573 10790
=======
=======
943
10819
0
29
0
10790
=======
======
0
10819
Figure 8-1 Hourly Report
ACCUSONIC MODEL 7500
8-25
Outputs and Reports
Data logging
Section and System Variables can be logged to a disk drive or printer at user-definable intervals. The
choice of disk drive is set at the time of system configuration at the factory and is burned into
Programmable Read Only Memory (PROM). The default drive is B:, the instrument’s integral floppy disk
drive.
The following procedure shows how to turn data logging on for an individual section. Logging of system
totals for flowrate and volumes, as well as log start time interval, is accessed under the General parameters.
Top region of the display
Press key(s)
Explanation
Accept Configure
[CONFIGURE] operate reset diagnose
Enter
Accept Parameter
[PARAMETER] variable outputs reports
Enter
Accept Section
[SECTION] general files password
Enter
Accept Section 1
[SECTION 1] Section 2 etc.
Enter
ON
Bypass
Bypass each successive option until
↓↓...
Data logging option is shown
Select ON
Data logging: [OFF] on
→
Accept ON
Data logging: off [ON]
↓
Select and accept ON to
Log Flow Data: [OFF] on
Enter or
log flowrates & volumes
→ Enter
Log acoustic path
Log Velocity Data: [OFF] on
Enter or
velocities
→ Enter
Log fluid level data
Log Stage Data: [OFF] on
Enter or
→ Enter
Return to Configure
Temperature Coefficient 1
Esc Esc
[SECT] General Leak Files Password
Sect [GENERAL] Leak Files Password
Bypass each successive option until
Data logging option is shown
Data logging [OFF] on
Data loggingoff [ON]
Log data to [DISK] printer both
Parameters Menu
Select General
Accept General
→
Enter
↓↓...
→
Enter
Enter or →
Enter
Data Log Start (HH:MM:SS):
00:00:00
Log Interval (HH:MM:SS):
00:10:00
Auto Start Switch:
Esc Esc
Bypass
Select On
Accept On
Accept Disk or choose
Printer or Both and
Accept one of these
options
Enter the time you want
data logging to begin
Enter to accept logging
at 10-minute intervals
or enter and accept
another interval
Return to Configure
Parameters Menu
Before leaving the Parameter menu you will be prompted to use/save the new settings.
8-26
ACCUSONIC MODEL 7500
Outputs and Reports
Data log file description
When data logging is turned on, variables Flowrate and Positive volume are logged automatically to the
file SECT1FLW.PRN. The number relates to the measurement section; so, for example, if data logging
is enabled for section 3, an additional log file will be generated with the filename SECT3FLW.PRN. The
logfiles are quote- and comma- delimited, and can be read directly into common spreadsheet programs.
Filenames and formats are as follows:
SECT1FLW.PRN contains true-running averages of Flowrate and Volume.
File format is:
“YYMMDDHHMMSS”,flow,total volume,temperature,,percent good<CR><LF>
If negative volume logging is enabled, file format will be:
“YYMMDDHHMMSS”,flow,total volume,temperature,positive volume,negative volume,percent
good<CR><LF>
SECT1STG.PRN contains averages of stage (fluid level) data for the section. Enabling logging for flow
will turn on stage logging automatically.
File format is:
“YYMMDDHHMMSS”,stage1,stage2,average stage,integration method<CR><LF>
Both Stage1 and Stage2 (if any) are averages over the data logging interval.
The third variable, Average stage, is the average of Stage1 and Stage2 when they are within the parameter
Maximum difference in stage. When they are not, Stage1 alone is used. This is the value used in the flow
calculation.
Integration method is not averaged. It is a snapshot of the method in use at the time the log is written.
SECT1VEL.PRN contains true running averages of velocities.
File format (4 path section) is:
“YYMMDDHHMMSS”,VEL1,VEL2,VEL3,VEL4<CR><LF>
If the section has 6 paths, the file format will be:
“YYMMDDHHMMSS”,VEL1,VEL2,VEL3,VEL4,VEL5,VEL6<CR><LF>
ACCUSONIC MODEL 7500
8-27
Outputs and Reports
SECT1AGC.PRN contains instantaneous snapshots of Automatic Gain Control (AGC) data. This
information is typically logged during troubleshooting only, as it uses up large amounts of disk space and
is not useful or required when the meter is operating normally. Enabling logging for velocities will turn
on AGC logging automatically.
File format is:
“YYMMDDHHMMSS”,path 1 forward gain,path 1 reverse gain,path 1 forward agc tattler, path 1
forward noise level, path 1 forward noise history,path 1 reverse agc tattler, path 1 reverse noise level,
path 1 reverse noise history,(repeat for all paths in the section)<CR><LF>
GENFLW.PRN
File format is:
“YYMMDDHHMMSS”,total flow,total volume,total positive volume,total negative volume,
<CR><LF>
Error Reporting
Error reporting is a troubleshooting tool. Enabling it will create a disk log of variables generated when the
flowmeter is in an error condition. This is a handy tool for trapping those errors which only occur when
the system cannot be attended, such as intermittent faults that only happen at night or during storms.
Variables are logged on every measurement that error conditions are met.
The error conditions are controlled by the parameter “Start Logging on Path Errors” as follows:
• If set to ON, logging will begin when any path is in error for more consecutive measurements than the
number entered in the parameter “Maximum Bad Measurements”.
• If set to OFF, error logging begins after “Maximum Bad Measurements” has been exceeded for a
measurement section and the section has been declared “bad”. Note that the if the failure is due to a
path error, “Maximum Bad Measurements” must be exceeded for the path before the counter starts for
the section, and that the failures in both cases must be sequential. For example, if “Maximum Bad
Measurements” is set to 10 and “Start Logging on Path Errors” is set to OFF, it will take 20
consecutive bad measurements before logging begins.
The first line of the log contains date and time, section number, and path, stage, section, and self-test error
codes.
Menu choices are available to log flowrate, velocities, stages, and gains:
• The logged flowrate is the instantaneous flow as calculated from all velocities that have not been
marked as bad (failed consecutively for more measurements than the parameter “Maximum Bad
Measurements”).
• Logged velocities are either:
• The current instantaneous value, or
• The last good value, which will be retained until exiting measurement mode. Retained
velocities will continue to be used in the flow calculation until “Maximum Bad
Measurements” has been exceeded. The status of this is not indicated in the error log.
• Three stage values are logged. They are (in order); Stage 1, stage 2, and averaged and arbitrated stage
(the stage in use at the time to calculate flow). If there is only one stage measurement device in the
system, stage 2 value will always be 0.0.
• Logged gains are instantaneous values as returned from the latest path measurement.
8-28
ACCUSONIC MODEL 7500
Outputs and Reports
FORECED PAGE BREAK FOR PAGE NUMBERING REASONS - REMOVE FROM MANUAL.
ACCUSONIC MODEL 7500
8-29
ACCUSONIC MODEL 7500
30
Chapter 9
Advanced Troubleshooting
This Chapter includes information for interpreting status errors reported by the system. It also includes
the procedure for monitoring raw path signals with an oscilloscope, and explains how to verify and adjust
the system power supply.
What to do first:
When approaching a “broken” 7500 to determine the fault, pay attention to what you see and hear. Much
troubleshooting can be done over the telephone by a call to Accusonic, and the more information you
have, the easier it will be. Look for the following things:
♦ Is there anything on the display?
If there is, what is it? If the flowmeter is operating normally, and you are looking at an
operational screen, you should see flowrate(s) and volumes, with the status area of the display showing
“GOOD”. This is normal operation.
If there is a problem at this level, the status area will display “BAD”. Press the ECODE
key on the keypad to switch to the status display. All error codes should be “1”. If not, refer to the tables
that follow for a detailed explanation of error codes, as well as possible causes and suggested
troubleshooting.
In cases where the flowmeter is located remotely and the only indication of proper
operation is a current loop or serial data stream, the flowmeter can appear to be “broken” if it is left out of
measurement mode. If left in the menu system, no measurements will be made, and no data will be
output. Current loops and relays will hold the value of the last measurement. Restart measurement mode
and see if things operate normally. If they do and this becomes a recurrent problem, refer to the manual
section on entering and enabling passwords.
Status Lights
♦ If there is nothing on the display, check the following:
Is the power switch turned on? If so, check the green power indicator lights to the left of
the path connections. They will be located on the lower left of the NEMA box, and on the left side of the
rear panel of a chassis/rack mount unit. These lights indicate the correct operation of the various power
supplies in the unit. All three should be lit. If all are extinguished and the power switch is on, verify that
there is power to the unit. If there is, check the system fuse. This is located adjacent to the power switch
in a NEMA unit. On a chassis unit, the fuse is located inside the IEC power receptacle on the rear of the
box. Pull out the power cord and use a small screwdriver to access the fuse. If the fuse is good, the main
system power supply may be bad.
♦ If there is power to the unit and all three lights are lit, look at the lights on the
communications board. There are two groups of indicator lights located on the communications board.
The first, a group of four, is used to indicate hardware/software errors. The leftmost is labeled “WP”. This
indicates operation of the Watchdog Timer, a hardware device which monitors software operation. It
should be flashing approximately once per second. The second one is labeled “R”, indicating reset.
During normal operation, it will not be lit. If the system is left out of measurement mode, it will flash
ACCUSONIC MODEL 7500
9-1
Advanced Troubleshooting
once every 22 seconds, resetting the transceiver. The last two lights in this group are labeled “+V” and “V”, and are system voltage monitors. If either of these are lit, the transceiver will not operate correctly. If
either is lit, look at the three green power-monitor lights just to the left of the path cable connections. If
the green lights are all lit but the power monitors on the communications board are not, the problem may
be in the connection to the boards or the power supply levels may need to be adjusted (see section). If one
or more of the green lights is also out, the problem is probably in the power supply.
The other group of lights, a set of eight, indicates measurement errors on the flow
transmitter. During normal operation, all are off; an error is signaled by a lit status light as shown in Table
6-2 on page Error! Bookmark not defined.. During power-up or immediately after a reset, all eight
lights will flash during a reinitialization test. The sequence is:
ON for one second
OFF for one second
ON again for one second
OFF.
During a power-up, all lights will stay off. If the system has been reset, light 0 will
remain on. During periods of inactivity, when the system is out of measurement mode and there is no
communication to the flow transmitter group, this initialization sequence will happen every 22 seconds.
Status Messages
Most of the Non-diagnostic display screens have a one-word status message displayed on the right side of
the screen. The following table describes the significance of the three possible messages:
Table 9-1 Status Messages
Message
GOOD
ALERT
BAD
9-2
Possible Cause
Normal Operation. Occasional path errors
will not cause an ALERT.
One or more paths have more consecutive
errors than allowed by the parameter
Maximum Bad Measurements,
-orThere is a Section Status error (causes
Alert message immediately).
There is a Section Status error that has
persisted for more measurements than
allowed by the parameter Maximum Bad
Measurements.
Recommended Action
No Action Required.
Switch to Status Code display to determine
fault. Refer to Path, Section, or Stage error
code tables starting on the next page of this
chapter.
Switch to Status Code display to determine
fault. Refer to Error Code listings later in
this chapter.
ACCUSONIC MODEL 7500
Advanced Troubleshooting
Error Codes
Path, Section and Self-test Status Codes
The status screen displays error codes based on internal diagnostics. The first 8 digits after the unit
number are path status error codes (labeled PATH), the second 2 digits represent stage or level (SG), the
next is the overall section status (S), and the last 2 digits are self-test (ST). Pressing the "ECODE" key or
the ± key will display the status screen. (Press unshift - on keyboard-only systems.)
For example, during normal operation, the status code for a meter measuring on 4 acoustic paths in each
of two sections will look like the following (note that there is no stage (level) being measured in this
example):
UNIT
--PATH-SG
S
ST
1
1111
1
11
2
1111
1
11
Note that signal quality and travel time checking is performed on every received signal. It is important to
understand that occasional (and in some cases, frequent) errors may be unavoidable in some installations
where there is a high level of signal attenuation and/or electrical or mechanical noise. The software
filtering parameters are designed to allow operation in these unfavorable conditions and to report the
source of the problem. Unless these errors are nearly continuous, there is no reason to suspect the
accuracy of the flowrate output.
For maintenance and troubleshooting purposes, it is the trend of error frequency that should be noted,
along with possible correlation with other site conditions. For example, more path status 3 (SQM) errors
would be expected at a hydro plant when operating at minimum lake levels. Possible air entrainment at
the intake caused by operating at minimum lake levels causes signal attenuation or occasional electrical
noise pulses, causing incorrect travel times, which in turn results in out-of-tolerance time measurements
or unreasonable path velocities, section flowrate or change in flowrate.
ACCUSONIC MODEL 7500
9-3
Advanced Troubleshooting
Table 9-2 Path Status Codes
CODE
1
2
3
4
5
6
7
8
9
9-4
PATH STATUS
Path on and working.
No forward time received.
Forward signal SQM1
error. (Signal is present
but not strong enough.)
Forward time greater than
expected.
No reverse time received.
Reverse signal SQM
error.
Reverse time greater than
expected.
Velocity greater than
maximum allowed. (All
SQM and range gate tests
have been passed, but
velocity calculates to be
greater than section
parameter Maximum
expected velocity.)
Path is turned off.
POSSIBLE CAUSE
Normal operation.
Broken cable.
Failed transducer.
Blocked path (air, logs, fish,
etc.)
Pipe not full of water.
The parameters Path length
and/or Transducer type may be
incorrectly set.
Weak or failing transducer.
Entrained air, fish, or debris.
Weak or failing cable.
Air in water.
Blocked direct path.
Path length parameter set too
short.
Any of the above combined
with electrical or mechanical
noise.
See 2.
See 3.
RECOMMENDED ACTION
No action required.
Check cable.
Replace transducer.
See 4.
See 4.
Section parameter Maximum
expected velocity may be set
too low.
Set section parameter Maximum
expected velocity higher.
Consistent source of validlooking spurious signal.
Normal condition if path
operation is not required.
Check path parameters.
Check transducer.
Check cable.
See introductory note and section
on monitoring raw path signals
with an oscilloscope.
See 2.
See 3.
Check all velocities in Variable
list for reasonableness. If
unreasonable or varying, see
introductory note and section on
monitoring raw path signals with
an oscilloscope.
None. To turn path on, change
path parameter to On.
ACCUSONIC MODEL 7500
Advanced Troubleshooting
CODE
A
PATH STATUS
Velocity changed faster
than allowed.
POSSIBLE CAUSE
If status code is sporadic, noise
or acoustic interference, or
section parameter Maximum
change in velocity may be too
low.
A cable or transducer may be
failing or transducer may be
misaligned.
C
Excessive difference in
signal level between
forward and reverse
direction.
(The difference between
forward and reverse
signal levels exceeds 6
dB.)
Communications error.
D
Impulse Noise detected.1
Interference from another flow
transmitter.
B
E
F
H
J
K
Impulse Noise in PastAdjusting Gain (Data will
not be rejected). 1
Impossible velocity
(∆T>1/16T) on the path.
Hardware error while
starting measurement.
Flow transmitter
parameter was not set.
Path is turned off at flow
transmitter.
ACCUSONIC MODEL 7500
7500 cannot communicate with
indicated flow transmitter.
Electrical noise pick up from
the AC mains, or induced
through the transducer cables.
See D.
Noise.
Interference on
communications line.
Error between communications
board and transceiver.
Error between communications
board and transceiver.
RECOMMENDED ACTION
Scope raw signal on path selector
backplane. See section on
monitoring raw path signals with
an oscilloscope.
Set section parameter Maximum
change in velocity higher. See
introductory note.
Check cables.
Check transducer alignment.
Replace transducer.
Check cabling between 7500 and
remote flow transmitter. Make
sure power switch on remote
flow transmitter is on. Check
green power supply LEDs on
remote flow transmitter.
Check power fail LEDs on
communications board.
Connect as-blank.
Turn off other flow transmitters
to isolate.
See section on monitoring raw
path signals with an oscilloscope.
See D.
See section on monitoring raw
path signals with an oscilloscope.
Restart.
Run self-test.
Run diagnostics to determine
cause.
Restart.
Run self-test.
Retry by going into parameter
list, exit and restart
(parameters will be downloaded).
9-5
Advanced Troubleshooting
CODE
L
M
PATH STATUS
Missed measurement.
(No response from flow
transmitter.)
POSSIBLE CAUSE
See K.
Continuous Noise in PastAdjusting Gain (Data will
not be rejected).
Continuous Noise
Detected
Noise Pickup on previous
measurement - See N.
RECOMMENDED ACTION
Contact Accusonic. Occasional
missed measurements are normal,
particulary if outputting a lot of
RS-232 data.
See N.
Determine cause of noise - See
section on Monitoring Raw Path
Sigs with an oscilloscope.
Path is above stage level
Normal operation.
No action required. System will
X
and has been turned off
turn path on when level rises and
by the system.
path is submerged.
1 Note that occasional SQM and noise errors are normal. They may occur while the AGC circuits are
seeking to normalize the system gain.
N
9-6
Electrical noise pickup thru AC
Line or on Transducer Cables.
ACCUSONIC MODEL 7500
Advanced Troubleshooting
Table 9-3 Section Status Codes
CODE
1
2
3
4
SECTION STATUS
Good flow calculation.
Too many bad paths.
Flow greater than
maximum allowed.
Flow changed faster
than allowed in
software.
POSSIBLE CAUSE
Normal operation.
Maximum bad measurements
exceeded on too many paths at
the same time.
If continuous:
Flow exceeds section parameter
Maximum expected flowrate.
If sporadic:
Interference causing validlooking velocities that calculate
to be too high a flow.
May happen when system is
turned on or when site
conditions change.
Section parameter Maximum
change in flowrate may be set
too low (default is 10% of
Maximum expected flowrate).
5
6
9
No response from flow
transmitter.
Interference causing validlooking velocities that calculate
to be too high a flow.
Hardware failure.
RECOMMENDED ACTION
No action required.
Check path status codes.
Check path parameters.
Increase section parameter
Maximum expected flowrate.
Increase value of parameter
Maximum velocity.
Recheck parameter values for
reasonableness.
Determine cause of excessive
noise, see introductory note.
Wait to see if status code
changes. Note any other errors.
Set section parameter Maximum
change in flowrate higher.
Reduce value of parameter
Maximum change in velocity.
Refer to introductory
comments; see above.
Check green power supply
LEDs on path select panel
(normally on).
Check power fail LEDs on
transceiver communications
board (normally off).
Check cabling, interface
converters, communication
lines.
Refer to power supply
procedures below.
Stage Error
See Stage Status code for
additional information.
Flowmeter section is
Normal condition. When section None. To turn section on,
turned off.
operation is not required.
change section parameter to
On.
Table 9-3 Section Status Codes (continued)
ACCUSONIC MODEL 7500
9-7
Advanced Troubleshooting
CODE
A
B
S
9-8
SECTION STATUS
Insufficient
information to choose
integration method.
Submerged path failure
Path substitution in
use.
POSSIBLE CAUSE
No stage information, no paths
available.
RECOMMENDED ACTION
See Stage and Path Codes to
determine fault.
One or more paths have failed.
Flow will be calculated based on
working paths, but accuracy will
be compromised.
One or more Acoustic paths are
bad, values from other paths are
being substituted.
See Path Codes to determine
fault; repair path(s).
See Path Codes to determine
fault.
ACCUSONIC MODEL 7500
Advanced Troubleshooting
Table 9-4 Self-test Status Codes
CODE
1
2
SELF-TEST STATUS
Good self-test.
Background test failure.
3
Transmitter not
connected.
Hardware failed to reset
Transmitter did not
charge.
4
5
POSSIBLE CAUSE
Normal operation.
Defective transmitter.
9
Travel time counter did
not start.
Self test is off
D
SQM error.
E
Noise error.
F
Impossible velocity on
the path.
Hardware error.
Electrical noise.
J
Self-test parameter not
set.
Transceiver/communication
board problem.
K
Self-test is turned off at
the flow transmitter.
Missed measurement
(no response from flow
transmitter)
See J.
6
H
L
ACCUSONIC MODEL 7500
Fatal transceiver error.
General parameter Self Test
Interval is set to 0.
Self-test relay failure.
180V inverter failure.
Transmitter failure.
Electrical noise entering
through AC line.
Error between processor
group and flow transmitter.
RECOMMENDED ACTION
No action required.
Run transceiver diagnostic for
more information.
Check cable between transceiver and
transmitter.
Turn off and restart.
Check 180V inverter.
(Green LEDs on path selector board
will indicate if 5V and 12V are on and
180V is not.)
Check LED on transmitter board. It
should be lit when charging, should
flash during normal operation.
Refer to power supply procedures
below.
Replace transceiver board.
Set General parameter Self Test
Interval to a value other than 0.
Replace transceiver board.
Determine source of noise; does
system work with self-test turned off?
See section on monitoring raw path
signals with an oscilloscope.
Replace transceiver.
See introductory comments..
Run transceiver diagnostic for more
information.
Restart by going into parameter list,
exiting and beginning Operate.
(Parameters will be downloaded.)
Replace hardware.
See J.
Occasional missed measurements are
normal, particularly if outputting a lot
of RS-232 data,or when operating with
all simulated velocities.
9-9
Advanced Troubleshooting
Table 9-5 Stage Status Codes
CODE
1
2
STAGE STATUS
Good stage.
No stage received.
POSSIBLE CAUSE
Normal operation.
Parameter Stage transducer type
incorrectly set.
Broken cable.
Transducer misaligned.
Broken stage sensor.
3
Stage changed too
rapidly.
Maximum change in stage
parameter set too low.
Transducer misaligned.
4
Stage less than
Minimum stage.
5
Stage greater than
Maximum stage.
9-10
Noise on stage cabling.
Fish, logs, etc. temporarily
blocking acoustic uplooker path
and causing early return.
Parameter Minimum stage set
too high.
May be real.
Parameter Maximum stage set
too low.
RECOMMENDED ACTION
No action required.
If an acoustic uplooking
transducer, run diagnostics.
Check that proper type of stage
transducer has been selected in
Stage transducer type parameter.
Check cable.
Check stage transducer alignment.
Must be 90° to surface
If external stage source (e.g.,
acoustic downlooker, pressure
transducer) check the analog input
line.
Replace stage sensor.
Check parameter Maximum
change in stage for
reasonableness.
Check stage transducer alignment.
See introductory Note.
Check parameter Minimum stage
for reasonableness.
Visually check water level, if
possible.
Check parameter Maximum stage
for reasonableness.
Check input scaling if not
acoustic.
ACCUSONIC MODEL 7500
Advanced Troubleshooting
Table 9-5 Stage Status Codes (Continued)
CODE
6
STAGE STATUS
Parameter Maximum
difference Stage 1 and
2 exceeded
POSSIBLE CAUSE
Parameter setting may be
unreasonable.
Transducer may be misaligned.
Broken stage sensor.
7
Stage out of range
8
Stage less than 2x
Minimum Stage
L
Missed measurement
(no response from flow
transmitter)
ACCUSONIC MODEL 7500
External source current loop
values out of range, i.e., system
read 21 mA in a 4-20 mA loop.
Broken stage sensor.
Stage value is less than twice
Minimum Stage - may be good,
or may be a multiple surfacetransducer bounce. This is only a
warning, data will not be
rejected.
Error between processor group
and flow transmitter
RECOMMENDED ACTION
Check parameter Maximum
difference Stage 1 and 2 for
reasonableness.
Check acoustic transducers'
alignment.
Check cabling.
If an acoustic uplooker, use system
diagnostics.
Verify actual stage, then turn off
stages one at a time to verify
which one is correct.
Recalibrate external stage sensor
for actual possible range of levels.
Replace stage sensor.
Verify actual stage, compare to
measured. If ok, ignore it. If not,
set Minimum Stage higher.
Increase “Stage Interval” or set
“Stage Mode” to fast. Occasional
missed measurements are normal.
9-11
Advanced Troubleshooting
Monitoring Raw Path Signals with Oscilloscope
At times, it may be useful to monitor the raw acoustic signals on the path selector backplane. This may
help identify noisy or fouled transducers or identify 60 Hz (AC line) or inverter noise in the system. It is
also used for transducer alignment. Oscilloscope requirements are: 100 Mhz minimum bandwidth, dual
timebase (for delayed trigger), external trigger. Due to the transient nature of the signal being viewed, it is
best to use a waveform-recording instrument such as a digital storage scope.
1. Connect the trigger probe of the scope to the terminal marked As-blank+, located
on the left side of the transducer connector panel. Ground the probe to the terminal
marked As-blank Com.
Connect the signal input probe to the raw signal test points on the path select back
plane, as shown in Figure 9-1. Access to these test points should not require any disassembly.
scope common
signal input
to scope
com
-
+
Figure 9-1 Raw Receive Signal
Note
The connector panel is located inside the NEMA cabinet, or on the back of the
rack-mount cabinet.
2. Estimate the expected signal transit time as:
transit time = path length / 4.8
where:
transit time is in milliseconds
path length is in feet
For example, the transit time is about 2 ms for a ten foot path.
Note
Be sure to use path length, not pipe diameter. If you don’t know the path lengths, use the
flowmeter menus to look up path parameters.
3. Set the scope horizontal sweep to about 1/4th the estimated transit time per division.
For example, for a 2 ms transit time, set the sweep to 0.5 ms/division.
4. Set triggering to external with negative sync. (Trigger from As-blank signal)
5. As the path fires, a signal similar to that shown in Figure 9-2 should appear on the scope.
Look at the area of the waveform just before the received pulse and just after the pulse for
noise or interference. Use delayed trigger to expand the critical area.
6. Switch the scope to line sync to see if 60 Hz or 120 Hz noise is present on the line.
9-12
ACCUSONIC MODEL 7500
Advanced Troubleshooting
Figure 9-2 Received Signal
Verifying and Adjusting Power Supplies
If the system is inoperative, first verify that the power switch is turned on. If so, verify that there are
lights on somewhere in the system. There are LED’s on the watchdog board, the transceiver
communications board, and the path-select backplane when the system is turned on. If not, the AC mains
power may be off, the fuse near the power switch may be blown, or the power supply may be damaged. If
there are lights, proceed to check the system voltages as described below. If the voltages are out of
specification, it may be possible to readjust the power supply (as described below), or it may be necessary
to replace the entire supply.
Note
There is also a fuse on the power supply. Its rating is quite high, so there is only a remote chance
that it will blow. The fuse is easily accessible from the bottom of the rack-mount cabinet. In the
NEMA cabinet, substantial disassembly of the unit is necessary before the power and its fuse are
accessible; consult Accusonic before attempting to reach the power supply in a NEMA cabinet.
ACCUSONIC MODEL 7500
9-13
Advanced Troubleshooting
Checking the system voltages
Check the system voltages by measuring them with a digital voltmeter to obtain accurate readings.
Voltages are distributed throughout the cabinet and may be measured at any convenient location. They
can be identified by standard colors used for DC wiring. Use the following table of standard wiring colors
to locate a test point for each voltage. For DC ground, use the As-blank Com terminal on the transducer
connector panel. Readings should be within 5% of nominal. If one or more voltages is present, but out of
spec, it may be possible to readjust that level at the power supply.
Table 9-6 Standard DC Wiring Colors
Color
Red
Yellow
Blue
Violet
Orange
Voltage (nominal)
+5.0 ± 0.25 volts
+12.0 ± 0.5 volts
-12.0 ± 0.5 volts
-5.0 ± 0.25 volts
180-225 volts
Adjusting the power supply - rack-mount cabinet
Power supply adjustments are easily accessible in the rack-mount cabinet. The adjustments are made with
the system turned on and with all cards and connections in place.
If the system is mounted on the slides in a relay rack, simply pull the unit all the way out on the slides.
Remove 6 screws from the bottom of the unit and drop the bottom panel.
If the system is on a table, turn it over, remove six screws and lift off the bottom plate. The power supply
will be exposed; the adjustment pots are located as shown in Figure 9-3.
Caution
AC mains voltages are exposed at the power supply.
9-14
ACCUSONIC MODEL 7500
Advanced Troubleshooting
Adjusting the power supply - NEMA cabinet
Exposing the power supply in a NEMA cabinet requires careful disassembly of the flowmeter electronics
and should only be undertaken after consultation with Accusonic.
Part of the complexity stems from the fact that the power supply adjustments need to be made under load,
so the system must be disassembled in a manner that leaves most of the electronics connected. However,
the transducers do not need to be connected. If possible, move the system to a bench in order to simplify
the process. Disconnect the transducer wiring from the instrument.
The procedure requires at least two people to carry out.
1. Power down the system before disassembling the unit.
2. Locate four nuts in the far corners of the cabinet retaining the white main plate.
These nuts hold the entire system in place.
3. Have another person hold the unit in place while you remove the four nuts.
4. Slowly start to pull the system out, and notice which cables must be detached.
Typically, these are the cables that run from the system electronics to the front panel.
5. Hold the system in place and disconnect the cables. It is good practice to mark the polarity of
each connector to eliminate the chance of miswiring later. If possible, do not disconnect the
DC wiring harness.
When the system frame is removed from the cabinet, the power supply is exposed. The
adjustment points are shown in Figure 9-3.
6. Support the system frame on the bench close enough to the cabinet so the DC wiring can be
connected, and if possible, reconnect the cables to the front panel.
Warning
Take appropriate measures to ensure that personnel will not come in contact with the
circuit cards or wiring when the unit is turned on.
Caution
AC mains voltages are exposed at the power supply and at other points in the system.
7. Turn on the system, and adjust the supplies as necessary. Be careful not to go over +5% above
range, or severe damage can be caused to many system components.
8. Turn off the system power.
9. Assemble the system and connect the transducers.
ACCUSONIC MODEL 7500
9-15
Advanced Troubleshooting
Figure 9-3 Power Supply Adjustment Locations
(150 Watt Supply - Gold Case)
9-16
ACCUSONIC MODEL 7500
Advanced Troubleshooting
Figure 9-4 Power Supply Adjustment Locations
(275 Watt Supply - Silver Case)
ACCUSONIC MODEL 7500
9-17
Advanced Troubleshooting
FORCED PAGE BREAK FOR PAGE NUMBERING REASONS - REMOVE FROM MANUAL.
9-18
ACCUSONIC MODEL 7500
Advanced Troubleshooting
ACCUSONIC MODEL 7500
19
Chapter 10
Transducer Maintenance
Ultrasonic transducers require little maintenance. They need attention only when the signal shows signs
of deterioration. The following safeguards apply:
• The connector-ends of transducers - those which lie outside of the conduit - should be
protected from the weather and from vermin so as to retain electrical integrity.
• Devices not in service should be protected from the weather and extreme humidity (95%
max) and stored at a temperature between -20°C and 60°C.
Signal deterioration
After a period of time, the signal level of the transducer signal may deteriorate. This is usually due to the
growth of algae or buildup of mineral deposits on the face of the transducer. The rate at which foreign
matter builds up on a transducer face varies, depending on the ambient water conditions. Under normal
water conditions, Accusonic recommends that transducer signals be checked for deterioration monthly at
first, and then annually. Under severe conditions, more frequent testing may be appropriate. The simplest
method is to monitor the AGC values for each path. See path variables Forward gain (7-39) and Reverse
gain (page 7-40) in Chapter 7.
In many cases, signal deterioration may be caused by loose, wet, frayed, or worn transducer cables or
connections. When signal deterioration is observed or suspected, be sure to check the wiring before
assuming that foreign matter has built up on the transducer face or that there is trouble with the transducer
itself. Consult the procedures given in Transducer and Cabling Checkout in Chapter 4 on 4-5. to check
out the transducer wiring and external junctions.
If signal strength drops below acceptable levels, the appropriate action to be taken depends on the type of
the transducer.
For internal mount transducers (Models 7630 and 7634) - most of which are installed with dual active
elements - try switching elements to see if the problem clears up. If not, the only option is to run the
flowmeter with a path shut down (which degrades accuracy), switch on path substitution (which also
degrades accuracy), or to dewater the pipe and clean, inspect, and possibly replace the unit.
Note
When switching to a backup element in a dual-element transducer, it is necessary to
change the path parameters Path length and Path angle accordingly, unless
the elements on both ends of the path are changed.
ACCUSONIC MODEL 7500
10-1
Transducer Maintenance
For fixed-window transducers (Models 7605 and 7625) the active elements of can be replaced from
outside the conduit, but cleaning of the acoustic window requires dewatering the conduit.
If the transducers are subjected to high temperatures (> 140°), which can occur if the pipe is dewatered
and exposed to strong sunshine, the coupling grease between the transducer element and the window can
deteriorate. If this occurs, or whenever the transducer element is removed for inspection or replaced, a
1/32” (1mm) layer of grease should be applied to the flat face of the transducer element. Appropriate
grease obtainable from Accusonic.
For removable transducers (Models 7600, 7601, 7635, 7620), remove the unit according to the procedures
recommended by Accusonic, and then clean, inspect, and possibly replace the unit.
Danger
Removing a transducer from a pressurized pipe MUST be done in strict accordance with
Accusonic procedures. Failure to do so may result in serious injury to personnel or in
damage to the transducer or other equipment nearby.
Note
Transducers are position-dependent. When replacing a transducer, always verify that the
replacement unit is of the same type as the unit removed. In particular, pay attention to the
angle, position, and length designators (i.e., 45°,60°,65°; inner vs. outer; Short or Long) that
are part of the model and serial number designators marked on the body of the unit.
10-2
ACCUSONIC MODEL 7500
Transducer Maintenance
7601 Series Transducers
The transducers are installed in special feedthroughs which allow for removal of the transducer without
dewatering the pipe or disturbing the alignment of the unit. A special tool must be used. The following is
a step-by-step procedure for removal, cleaning, and reinsertion of the transducer.
DANGER
THE TRANSDUCER IS PROBABLY UNDER CONSIDERABLE PRESSURE FROM THE
LIQUID IN THE PIPE. ANY ATTEMPT TO REMOVE A TRANSDUCER IN ANY OTHER
MANNER THAN OUTLINED BELOW MAY CAUSE SERIOUS INJURY TO PERSONS
IN THE GENERAL AREA.
Caution
The 7601 transducers are equipped with a gauge for confirming that the locking pin is
fully engaged. Measurements with the gauge and an independent test is required to
confirm that the locking pin is seated. If the gauge is missing, do not proceed. Never
loosen the locking pin unless the transducer removal tool supplied by Accusonic is
installed in complete accordance with the procedure given below.
Caution
Always work from the side of the transducer feedthrough, so that if an error or a
component failure results in the transducer blowing out of its seat, you are not in the exit
trajectory. Keep the trajectory area clear of other personnel.
Warning
Read through the entire procedure below to be certain you understand it completely.
IF YOU DO NOT UNDERSTAND ANY PORTION OF THIS PROCEDURE, STOP
FURTHER WORK, DO NOT CONTINUE!
Notes
Transducers are position-specific. Always reinstall a transducer in the same feedthrough
position from which it was removed. When replacing one transducer with a new one, double
check that the part number of the new unit exactly matches the number of the old one.
Hydrostatic pressure is pushing radially outward on the transducer at all time, including
during removal and replacement of the transducer. During normal operations, the
transducer is held in place against this pressure by the union nut shown in Figure 10-1 on page 10-14.
When the nut is removed, then the locking pin prevents transducer movement. It is
extremely important that locking pin engagement be confirmed (using the supplied gauge)
before attempting to remove the union nut.
The locking rings which are installed in numbered pairs - the serial numbers are stamped on
the opposite mating faces. Parts from on locking ring must not be interchanged with
other units. If a ring is disassembled, it must be reassembled using a matched pair.
ACCUSONIC MODEL 7500
10-3
Transducer Maintenance
Tools Required
♦
♦
♦
♦
7601 series clearance gauge (attached to transducer fitting on the conduit)
Model 7642 series transducer jacking mechanism (order from Accusonic)
Medium (8 inch) crescent wrench (or 1/2 inch (13mm) open-end wrench)
3/8 inch hex (Allen) wrench
1.
Verify the following safety conditions are met as shown in Figure 10-1 on page 10-14.
Locking pin is fully engaged - Check that the clearance between the shoulder of the pin
and the face of the locking ring is less than the specified limit. Check this by trying to
slide the u-shaped end of the clearance gauge under the pin as shown. It must not fit.
Locking Ring is tightly installed - Check that lock washers (spacers) are installed
between both sets of mating faces of the two halves of the locking ring. Verify that the
hardware is tight and that the lock washers are compressed flat.
Union nut rotates freely - Check that the union nut turns freely and exhibits no
resistance to turning caused by back pressure on the nut from the transducer behind
it after it has been loosened one-half turn.
If any one of these conditions is not met, there may be a safety hazard. Leave the union
nut in place, STOP WORK on the transducer IMMEDIATELY and contact Accusonic
for advice.
2.
Locate the jacking screw in the jacking mechanism, shown in Figure 10-2 on page 10-15. Make
certain that the valve on the jacking mechanism is fully open.
3.
Spin the bearing lever so that the threaded tip of the jacking screw is retracted inside
the tool valve. The jacking screw should extend beyond the bearing lever about two
inches (50mm) as shown in the inset of Figure 10-2 on page 10-15. It may be necessary to rock the
valve slightly to allow the jacking screw clearance. Set the jacking mechanism on a clean surface
(free
of mud or debris), in easy reach for the following steps.
4.
Slowly loosen the union nut.
Caution
There should be no resistance caused by back pressure from the transducer acting upon it
after it has been loosened one-half turn. If there is, or if you observe any movement of the transducer
itself, STOP WORK.Immediately clear the area around the transducer
of personnel and contact Accusonic for advice.
5.
Gently remove the union nut from the feedthrough assembly as shown in Figure 10-3 on page 10-
16.
At all times, be alert for any transducer movement.
10-4
ACCUSONIC MODEL 7500
Transducer Maintenance
Caution
If, at any time before the jacking tool finally is in place, you observe that the
transducer moves even slightly, STOP ALL WORK. Immediately clear the area around the
transducer of personnel and contact Accusonic for advice.
6.
Gently pull the E-O connector out of the body of the transducer as shown in Figure 10-3 on page
10-16. Be alert for transducer movement.
7.
Slowly screw the threaded collar of the jacking mechanism valve over the mating thread
of the transducer feedthrough. Screw the tool on until in bottoms.
Note
For the first three full turns, be sure to support the far end of the jacking tool so that it
does not exert undue torque on the transducer and feedthrough assembly. Be alert for
transducer movement.
8.
Slowly rotate the bearing lever to advance the tip of the jacking screw into contact with
the end of the transducer. This must be done by feel, since the two components meet inside
the tool valve. Stop when contact is made.
9.
While holding the bearing lever stationary, use a wrench to gently and slowly turn the
jacking screw so that it advances into the end of the transducer and begins to engage
the inside thread of the transducer.
10. Alternate between turning the bearing lever and then holding it stationary and
advancing just the jacking screw to continue threading the jacking screw into the
transducer. Do not force it. Continue until the screw bottoms.
Note
As you screw the tool into place, it is necessary to alternately advance and back off on
the bearing handle because two threads of different pitches are being taken up at the
same time.
11. After the jacking screw bottoms in the transducer, back the screw off slightly so that it
will be easier to separate the two later.
12. Turn the bearing lever so that the jacking screw presses the transducer unit assembly
inward slightly, thereby releasing tension on the locking pin.
Note
The locking pin should rotate easily when it is freed. If necessary, work the bearing lever
forward and backward (moving the transducer slightly in and out of the feedthrough)
until the pin is free.
13. Slowly loosen the transducer locking pin.
14. Rotate the bearing lever to withdraw the transducer 3/4 of an inch (20mm).
15. Tighten the locking pin firmly against the shaft of the transducer and then back it off
one quarter of a turn. This prevents water leakage from around the locking pin.
ACCUSONIC MODEL 7500
10-5
Transducer Maintenance
16. Continue to extract the transducer just until the second O-ring on the transducer body
becomes visible - about 3/4 (20mm) inch of the transducer is visible. The transducer face is now
clear of the ball valve. (See Figure 10-4 on page 10-17)
17. Close the jacking tool valve.
18. Continue turning the bearing lever until the transducer is entirely clear of the valve.
Unscrew and remove the transducer from the jacking screw.
19. Inspect the transducer face for growth or buildup. Remove any buildup with a hard nylon
scrubber (Dobie) and a mild detergent (Joy).
Note
Handle the transducer with care. Do not cut or nick the O-rings or try to remove them
from the transducer.
Caution
Once a transducer face has been cleaned, do not contaminate it with grease, oil or hand
or finger prints, as such film will degrade performance of the unit.
20. Screw the transducer back onto the jacking tool.
Notes
Transducers are position-specific. Always reinstall a transducer in the same location from
which it was removed.
When replacing one transducer with a new one, double check that the part number of
the new unit exactly matches the number of the old one. Make certain that an inner path
transducer is replaced with an inner unit and that an outer path transducer is replaced
with an outer unit.
21. Just prior to assembly, lightly lubricate the O-rings with an appropriate O-ring grease,
Parker O-Lube or equivalent.
Warning
Do not use a silicone-based grease.
22. Turning the bearing lever, advance the face of the transducer until it just reaches the
valve opening.
23. Use a 1/2 inch (13mm) open face wrench on the hex end of the jacking screw to rotate the
jacking screw until the alignment slot on the transducer is in alignment with the locking
pin on the conduit.
10-6
ACCUSONIC MODEL 7500
Transducer Maintenance
Note
Hold the wrench in place during the following steps to help keep the transducer in
alignment until it engages the alignment pin located on the inside end of the feedthrough.
24. Continue to turn the bearing lever, advancing the transducer into the valve housing until
the middle O-ring on the transducer just slips inside the valve housing.
25. Slowly open the valve all the way.
26. Continue to ease the transducer into the mount until either it meets increased
resistance or until the shoulder of the jacking screw comes flush with the bearing lever.
Do not advance the jacking screw shoulder past the surface of the bearing lever.
Notes
It may be necessary to rock the valve handle back and forth slightly to allow the
transducer to slip through the valve.
If the transducer stops prior to the fully inserted position, it is probably out of alignment.
Rock the jacking screw back and forth slightly using the 1/2 inch (13mm) wrench until the unit
aligns with the alignment pin and is free to advance further.
Caution
Use only enough pressure during insertion to overcome the back pressure from fluid in
the pipe. If you try to force the transducer into place when it is misaligned, you will
damage the unit, possibly jamming it in the fitting.
27. When the transducer is home, screw in the locking pin until it bottoms. Then back off
the pin one quarter turn to allow the transducer to center itself in the mount.
28. Refer again to Figure 10-1 on page 10-14 and verify that the following safety conditions are met:
Locking pin is fully engaged - Check that the clearance between the shoulder of the pin
and the face of the locking ring is less than the specified limit. Check this by trying to
slide the u-shaped end of the clearance gauge under the pin as shown. It must not fit.
Locking Ring is tightly installed - Check that lock washers (spacers) are installed
between both sets of mating faces of the two halves of the locking ring. Verify that the
hardware is tight and that the lock washers are compressed flat.
If any of these conditions is not met, there may be a safety hazard. Leave the tool in
place. Try removing and reinserting the transducer, and rechecking the safety conditions.
If that doesn't solve the problem, STOP WORK IMMEDIATELY and contact Accusonic
for advice.
29. Remove the jacking mechanism assembly from the transducer's feedthrough assembly.
ACCUSONIC MODEL 7500
10-7
Transducer Maintenance
30. Reconnect the E-O connector and screw in the union nut.
Caution
Before leaving the transducer, be certain that the locking pin is fully engaged and that
the union nut and the E-O connector are installed as shown in Figure 10-1 on page 10-14.
This completes removal and assembly of the 7601 Series transducer.
10-8
ACCUSONIC MODEL 7500
Transducer Maintenance
7600 Series Transducers
The transducers are contained in a special mount which allows for removal of the transducer without
dewatering the pipe or disturbing the alignment of the unit. A special tool must be used.
The following is a step-by-step procedure for removal, cleaning, and reinsertion of the transducer.
DANGER
THE TRANSDUCER IS PROBABLY UNDER CONSIDERABLE PRESSURE FROM THE
LIQUID IN THE PIPE. ANY ATTEMPT TO REMOVE A TRANSDUCER IN ANY OTHER
MANNER THAN OUTLINED BELOW MAY CAUSE SERIOUS INJURY TO PERSONS
IN THE GENERAL AREA.
Caution
The 7600 transducers are equipped with a padlock locking rod to prevent tampering
with the transducer when the proper tool is not in place. Never unlock the padlock
unless the transducer removal tool supplied by Accusonic has been installed as
described in the following procedures. Never leave an unlocked transducer unattended
for even a short period of time.
Caution
Always work from the side of the transducer feedthrough, so that if an error or a
component failure results in the transducer blowing out of its seat, you are not in the exit
trajectory. While working on the transducer, keep the trajectory area clear of other personnel.
Warning
Read through the entire procedure below to be certain you understand it completely.
IF YOU DO NOT UNDERSTAND ANY PORTION OF THIS PROCEDURE, STOP
FURTHER WORK, DO NOT CONTINUE!
Note
Transducers are position-specific. Always reinstall a transducer in the same location from
which it was removed. When replacing one transducer with a new one, double check that
the part number of the new unit exactly matches the number of the old one.
Tools Required
♦
♦
♦
♦
7661-L or 7661-S series transducer jacking mechanism (order from Accusonic)
Medium (8 inch) crescent wrench
(or a 1/2 inch (13mm) open-end wrench and a 1 inch (25mm) open-end wrench)
Key to the transducer padlock (all padlocks shipped by Accusonic use the same key)
1/8 inch (3mm) hex (Allen) wrench
ACCUSONIC MODEL 7500
10-9
Transducer Maintenance
1.
Verify the following three safety conditions are met as shown in Figure 10-6 on page 10-19:
Locking Rod is padlocked - Check that the padlock on the locking rod is locked. The locking rod
should not be in contact with the transducer, and it should be free to slide back and forth.
Clamp bar is secure - Check that the two bolts (1/2 inch (13mm) heads) holding the clamp bar are
tight.
Clamp bar jack screw is fully engaged - Check that the jack screw on the clamp bar presses
tightly against the shoulder of the transducer.
If any of these conditions is not met, STOP WORK on the transducer immediately and contact
Accusonic for advice.
Caution
If, at any time before the jacking tool is finally in place, you observe that the
transducer moves even slightly, STOP ALL WORK. Immediately clear the area around
the transducer of personnel and contact Accusonic for advice.
Warning
Do not loosen any set screws on the transducer mount. They are locked in place during
setup and alignment of the unit, and must not be disturbed.
2.
Locate the jacking tool and retract the jacking screw so that the hex end of the screw
extends 1 inch (25mm) from the tool. Set the tool on a clean surface (free of mud or debris), in easy
reach for the following steps.
3.
Remove the conduit clamp and gently pull the E-O connector out of the body of the
transducer cable connector as shown in Figure 10-5 on page 10-18.
4.
Slowly loosen the clamp screw. Fluid pressure should press the transducer tightly against
the screw as it turns, pushing the transducer up and out of its seat slightly. Continue loosening the
screw until the transducer moves out of its seat about 1/8 inch (3mm) and the shoulder of the
transducer back contacts the locking rod.
Note
If the transducer fails to move as the screw is loosened, it may be jammed, or there may
be low pressure in the conduit. Try alternately tightening and loosening the clamp screw
or manually pulling on the transducer to release it. If it does not move, contact Accusonic
for advice.
Warning
Never allow more than 1/16 (1.5mm) inch clearance between the contact point of the clamp screw
and the transducer. If the transducer is caught and suddenly breaks free when there is
too much clearance, the resulting impact could damage the equipment or cause a safety
hazard.
5.
10-10
Loosen the clamp screw another full turn, retracting it completely from the transducer.
ACCUSONIC MODEL 7500
Transducer Maintenance
6.
Unscrew the two bolts (1/2 inch (13mm) heads) holding the clamp bar and remove it.
Caution
Always work from the side of the transducer mount, so that if an error or a component
failure results in the transducer blowing out of its seat, you are not in the exit path. While
working on the transducer, keep the downrange trajectory area clear of other personnel.
7.
Bolt the jacking tool to the transducer mount using the clamp bar mounting holes as
shown in Figure 10-7 on page 10-20. Tighten all four bolts.
8.
Rotate the jacking screw to advance the tip of the screw into the recess on the transducer.
9.
Use a wrench to tighten the jacking screw until the transducer no longer presses on the
locking rod. When pressure on the locking rod is released, the rod should slide freely from side to
side.
Note
Do not tighten the jacking screw past the point where the locking rod is freed.
10. Unlock and remove the padlock and remove the locking rod.
11. Retract the jacking screw slightly (fluid pressure should press the transducer tightly
against the jacking screw), and push it out of its seat as the screw is backed off.
Note
If the transducer fails to move as the jacking screw is loosened, it may be jammed or
there may be low pressure in the conduit. Try alternately tightening and loosening the
jacking screw and pulling on the transducer to release it. If it does not move, contact
Accusonic for advice.
Warning
Never allow more than 1/16 (1.5mm) inch clearance between the contact point of the jack and
the transducer. If the transducer is caught and then suddenly breaks free when there is
too much clearance, the resulting impact could damage the equipment and cause a
safety hazard.
12. Continue to retract the transducer until 7 5/8 (195mm) inch of the round transducer body (not
counting the square back) is exposed.
Warning
Retracting the transducer too far may allow fluid to leak from the mount.
13. Close the valve on the transducer mount.
14. Completely back off the jacking screw.
15. Grasp the transducer by the square shank and the cable connector and rotate it back
and forth slightly to pull it completely out of the mount.
ACCUSONIC MODEL 7500
10-11
Transducer Maintenance
Note
The transducer mount has a movable collar and yoke that serve to align the transducer
in the conduit. These were set, locked and sealed during installation. If the collar or yoke
are loose now, the transducer will need to be realigned; contact Accusonic for advice.
16. Inspect the transducer face for growth or buildup. Remove any buildup with a hard
nylon scrubber (Dobie) and mild detergent (Joy).
Note
Handle the transducer with care. Do not cut or nick the O-rings or try to remove them
from the transducer. Do not bend the connector. Protect sealing surfaces from abuse.
Caution
Once the transducer face has been cleaned, do not contaminate it with grease, oil or hand
or finger prints, as such film will degrade the performance of the unit.
17. Just prior to assembly, lightly lubricate the O-rings with an appropriate O-ring grease,
Parker O-Lube or equivalent.
Warning
Do not use silicone-based grease.
18. Gently slide the transducer approximately 1/2 inch (13mm) into the mount - just until it remains
in place.
Notes
Transducers are position-specific. Always reinstall a transducer in the same location from
which it was removed.
When replacing one transducer with a new one, double check that the part number of
the new unit exactly matches the number of the old one. Make certain that an inner path
transducer is replaced with an inner unit and that an outer path transducer is replaced
with an outer unit.
Caution
Be sure that the connector shaft that extends from the transducer back is positioned so
that it will engage with the saddle located on the mount as the transducer is pressed into
place.
19. Tighten the jacking screw until the pointed tip engages the recess on the transducer.
20. Use a 1/2 (13mm) inch open face wrench on the hex end of the jacking screw to tighten the
jacking screw and press the transducer into the mount. Stop when only 7 5/8 inches (195mm) of the
round transducer body (excluding the square back) is visible above the shoulder of the mount.
21. Slowly open the valve all the way.
10-12
ACCUSONIC MODEL 7500
Transducer Maintenance
22. Continue to tighten the screw and press the transducer into the mount until either it
meets increased resistance or until the shoulder of the jacking screw comes flush with the bearing
level. Do not advance the jacking screw shoulder past the surface of the face of the jacking tool.
Notes
It may be necessary to rock the valve handle back and forth slightly to allow the
transducer to slip through the valve.
Be sure that the connector shaft of the transducer properly seats in the alignment yoke.
If necessary, rotate the transducer into alignment by pulling on the body of the cable connector.
23. When the transducer is home, reinstall the locking rod and lock the padlock. Make certain
that the locking rod cannot be removed from the mount.
24. Slowly loosen the jacking screw until the shoulder of the transducer presses tightly against
the locking rod.
Caution
Until the transducer is snug against the locking rod, never allow more than 1/16 inch (1.5mm)
clearance between the contact point of the jack and the transducer. If the transducer is
caught and suddenly breaks free when there is too much clearance, the resulting impact
could damage the equipment or cause a safety hazard.
25. Loosen four bolts (1/2 inch (13mm) heads) and remove the jacking tool from the transducer
mount.
26. Install the clamp bar using the same bolts; tighten both bolts.
27. Finger-tighten the clamp screw until it is snug against the recess on the transducer.
28. Tighten the clamp bar jack screw with a 1 inch (25mm) wrench until the transducer bottoms in
the mount. Do not over tighten.
29. Connect the E-O connector and screw on the conduit clamp.
Caution
Before leaving the transducer, be certain that the locking rod is fully engaged and
padlocked and that the E-O connector is installed as shown in Figure 10-6 on page 10-19 .
This completes removal and assembly of the 7600 Series transducer.
ACCUSONIC MODEL 7500
10-13
Transducer Maintenance
Figure 10-1 Use of Transducer Installation Gauge
10-14
ACCUSONIC MODEL 7500
Transducer Maintenance
Figure 10-2 7601 Transducer Extraction Tool (uninstalled)
ACCUSONIC MODEL 7500
10-15
Transducer Maintenance
Figure 10-3 Connection to 7601 Transducer
10-16
ACCUSONIC MODEL 7500
Transducer Maintenance
Figure 10-4 Extracting 7601 Transducer using Withdrawal Tool
ACCUSONIC MODEL 7500
10-17
Transducer Maintenance
Figure 10-5 Connection to 7600 Transducer
10-18
ACCUSONIC MODEL 7500
Transducer Maintenance
Figure 10-6 7600 Transducer/Valve Assembly
ACCUSONIC MODEL 7500
10-19
Transducer Maintenance
Figure 10-7 7600 Transducer Assembly with Extraction Tool Installed
10-20
ACCUSONIC MODEL 7500
Transducer Maintenance
Figure 10-8 Model 7605 Stainless Steel Transducer
ACCUSONIC MODEL 7500
10-21
Transducer Maintenance
Figure 10-9 Model 7625 PVC Transducer
10-22
ACCUSONIC MODEL 7500
Transducer Maintenance
Figure 10-10 Model 7630/34 Internal Mount Transducer
ACCUSONIC MODEL 7500
10-23
Transducer Maintenance
10-24
ACCUSONIC MODEL 7500
ACCUSONIC MODEL 7500
25
Chapter 11
Miscellaneous Technical Info
The chapter contains information that may be useful when using the 7500, however, the information
following doesn’t fall into specific categories. The following information is included:
• Entering special keys
• Flow transmitter addressing
• System specifications
• Remote operation via modem
Entering Special Keys
In addition to the basic 7500 keys, the following "hidden" keys are available. Some keys may not be
available on older versions.
Key
Combination
<CTRL 1>
<CTRL 2>
<CTRL 3>
<CTRL 4>
<CTRL 5>
<CTRL 6>
<CTRL 7>
<CTRL 8>
<CTRL 9>
<CTRL 0>
<CTRL ±>
<CTRL
DownArrow>
Resulting
Keystroke
:
<space>
*
>
\
?
=
Q
Z
,
Insert
PageDown
Notes
Colon
Space
star (filename or extension wildcard)
Right Arrow (redirect)
Backslash (shows as forward slash on LCD display)
Question Mark (single character wildcard)
Equals
Uppercase Q (not directly available on keypad)
Uppercase Z (not directly available on keypad)
Comma
Insert State toggle. Handy when editing lines of text.
Will get you to the top of the next lower menu structure.
For example, if you are in a Section menu , this will jump
directly down to a Path menu.
<CTRL ESC>
Escapes from any point in Configure menu, saves changes
to flowmeter, and goes back to operate mode.
STATUS or When pressed at the top-level menu, will display software
revision information.
Also, since the keypad hardware emulates the PC numeric Keypad, any keystroke can be entered by use
of the three-key ALT sequence. A table of equivalents is available.
For Example,
to enter:
_ (underscore)
" (quote)
press ALT and the numbers:
95
34
ACCUSONIC MODEL 7500
11-1
Miscellaneous Technical Info
Flow Transmitter Addressing
In order for the 7500 system to communicate with the 7520 remote flow transmitter, the transceiver
communication boards in the 7520(s) are addressed. The address is set via a set of jumpers on the
communications board. Each 7520 flow transmitter in a system must have a unique address, and the
address must be one that the 7500 is expecting (these are set at the factory and burned into PROM). If
the 7520 is not addressed correctly, it will not make measurements or respond with measurement data. If
two or more 7520s are set to the same address, they will respond to the same commands, causing data
collisions and very unstable operation. Figure 1 shows the location of the address jumpers on the
communication board and Table 1 on the next pagelists the available addresses and jumper settings. Note
that if an address is changed, the system must be restarted for the new address to be read in and used.
There may be jumpers in positions 11 to 26, these do not affect addressing and should be left alone.
These are the
address jumpers
WP R +V -V
26
10 8 6 4 2
25
9 7 5 3 1
0
1
2
3
4 5
TATTLER
6
7
6
7
Figure 11-1 Address 1, the default address
WP R +V -V
26
10 8 6 4 2
25
9 7 5 3 1
0
1
2
3
4
5
TATTLER
Figure 11-2 Address 3
11-2
ACCUSONIC MODEL 7500
Miscellaneous Technical Info
Table 11-1 Jumper positions
jumper
position
address
1
9 to 10
7 to 8
5 to 6
3 to 4
1 to 2
1
1
0
0
1
2
3
4
5
1
1
1
1
1
0
0
0
0
1
1
1
0
1
1
0
0
1
0
1
6
7
8
9
10
1
1
1
1
1
0
0
0
0
0
1
0
0
0
0
0
1
1
0
0
0
1
0
1
0
11
12
13
14
15
0
0
0
0
0
1
1
1
1
1
1
1
1
1
0
1
1
0
0
1
1
0
1
0
1
16
17
18
19
20
0
0
0
0
0
1
1
1
0
0
0
0
0
1
1
1
0
0
1
1
0
1
0
1
0
notes
Default address.
Use in 7500's.
First 7520 address.
2nd 7520 address.
Example: The address for the board shown in Figure 11-1 is 1, the default address. Figure 11-2 shows a
board set at address 3.
ACCUSONIC MODEL 7500
11-3
Miscellaneous Technical Info
System Specifications
ACCUSONIC MODEL 7500 Console
Power Requirement
90-250 VAC, 47-63 Hz
160 VA Nominal
(Optional Heater can consume an additional 200 Watts)
Enclosure Dimensions
NEMA 4 Wall Mount: 24”h x 20”w x 11”d, 38 kg/85 lbs.
NEMA 4X Wall Mount: 24”h x 20”w x 11”d, 38 kg/85 lbs.
Chassis (table-top or rack-mount): 11”h x 19”w x 21”d`, 20.4 kg/45 lbs.
Environmental Requirements
Storage:
0° - 140° F (60° C)
0% - 95 % Relative Humidity
Operating:
32° - 122° F (0-50° C) - without optional heater
-20° - 122° F (-29°-50° C) - with optional heater
0% - 95% Relative Humidity
Miscellaneous
Equivalent Clock counting Frequency: 160 Mhz
Number of Acoustic Paths:
1-8 (can be increased by adding Model 7520
remote flow transmitters)
Number of Measurement Sections:
1-8 (can be increased to 16 by adding Model
7520 remote flow transmitters)
Model 7520 Remote Flowmeter Transmitter
(Requires ACCUSONIC MODEL 7500 for system operation)
Power Requirement
90-250 VAC, 47-63 Hz
135 VA Nominal
(Optional Heater can consume an additional 200 Watts)
Enclosure Dimensions
NEMA 4 Wall Mount: 20”h x 20”w x 10”d, 27 kg/60 lbs.
NEMA 4X Wall Mount: 20”h x 20”w x 10”d, 27 kg/60 lbs.
Chassis (table-top or rack-mount): 11”h x 19”w x 21”d, 20.4 kg/45 lbs.
11-4
ACCUSONIC MODEL 7500
Miscellaneous Technical Info
Environmental Requirements
Storage:
0° - 140° F (60° C)
0% - 95% Relative Humidity
Operating:
32° - 122° F (0° - 50° C) without optional heater
-20° to 122° F (-29° - 50° C ) with optional heater
0% - 95% Relative Humidity
Miscellaneous
Equivalent Clock counting Frequency:
Number of Acoustic Paths:
Communication Link with Model 7500:
Max Distance from 7500:
Number of Measurement Sections:
160 Mhz
1-8
2-wire RS-485 (Proprietary Protocol)
4000 feet (1220 Meters)
1-8 (defined in Model 7500)
Note:
Specifications are subject to change without notice.
ACCUSONIC MODEL 7500
11-5
Miscellaneous Technical Info
Remote Operation via Modem
Some consoles are supplied with auto-answer modems for monitoring and troubleshooting of the
flowmeter from any off-site location. Check the configuration sheet supplied with your unit to determine
whether modem operation is included. Note that the following are required for operation via modem:
- Telephone line dedicated to flowmeter use
- PC at the off-site location with compatible modem and Remote 2 Call software package
Modem Hookup Procedure
If modem operation is included in your system, locate the modem. Plug one end of the extension cable
supplied with the system into the modem. Plug the other end into a nearby telephone jack. Any extension
with standard RJ-11 connectors can be used for this connection.
Remote Operation
On the PC at the off-site location, activate the software program used to invoke modem operation.
Through the software program, call the telephone number of the dedicated flowmeter line. The flowmeter
modem will answer the call, and all information on the flowmeter screen will be shown on the off-site PC
screen as well.
The flowmeter can now be monitored and controlled by the keyboard from the off-site PC, including
changing system parameters and examining system variables, for example, flowrates, volumes, and
individual path status, travel times, velocities and gains. Other actions available from the off-site location
include enabling datalogging or other outputs, running diagnostics, and troubleshooting.
See Chapter 5 for information on control of the meter from an external keyboard and for procedures for
stepping through program menus.
Calling up the 7500
The Accusonic Remote2 Call program is used for calling up the 7500 from a remote PC and for
downloading data to the remote PC. The Remote2 Call program must be loaded on the remote PC, and the
dialing directory must contain the telephone number of the flowmeter and any necessary passwords. The
following procedure is then used to call up and download data from the 7500.
•
•
At the remote computer, invoke the program by typing R2CALL<Enter>.
Using the down cursor, highlight the flowmeter phone number and press <Enter>. R2CALL will
complete the connection and log in. The flowmeter measurement screen should appear:
# FLOW POS-VOL NEG-VOL Oct 26 94
S1 142.9
9801
0
GOOD
S1 155.1
1202
0
GOOD
T 398.0 11003
0
12:45:30
At this point, any operation that can be performed when in front of the flowmeter can be performed
remotely. Some typical uses:
• Parameters, operational modes, or display screens can be changed.
• Diagnostics can be run.
• Variables can be viewed.
• Data or error log files can be downloaded to the calling PC.
11-6
ACCUSONIC MODEL 7500
Miscellaneous Technical Info
Downloading Data Files
•
•
•
•
•
Press <Escape> to exit measurement mode. (This is important, as Remote2 can tie up the flowmeter
for longer than the 50-second watchdog timer reset time, causing the flowmeter to reset and
disconnect unexpectedly).
Press <CTRL><ESCape> keys. The Remote2 menu will pop up.
Type “R” or scroll down to menu choice Receive a file from the host.
Press <Enter> to receive files.
Where prompted to enter a filename, type B:\*.PRN and press <Enter>.
The next menu choice tells Remote2 where to put the log files:
• Press <Enter> to put the files in the current directory.
• Press <Enter> again to start the transfer. Transfer progress will be displayed with gas-gauge-style
progress indicators.
When the transfer has been completed, the screen will display a menu of the transferred files. There will
be files for flowrate and volume, there may also be files for stage and velocities depending on whether
these variables were selected for logging.
• Press <Escape> to exit this menu and return to the Main Menu.
A note on Data Logging quantities:
With logging turned on for three sections of flowrate and stage, each log point adds approximately 250
bytes to the disk. Therefore, if the log interval is set to five minutes, about 72 Kbytes of data will be
logged per day. The disk will fill up in a little over two weeks.
Consideration should also be given to the time required to download quantities of data over the telephone
line. For example, 72 Kbytes of data will take approximately 15 minutes to download at 2400 baud.
Re-entering Measurement Mode and Exiting the Remote2 Program
At the Main Menu:
•
•
•
•
•
•
•
•
•
•
•
Select “Continue using the host” and press <Enter>.
From the 7500 menu, select “Diagnose”.
When the diagnostic menu appears, press the “.” key to enter the utility menu.
From the utility menu, select “System”.
At the “A>“ prompt, type DEL B:*.PRN and press <Enter>. This will erase all of the data files from
the log disk in the flowmeter.
Press <Escape> three times to return to the Main Menu.
Select “Operate” from the Main Menu.
Wait for all of the status indicators to show GOOD, the press <CTRL><Escape> to pop up the
REMOTE2 menu again.
Press “H” to select “Hang Up”.
Press <Enter>.
Press <Escape> again to exit Remote2.
ACCUSONIC MODEL 7500
11-7
Miscellaneous Technical Info
Electrical Surge Protection for Accusonic Flowmeters
This section provides an overview of the types of protection available to suppress damaging electrical
transients, and their specific application to Accusonic flowmeters.
Overview - Surges and Transients
Transients and surges can come from many sources. The most common are:
• Industrial transients. These can be generated by switching electrical equipment such as pumps.
• Static discharges when personnel in a dry environment touch grounded electrical equipment.
• Lightning strikes.
There are several mechanisms by which transients can cause damage. The first, and most common, is
when a transient is either directly, inductively, or capacitively coupled into electronic circuitry.
Induced transients are typically fast pulses, having rise times of less than 10 microseconds. If one were to
select a component to carry such pulses, one would probably use a very small capacitor. This is relevant
to this discussion, as will be seen shortly.
Damage to equipment is caused when a high voltage transient attempts to return to ground through the
flowmeter electronics. Transient protection schemes attempt to divert the transient energy to ground
before it reaches the equipment. The intent is to provide an easier (lower impedance) path for the transient
to get to ground via the protection circuitry than through the flowmeter electronics, so a good earth
ground is essential. Large-diameter ground cable should be used to minimize the resistance to ground.
The second mechanism is ground potential difference between electrical units. This can be caused by a
variety of reasons, ranging from an event such as the energy from a near lightning strike raising the local
grid potential to a poor ground connection. The damage is caused when one devices potential is
significantly different than another and they are electrically connected by a communication line or current
loop. The voltage difference becomes greater than the driving or receiving device can tolerate, and
damage occurs.
This type of damage can also be caused simply as a result of a poor ground connection, allowing one
device to charge, or “float” above ground by an excessive amount.
Two types of transient current flow may occur:
• Differential mode (also called normal mode) transients are transients that occur from line to line.
These are the most common.
• Common mode transients appear from line to ground.
11-8
ACCUSONIC MODEL 7500
Miscellaneous Technical Info
The Case for an External Surge-Protection Enclosure
The American Heritage Dictionary defines a capacitor as “an electric circuit element ... consisting of two
metallic plates separated by a dielectric”. The Teflon and PVC insulation used in the flowmeters wiring
have excellent dielectric properties. Therefore, any two pieces of insulated wire running in parallel or
even laying across one another will form a capacitor. The value will probably be very small, but
remember that very small capacitors are ideal for coupling the narrow pulses that characterize transients.
Any two wires in contact with one another can provide a path for conduction of transients, even if their
conductors are insulated.
In a system such as the ACCUSONIC MODEL 7500, there are many subsystems. Wires are routed
throughout the enclosure, with power wires crossing digital and signal cables. If a transient enters the
enclosure on a transducer cable and this cable crosses other wiring, the transient will attempt to flow to
ground through the easiest path. If the relay for that path is open (it usually will be), the easiest path to
ground will be through the crossed wiring and the electronics.
The best defense against transients is space filled with air. A 7540LP (separate non-conductive enclosure
containing transient-diversion devices) has a large, carefully laid-out air gap between protected and
unprotected wiring. There is no danger of susceptible wiring accidentally crossing when the equipment is
properly installed.
Where space does not allow for mounting a second enclosure, protective circuitry can be mounted inside
the flowmeter enclosure. Great care must be taken to insure that wiring is routed correctly, and cannot be
moved in the future to create a transient path that would result in damage.
Protection Components
This section describes individual types of protection components. Their application will be discussed in
the next section.
• Isolation Transformers - Generally provide very good rejection of high-energy transients. A properly
applied transformer will couple only the required amount of energy, any excess is radiated harmlessly
to air. They can be used for AC signals only, as they block the passage of Direct Current.
Transducer/Path transformers have an additional interwinding layer to prevent arcing between
primary and secondary windings. This layer is intended to be connected to ground.
• Gas tubes are used to absorb high-energy transients. They are composed of a gas-filled tube with
conductors at either end. When the voltage between the conductors rises sufficiently, the gas between
them ionizes, becoming a conductor. Gas tubes are relatively slow to fire (typically 1 to 100 µS, time
depends on rise time of the transient), but will shunt tremendous amounts of energy without damage
to themselves.
• Zener or avalanche diodes are semiconductor devices with controlled breakdown voltage properties.
Below the breakdown voltage, they are essentially an open circuit, above the voltage, they conduct.
They are fairly slow to conduct and will not handle much power.
• Transzorbs are used to absorb fast, low-energy transients. They are equivalent to a very fast (response
times are typically in the single nanosecond range) zener diode. They are available in a variety of
voltage ranges.
• Metal Oxide Varistors (MOVs) are devices which change resistance as the applied voltage changes.
They have a relatively high capacitance, which delays their conductance on fast transients.
• Line filters are inductor/capacitor combinations designed to block pulsed, continuous, and
intermittent radio-frequency interference. They are not designed to be transient protection devices,
although they may be partially effective in many cases.
ACCUSONIC MODEL 7500
11-9
Miscellaneous Technical Info
As can be seen from the above descriptions, each type of component has its advantages in terms of
response speed and power handling. Until somebody designs a fast transient absorption device with
unlimited power-handling capability, carefully chosen combinations of devices are usually the most
effective.
Application of Protection Devices to Accusonic Flowmeters
Power Line:
• Accusonic typically uses Line Isolation Transformers combined with MOVs. The transformer radiates
the excess energy from large spikes, the MOVs absorb anything that gets through the transformer.
The transformer isolates the AC line side of the electronics from ground, providing protection from
both normal and common mode transients, and allowing it to lift above ground when necessary.
Equipment ground is maintained for safety, and the transformer case, core, and an internal
electrostatic shield are all tied to ground.
• Active transient suppression can be used in applications where space is unavailable for an isolation
transformer. The system has a response time of less than five nanoseconds, and “tracks” the AC
sinusoid, normalizing any defects. Spikes on the line are blocked and any notches are filled. Although
it sounds like the ideal solution, this type of system provides no security against ground potential
differences.
• Line filters are installed in the model 7510 flowmeter as standard equipment.
Transducers and cables:
• Transducer inputs to the flowmeter electronics console are protected by specially-wound
transformers. The transformer is matched to the frequency of the transducer. The transducers
themselves require no protection, as they handle 1,000 Volt transmit pulses repeatedly in the course
of flow measurement.
4-20 mA Process Control Loops:
• Process control loops are DC coupled, so they can’t be positively protected against transients. There
will always be a direct path for the transient to enter the equipment. The only defense is to try to
shunt it to ground before it causes any damage. Accusonic offers transzorb-based “protectors”, which
will help somewhat with common-mode transients in a non-isolated control loop output. If the
transient is big enough, the protection device may absorb it, fail, and not be available to protect
against the next incident.
• Process loops are typically one of the first things to fail in the event of ground potential differences
between the flowmeter and other equipment. The ground potential difference exceeds the compliance
of the output, and the device fails.
• The solution to both of these problems is to use an isolated output. The input-to-output isolation is
typically over 1,000 Volts, handling all but the most extreme differences, in addition to providing
inherent protection against common-mode transients. Transzorb-based “protectors” can also be
installed, which will help absorb differential-mode transients in an isolated system.
11-10
ACCUSONIC MODEL 7500
Miscellaneous Technical Info
RS-232 Serial links:
RS-232 outputs are also DC-coupled (see discussion in 4-20 process loops above). Zener or avalanche
diode-based protectors are used, with the same effectiveness discussed above.
RS-485 Serial data bus:
The RS-485 serial data bus is also DC coupled, making it very difficult to protect. In addition, the signal
voltage levels are very low. Typical signal levels are only around 5 Volts, with the absolute maximum
levels being +12 and -7 Volts. Any difference in ground potential between remote flow transmitters on
the bus will cause, at minimum, communications link failure, or at maximum, extensive electronic
component failure in the equipment.
After mixed results with commercially-available RS-485 communications devices, Accusonic has
designed their own. The device electrically isolates the flowmeter from the bus up to a maximum of 1500
Volts. Each leg of the communications bus is protected by:
• A gas tube, chosen to activate above 70-90 Volts, and absorb large amounts of energy.
• A Transzorb, which quickly clamps the line to 7 volts.
• A fast, high-current diode, which protects against transients with negative polarity.
• A thermal fuse. If large continuous voltages are placed on the communications lines, this will heat up
and increase resistance, decreasing the voltage to the RS-485 device.
• There is an additional gas tube which conducts above 1000V. It is to keep both communication lines
within 1000V of ground, protecting the RS-485 device from isolation-barrier damage.
Summary of Standard and Optional Equipment
This section lists which protection equipment is stock and what is optionally available.
Standard Equipment:
RS-485 protection as described above (RS-485 is installed to communicate with 7520 remote
flow transmitters. 7520s have the same level of protection.)
Optional Equipment:
AC Line isolation transformer
Active transient suppressor for AC Line (Amber Industries AI-105)
External path isolation transformers (mounted in 7540LP)
Isolated analog outputs
RS-232 output surge protector
Parallel printer port surge protector
Telephone line “lightning sponge” (when remote access modem is installed)
ACCUSONIC MODEL 7500
11-11
Miscellaneous Technical Info
FORCED PAGE BREAK FOR PAGE NUMBERING REASONS - REMOVE FROM MANUAL.
11-12
ACCUSONIC MODEL 7500
Miscellaneous Technical Info
ACCUSONIC MODEL 7500
13
Chapter 12
Leak Detection System
The Accusonic Leak Detection System operates by comparing flowrates measured over time by
flowmeters located at two or more locations on a pipeline. While the leak detection system must be
sensitive enough to detect a leak, it must also be designed to minimize the possibility of false alarm trips
due to transient flow conditions that occur during normal plant operation and load changes, or due to
normal measurement variability, rejected readings, and hardware failure.
In many systems, the pipe diameter and configuration are not the same at the two ends, and the upstream
pipe geometry is normally complicated by the presence of bends and valves very close to the meters. If
the two flowmeters are to be compared, they must therefore be tolerant of these effects. By using
multiple acoustic paths in each measurement section, Accusonic flowmeter accuracy is high and relatively
unaffected by upstream flow conditions. This allows optimum leak detection performance.
Accusonic has developed specialized leak detection algorithms to aid in detecting small leaks where the
differential flows might be small but steady over along period of time, and large, potentially catastrophic,
leaks where the differential flows will be large but must be detected within a very short period of time.
Relays are provided to signal a warning or an alarm if the differential flowrates indicate a leak. These
relays can be used to operate annunciators or to initiate valve or gate closures.
The system also provides for warning or alarm relays based on excessive velocities measured through one
or more of the flowmetering sections.
System Components
The leak detection system comprises a 7500 console, possibly with remote flow transmitters, and one or
more remote flow transmitters, together with associated transducers and cables sufficient for flow
measurement in each section. All remote flow transmitters communicate with the 7500 console via a
serial communications link. The 7500 console contains specialized software to carry out the flow
comparison/leak detection functions and provides an alarm if a leak is detected.
Under ideal operating conditions, the combined flowrates through all sections at either end of the pipeline
should be the same. Ideal conditions are seldom achieved, however, and under normal conditions
flowrates can vary significantly from one end of the penstock to the other. These differences can be
caused by many things, for example, the time lag after a valve is closed or the oscillations caused by a
surge chamber. To compensate for these conditions the leak detection software filters the differential
flowrates and provides multiple detection thresholds, all under operator control.
ACCUSONIC MODEL 7500
12-1
Leak Detection System
Note
The following terms are used when setting parameters in the 7500 Leak Detection System.
Section - Used to describe each location in which transducers are installed. One flowmeter electronics
console can measure flow in more than one section.
End - Used to describe one or more sections whose flowrates are added to determine a total flowrate at
one end of a pipeline. Typically, a leak detection system contains two ends, whose flowrates are
compared to detect a leak. Either end may be composed of one or more sections, as shown below.
Pipeline or penstock - Used to describe the overall configuration of a flowmeter system which might be
composed of one or more ends, each composed of one or more sections. This is a typical configuration
used in leak detection systems where one or more section flowrates are combined into end flowrates for
purposes of comparison.
E
E
S
S
P
S
S
P
P
S
E
E
S
S
P
S
S
E
E
S
S
E
S
E
S = SECTION
E = END
P = PIPELINE/PENSTOCK
Figure 12-1 Typical Section/End/Penstock Configuration
12-2
ACCUSONIC MODEL 7500
Leak Detection System
System Operation
Differential Flow Determination
The 7500 leak detection system maintains a running average of the difference between the total flowrates
at each end of each pipeline. This average is calculated from a queue of instantaneous signed flowrate
differences between ends of each pipeline. Operator-settable parameters control the number of
measurements that will be averaged (queue size), as well as the values representing warning and alarm
thresholds. If the average differential exceeds the first threshold, a warning relay is closed; if the average
differential flowrate exceeds the second threshold, an alarm relay is closed. These thresholds are sitespecific and are determined at the time of system commissioning based on typical operating conditions.
Differential flow calculations do not occur unless the flow measurements at each end are valid.
Additionally, any system failure will prevent the flow differential relay from tripping. In particular, the
watchdog timer, individual transceiver self tests, section and path measured values must all be within
limits specified by their respective parameters, with no path/section errors present.
At startup (first measurement), the averaging queue contains zeroes, so the flow differentials can appear
abnormally high because of normal measurement variability, which is typical of instantaneous flow
measurements. To prevent an erroneous differential flow alarm, the program calculates the differential
average as the sum of the values currently in the queue divided by the total size of the queue. This has the
effect of raising the threshold values at startup to prevent false trips.
Over Velocity Detection
In addition to differential flow warnings and alarms (for pumping and siphons), the leak detection system
also provides for warnings and alarms based on positive and negative over-velocity thresholds. Extreme
velocities can be used to detect a leak even in the case where a pipe rupture causes acoustic paths to stop
operating so that the meter is unable to calculate flow in one or more sections.
The system operates by calculating the instantaneous average of all good velocities for each section. This
average velocity is then compared to the over-velocity warning and alarm threshold values entered as sitespecific parameters. The threshold is an absolute value, but totals of the threshold crossings are signed.
A positive threshold count is incremented each time the velocity exceeds the positive threshold value and
is decremented each time it falls below the positive threshold value. The same concept is applied to the
negative threshold, but the signs are reversed for negative flow. If either count exceeds a user-entered
value, a relay is closed.
ACCUSONIC MODEL 7500
12-3
Leak Detection System
Velocities used in the average velocity calculation must pass all the normal requirements of a good
velocity except the Signal Quality Monitor (SQM), and the section parameters Minimum good paths,
Maximum expected velocity and Maximum change in velocity. The reason for not requiring valid SQM is
that very high velocities produce low pressures, which increase the likelihood of cavitation in the vicinity
of the transducers. Cavitation will reduce signal strength.
Since the pipe will probably flow partially empty in the event of a major rupture, acoustic paths should
always be installed horizontally in a leak-detection system.
Note
All relays are not latching; the closure is present as long as the condition causing the closure
is present. In the event of a catastrophic leak, once the over velocity alarm relay is tripped,
acoustic paths will begin to fail, and the hardware failure alarm relay will close. At this point, the
over velocity alarm relay will open. A second, latching relay tripped by the over velocity relay is
required to ensure valve closure under these conditions.
12-4
ACCUSONIC MODEL 7500
Leak Detection System
General System Operation
The leak detection program sequence follows.
♦ Measure travel times for each section at both ends of the pipeline (as described in Chapter 3,
beginning on page Error! Bookmark not defined..)
♦ Calculate average velocity for each section (ignoring SQM and Minimum good paths parameter)
♦ Calculate instantaneous flowrate for each section (using all filtering parameters)
♦ Calculate average flowrate for each section
♦ Calculate total instantaneous flowrate for each end of the pipeline (if more than one section at either
end of the pipeline)
♦ Calculate total average flowrate for each end of the pipeline.
♦ If all average flowrates are good, calculate differential flow from instantaneous flowrates at both ends
and add to queue.
♦ if average velocity > positive over velocity warning threshold
♦ positive over velocity warning count = positive over velocity warning count + 1
else
♦ positive over velocity warning count = positive over velocity warning count -1 (not to
decrement below 0)
♦ If average velocity < negative over velocity warning threshold
♦ negative over velocity warning count = negative over velocity warning count + 1
else
♦ negative over velocity warning count = negative over velocity warning count - 1 (not to
decrement below 0)
♦ if positive over velocity warning count > maximum over velocity warning count
♦ enable positive over velocity warning relay
else
♦ disable positive over velocity warning relay
♦ if negative over velocity warning count > maximum over velocity warning count
♦ enable negative over velocity warning relay
else
♦ disable negative over velocity warning relay
♦ if average velocity > positive over velocity alarm threshold
♦ positive over velocity alarm count = positive over velocity alarm count + 1
else
♦ positive over velocity alarm count = positive over velocity alarm count - 1 (not to decrement
below 0)
ACCUSONIC MODEL 7500
12-5
Leak Detection System
♦ If average velocity < negative over velocity alarm threshold
♦ negative over velocity alarm count = negative velocity alarm count + 1
else
♦ negative over velocity alarm count = negative over velocity alarm count -1 (not to
decrement below 0)
♦ if positive over velocity alarm count > maximum over velocity alarm count
♦ enable positive over velocity alarm relay
else
♦ disable negative over velocity alarm relay
♦ if | differential flow | > warning threshold, close the differential warning relay
♦ if | differential flow | > alarm threshold, close the differential alarm relay
Note
All relays are not latching; the closure is present as long as the condition causing the
closure is present. In the event of a catastrophic leak, once the over velocity alarm
relay is tripped, acoustic paths will begin to fail, and the hardware failure alarm relay
will close. At this point, the over velocity alarm relay will open. A second, latching
relay tripped by the over velocity relay is required to ensure valve closure under
these conditions.
12-6
ACCUSONIC MODEL 7500
Leak Detection System
Leak Detection Parameter List
Always display plant totals
Although this is not a leak detection parameter, its setting affects the operation of a leak detection system. As
previously stated, flow comparison will not be done if one or more flow rates are “BAD”. Setting this parameter to
“ON” will allow comparison (and potentially false detection of leaks) during hardware failure conditions.
It is strongly suggested that this parameter be set to OFF.
Menu levels:
Range:
Default:
Extended
OFF, ON
OFF
Differential alarm threshold
The value with which the differential flow average is compared in determining whether to close the alarm
relay. This value is typically determined at the time of system commissioning based on site-specific
operations. This threshold should be set to a higher value than the parameter Differential warning
threshold.
Menu levels:
Range:
Default:
Setup, Limited, Extended
#
0
Differential flow average size
Defines the number of different flowrate measurements that will be averaged by the leak detection
software. This represents the size of the a queue in which the difference between flowrates at the two
ends of a pipeline are stored for averaging. As each differential flowrate is calculated, an entry is added
to the averaging queue until the differential flow averaging queue equals this setting. Once the queue is
filled, each new entry replaces the oldest entry in the queue. Upon first startup, the differential flow
average queue is zeroed.
Menu levels:
Range:
Default:
ACCUSONIC MODEL 7500
Setup, Limited, Extended
#
25
12-7
Leak Detection System
Differential warning threshold
The value with which the differential flow average is compared in determining whether to close the
warning relay. This value is typically determined at the time of system commissioning based on sitespecific operations. This threshold should be set to a lower value than the parameter Differential alarm
threshold.
Menu levels:
Range:
Default:
Setup, Limited, Extended
#
0
Leak detection switch
Enables the leak detection system algorithms. Note that this parameter appears twice on the flowmeter
menu--once as a General parameter and again under the specific Leak detection option. The switch must
be turned on in the General parameter list in order to enable the system to perform the calculations
required for leak detection. It must also be enabled under the Leak detection option for each
pipeline/penstock for which leak detection functions should be performed.
Type:
Menu levels:
Range:
Default:
General and Leak detection
Setup, Limited, Extended
Off On
Off
Negative over velocity alarm threshold
Defines the velocity at which a negative velocity alarm counter will be incremented for leak detection
purposes. All available instantaneous path velocities reported for a meter section are averaged; this
average is then compared to the Negative over velocity alarm threshold and a counter is
incremented/decremented based on whether the threshold is exceeded.
Type:
Menu levels:
Range:
Default:
Section
Setup, Limited, Extended
#
Negative 150% of Maximum expected velocity
Negative over velocity warning threshold
Defines the velocity at which a negative velocity warning counter will be incremented for leak detection
purposes. All available instantaneous path velocities reported for a meter section are averaged; this
average is then compared to the Negative over velocity warning threshold and a counter is
incremented/decremented based on whether the threshold is exceeded.
Type:
Menu levels:
Range:
Default:
12-8
Section parameter
Setup, Limited, Extended
#
Negative Maximum expected velocity
ACCUSONIC MODEL 7500
Leak Detection System
Over velocity alarm count
A value which, when reached, will cause the meter to close the alarm relay. The flowmeter increments
the positive over velocity counter each time the average of all available instantaneous path velocities
exceeds the Section parameter Positive over velocity alarm threshold and decrements the counter each
time the average falls below that threshold. If the running total in the counter reaches this value, the over
velocity alarm relay is closed. A separate counter is incremented/decremented for negative velocities
based on the parameter Negative over velocity alarm threshold.
Type:
Menu levels:
Range:
Default:
Section
Setup, Limited, Extended
#
25
Over velocity warning count
A value which, when reached, will cause the meter to close the warning relay. The flowmeter increments
the positive over velocity counter each time the average of all available instantaneous path velocities
exceeds the Section parameter Positive over velocity warning threshold and decrements the counter each
time the average falls below the threshold. If the running total in the counter reaches this value, the over
velocity warning relay is closed. A separate counter is incremented/decremented for negative velocities
based on the parameter Negative over velocity warning threshold.
Type:
Menu levels:
Range:
Default:
Section
Setup, Limited, Extended
#
25
Positive over velocity alarm threshold
Defines the velocity at which a positive velocity alarm counter will be incremented for leak detection
purposes. All available instantaneous path velocities reported for a meter section are averaged; this
average is then compared to the Positive over velocity alarm threshold and a counter is
incremented/decremented based on whether the threshold is exceeded.
Type:
Menu levels:
Range:
Default:
Section
Setup, Limited, Extended
#
Positive 150% of Maximum expected velocity
Positive over velocity warning threshold
Defines the velocity at which a positive velocity warning counter will be incremented for leak detection
purposes. All available instantaneous path velocities reported for a meter section are averaged; this
average is then compared to the Positive over velocity warning threshold and a counter is
incremented/decremented based on whether the threshold is exceeded.
Type:
Menu levels:
Range:
Default:
ACCUSONIC MODEL 7500
Section parameter
Setup, Limited, Extended
#
Positive Maximum expected velocity
12-9
Leak Detection System
Table 12-1 Checklist of Initial Setup Parameters for Leak Detection System
Parameter
Value
The following General Parameters are required for leak detection:
Leak Detection Switch (should be ON):
The following Leak Detection System Parameters are required for each pipeline:
Leak Detection Switch (should be ON for each pipeline for which leak detection is desired):
Differential flow averaging size
Differential warning threshold
Differential alarm threshold
The following parameters are required for each section:
Positive over velocity warning threshold
Negative over velocity warning threshold
Over velocity warning count
Positive over velocity alarm threshold
Negative over velocity alarm threshold
Over velocity alarm count
12-10
ACCUSONIC MODEL 7500
Glossary of Terms
~A~
Accumulated total flow - The quantity of liquid that has flowed over a period of time. This is the flowrate
with time removed. For example, if the flowrate was 10 cubic feet per second, and 10 seconds had
elapsed, the Accumulated Total Flow would be 100 cubic feet. Also called Totalized Flow or Total
Volume.
Acoustic Path - In the 7500 system, an acoustic path is comprised of a pair of aligned transducers and the
liquid between them. This is the required hardware to measure the velocity of the liquid at one elevation.
Analog output interfaces - Outputs are used to communicate variables (such as flowrate or volume)
calculated by the 7500 to external equipment, such as a SCADA system or datalogger. A typical example
of an analog output would be a 4-20 milliamp current loop representing flowrate. As the flowrate
incresed, the current in the loop would increase. A variety of interface types are available to communicate
with most types of systems.
Analog stage inputs - Stage (level) measurement information can be input to the 7500 as a 4-20 mA
current loop. Parameters are available to scale and offset the current loop input to represent fluid
elevation. Analog stage inputs are an optional feature, they must be installed and inititally cofigured at
Accusonic.
Automatic gain control (agc) - A patented feature of the 7500 system, causes the signal level from each
transducer to be adjusted independently on each measurement cycle. This is most useful where there are
changing acoustic conditions in the measurement section, such as temporary occurrences of entrained air,
or schools of fish. This will also compensate for slowly failing transducers, providing a longer service
life.
Autoswitching P.C. keyboard - A PC-Compatible keyboard that senses the type of CPU at boot or powerup time and adjusts its output to be compatible.
Average flow rate - The 7500 calculates an instantaneous flowrate by integrating velocities at various
levels in the fluid. Due to hydraulic conditions, the instantaneous flowrate can be somewhat unstable.
Therefore, flowrates are averaged - many samples are added together and the sum is divided by the
number of measurements to provide a smoother flowrate for display and outputs.
ACCUSONIC MODEL 7500
1
Glossary of Terms
~B~
Balanced-line - A method of transducer-to-electronics connection for use in electrically noisy
environments. Twin-axial cable is used, and positive and negative signal lines are run ungrounded. Any
electrical noise present is induced onto both lines. Since the receiving electronics only looks at the
difference between the lines, the noise common to both is ignored.
BCD (Binary Coded Decimal) - A form of parallel digital I/O (Input/Output), in which numbers are
represented in binary format, but arranged by digit. Each digit is made up of four bits, so a three-digit
number (the output range would be 0 to 999), would require 12 discreet output lines. This type of I/O has
some inherent error-checking, in that the total of the binary weights can add up to 15, but a ‘9’ is the
maximum allowable conversion value.
Binary I/O interfaces - A type of I/O (Input/Output) where data is transferred via parallel digital lines.
Each line has a binary (1, 2, 4, 8, 16, etc.) value, adding all of the lines yields the value. Depending on the
accuracy required, as many as 24 discreet lines could be required for a single data point. This type of I/O
is generally faster than a serial I/O port and more accurate than an analog connection, but much more
complex than either, due to the greater number of connections that must be made.
~C~
Coaxial cable - A transmission cable consisting of a conducting outer metal tube enclosing and insulated
from a central conducting core. This type of cable is used for carrying the high-frequency electrical signal
between flowmeter and transducers.
Compound - A closed conduit which can flow partially full as well as surcharged, exhibiting the flow
characteristics of both an open channel and full pipe.
Cross flow - Where the streamlines of flow are not parallel to the conduit centerline as a result of an
upstream obstruction or a transition in conduit shape or dimensions.
~D~
Datalogging - A feature of the 7500 flowmeter allowing flow measurement data to be stored on an
internal floppy disk.
2
ACCUSONIC MODEL 7500
Glossary of Terms
~E~
End - A combination of one or more sections. Provides a subtotal of flowrates and volumes for multiple
sections. A typical use would be in a low-head hydroelectric station where several conduits, each with a
measurement section, would feed a single turbine, and the total flowrate through the turbine should be
displayed. The result of these subtotals is called an end variable in this manual (these are subtotals of
section variables).
Extrapolation error - A form of error occurring when there are an insufficient number of acoustic paths
to accurately measure real variations in velocity across a measurement section, and the flowmeter must
extrapolate by using the velocity of the closest working path for the unknown velocity.
~F~
Flow calculation - Integrate the measured velocities over the entire cross-sectional area of fluid to
determine total volumetric flow.
Flow Transmitter - A subsystem which measures acoustic travel times in a measurement section and
returns the results. In the 7500/7520 system, this is comprised of a transceiver, transceiver
communication board, transmitter, path selectors, and path-select backplane.
~G~
Gain - The amount of amplification required to make the raw acoustic signal (as returned from the
receiving transducer) usable by the transceivers signal-detection circuitry.
General parameter - Any parameter (user input defining system operation) common to all of the
measurement sections in a flowmeter. Examples would be measurement repetition rate, display contrast,
or speed of sound in water.
General variable - Any variable (result calculated by the flowmeter) that is the sum of all measurement
sections. Examples would be total flowrate and total volume.
~H~
Hardware handshake - A flow control interface consisting of one or more hardware lines designed to
assure proper data flow with no loss. For example, two pieces of equipment using a serial line to
communicate would use handshake lines to signal each other when they needed more time to receive
data.
ACCUSONIC MODEL 7500
3
Glossary of Terms
~L~
Leak Detection - A special system configuration where flow measurement is made at two ends of a pipe
and compared. If the difference is outside of a user-set limit for a user-set time, a valve-closure signal is
generated to prevent leaks.
Leak parameter - Any parameter (user input defining system operation) used to configure leak detection
(see above) system operation. Examples would be Differential Warning Threshold and Differential Alarm
Threshold.
Leak variable - A variable (result calculated by the flowmeter) used for leak detection (see above).
Examples would be Maximum Differential Flow and Differential Alarm Status.
Loop noise - Electrical noise in an analog current loop output. Noise can be induced onto an output loop
by nearby electrical noise sources, or can be caused by the loop source. If the noise is caused by external
sources, it can usually be cured by proper grounding.
~M~
Measurement cycle - A complete measurement, including acquisition of path travel times, acquisition of
stage (fluid level), calculation of flowrate and totalized volume, display of calculated variables, and
output of results.
Multipath reflection - A condition which exists when an acoustic path is located too close to a reflector,
such as a pier or the fluid surface. The acoustic signal takes both a direct path and a bounce path,
combining with itself at the receiving transducer. The result is a distorted signal which rarely yields a
correct result.
~N~
Negative-going edge - The part of the received acoustic signal used for detection. Also called first
negative.
NEMA-4 - A specification of the National Electric Manufacturers Association which states that an
enclosure will protect the contents against windblown dust, rain, splashing water, and hose-directed
water.
Net total volume -The combination of Positive and Negative Volumes for all measurement sections.
Non-volatile storage - A type of parameter storage that retains information when power is interrupted. In
the 7500 system, this is accomplished by using an internal battery to continuously power a small section
of memory.
4
ACCUSONIC MODEL 7500
Glossary of Terms
~O~
Open Channel - Any conduit, whether open or closed, in which water flows with a free surface.
Overvelocity - A special alarm type which will actuate when the fluid in a pipe flows faster than a preset
level. Flowrate and status of most other alarms are disregarded. Intended to close a safety valve in the
event of a large break in a pipe.
~P~
Parallel port - A type of I/O (Input/Output) where data is transferred via multiple digital lines. In the
7500 system, this usually refers to the printer connection.
Parameter - An entered value that the flowmeter uses for measurement and calculation.
Path parameter - Any parameter (user input defining system operation) used to configure the operation
of a single acoustic path. Examples: Path Length, Transducer Type.
Path variables - A variable (result calculated by the flowmeter) calculated for a single acoustic path.
Examples: Velocity, Speed of Sound.
Pipe - Normal enclosed conduit which flows completely full.
Predicted-arrival gates - These are part of the 7500’s data-validity system. The maximum and minimum
possible arrival times of the signal on the acoustic path are calculated based on the speed of sound in the
fluid and the maximum velocity of the fluid. Any signal appearing outside of these times is considered to
be noise and is ignored.
Processor group - The “smart side” of the 7500 system. Controls the measurement cycle. Takes travel
time and error information from the Flow Transmitter, calculates flow rates, volumes, and all other
variables, then displays and outputs the results.
Pulse output interface - A form of serial output, usually used to transmit increments of totalized volume.
Normally consists of a relay which closes briefly (closure time is 1/4 second in the 7500), then re-opens.
ACCUSONIC MODEL 7500
5
Glossary of Terms
~S~
Section - Used to describe each conduit in which transducers are installed. A section can be part of a pipe,
a river or a sewer. One flowmeter electronics console can measure flow in more than one section.
Section parameter - Any parameter (user input defining system operation) used to configure the
operation of a measurement section (see above). Examples: Pipe Radius, Maximum Expected Flowrate.
Section variable - A variable (result calculated by the flowmeter) calculated for a measurement section
(see above). Examples: Flowrate, Volume.
Stage - The level of fluid in a conduit.
Survey uncertainty - Used to describe an error condition when the walls of the conduit are irregular,
asymmetric, or (as is often the case in a river) cannot be surveyed exactly or permanently.
System - Used to describe the flowmeter console with any remote transmitters, transducers in all sections
controlled by the console and remote transmitters, and associated cabling.
~T~
Totalizer cutoff time - The maximum time limit over which the flowmeter will interpolate flow if
measurements are suspended or interrupted. This is entered into the 7500 as a parameter. If the
interruption is shorter than the entered time, the 7500 calculates volume for the outage time. If the
interruption exceeds the specified time limit, the instrument does not calculate volume for the outage
period. Refer to Chapter 3, Flow Calculation Formulas, beginning on page Error! Bookmark not defined.
for formula describing what is used for flowrate.
Total forward volume - The quantity of liquid that has flowed over a period of time in the positive
direction (positive is defined as “in the direction of gravity”. In this direction, a turbine at a pump/
generation plant would be generating). This is the flowrate with time removed. For example, if the
flowrate was 10 cubic feet per second, and 10 seconds had elapsed, the forward volume would be 100
cubic feet. Total forward volume is the sum of all section forward volumes.
Total reverse volume - Same as Total forward volume (see above), but in the negative direction. Negative
is defined as “opposing gravity”. In this direction, a turbine at a pump/generation plant would be
pumping.
Twin-axial cable - A transmission cable consisting of a conducting outer metal tube enclosing and
insulated from two central conducting cores. This type of cable is used for carrying the high-frequency
electrical signal between flowmeter and transducers. Twin-axial cable is used in place of coaxial cable in
high-noise environments, so that the signal can be carried in balanced-line mode.
6
ACCUSONIC MODEL 7500
Glossary of Terms
~V~
Variable - The result of a measurement and flow calculation.
Velocity measurement - measures the average velocity along one or more linear paths through the
moving fluid.
Velocity Substitution -An Accusonic flowmeter feature which can allow the flowmeter to continue to operate and
make a best-guess estimate of the flowrate if one or more acoustic paths fail. The velocity of the “mirror” path (most
likely to reflect any changes in velocity profile) is substituted for the failed path. See the description of the velocity
substitution parameters (page Error! Bookmark not defined.) for information on how to enable and configure this
feature.
Elevation
Velocity Profile -A graphical representation of the fluid velocities at various elevations in the conduit. The velocity
profile can change substantially as flowrate changes.
10
9
Path 4
8
7
Path 3
6
5
4
Path 2
3
Path 1
2
1
0
0 1 2 3 4 5 6 7 8 9 10
Velocity (Ft/Sec)
~W~
Watchdog timer - A hardware timer chain and relay designed to reset the system if there is a loss of
software control. The timer continually tries to count down to zero. The system software, if in control,
resets the timer after every measurement cycle. If the software goes out of control and the timer is allowed
to count down to zero, a hardware reset occurs.
Waveform - A two-dimensional representation of a electrical signal, usually on an oscilloscope.
ACCUSONIC MODEL 7500
7
Index
ACCUSONIC MODEL 7500
7
Index
—A—
AC Power Connections, 4-2
Accuracy, 1-2, 3-28
Addressing the Flow Transmitter, 11-2
Always display flow totals, 12-7
Analog
error conditions, 8-3
offsets and scale factors, 8-2
setting up, 8-1
Automatic Gain Control (agc), 2-10, 3-13
—H—
Help, 5-8
—I—
Installation, 4-1
Integration method
description, 3-18
displaying, 5-31
selecting, 7-16, 7-25, 7-28
—C—
Cables
RS-232, 4-9
RS-485, 4-11
Compound Sections in Round Pipes 5-34
Connecting Transducer Cabling, 4-3
Contrast
adjusting, 5-16
—D—
Data Log File Description, 8-27
Data Logging, 8-26
Diagnostics, 5-17, 6-1
Differential alarm threshold, 12-7
Differential flow average size, 12-7
Differential warning threshold, 12-8
Display Screen, 5-31
—E—
Error Codes, 9-3
path, 9-4
section, 9-7
self-test, 9-9
Stage, 9-10
Error Reporting, 8-12, 8-15, 8-28
—F—
Flow
calculating, 3-17, 9-7
differential, 12-3
Flow Transmitter, 2-1, 2-7, 2-8, 2-9
Flow Transmitter Group, 2-4, 2-9–2-11
—G—
Gain
displaying, 5-33
entering, 7-12, 7-22
8
—K—
Keyboard, 2-9
Keys
hidden, 11-1
—L—
Leak Detection
description, 12-1
Leak detection switch, 12-8
Lights, Error 6-6, 9-1
—M—
Maintenance, 6-1
Menu Access, 5-9
Menus, 5-1
hierarchy, 5-5
stepping through, 5-3
tree, 5-7
Monitoring Raw Path Signals, 9-12
—N—
Negative over velocity alarm threshold, 12-8
Negative over velocity warning threshold, 12-8
—O—
Outputs, 8-1
analog, 8-1
relay, 8-4, 8-6
setting up, 8-10
specifications, 8-8
RS-232, 8-16
connection, 4-9
format, 8-17
setting up, 8-19
verifying, 8-20
testing, 8-1
totalizer, 8-4, 8-9
setting up, 8-11
verifying, 8-4
watchdog, 8-9
ACCUSONIC MODEL 7500
Index
Over velocity alarm count, 12-8
Over Velocity Detection, 12-3
Over velocity warning count, 12-9
—P—
Parameters
always display plant totals, 7-1, 12-7
autostart switch, 5-8, 7-1
available velocity enabled, 7-2
average cable length per path, 7-2
average stage cable length, 7-2
averaging queue length, 7-2
bidirectional flow, 7-3
bottom channel width, 7-3
bottom velocity ratio, 7-3
channel bottom height, 7-3
cross sectional area, 7-4
current date, 7-4
current time, 7-4
data log start, 7-5
data logging, 7-4
delay time of other ducer, 7-5
display contrast, 7-5
display mode, 7-6
display totals line, 7-6
ducer connection, 7-6
ducer type (7600, 7601, 7605, 7612...), 7-6
end label character, 7-6
end starting number, 7-7
entering, 5-10
error reporting, 7-7
flowrate scale factor, 7-7
format, 7-8
frequency of other ducer, 7-8
full pipe, 7-8
general, 5-10, 5-22
inactivity timeout, 5-30, 7-9
K, 7-9
layer boundary elevation 1 - n, 7-9
layer boundary width 1 - n, 7-10
leak detection
Always display flow totals, 12-7
differential alarm threshold, 12-7
differential flow average size, 12-7
differential warning threshold, 12-8
leak detection switch, 12-8
negative over velocity alarm threshold, 12-8
negative over velocity warning threshold, 12-8
over velocity alarm count, 12-9
over velocity warning count, 12-9
positive over velocity alarm threshold, 12-9
positive over velocity warning threshold, 12-9
leak detection switch, 7-10
loading and saving, 5-27, 5-28
log data to, 7-10
log interval, 7-11
log negative volume data, 7-11
log velocity data, 7-11
manning coefficient of roughness, 7-11
ACCUSONIC MODEL 7500
manual gain, 7-12
manual stage (1 or 2) value, 7-12
maximum bad measurements, 7-12
maximum change in flowrate, 7-12
maximum change in stage, 7-13
maximum change in velocity, 7-13
maximum expected flowrate, 7-13
maximum expected velocity, 7-13
maximum stage, 7-14
maximum stage difference 1 and 2, 7-14
menu access, 7-14
minimum flowrate, 7-14
minimum good paths, 7-15
minimum path submersion, 7-15
minimum stage, 7-15
non-surcharged integration method, 7-16
number of channel layers, 7-16
password control, 7-17
path, 5-14, 5-25
path angle, 7-17
path elevation, 7-17
path length, 7-17
path percent active, 7-18
path position, 7-18
path simulation, 7-18
path switch, 7-19
penstock label character, 7-19
penstock starting numbers, 7-19
pipe height, 7-19
pipe integration, 7-20
pipe shape, 7-20
pipe slope, 7-20
printing, 5-29
protrusion of other ducer, 7-21
Q FWD 1 - n, 7-21
Q REV 1 - n, 7-21
radius, 7-21
receiver gain, 7-22
repetition time, 7-22
saving and loading, 5-15, 5-27
section, 5-11, 5-23
section label character, 7-22
section starting number, 7-22
section switch, 7-22
section type, 7-23
self test interval, 7-23
shape factor, 7-23
signal detection method, 7-23
simulation forward time, 7-24
simulation reverse time, 7-24
simulation source, 7-24
simulation velocity, 7-24
simulation velocity ramp scale, 7-25
single coefficient (1 - 5), 7-25
single integration, 7-25
speed of sound in fluid, 7-26
SQM, 7-26
stage (1 or 2) offset, 7-27
stage (1 or 2) range maximum, 7-27
stage (1 or 2) range minimum, 7-28
stage averaging size, 7-26
9
Index
stage ducer type, 7-26
stage interval, 7-27
stage mode, 7-27
stage source, 7-28
surcharged integration method, 7-28
temperature coefficient, 7-29
top weight, 7-30
totalizer cutoff time, 7-31
travel time tolerance, 7-31
units, 7-31
V FWD 1 - n, 7-34
V REV 1 - n, 7-34
velocity substitution, 7-31
velocity substitution ratio, 7-32
volume scale factor, 7-34
weight, 7-35
which section, 7-35
width at path elevation, 7-35
zero flow offset, 7-35
Password, 5-8, 5-26
Path Selector, 2-4
Paths
crossed, 3-7, 3-21
Positive over velocity alarm threshold, 12-9
Positive over velocity warning threshold, 12-9
Power Interruption, 2-8
Power Supply, 2-4, 11-4
checking and adjusting, 9-13
color code, 9-14
Printer
connection, 4-6
printing listings. Also see "Reports"
Processor Group, 2-2, 2-6, 2-8
Pulse Transmitter, 2-3
—R—
Remote Access, 11-6
Repairs, 6-6
Reports, 8-21
printer connection, 4-6
setting up, 8-23
RS-232. See Outputs
RS-485
Interconnect cable, 4-11
—S—
Scaling
flowrate, 7-7
volume, 7-34
Self-Test, 9-9
Setup, 5-1, 5-22
initial, 5-21
Simulating flowrate, 7-18
Specifications, 11-4
Stage
10
connection, 4-7
description, 2-1, 2-3, 2-10
displaying, 5-33
error codes, 9-10
measuring, 2-8, 3-16
Stage Range, 4-7, 7-27
Surge Protection 11-8
—T—
Temperature
coefficients, 7-29
displaying, 5-33
Transceiver, 2-3, 2-10
diagnostics, 6-3
resetting, 6-2
Transducer
connection, 4-3
Transducer and Cabling Checkout, 4-5
Transducer Maintenance, 10-1
Transducers
7600 series
replacing, 10-9
7601 series
replacing, 10-3
models, 1-3
Transmitter, 2-10
Troubleshooting, 9-1
—V—
Variables, 7-37
average temperature, 7-37
average velocity of sound, 7-37
averaged stage, 7-37
delta flow, 7-37
delta flow average, 7-37
differential flow alarm, 7-38
differential flow warning, 7-37
flow average, 7-38
flow error count, 7-38
Flowrate, 7-38
forward gain, 7-38
forward time, 7-38
negative volume, 7-38
positive volume, 7-39
reverse gain, 7-39
reverse time, 7-39
section status, 7-39
signal delay, 7-39
stage 1, 7-39
stage 1 signal delay, 7-40
total average flow, 7-40
total flow, 7-40
total negative volume, 7-40
total positive volume, 7-40
total volume, 7-40
velocity, 7-40
ACCUSONIC MODEL 7500
Index
velocity error count, 7-41
velocity of sound, 7-41
volume, 7-41
resetting, 7-37
Velocities, 8-17
calculating, 3-14
displaying, 5-32
simulating, 7-18
substituting, 7-31
ACCUSONIC MODEL 7500
11
Index
12
ACCUSONIC MODEL 7500
IMPORTANT
NOTE TO ELECTRICIAN AND/OR INSTALLER OF THIS
EQUIPMENT:
IF THIS EQUIPMENT IS BEING INSTALLED IN A
WASTEWATER ENVIRONMENT, BE SURE TO OBSERVE
THE FOLLOWING:
TO PREVENT DAMAGE TO ELECTRICAL AND
ELECTRONIC CIRCUITS IT IS IMPERATIVE THAT ACIDIC
SEWER AND OTHER CONDENSING VAPORS BE
PREVENTED FROM ENTERING FLOWMETER
ENCLOSURE.
MAKE SURE THAT ALL CONDUITS AND CABLES
ENTERING THIS ENCLOSURE ARE SEALED WITH
POURED SEALS IN ACCORDANCE WITH THE NATIONAL
ELECTRICAL CODE SAFETY REQUIREMENTS.
IF PERMANENT SEALS ARE NOT BEING INSTALLED AT
THIS TIME,BE SURE TO PROVIDE TEMPORARY
SEALING MEANS SUCH AS ELECTRICIAN'S PUTTY.
(DO NOT USE RTV SEALANT, IT GIVES OFF ACETIC
VAPORS).
Accusonic REV 11/97
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising