D-2 INCORPORATED Jet Fuel 1A Conductivity Sensor JF

D-2 INCORPORATED Jet Fuel 1A Conductivity Sensor JF
JF-1A CONDUCTIVITY SENSOR
D-2 INCORPORATED
Jet Fuel 1A Conductivity Sensor
JF-1A
OPERATION MANUAL
REVISION 1.0
FIRMWARE VERSION 2.2
P/N A440-009
This manual covers the operational aspects of the D-2 JF-1A Conductivity Sensor. D-2
continuously strives to meet the full expectations of our customers and we welcome
comments on the structure, content and the ability of this manual to answer your
questions regarding our product. If you have any suggestions or comments please
contact us at Mail@D-2inc.com. This document is provided with the understanding that
future versions of this instrument may have additional commands, and the function of
the commands shown in this document may vary from the present operation.
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JF-1A CONDUCTIVITY SENSOR
TABLE OF CONTENTS
OPERATION MANUAL
1
P/N A440-009
1
1.0 GENERAL
4
2.0 USAGE
4
3.0 FUNCTION
4
4.0 THEORY OF OPERATION
5
5.0 D-2 JF-1A SENSOR
7
6.0 MECHANICAL INSTALLATION
8
7.0 ELECTRICAL INSTALLATION
9
8.0 TEST PROCEDURE
15
9.0 SENSOR REMOVAL
17
10.0 SPECIFICATIONS
17
11.0 SERIAL DATA INTERFACE
18
12.0 CALIBRATION
23
13.0 COMPENSATED OUTPUT
24
14.0 FILTERED OUTPUT
25
15.0 MAINTENANCE
27
16.0 OPTIONAL 2-WIRE TEMPERATURE INTERFACE
28
Appendix A: Service & Warranty Policy
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JF-1A CONDUCTIVITY SENSOR
1.0 GENERAL
The D-2 JF-1A Conductivity Sensor is a reliable instrument for the continuous
measurement of electrical conductivity of fuels. The JF-1A Conductivity Sensor
incorporates innovative electronics Digital Signal Processing (DSP) techniques to
accurately determine the electrical conductivity of fuel products. The instrument will
measure fuel electrical conductivities between 0 and 2000 picosiemens/meter (pS/M),
although it is optimized and normally used in the 0 to 500 pS/M range. The sensor
offers RS-232 data output, or traditional industrial loop compliant 4-20 mA. The 4 -20
mA output can be user programmed to represent a prescribed range of conductivity.
User configurations and instrument calibration terms are stored in internal non-volatile
memory. The D-2 sensor is continuously internally electronically calibrated. Absolute
calibration relies only on the sensor cell constant that is very stable by design. The
conductivity sensor has a built-in temperature sensor. Output from the temperature
sensor is used to fully compensate the conductivity output from variations due to
changes in electrical conductivity as a function of temperature per the ASTM D 2624,
Appendix X2 Standard (Appendix A), (See Also Document “NRC-22648 The Relationship
Between Electrical Conductivity and Temperature of Aviation Turbine Fuels Containing
Static Dissipater Additives”. The sensor can be provided with an optional 2 (4 – 20mA)
wire temperature interface, allowing remote monitoring of fuel temperature.
Figure 1
Typical Installation Courtesy of Motiva
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JF-1A CONDUCTIVITY SENSOR
2.0 USAGE
Fuel products such as jet aviation and diesel fuels that are transferred at high pumping
rates may develop a static electrical charge due to the very low conductance of the
fluid. The D-2 JF-1A Conductivity Meter measures the ability of the fuel to dissipate
that charge. The conductivity of aviation fuels is purposely increased using additives
that reduce the ability of the fuel to store static charge. These additives are normally
injected prior to transfer to the load vessel. The D-2 JF-1A Conductivity Sensor has the
ability to monitor the electrical conductivity of fuel continuously, allowing its use as a
sensing element in an automated additive injection system. The D-2 JF-1A ability to
measure with high precision continuously at a high sampling rate (1 hertz) allows for
precision control of additive injection. The industrial standard 4-20 mA sensor allows for
its use with industry standard PID Controller/Display units combined with additive
injector pumps to provide real-time control over addition of conductivity-enhancing
additives during the transfer process. The Digital Signal Processing (DSP) full numerical
compensation of conductivity for fuel temperature allows the system to be used in
facilities independent of a wide range of ambient temperatures. The D-2 JF-1A provides
consistent results independent of temperature (when temperature compensation is
enabled). Optionally a second 2 Wire (4 – 20 mA) temperature output interface is
available.
3.0 FUNCTION
The D-2 JF-1A Conductivity Meter reads conductivity in picosiemens/meter, fuel
temperature in ITS-90 degrees C, and fully compensated Conductivity in picosiemens/
meter per ASTM D 2624, Appendix X2. These measures are equivalent to CU or
Conductivity Units. The sensor can be used in a 2 wire 4-20 mA industrial control loop
or in conjunction with a serial input device using RS-232 IEEE Standard ASCII Serial
Input Data. Optionally a 2 wire (4-20 mA) temperature interface can be added to allow
remote monitoring of fuel temperature.
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JF-1A CONDUCTIVITY SENSOR
Figure 2
Major System Components
7
4
3
2
1
4
6
3
2
1
8
9
1
2
3
4
Ball Valve
Sensor Mount Adaptor
Mounting Nut
Locking Collar
6
7
8
9
Electronics Housing
Electrical Connection Side
Label
Installation Reference Plane
4.0 THEORY OF OPERATION
The D-2 JF-1A Conductivity Sensor uses a probe consisting of two concentric
stainless steel electrodes. When the probe is immersed in fuel, a very low
frequency AC voltage is applied to the electrodes. Conduction through the fuel
results in an AC electrical current that is amplified, detected, and output as
either direct serial ASCII data, or as a standard 4-20 mA industrial current loop.
The use of a precision AC voltage overcomes the problem associated with
electrode polarization impedance typical of DC type meters, and residual DC
charges that may exist in the fuel due to static generation from high-speed
pumping. Fluids such as aviation fuels can hold DC charge due to the very low
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JF-1A Conductivity Sensor
conductance of the fluid. These fuels can have conductivities lower than 5 pS/M
in the absence of conductivity-increasing additives.
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JF-1A Conductivity Sensor
5.0 D-2 JF-1A SENSOR
Figure 3
D-2 JF-1A On-Line Fuel Sensor
With Retractable Mount
The D-2 JF-1A Conductivity Sensor with Retractable Mount is shown in Figure 3.
The unit is fully contained in a sealed approved housing. The sensor is designed
to be fully intrinsically safe for operation in fuel facilities. The back cover allows
for direct conduit connection to the meter and offers both 4 - 20 mA output and
Serial Data Output Connections. The D-2 JF-1A Conductivity Sensor can be
operated as a “two wire” device under ISA 4 - 20 mA loop specification
ANSI/ISA-12.12-1994 – Non-incendive Electrical Equipment for Use in
Hazardous Locations.
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JF-1A Conductivity Sensor
6.0 MECHANICAL INSTALLATION
See Installation and Safe Use Manual for detailed mechanical installation
instructions.
6.1 LOCATION
The JF-1A Sensor should be mounted in downstream proximity to the additive
injection site. The user MUST insure that additive will be completely mixed at
the point at which the fuel is sensed by the JF-1A sensor. An in-line mixer can
be used, or more conveniently the injection site can be followed by a pipe “T” or
bend to cause turbulent flow mixing of additive. Insufficient mixing will result in
poor controller results and erratic average load conductivities.
NOTE: The Sensor should be mounted well away from possible
sources of electromagnetic noise, such as large pump motors, AC
power Lines, or electrical circuits containing large transient switching
currents.
Note: Prior to arc welding in proximity to the JF-1A sensor (closer
than 10 meters (30 feet) the sensor should be either removed from
the product line or at a minimum disconnected from all electrical
connections to the sensor. Welding circulation voltages can exceed
protection ratings of the sensitive output circuits located in the JF-1A
sensor.
6.2 PIPE CONNECTIONS
See Installation and Safe Use Manual for detailed mechanical pipe connections
instructions.
6.3 PIPE VALVE
The nipple should be supplied with a 1” Open Throat Ball Valve.
NOTE: The Ball Valve MUST Have a Clear Opening of 1.0” through its
center to allow the D-2 sensor to pass unobstructed. Ball valves can be
purchased directly from D-2.
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JF-1A Conductivity Sensor
6.3 SENSOR ADAPTOR
The D-2-supplied sensor adaptor should be mounted directly into the outboard
side of the ball valve using Teflon tape or other suitable thread sealer.
6.5 High Flow Rate Installation
See Installation and Safe Use Manual for detailed mechanical installation in high
flow rate lines.
7.0 ELECTRICAL INSTALLATION
See Installation and Safe Use Manual for detailed electrical installation
instructions.
7.1 2-Wire 4-20mA LOOP CONSIDERATIONS
Warning 2-Wire Loop Maximum Resistance including wire can not
exceed 500 ohms, or internal intrinsic over voltage safety devices in
the JF-1A sensor may be activated.
The 4-20 mA Loop supply open circuit voltage must be consistent with the
“Open Circuit Supply” needs of the JF-1A at both its minimum and maximum
indicating currents. The JF-1A has both input voltage limiting protection and
polarity protection.
These protection devices affect user supply voltage
requirements. If proper loop supply voltage is not maintained, errors in
indicated conductivity current may occur. The 4-20 mA loop supply voltage
should comply with specifications section of the manual.
The maximum loop power supply voltage, under all conditions, must also
prevent the voltage across the sensor loop terminals from exceeding the
maximum voltage listed in the specifications section of the manual. If this
condition is not maintained, errors in the current output may occur.
D-2 recommends that a 24 VDC isolated supply be used to power the
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instrumentation loop. The supply should have high isolation (>500 Mohm), and
be single point grounded. The current loop should be wired using shielded
twisted pair wire. The shield should also be single point grounded to a solid
earth ground.
Sensing resistors should be capacitive by-passed to ensure low common mode
loop noise. Sense resistors should be by-passed using the following table as a
guide. Note the capacitor should be rated to sustain the working voltage for the
loop and should comply with the requirements of the local electric code.
R-Loop
OHMS
250
350
500
By-Pass
uF
1
2.2
3.3
In the figure below a typical loop wiring with by-pass capacitors is shown for the
JF-1A sensor. The loop shows two sensing resistors in series with the JF-1A
sensor. At the negative terminal of the Isolated Power Supply the “loop” is AC
grounded using a capacitor. This capacitor helps to eliminate “common mode”
voltages that may be coupled to the loop. Note the sense resistors should be
connected to isolated input detectors such that entire loop remains floating
eliminating any ground conflicts of differences. Please consult the factory for
specific application support in the design of your measurement system.
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JF-1A Conductivity Sensor
JF-1
SENSOR
4-20 mA
PROPERLY BYPASSED 4-20 mA
INSTRUMENTATION
LOOP
R1
SENSE
C1
BY-PASS
C2
BY-PASS
DC
POWER SUPPLY
R2
SENSE
C3
GROUND
SHUNT
EARTH GROUND
NOTE: Sensor wiring should be performed as defined by the National
Electric Code (NEC), and ATEX sensor certificate.
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JF-1A Conductivity Sensor
7.2 4 – 20 mA CONDUCTIVITY READINGS
The following table details current output readings for the JF-1A sensor with a
nominal 0-500 pS/M range representing 4 – 20 mA. (Please consult the factory
for alternate range settings of the current output):
CONDUCTIVITY (Ps/M)
0.0
62.5
125.0
187.5
250.0
312.5
375.0
437.5
500.0
•
Current (mA)
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
Voltage * (Volts)
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
250 Ohm Voltage Sensing Resistor Used
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JF-1A Conductivity Sensor
7.3 RS-232 CONNECTIONS Considerations (4-Wire)
Figure 8A
4-WIRE ELECTRICAL CONNECTION DETAIL
1 2 3 4
3
2
1
3
2
1
The 4 Terminal Screw Connector has both Power Input and RS-232/RS-485
Connections as listed in Table 1 below:
TABLE 1
SCREW TERMINAL CONNECTION PIN DETAIL
TERMINAL
1
2
3
4
Function
Data/Power Ground
RS-232 Data In (RXD)
Power Input +
RS-232 Data Out (TXD)
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The RS-232 Interface is fully isolated from the sensor electronics through the
use of optical isolators located in the JF-1A/ATEX sensor.
7.4 RS-232 Wiring Considerations (4-Wire)
Data cable for the RS-232 should be low capacitance data cable. Lengths in
excess of 20 meters may result data degradation of the RS-232 signals.
7.5 Power Input (4-Wire)
Power input to the 4-Wire power connections should be clean filtered DC
voltage in the range of 7 – 35 VDC. Current consumption is approximately 10
mA.
8.0 TEST PROCEDURE
8.1 POWER INSTRUMENT
Connect Instrument to suitable power supply (See Section 7.0 for detailed
electrical connections). Attach D-2 Test Cable P/N A440-043 to the 4-Wire
connector located on the user connection interface. See Figure 7.
8.2 INSTALL WINDOWS SOFTWARE
Install D-2 JFWIN Windows Program. From the File Menu Bar press the
“Confirm Instrument” menu selection. The program will respond with unit on
line and the serial number of the unit if connections are correct and power has
been applied.
8.3 CONFIRM UNIT SERIAL NUMBER
Confirm the serial number of the unit matches the serial number the JFWIN
program has reported.
8.4 CHECK ZERO READING
With the sensor removed from the Load line rinse the sensor in “Clean”
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Isopropyl Alcohol and blow dry using “dry” compressed air. Note that this step
should be repeated until all signs of fuel residual have been removed from the
sensor.
Note: Isopropyl Alcohol is highly conductive and any residual traces
inside the sensor between the two electrodes will overage the
instrument. To flush the Isopropyl Alcohol a reagent grade toluene can
be used as an after rinse and allowed to air dry. Note that if the
Isopropyl Alcohol is well blown off with dry compressed air no
residuals will be left, eliminating the need to use the more exotic
Toluene.
When JFWIN is reporting low values (less than 5 pS/M) the user can be satisfied
that the sensor is clean. When ready to zero, press the “Zero Calibration” data
button in the JFWIN Menu. The program will report data being taken and
completion when done. Readings on the screen should report less than 2 pS/M
and should be stable. The Green Zero OK Light will light when complete.
8.5 SCALE CHECK SENSOR
Place the sensor in a fuel with additive that is near the full-scale range of
interest. We suggest a value “higher” than the range over which the sensor is
going to be operated. For example, if the user intends to measure conductivity
in the 0 – 500 pS/M range a good value to calibrate the sensor with is 750 –
1000 pS/M. This reduces uncertainty over the range of interest. The value of
the standard can be measured using an Emcee hand-held meter or other
suitable and industry-accepted standardization device. On the JFWIN screen
depress the “SCALE CALIBRATE” menu button, and enter the sample standard
value when requested. When the program cycle is complete the Scale Complete
Light will light and values reported should correspond to the standard sample
value entered in the program.
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9.0 SENSOR REMOVAL
See Installation and Safe Use Manual for detailed mechanical removal
instructions.
10.0 SPECIFICATIONS
The electrical parameters are factory calibrated to 1% of reading. However, due
to fuel measurement characteristics, the repeatability and reproducibility limits
are as follows:
Table 2
SENSOR SPECIFICATIONS
SENSORS:
Parameter
Range
Accuracy *
Resolution
Sensor Type
Calibration
Conductivity
0 – 500 pS/M
+/- 2 pS/M (+/2%) of Reading
0.1 pS/M
Coaxial
Electrode
Internal Zero &
Scale
Temperature
-5 – 50 C
+/- 0.5 C
0.1 C
Platinum RTD
NIST ITS-90
* This is at temperatures +/- 10° C of 20° C for the compensated output data
only.
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JF-1A Conductivity Sensor
Table 3
SYSTEM SPECIFICATIONS
SYSTEM:
ELEMENT
Flow Range
Environmental
Power 2-Wire Input
Power 4-Wire Input
Pressure
Certification Housing
Certification Sensor
Usage
ATEX Certification
FM Certification
UL Certification
SPECIFICATION
0 – 7.0 M/s Max
-10 to 60 C Operation
-40 to 80 C Storage
24 VDC Minimum
38 VDC Maximum
7 VDC Minimum
38 VDC Maximum
200 PSIA Maximum
FM, CSA, UL, CENELEC
ATEX
Class 2, Division 2
EExd [ia] IIC T4/5/6
11.0 SERIAL DATA INTERFACE
The D-2 JF-1A has a comprehensive serial interface. The instrument contains
no internal electrical adjustments. All instrument calibration constants and
configurations are stored in internal non-volatile memory. The unit also has
programmable output span range for the 4-20 mA output, allowing the user to
customize the unit to a specific application. The factory default range is for the
4 - 20 mA range to represent 0 - 500 pS/M conductivity range. The unit also has
programmable temperature compensation constants, for observing alternate
thermal compensation for the specific additive effect on the conductivity of the
treated fuel. Lastly, the user has the ability to set averaging of data that is
applied to both serial output data and to 4-20 mA data.
Note: D-2 Windows 98/NT compatible program JFWIN can be
provided. This program provides a complete PC interface to the D-2
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JF-1A Conductivity Sensor
JF-1A Conductivity Sensor, providing calibration, data collection, realtime display, and data logging for this sensor system. Consult the
factory.
11.1 RUN MODE
When powered the unit commences operation in the “RUN MODE.” The unit
sends the following sign on ASCII message at 9600 Baud, 8 Data Bits, No Parity
and 1 Stop bit:
(Note: Orator Text Used For All Instrument Outputs)
D-2 Incorporated
Fuel Cell JF1
1.6
COND, TEMP, COMP COND
(ps/m)
(C) (ps/m-C)
The last two lines are headers for the data output columns. To collect data the
user need only send an ASCII Carriage Return (Hex 0A) <CR> or ASCII Line
Feed (Hex OD) <LF>. The unit will respond with a single line of data:
13.0,
15.4,
23.8<CF><LF>
Where: 13.0 = Conductivity Measured
15.4 = Temperature of Fuel in Celsius
23.8 = Compensated Conductivity
11.2 CONTINUOUS DATA
To have the unit send data continuously without polling, the user can send the
“SC” Set Continuous Command. The unit will commence sending data at the
data rate and current averaging rate. If the averaging is set to 1 sample then
the data rate is approximately 2.0 hertz. If the averaging is set to 2 samples
then the 2 samples are averaged together and the data rate is 1 hertz. Boxcar
averaging is used, i.e., Data Average = 1/N New Data + N-1/N Old Data. To
stop continuous data the unit will only accept one command, which is the capital
“S” Stop Command followed by a carriage return or line feed.
Note: The Stop Command is the only case sensitive command!
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11.3 OPEN MODE
In OPEN MODE the unit stops collecting data and awaits user instructions such
as calibration constants, or averaging settings, etc. The OPEN MODE can be
attained by sending the “***O” command. The unit after entering open mode
will send “OPEN MODE” when polled using a carriage return or line feed. From
open mode the user can view all constants using the “RCAL” command. The
RCAL Command will return the following:
***O
Open Mode
RCAL
1314
ZERO=55.000000
FS=1900.000000
BT=67.759354
MT=-9.510620E-05
TREF=20.100000
MC=1.280000E-02
N=1.000000
W=30
NREF=1.000000
DAO=375
DAF=500.000000
In the Table Below the definition of each of these constants is given:
Table 4
OPERATIONAL CONSTANTS
Constant
1314
ZERO
FS
BT
MT
Definition
Unit Serial Number
The value assigned to the zero
reference reading, used to set
Y=MX+B for the conductivity
channel
The value assigned to the Full
Scale reference reading, used to
set Y=MX+B for the conductivity
channel
The
Temperature
Channel
Offset
Value
The
Temperature
Channel
Slope
Value
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TREF
MC
N
NREF
DAO
DAF
W
The
Temperature
Reference
for
Conductivity Compensation
The Temperature Coefficient of Jet
Fuel with Additive Per ASTM
The
Number
of
Samples
of
Conductivity Box Car Averaged See
Section 13.0
The number of Reference Channels
Averaged
The 4-20 mA output offset counts
to trim current to 4.0 mA at Zero
Conductivity
The 4-20 mA full Scale in pS/M for
an load current of 20 mA Total
Anti Spike Filter Maximum ScanScan Change in pS/M
Any constant can be read individually by entering the reference name followed
by a <CR>. Any constant can be set by entering the reference followed by an
equal’s sign and then the new value to be entered. All constants can be stored
in non-volatile memory using the ***E command. Note, cycling power after
changing constants and before storing them in non-volatile memory using the
***E command will result in the unit reverting to the original values stored.
To return to run mode, issue the ***R command or cycle power.
Current Loop Output Testing
The JF-1A, while in OPEN MODE, can temporarily output a current equal to a
given conductivity reading for system testing. To output a current equal to a
given conductivity, as example 250 pS/M, while in OPEN MODE issue the
command COND=250. This command will configure the output to draw current
equal to a reading of 250 pS/M, or on a 0 – 500 pS/M configured sensor 12
milliamps. Readings and output currents for various range configured units is
given in the table below. (Note, the JF-1A is normally configured for a 0 – 500
pS/M range equating to a 4 – 20 mA current range.)
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Conductivity
0
125
250
375
500
750
1000
1250
1500
1750
2000
0-500 pS/M *
CURRENT mA
4
8
12
16
20
-
0-1000 pS/M
CURRENT mA
4
6
8
10
12
16
20
-
0-2000 pS/M
CURRENT mA
4
5
6
7
8
10
12
14
16
18
20
11.4 CALIBRATION MODE
In CALIBRATION OPEN MODE the unit collects data and outputs all raw data
and processes measurements allowing the JFWIN Program to calculate
operational constants. To enter the CALIBRATION MODE the “***C” command
sent from the OPEN MODE (See Open Mode Above).
After entering
CALIBRATION MODE the unit will send the following frame of data when polled
using a carriage return or line feed. The SET CONTINUOUS “SC” command also
operates in Calibration Mode
***C
-9433, 639606, -8351, 491805, 2.2, 21.0, 2.1
Where:
-9433 = Counts Electronic Zero Reference
639606 = Counts Electronic Full Scale Reference
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-8351 = Counts Conductivity Circuit Reference
491805 = Counts Temperature Circuit
2.2
= Calculated Conductivity pS/M
21.0 = Calculated Temperature Celsius
2.1 = Calculated Compensated Conductivity pS/M
(Note that the numbers above are examples only; actual values obtained will
vary)
12.0 CALIBRATION
If either AIR Reading of ZERO larger than +/- 2pS/M is observed or the user
suspects that the unit is not reading correctly the following steps should be
completed.
12.1 SENSOR REMOVAL
To remove the probe from the fuel load line, please refer to section 9.0.
12.2 POWER SENSOR
Using D-2 Test Cable P/N A440-043 Connect the sensor to a suitable power
supply, and the serial connector to COM 1 of the PC. Load and run the D-2
program JFWIN.
12.2 CLEAN SENSOR
Clean the sensor in “Clean” Isopropyl Alcohol and blow dry using “dry”
compressed air. Note that this step should be repeated until all signs of fuel
residual have been removed from the sensor.
Note: Isopropyl Alcohol is highly conductive and any residual traces
inside the sensor between the two electrodes will overage the
instrument. To flush the Isopropyl Alcohol a reagent grade toluene can
be used as an after rinse and allowed to air dry. Note that if the
Isopropyl Alcohol is well blown off with dry compressed air no
residuals will be left, eliminating the need to use the more exotic
Toluene.
When JFWIN is reporting low values (less than 5 pS/M), the user can be
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satisfied that the sensor is clean. When ready to zero, press the “Zero
Calibration” data button in the JFWIN Menu. The program will report data
being taken and completion when done. Readings on the screen should report
less than 2 pS/M and be stable. The Green Zero OK Light will light when
complete.
12.3
SET SENSOR SCALE
Place the sensor in a fuel with additive that is near the full-scale range of
interest. We suggest a value “higher” than the range over which the sensor is
going to be operated. For example, if the user intends to measure conductivity
in the 0 – 500 pS/M range a good value to calibrate the sensor with is 750 –
1000 pS/M. This reduces uncertainty over the range of interest. The value of
the standard can be measured using an Emcee hand-held meter or other
suitable and industry-accepted standardization device. On the JFWIN screen
depress the “SCALE CALIBRATE” menu button, and enter the sample standard
value when requested. When the program cycle is complete the “Scale
Complete Light” will light and values reported should correspond to the standard
sample value entered in the program.
13.0 COMPENSATED OUTPUT
The D-2 JF-1A Conductivity Sensor outputs conductivity compensated for
temperature differences in the fuel from the temperature at which the sensor
was physically calibrated. The compensation is based on a numerical algorithm:
Ci = 10^ (MC* (TREF - t) + Log (C)
Where:
Ci = Compensated Conductivity Reading
C = Measured Conductivity Reading
MC = Compensation Constant (Nominally 0.028 for fuels treated with Stadis
450)
TREF = Reference Temperature (the temperature at which the sensor was
initially calibrated)
T = Measured Temperature
Log = Log Base 10
This formula is based on the ASTM D 2624, Appendix X2 Standard See also
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NRC-22648 The Relationship Between Electrical Conductivity and Temperature
of AVIATION Turbine Fuels Containing Static Dissipater Additives”
Table 5 gives the change in conductivity as a function of temperature for several
values of initial conductivity at 22 C.
Table 5
Conductivity (pS/M) as a Function of Temperature (Aviation Fuel Treated with
Stadis 450)
Conductivity
50
150
250
350
450
Temperature
-2
2
6
10
14
18
22
26
30
34
38
42
46
50
25
28
31
35
39
44
50
56
63
71
80
90
101
114
74
83
94
105
118
133
150
169
190
214
240
270
304
342
123
139
156
176
197
222
250
281
316
356
401
451
507
571
173
194
218
246
276
311
350
394
443
499
561
631
710
799
222
250
281
316
355
400
450
506
570
641
721
811
913
1027
The D-2 JF-1A Current Output is base on Compensated Conductivity. To
prevent compensation the user must set “MC” to zero (See Serial Command
Section of this manual).
14.0 FILTERED OUTPUT
Boxcar (low pass filter) Average:
The D-2 JF-1A Conductivity Sensor has a user specified filtered output. The
output is box car averaged. The number of box cars can be set from 1 (no
filtering) to 10 (maximum filtering). The box car filter has the numerical
equivalent of a low pass filter. Mathematically the form is:
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JF-1A Conductivity Sensor
Filtered Output = 1/n * new reading + n-1/n * old reading
In the table below 63% and 90% response times are given for each box card
setting. See Section 10.0 for setting the box car number constant n.
Box Car Average N
1
2
3*
4
5
6
7
8
9
10
•
63% Response
Seconds
1
3
6
7
9
11
13
15
17
19
90% Response Seconds
1
7
11
17
21
26
30
36
40
44
N= 3 is Factory Default
Window (Data De-Spike filter):
Window Filter “W”. This Window filter can be used with or without N set.
Essentially the window filter limits the rate at which the JF-1A sensor output can
change from scan to scan. W has units pS/cm/scan, and can be set from 0 –
999. W is an effective tool to reduce data output spikes in installations where
sudden physical changes of the system may cause data spikes. In essence if
the raw conductivity value changes greater more than the current setting of W,
the output change is limited to W. If N is also set then the output change is
limited to W * 1/N.
The mathematical formula for Window Filter has the form:
Test = Raw old – Raw new
If Test > W then Limit Change to W
De-spiked Output = 1/n * W + n-1/n * old reading
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JF-1A Conductivity Sensor
15.0 MAINTENANCE
NOTE: There are no user-serviceable components inside the D-2 JF-1A
Conductivity Sensor. There are NO Electronic adjustments inside the
sensor.
15.1 Calibration Interval
The D-2 JF-1A Conductivity sensor should be calibrated annually. The sensor
can be returned to the factory or the procedures found in the calibration section
of this manual performed. The instrument has no internal electrical adjustments
that need to be maintained.
15.2 Cleaning
The JF-1A Conductivity Sensor should be cleaned every 6 months of use. Fuel
additives or particulate may build up on the sensor, degrading its performance.
The sensor can be cleaned using the same procedure found for checking the
instrument Zero in the previous sections.
15.3 Sensor
The main electronics housing is sealed to the environment. The housing is
purged prior to sealing with dry nitrogen after drying. This ensures that
moisture or condensation do not develop inside the electronics compartment
that would degrade the ability of the sensor to measure the very low
conductivities typical of aviation fuels. If the housing is opened the unit must
be returned to the factory for re-calibration.
15.4 ZERO TESTS
The best indicator of static operation of the sensor is the reading of the sensor
(after appropriate cleaning) in dry air (note excessively humid air may result in
higher zero readings). With the sensor cleaned and dry, zero readings should
be stable and less than 5 pS/M when read from the serial data port. If the
current loop is being monitored zero current should read less than 4.25 mA. If
readings are in excess of these values or unstable readings occur, the unit
should be returned to the factory for servicing and possible re-calibration.
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JF-1A Conductivity Sensor
16.0 Optional 2 Wire Temperature Interface
The connection details are shown in figure 8. The optional 2-wire temperature
interface is connected to JP2 Terminals. These are “snap” out Molex screw
terminals which can be removed to assist in wiring. Cabling used should be in
compliance with the JF-1A Ex examination certificate. The 2 wire temperature
interface is “polarity insensitive”. The loop is not powered; power must be
supplied by the user.
Figure 8
OPTIONAL TEMPERATURE LOOP
ELECTRICAL CONNECTION DETAIL
1 2 3 4
3
2
1
3
2
1
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JF-1A Conductivity Sensor
16.1 2-Wire 4-20mA LOOP CONSIDERATIONS
Warning 2-Wire Loop Maximum Resistance including wire can not
exceed 500 ohms, or internal intrinsic over voltage safety devices in
the JF-1A sensor may be activated.
The maximum loop power supply voltage, under all conditions, must also
prevent the voltage across the sensor loop terminals from exceeding the
maximum voltage listed in the specifications section of the manual.
D-2 recommends that a 24 VDC isolated supply be used to power the
instrumentation loop. The supply should have high isolation (>500 Mohm), and
be single point grounded. The current loop should be wired using shielded
twisted pair wire. The shield should also be single point grounded to a solid
earth ground.
NOTE: Sensor wiring should be performed as defined by the National
Electric Code (NEC), and ATEX sensor certificate.
14.2 4 – 20 mA Temperature Readings
The following table details current output readings for the JF-1A sensor with a
nominal -10 to 60 Celsius range representing 4 – 20 mA. (Please consult the
factory for alternate range settings of the current output):
Temperature (C)
-10.0
0.0
10.0
20.0
30.0
40.0
50.0
60.0
•
Current (mA)
4.0
6.3
8.6
10.8
13.1
15.4
17.7
20.0
Voltage * (Volts)
1.00
1.57
2.14
2.71
3.28
3.85
4.42
5.00
250 Ohm Voltage Sensing Resistor Used
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JF-1A Conductivity Sensor
APPENDIX A:
LIMITED WARRANTY
One year from date of shipment, D-2 Incorporated, guarantees its products to
be free of defects in materials and workmanship. In the event a product
malfunctions during this period, the company obligation is limited to repair of
the defective item at our factory, or the defective item may be replaced at our
option. Instruments found defective should be returned to the factory prepaid
and carefully packed, as customer will be responsible for freight damage. D-2
will pay return shipping on any warranty repairs.
Repairs or replacements under warranty will be at no cost to the customer for
parts, labor, or return shipment from our factory to the customer. This
warranty is void if in our opinion the instrument has been damaged by accident,
mishandled, altered or repaired by the customer where such treatment has
affected its performance or reliability. In the event of such abuse by the
customer, all costs for repairs plus freight costs will be borne by the customer.
All equipment supplied by D-2 that is designed for use under hydrostatic loading
has been certified by actual pressure testing prior to shipment.
The customer will be charged a diagnostic fee plus all shipping costs if an
instrument is returned for warranty repair and no defect is found by the factory.
Incidental or consequential damages or costs incurred as a result of product
malfunction are not the responsibility of D-2 Incorporated.
Equipment not manufactured by D-2 Incorporated, is supported only to the
extent of the original manufacturer’s original warranties. All OEM sensors which
utilize electrodes (oxygen cartridges, pH, ORP, etc.) is warranted at the time of
shipment, and shall perform upon initial installation within stated specifications.
If the product proves to be defective within the OEM’s warranty we will replace
the product or defective part with a similar model, product or part, but only to
the extent that the OEM will warrant.
All returned products must be accompanied by a Returned Material
Authorization (RMA) number issued by D-2 Incorporated. Shipments will not be
accepted without the RMA number. An RMA number can be obtained by calling
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JF-1A Conductivity Sensor
Customer Service Department at 508-329-2046 or by emailing Mail@D2inc.com.
The following information should accompany any instrument being returned to
the factory:
Return Authorization Number
Model/Serial Number
Brief Description of the Problem
Customer Contact/Telephone Number
CALIBRATION SERVICE POLICY
A calibration only service is available for JF-1A Conductivity Sensors.
The service is limited to instruments requiring only calibration and minor
adjustment. Instruments that are not operating properly and require repair or
replacement parts will not be covered. If repair is necessary the customer will
be contacted and apprised of the additional cost. The customer will be charged
the standard repair cost, which includes repair and calibration. In the event
that the customer does not approve repair, the unit will be returned in "as
received" condition and the teardown and inspection charge will be invoked.
The customer will be required to obtain a return authorization number from
Customer Service at D-2 Incorporated prior to the return of the instrument.
This number should be displayed on the outside of the container, preferably on
the shipping label, and included on the shipping documentation sent with the
instrument.
If possible, the following information should accompany the instrument:
Return Authorization Number
Model/Serial Number
Customer Contact/Telephone Number
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