Bacharach MGS SERIES Specifications

Infrared Gas Detector
Installation and Operation Manual
Instruction 6490-9000
February 2014
Revision 1
Product Leadership • Training • Service • Reliability
MGS-250 Manual
WARRANTY POLICY
BACHARACH, INC. WARRANTS THIS GAS DETECTOR TO BE FREE FROM DEFECTS
IN MATERIALS AND WORKMANSHIP FOR A PERIOD OF ONE YEAR FROM THE DATE
OF PURCHASE BY THE ORIGINAL OWNER. IF THE PRODUCT SHOULD BECOME
DEFECTIVE WITHIN THIS WARRANTY PERIOD, WE WILL REPAIR OR REPLACE IT AT
OUR DISCRETION.
THE WARRANTY STATUS MAY BE AFFECTED IF THE GAS DETECTOR HAS NOT
BEEN USED AND MAINTAINED PER THE INSTRUCTIONS IN THIS MANUAL OR HAS
BEEN ABUSED, DAMAGED, OR MODIFIED IN ANY WAY. THIS GAS DETECTOR IS
ONLY TO BE USED FOR PURPOSES STATED HEREIN. THE MANUFACTURER IS NOT
LIABLE FOR AUXILIARY INTERFACED EQUIPMENT OR CONSEQUENTIAL DAMAGE.
DUE TO ONGOING RESEARCH, DEVELOPMENT, AND PRODUCT TESTING, THE
MANUFACTURER RESERVES THE RIGHT TO CHANGE SPECIFICATIONS WITHOUT
NOTICE. THE INFORMATION CONTAINED HEREIN IS BASED ON DATA CONSIDERED
ACCURATE. HOWEVER, NO WARRANTY IS EXPRESSED OR IMPLIED REGARDING
THE ACCURACY OF THIS DATA.
ALL GOODS MUST BE SHIPPED TO THE MANUFACTURER BY PREPAID FREIGHT.
ALL RETURNED GOODS MUST BE PRE-AUTHORIZED BY OBTAINING A RETURN
MERCHANDISE AUTHORIZATION (RMA) NUMBER. CONTACT THE MANUFACTURER
FOR A NUMBER AND PROCEDURES REQUIRED FOR PRODUCT TRANSPORT.
SERVICE POLICY
BACHARACH, INC. AND MURCO MAINTAIN SERVICE FACILITY AT THEIR
RESPECTIVE FACTORIES. SOME DISTRIBUTORS / AGENTS MAY ALSO HAVE
REPAIR FACILITIES, HOWEVER, BACHARACH AND MURCO ASSUME NO
LIABILITY FOR SERVICE PERFORMED BY ANYONE OTHER THAN BACHARACH
OR MURCO PERSONNEL. REPAIRS ARE WARRANTED FOR 90 DAYS AFTER
DATE OF SHIPMENT (SENSORS, PUMPS, FILTERS AND BATTERIES HAVE
INDIVIDUAL WARRANTIES). SHOULD YOUR GAS DETECTOR REQUIRE NONWARRANTY REPAIR, YOU MAY CONTACT THE DISTRIBUTOR FROM WHOM IT
WAS PURCHASED OR YOU MAY CONTACT BACHARACH OR MURCO
DIRECTLY.
IF BACHARACH OR MURCO IS TO DO THE REPAIR WORK, SEND THE GAS
DETECTOR, PREPAID, TO THE APPROPRIATE ADDRESS BELOW.
BACHARACH, INC.
621 HUNT VALLEY CIRCLE
NEW KENSINGTON, PA 15068
ATTENTION: SERVICE DEPT
MURCO - A BACHARACH COMPANY
114A GEORGES STREET LOWER
DUN LAOGHAIRE
CO DUBLIN IRELAND
ALWAYS INCLUDE YOUR RMA #, ADDRESS, TELEPHONE NUMBER, CONTACT
NAME, SHIPPING/BILLING INFORMATION AND A DESCRIPTION OF THE
DEFECT AS YOU PERCEIVE IT. YOU WILL BE CONTACTED WITH A COST
ESTIMATE FOR EXPECTED REPAIRS PRIOR TO THE PERFORMANCE OF ANY
SERVICE WORK. FOR LIABILITY REASONS, BACHARACH AND MURCO HAVE A
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POLICY OF PERFORMING ALL NEEDED REPAIRS TO RESTORE THE GAS
DETECTOR TO FULL OPERATING CONDITION.
PRIOR TO SHIPPING EQUIPMENT TO BACHARACH OR MURCO, CONTACT OUR
OFFICE FOR AN RMA # (RETURN MERCHANDISE AUTHORIZATION). ALL
RETURNED GOODS MUST BE ACCOMPANIED BY AN RMA NUMBER.
PACK THE EQUIPMENT WELL (IN ITS ORIGINAL PACKING IF POSSIBLE), AS
BACHARACH CANNOT BE HELD RESPONSIBLE FOR ANY DAMAGE INCURRED
DURING SHIPPING TO OUR FACILITY.
NOTICES
COPYRIGHTS: THIS MANUAL IS SUBJECT TO COPYRIGHT PROTECTION; ALL
RIGHTS ARE RESERVED UNDER INTERNATIONAL AND DOMESTIC
COPYRIGHT LAWS. THIS MANUAL MAY NOT BE COPIED OR TRANSLATED, IN
WHOLE OR IN PART, IN ANY MANNER OR FORMAT, WITHOUT THE WRITTEN
PERMISSION OF BACHARACH, INC.
ALL SOFTWARE WHICH BACHARACH UTILIZES AND/OR DISTRIBUTES, HOLDS
A PROPRIETARY INTEREST AND IS ALSO SUBJECT TO COPYRIGHT
PROTECTION AND ALL RIGHTS ARE RESERVED. NO PARTY MAY USE OR
COPY SUCH SOFTWARE IN ANY MANNER OR FORMAT, EXCEPT TO THE
EXTENT THAT BACHARACH GRANTS THEM A LICENSE TO DO SO. IF THIS
SOFTWARE IS BEING LOADED ONTO MORE THAN ONE COMPUTER, EXTRA
SOFTWARE LICENSES MUST BE PURCHASED.
TECHNICIAN USE ONLY
THIS UNIT MUST BE INSTALLED BY A QUALIFIED TECHNICIAN WHO WILL
INSTALL THIS UNIT IN ACCORDANCE WITH THESE INSTRUCTIONS AND THE
STANDARDS IN THEIR PARTICULAR INDUSTRY/COUNTRY. OPERATORS OF
THE UNIT SHOULD BE AWARE OF THE REGULATIONS AND STANDARDS IN
THEIR INDUSTRY/COUNTRY FOR THE OPERATION OF THIS UNIT. THESE
NOTES ARE ONLY INTENDED AS A GUIDE, AND THE MANUFACTURER BEARS
NO RESPONSIBILITY FOR THE INSTALLATION OR OPERATION OF THIS UNIT.
FAILURE TO INSTALL AND OPERATE THE UNIT IN ACCORDANCE WITH THESE
INSTRUCTIONS AND WITH INDUSTRY GUIDELINES MAY CAUSE SERIOUS
INJURY INCLUDING DEATH, AND THE MANUFACTURER WILL NOT BE HELD
RESPONSIBLE IN THIS REGARD.
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Table of Contents
SECTION 1.
INTRODUCTION ........................................................................ 9
1.1. Overview ...................................................................................................... 9
1.2. Detection Options ...................................................................................... 10
1.2.1. Broadband vs. Gas Specific .............................................................. 10
1.2.2. Broadband Gas Detection ................................................................ 10
1.2.3. Detecting Specific Gases .................................................................. 11
1.3. Remote Controller Options ........................................................................ 15
1.4. Parts List ..................................................................................................... 15
1.5. Specifications ............................................................................................. 16
SECTION 2.
MOUNTING THE GAS DETECTOR ............................................. 17
2.1. Warnings and Prerequisites ....................................................................... 17
2.2. Mounting Locations ................................................................................... 17
2.2.1. General Placement Guidelines ......................................................... 17
2.2.2. Machinery Rooms ............................................................................ 18
2.2.3. Refrigerated Spaces ......................................................................... 18
2.2.4. Chillers ............................................................................................. 19
2.3. Mounting Procedure .................................................................................. 19
SECTION 3.
3.1.
3.2.
3.3.
3.4.
3.5.
3.6.
Overview .................................................................................................... 22
Wiring Supply Power (24VAC or 24VDC) .................................................... 23
Wiring Alarm Output (Analog Signal) ......................................................... 25
Wiring the Digital Alarm Output Relay....................................................... 26
Modbus Network Configuration ................................................................ 27
Conclusion .................................................................................................. 29
SECTION 4.
4.1.
4.2.
4.3.
4.4.
4.5.
WIRING AND CONFIGURATION ............................................... 22
OPERATION AND STABILIZATION ............................................ 30
Power Up and Warmup.............................................................................. 30
Stabilization ................................................................................................ 30
Perform a Manual Zero .............................................................................. 30
Alarms ........................................................................................................ 31
Gas Detector Faults .................................................................................... 31
4.5.1. Overview .......................................................................................... 31
4.5.2. Non-Critical Faults ............................................................................ 31
4.5.3. Critical Faults .................................................................................... 32
SECTION 5.
CONFIGURE THE GAS DETECTOR ............................................. 33
5.1. User Interface Overview ............................................................................ 33
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5.2. Setting Parameters..................................................................................... 34
5.2.1. Overview .......................................................................................... 34
5.2.2. Configuration Parameters ................................................................ 34
5.3. Completing Setup ....................................................................................... 42
SECTION 6.
6.1.
6.2.
6.3.
6.4.
Introduction ............................................................................................... 43
Bump Testing vs. Adjusting Detector Response......................................... 44
Bump Testing ............................................................................................. 45
Adjustment Using Calibration Gas ............................................................. 46
SECTION 7.
7.1.
7.2.
7.3.
7.4.
7.5.
7.6.
MODBUS COMMUNICATIONS ................................................ 49
Introduction ............................................................................................... 49
Communications Settings .......................................................................... 49
Analog Input Registers ............................................................................... 50
Analog Output Registers ............................................................................ 51
Input Status Flags ....................................................................................... 52
Output Status Flags .................................................................................... 52
SECTION 8.
8.1.
8.2.
8.3.
8.4.
FUNCTIONAL TESTS AND ADJUSTMENTS ................................ 43
TROUBLESHOOTING ............................................................... 53
Fault Codes ................................................................................................. 53
Diagnostics Attributes (P.-18) .................................................................... 55
Resetting MGS-250 to Default Values ........................................................ 56
Other Symptoms ........................................................................................ 57
SECTION 9. REPLACEMENT PARTS AND ACCESSORIES ................................... 58
CE DECLARATION OF CONFORMITY ............................................................... 59
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List of Figures
SECTION 1.
Figure 1.
Figure 2.
Figure 3.
Figure 4.
INTRODUCTION ........................................................................ 9
MGS-250 Components ......................................................................... 9
Broadband Gas Groups 1-3 ................................................................ 11
Gas Specific MGS-250 Gas Detectors ................................................. 12
Changing Gas Types and Accuracy ..................................................... 14
SECTION 2.
MOUNTING THE GAS DETECTOR ............................................. 17
Figure 5. Initial Housing Separation .................................................................. 20
Figure 6. Front and Back Views of MGS-250 Base ............................................ 21
SECTION 3.
WIRING AND CONFIGURATION ............................................... 22
Figure 7. Terminal Blocks and Cable Glands ..................................................... 22
Figure 8. Supply Power Wiring Options ............................................................ 23
Figure 9. Maintaining Neutral Polarity .............................................................. 24
Figure 10. Analog Output Wiring ...................................................................... 25
Figure 11. Sample Relay Output Wiring ............................................................ 26
Figure 12. Modbus Network Wiring .................................................................. 27
Figure 13. Setting Network Termination Resistors ........................................... 29
SECTION 5.
CONFIGURE THE GAS DETECTOR ............................................. 33
Figure 14. The User Interface of the MGS-250 ................................................. 33
Figure 15. Analog Output Scaling Options ........................................................ 39
SECTION 6.
FUNCTIONAL TESTS AND ADJUSTMENTS ................................ 43
Figure 16. Using Calibration Gas ....................................................................... 46
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List of Tables
SECTION 1.
INTRODUCTION ........................................................................ 9
Table 1: Broadband Gas Groups and Performance (P/N 6401-0500) ................ 10
Table 2: Gas Specific Detector Measurement Performance .............................. 13
Table 3: Parts List ............................................................................................... 15
Table 4: Technical Specifications ....................................................................... 16
SECTION 3.
WIRING AND CONFIGURATION ............................................... 22
Table 5: Power Options and Terminal Block Connections ................................. 23
Table 6: Alarm Output Terminal Block Connections .......................................... 25
Table 7: Relay Output Terminal Block Connections ........................................... 26
Table 8: Modbus Network Communications Connections ................................ 27
SECTION 4.
OPERATION AND STABILIZATION ............................................ 30
Table 9: MGS-250 Behavior during Alarm Conditions ....................................... 31
Table 10: MGS-250 Behavior during a Non-Critical Fault .................................. 32
Table 11: MGS-250 Behavior during a Critical Fault .......................................... 32
SECTION 5.
CONFIGURE THE GAS DETECTOR ............................................. 33
Table 12: Button Functions ................................................................................ 33
Table 13: Parameter Numbers, Names and Descriptions .................................. 34
SECTION 7.
MODBUS COMMUNICATIONS ................................................ 49
Table 14: Analog Input Registers ....................................................................... 50
Table 15: Analog Output Registers .................................................................... 51
Table 16: Input Status Flags ............................................................................... 52
Table 17: Output Status Flags ............................................................................ 52
SECTION 8.
TROUBLESHOOTING ............................................................... 53
Table 18: Fault Codes ......................................................................................... 54
Table 19: Diagnostic Attributes.......................................................................... 55
Table 20: Other Symptoms and Possible Causes ............................................... 57
SECTION 9. REPLACEMENT PARTS AND ACCESSORIES ................................... 58
Table 21: Replacement Parts and Accessories ................................................... 58
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Section 1.
Introduction
1.1. Overview
The MGS-250 NDIR (non-dispersive infrared) is a state-of-the-art fixed
gas detector which can detect a wide range of refrigerant gases. The
MGS-250 can be used on a stand-alone basis or integrated into controls
or a Building Management System (BMS).
The MGS-250 can be used in locations that require continuous
monitoring and to add gas detection solutions to an existing system.
Figure 1. MGS-250 Components
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1.2. Detection Options
1.2.1. Broadband vs. Gas Specific
The MGS-250 NDIR refrigerant gas detectors are available in two
versions: broadband and gas specific.
1.2.2. Broadband Gas Detection
The broadband gas detector (P/N 6401-0500) is used as a general
purpose gross leak detector and is factory tested and certified. It is
shipped from the factory with accuracy as shown in Table 1 (gas
dependent). If more accurate detection is needed, gas specific versions
are available, which are factory certified and calibrated to the target
refrigerant.
The broadband gas detector combines refrigerants into three groups
shown in Figure 2. Measurement performance is based on an average
response profile for all of the gases within the group.
NOTE: Greater accuracy may be achieved through the use of
calibration gas and the adjustment procedure detailed in
Section 6.
Table 1: Broadband Gas Groups and Performance (P/N 6401-0500)
Group #
1
1
10
Value for Param 11
P.-11 = 1
2
P.-11 = 2
3
P.-11 = 3
1
Refrigerant
As Shipped Accuracy
R123
R134a
R404a
R407a
R407c
±30 ppm ±35%
±30 ppm ±25%
±30 ppm ±35%
±30 ppm ±25%
R407f
R410a
R427a
R507
R422a
R422d
HFO1234YF
HFO1234Ze
R22
±30 ppm ±20%
±30 ppm ±20%
±30 ppm ±20%
±30 ppm ±15%
±30 ppm ±35%
±30 ppm ±25%
±30 ppm ±20%
±30 ppm ±25%
±30 ppm ±25%
±30 ppm ±25%
See Section 5 for information on Parameter 11 and other configuration instructions.
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Figure 2. Broadband Gas Groups 1-3
1.2.3. Detecting Specific Gases
Each gas-specific gas detector (PNs 6401-0501 to 6401-0514) is
shipped factory calibrated to its specific target refrigerant. Refer to
Figure 3 and Table 2.
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Figure 3. Gas Specific MGS-250 Gas Detectors
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Table 2: Gas Specific Detector Measurement Performance
1
1
Part Number
Refrigerant
6401-0501
6401-0502
6401-0503
6401-0504
6401-0505
6401-0506
6401-0507
6401-0508
6401-0509
6401-0510
6401-0511
6401-0512
6401-0513
6401-0514
R22
R123
R134a
R404a
R407a
R407c
R407f
R410a
R422a
R422d
R427a
R507
HFO1234YF
HFO1234Ze
Accuracy
±30 ppm ±5%
±30 ppm ±5%
±30 ppm ±5%
±30 ppm ±5%
±30 ppm ±3%
±30 ppm ±3%
±30 ppm ±3%
±30 ppm ±3%
±30 ppm ±5%
±30 ppm ±5%
±30 ppm ±3%
±30 ppm ±5%
±30 ppm ±5%
±30 ppm ±5%
See Section 5 for information on Parameter 11 and other configuration instructions.
NOTE: Gas specific detectors can be re-calibrated in the field
to new target gases. Use optional calibration instructions in
Chapter 6 for increased accuracy when detecting a new target
gas that is different from the “as shipped” target gas. Refer to
the example in Figure 4.
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Optional Recalibration
(For Improved Accuracy)
Changed Gas Type
(Reduced Accuracy)
As Shipped
MGS-250 Manual
Part number 6401-0501 (R22) is factory calibrated to R22 and
has an as-shipped R22 response accuracy of ±30 ppm ±5% of
reading.
The gas detector may be changed to respond to any of the
other listed refrigerants (see parameter P.-11, in section 5.2). If
changed, the gas detector will have a lower accuracy for the
target refrigerant (without calibration). In this example, that
accuracy is ±30 ppm ±16% of reading.
By applying calibration gas containing the new target
refrigerant, and via the routine described in Section 6.4, the gas
detector may then be adjusted to respond with the calibrated
accuracy of ±30 ppm ±5% of reading as shown in Table 2 for
the new target refrigerant.
Figure 4. Changing Gas Types and Accuracy
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1.3. Remote Controller Options
The MGS can connect to any controller through the standard analog
output (voltage and current; see Table 4 for options), the standard alarm
relay, or the digital Modbus RTU communications interface.
1.4. Parts List
Table 3 shows a list of components that are shipped with your order.
Table 3: Parts List
Various (Depends on Model Ordered)
Part Number
Description
6401-0500
MGS-250, Broadband
6401-0501
MGS-250, R22
6401-0502
MGS-250, R123
6401-0503
MGS-250, R134a
6401-0504
MGS-250, R404a
6401-0505
MGS-250, R407a
6401-0506
MGS-250, R407c
6401-0507
MGS-250, R407f
6401-0508
MGS-250, R410a
6401-0509
MGS-250, R422a
6401-0510
MGS-250, R422d
6401-0511
MGS-250, R427a
6401-0512
MGS-250, R507
6401-0513
MGS-250, HFO1234YF
6401-0514
MGS-250, HFO1234ZE
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MGS-250 Manual
1.5. Specifications
Table 4: Technical Specifications
Specification
Description
Power Supply
24 VDC, 24 VAC 50/60 Hz, 2.5 W max
Power Monitoring
Green LED
Visual Alarm
Red 4-digit LED display
Audible Alarm
Buzzer (audible alarm), enable/disable
Fault Monitoring
Fault codes presented to user
Analog Outputs
4-20 mA; 0-5 V; 0-10 V; 1-5 V; 2-10 V
Relay
1 relay rated 1 A @ 24 VAC/VDC (0.5A, 125V AC
UL rating)
Range
Squelch
0-3500 ppm
1
Readings below 75 ppm are squelched by default
Communication:
Modbus RTU over
RS-485
Baud rate:
Start bits:
Data bits:
Parity:
Stop bits:
Retry time:
End of msg:
Alarm Delay
Selectable; 0 to 15 minutes
IP Rating
Not IP rated. An accessory splash shield is
available for areas requiring additional protection
from wash down.
Response Time, T90
< 5 minutes
Temperature Rating
-22° to 104° F (-30° to 40° C)
Humidity and Elevation
5-90% relative humidity, non-condensing,
0-10,000 ft. altitude
Standard Dimensions
and Weights
4.0” x 5.5” x 1.5”
102 x 140 x 37 mm
Approvals
CE, UL/CSA/IEC/EN 61010-1
9,600 or 19,200 (selectable)
1
8
None, odd, even (programmable)
1 or 2, programmable
500 ms (min time between retries)
Silent 3.5 characters
6.3 oz
180 g
1 When filtering is disabled (see parameter P.-19 on page 42), the unit will respond to
concentrations sub-10 ppm.
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Section 2.
Mounting the Gas Detector
2.1. Warnings and Prerequisites
WARNING: Explosion hazard! Do not mount the MGS-250 in
an area that may contain flammable liquids, vapors, or
aerosols. Operation of any electrical equipment in such an
environment constitutes a safety hazard.
CAUTION: The MGS-250 contains sensitive electronic
components that can be easily damaged. Do not touch or
disturb any of these components.
NOTE: The mounting location of the monitor should allow it to
be easily accessible for visual monitoring and servicing.
NOTE: The monitor must be connected to a marked, suitably
located and easily reached switch or circuit-breaker as means
of disconnection.
NOTE: Connect monitor power and signaling terminals using
wiring that complies with local electrical codes or regulations for
the intended application.
CAUTION: Do NOT mount the MGS-250 directly to vibrating
machinery as the vibrations may degrade the gas detector’s
performance.
2.2. Mounting Locations
2.2.1. General Placement Guidelines
NOTE: The MGS-250 should be installed plumb and level
and securely fastened to a rigid mounting surface.
NOTE: When installed in areas that may be subjected to
water spray, the optional splash guard (P/N: 6900-0001)
should be used in conjunction with the MGS-250.
Gas detectors must be located within the appropriate wire lengths from
the central control unit (if used).
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2.2.2. Machinery Rooms
There is no absolute rule in determining the number of gas detectors and
their locations. However, a number of simple guidelines will help to make
a decision. Gas detectors monitor a point as opposed to an area. If the
gas leak does not reach the detector then no alarm will be triggered.
Therefore, it is extremely important to carefully select the gas detector
location. Also consider ease of access for maintenance.
The size and nature of the site will help to decide which method is the
most appropriate to use. Locations requiring the most protection in a
machinery or plant room would be around compressors, pressurized
storage vessels, refrigerant cylinders or storage rooms or pipelines. The
most common leak sources are valves, gauges, flanges, joints (brazed or
mechanical), filling or draining connections, etc.
•
•
In machinery rooms where there is little or no airflow, placement
options are:
o Point Detection, where gas detectors are located as near as
possible to the most likely sources of leakage, such as the
compressor, expansion valves, mechanical joints or cable duct
trenches.
o Perimeter Detection, where gas detectors completely surround
the area or equipment.
Halocarbon and hydrocarbon refrigerants are heavier-than-air
gases and as such the gas detectors should be located near ground
level (6 to 18 inches from the floor).
NOTE: Gas detectors should be positioned just far enough
back from any high-pressure parts to allow gas clouds to form
and be detected. Otherwise, a gas leak might pass by in a highspeed jet and not be detected by the gas detector.
•
•
•
Make sure that pits, stairwells and trenches are monitored
since they may fill with stagnant pockets of gas.
For racks or chillers pre-fitted with refrigerant gas detectors,
these should be mounted so as to monitor the compressors.
Do not mount the gas detector directly to pipes or structures
that are subject to strong vibration.
2.2.3. Refrigerated Spaces
In refrigerated spaces, gas detectors should be located away from doors,
in the return airflow to the evaporators on a sidewall (below head-high is
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preferred), or on the ceiling, not directly in front of an evaporator, nor in
any direct airflow. In large rooms with multiple evaporators, gas detectors
should be mounted on the central line between 2 adjacent evaporators,
as turbulence will result in airflows mixing.
2.2.4. Chillers
In the case of small water- or air-cooled enclosed chiller units mount the
gas detector so as to monitor airflow to the extract fans. With larger
models also place a gas detector inside the enclosure under or adjacent
to the compressors.
For enclosed air-cooled chillers or the outdoor unit for
variable refrigerant volume and variable refrigerant flow (VRV/VRF)
systems, mount the gas detector so as to monitor airflow to the extract
fan. With large units also place a gas detector inside the enclosure
under or adjacent to the compressors.
2.3. Mounting Procedure
To open the housing as received use a flat blade screwdriver and
depress the top latch. While pushing the latch grasp the back edge of the
housing near the latch and pull the back away.
When mounted, the housing is simply opened by pressing the top latch
with a suitable screwdriver or other flat blade. With the top latch
depressed pull the housing apart by grasping the sides and pulling
straight out. With the housing separated the mounting base with terminal
blocks will be visible. See Figure 5.
IMPORTANT: Do not apply caulking or other material around
the gas detector base. The gas detector relies on air
exchange through the spaces between the base and the gas
detector housing. Do not obstruct the small gap around the
housing and the base with any material.
Step
Mounting Procedure
1
Open the housing (see Figure 5).
2
Position the base to the pre-determined (acceptable) mounting
location. Use the gas detector base to mark the mounting
locations as needed. The hole pattern on the back plate is
sized to mount the gas detector onto various electrical junction
boxes. The other holes may be used as needed to mount the
gas detector to other structures, or onto a wall.
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Step
Mounting Procedure
3
Wall Mount
Attach the MGS-250 base to
the mounting surface using
two #6 screws (provided)
through two of the 7 mounting
holes, being careful not to
over-tighten the screws.
Refer to Figure 6 for the
locations of mounting holes on
the base.
4
Unless you are ready to wire the device (see section 3),
carefully snap the cover onto the base unit.
Junction Box Mount
Attach the MGS-250 base to
the junction box (using
mounting hardware provided
with your junction box)
through the two junction box
holes. Refer to Figure 6 for
the locations of the two
junction box mounting holes
on the base.
Figure 5. Initial Housing Separation
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Figure 6. Front and Back Views of MGS-250 Base
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Section 3.
Wiring and Configuration
3.1. Overview
Prior to wiring and configuring the MGS-250, assure the following
conditions have been met:
•
•
MGS-250 backplate is mounted in an appropriate location
the cover panel is removed.
If the cover panel was reattached after mounting, open the gas detector
enclosure by pressing the top latch with a suitable screwdriver or other
flat blade. With the top latch depressed pull the housing apart by
grasping the sides and pulling straight out. Align and press together to
close.
Figure 7. Terminal Blocks and Cable Glands
NOTE: The pre-installed cable gland (left) and optional cable
gland (right) have a ¼” cable capacity (each).
NOTE: Install the optional cable gland on the right side of
the base unit if needed. Otherwise, install the blanking plug
that is included in the mounting kit.
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3.2. Wiring Supply Power (24VAC or 24VDC)
WARNING: Incorrect wiring may permanently damage the gas
detector, and void the warranty. Double check all terminations
before applying power.
Either 24VAC or 24VDC may be used to power the MGS-250. Connect
wiring to the appropriate terminal locations (see Table 5). Use 2 wires,
between 14 and 22 AWG. Refer to Figure 8 for (AC wiring left) or DC
wiring (right).
Figure 8. Supply Power Wiring Options
Table 5: Power Options and Terminal Block Connections
Power Option
24 VAC
24 VDC
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Pin
Label
Wiring Termination
1
L
24V AC line
2
N
24V AC neutral
3
+
24V DC positive
4
GND
24V DC ground
23
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WARNING: The MGS-250 must be powered by either:
•
•
a suitable UL 60950/CSA certified power supply that is
isolated from line voltage by double insulation, or
an appropriately rated UL listed/CSA Class 2 transformer.
Failure to comply can result in personal injury or death.
WARNING: Neutral polarity must be maintained across units.
Refer to Figure 9.
Figure 9. Maintaining Neutral Polarity
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3.3. Wiring Alarm Output (Analog Signal)
The MGS-250 provides an analog output signal that is proportional to the
level of gas detected.
NOTE: No jumpers or hardware switch settings are required
to configure the analog output. This is done electronically
from the front panel display.
Connect two 18 to 20 AWG wires to terminal block positions 5 and 6 (see
Figure 10), noting ground and signal polarity per Table 6.
Figure 10. Analog Output Wiring
Table 6: Alarm Output Terminal Block Connections
Function
Pin
Wiring Termination
Analog
Output
5
Analog output ground
6
Analog output signal (+)
The type of output signal on pins 5 and 6 is programmable using the
analog output type parameter P.-03. Refer to Section 5 for details.
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3.4. Wiring the Digital Alarm Output Relay
An alarm setpoint may be programmed from the front panel of the
MGS-250. When the the sensed gas level exceeds the alarm setpoint,
the MGS-250 enters the alarm state. An on-board relay is tied to the
alarm state, so you may activate (or deactivate) external equipment
based on the MGS-250’s current alarm status.
Figure 11. Sample Relay Output Wiring
NOTE: The relay can be programed to be failsafe (normally
energized). By default, the relay is set to be normally deenergized. This can be set using parameter P-06.
Make relay connections (NO, NC, or both) using 18 to 20 AWG wires to
terminal block positions 10, 11, and 12 (see Figure 11), noting normally
open, normally closed, and common connectors per Table 7.
Table 7: Relay Output Terminal Block Connections
Function
Relay (Alarm)
Output
26
Pin
Wiring Termination
10
Relay NC contact
11
Relay common contact
12
Relay NO contact
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3.5. Modbus Network Configuration
If your application includes a Modbus network, make network
connections (RS-485 A and RS-485 B) using 18 to 24 AWG shielded
twisted pair wires (with 120 ohm characteristic impedance) to terminal
block positions 7 and 8 (see Figure 12), noting inverted B (-) and noninverted A (+) signal connectors per Table 8.
Figure 12. Modbus Network Wiring
Table 8: Modbus Network Communications Connections
Function
Modbus Network
Communications
Pin
Wiring Termination
7
RS-485 “B” (inverted)
8
RS-485 “A” (non-inverted)
9
RS-485 shield
IMPORTANT: For Modbus network communications wiring,
use only 18-24 AWG shielded twisted pair wire with 120 ohm
characteristic impedance.
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IMPORTANT: Connect the RS-485 cable shield to pin 9
(board ground).
NOTE: Selection of the Modbus Address and Baud Rate is
completed through the gas detector setup menu, described
later. No jumpers or hardware switch settings are required to
configure the Modbus communications network. This is done
electronically from the front panel display.
NOTE: For Modbus communications with the MGS-250, the
default communications parameters are as follows.
•
•
•
Baud rate = 9,600
Parity = no parity
Stop bits = 1
Confirm that all devices on the Modbus communications
network (including a Building Management System) are
configured similarly.
If the MGS-250 is at the end of the RS-485 network, then be sure to set
the RS-485 terminator on the printed circuit board (PCB) to IN. This
applies a terminating resistor to the end of the wires per the
requirements of the RS-485 protocol. The terminator should be set to
OUT for all other installation conditions.
IMPORTANT: Be sure to enable the termination resistor on
the device at each end of the network (see Figure 13). This
includes the Building Management System (if used).
NOTE: Care should be exercised when changing the
terminator switch. Before powering the gas detector, use a
fine pointed device or paper clip to slide the switch position.
Do not apply force to the switch or push on the switch with
any device. The switch changes position up and down along
the access slot direction.
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Figure 13. Setting Network Termination Resistors
3.6. Conclusion
Once the base is mounted and all wiring is complete, align the gas
detector housing and press it onto the base. The gas detector will snap
into position, completing all electrical connections. Ensure the top and
bottom snap locks are engaged.
IMPORTANT: If the right cable gland was not needed during
installation and wiring, be sure to install the blanking plug.
IMPORTANT: Do not apply caulking or other material around
the gas detector base. The gas detector relies on air
exchange through the spaces between the base and the gas
detector housing. Do not obstruct the small gap around the
housing and the base with any material.
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Section 4.
Operation and Stabilization
4.1. Power Up and Warmup
On powering up, the MGS-250 will sense for the presence of gas after an
initial warm-up period of 2 to 5 minutes. The green LED will flash at a 1
second interval during the warm up.
4.2. Stabilization
IMPORTANT: It is vital when first installing the gas detector
that it warms up in an atmosphere that is known not to
contain any background concentrations of refrigerant.
Bacharach offers portable gas detectors for this purpose.
Contact the factory for more information.
4.3. Perform a Manual Zero
After the gas detector stabilizes, the power LED stops flashing and is lit
continuously. Bacharach recommends manually zeroing the MGS-250
after a 1-hour stabilization period.
To manually zero the gas detector, press and hold the UP and DOWN
buttons simultaneously for 5 seconds. The gas detector will beep and
the display will show “zEro” when zeroing is complete. The display will
show fAiL if the temperature is changing too quickly or there is an active
alarm condition.
NOTE: Manual zero should be performed in the environment
of operation and at the typical operating temperature.
NOTE: Subsequent manual zeroes may be performed,
provided the atmosphere around the gas detector is free of
all background concentrations of refrigerant. Clean air or
nitrogen applied to the calibration port for five minutes may
be used to ensure the gas detector is clear of all background
gas. Re-zeroing with background refrigerant present will
cause the gas detector to report incorrect readings.
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4.4. Alarms
The following occurs during an alarm condition.
Table 9: MGS-250 Behavior during Alarm Conditions
Item
Green LED
Display
Behavior During Alarm State
On (solid)
On (blinks); reports detected PPM concentration
Audible Alarm
On (if enabled and after programmed delay
expires)
Relay Output
Activates (after any programmed delay expires)
Analog Output
Changes proportionally with gas concentration
(as configured)
Modbus Registers
Registers indicate the alarm condition, ppm
concentration, etc.
NOTE: The alarm feature includes a 20% dead band to
prevent alarm ‘chatter’ if the concentration hovers near the
alarm setpoint. Once the alarm has been triggered it will
remain latched until the concentration drops below 80% of
the alarm setpoint.
4.5. Gas Detector Faults
4.5.1. Overview
There are two levels of fault monitoring built into the gas detector.
• Non-critical
• Critical
4.5.2. Non-Critical Faults
Non-critical faults typically recover by allowing the gas detector
surroundings to stabilize, for example, after a defrost cycle. The gas
detector continues to monitor its surroundings during non-critical faults,
but may report inaccurate readings.
The following occurs when a non-critical fault condition exists.
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Table 10: MGS-250 Behavior during a Non-Critical Fault
Item
Green LED
Display
Analog Output
Modbus Registers
Behavior During Non-Critical Fault State
On (solid)
Shows the appropriate fault code
Operates normally
Modbus registers indicate the fault.
4.5.3. Critical Faults
Critical faults may indicate an unrecoverable condition. Please refer to
Section 8 for more information. The following occurs when a critical fault
condition exists.
Table 11: MGS-250 Behavior during a Critical Fault
Item
Green LED
Display
Analog Output
Modbus Registers
32
Behavior During Critical Fault State
Off (indicating the gas detector is off-line)
Shows the appropriate fault code
4-20 mA output
Changes to 2 mA
1-5 V output
Changes to 0.5 V
2-10 V output
Changes to 1.0 V
Modbus registers indicate the fault.
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Section 5.
Configure the Gas Detector
5.1. User Interface Overview
The gas detector is configured through the built in menu system. Once
mounting is complete, attach the gas detector to the base and apply
power.
Figure 14. The User Interface of the MGS-250
The user interface consists of four pushbuttons, a four digit LED numeric
display, and a power LED. When the display is off, press any button to
wake the display for 10 seconds. Buttons functions are listed in
Table 12.
Table 12: Button Functions
Button
Description
Used to access the parameter list. Used to back up
one level without writing to memory when the
parameter list is active. Used to mute the audible
alarm for the time period configured in parameter
P.-12.
+
Used to increment
displayed.
the
value
or
parameter
Used to decrement
displayed.
the
value
or
parameter
When pressed together and held for 5 seconds, this
key combination manually zeroes the gas detector.
Saves the
memory.
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displayed
parameter
to
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5.2. Setting Parameters
5.2.1. Overview
Press and hold the information button () for 5 seconds to activate the
parameter list. Each parameter is shown in turn by using the UP or
DOWN buttons. The parameter is shown as P.-XX, with XX being the
parameter value. Pressing Enter while a parameter is displayed allows
the attributes of the parameter to be set. Each Parameter has its own
attributes, as shown in the following table. Set the attributes as desired,
and then press Enter to save the setting.
5.2.2. Configuration Parameters
Table 13: Parameter Numbers, Names and Descriptions
Parameter
Description
Maintenance Mode
Sets gas detector to offline mode for 30 minutes.
00
Gas detector is online, with normal response
to its surroundings (default).
01
Gas detector is offline, and suppresses all
outputs. Display reads “oFFL” (offline) during
30 minute timeout.
Alarm Setpoint
Sets desired PPM value (range 75 to 3500 ppm)
above which alarm occurs. Use UP or DOWN
buttons. For faster “coarse” adjustment, hold either
button to sweep through the adjustment range
quickly. Default setpoint is 100 ppm.
Analog Output Type
Selects output type.
00
Selects 0-5 V (default)
01
Selects 1-5 V
02
Selects 0-10 V
03
Selects 2-10 V
04
Selects 4-20 mA
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Parameter
Description
Alarm ON Delays
Sets the ON delay time (0-15 minutes) for the alarm
output signals (relay, Modbus). The default delay is
0 minutes.
Alarm OFF Delays
Sets the OFF delay time for the alarm output signals
(relay, Modbus) in minutes (0-15). The default delay
is 0 minutes.
Relay Contact Behavior (Failsafe Mode)
Sets the default relay power state so that power loss
can be detected.
The behavior of the relay changes from energizing
when an alarm condition occurs (default) to
energizing at power up (Failsafe). In both cases the
relay changes state when an alarm occurs, failsafe
is simply inverted. This allows power failures to be
detected as alarms.
00
NO (default mode)
01
Failsafe mode
Relay Latching
Controls the relay latching behavior.
00
OFF (default). Relay does not latch, and
resets once the alarm condition is removed.
01
ON. Relay remains latched; reset by BMS
command over RS-485, or by pressing and
holding the Enter button for 5 seconds.
Audible Alarm
The units have an internal audible alarm. You can
disable this, but the default setting is “enabled” in
compliance with EN378.
00
OFF
01
ON (default)
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Parameter
Description
Display Mode
The display can be turned on by using this
parameter. When set to ON the display never shuts
off (all operating modes). When ON the display
shows the current gas concentration (or 0 if below
the squelch). Note that P.-09 is disabled if P.-19=0.
00
OFF during normal operation when the ppm
value is below the alarm setpoint (default)
01
ON
In either case, the display will blink the measured
PPM value during an alarm state.
RS485 Node Address
Sets the RS-485 node address (0001 to 0255).
Gas Groups / Specific Gas Selection
Selects either gas group number for broadband
operation or specific gas name for gas-specific
mode.
Broadband: Select from 3 groups of gases:
1
R134a, R404a, R407a, R407c,
R407f, R427a, R507,
2
R422a, R422d HFO1234YF,
and HFO1234Ze
3
R22 (by itself).
Specific Gas: The actual refrigerant name is shown.
Select the appropriate refrigerant.
NOTE: Gas-specific detectors are factory calibrated
to a single refrigerant using specialized
manufacturing equipment. If another refrigerant is
selected which differs from the factory calibrated
setting, the built in calibration no longer applies.
Further improvement in detector accuracy may be
gained by applying calibration gas containing the
newly selected refrigerant and adjusting the gas
detector reading to match (see Parameter P.-17).
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Parameter
Description
Buzzer Mute Time
Sets a time (0-59 minutes) during which the active
buzzer remains muted:
• after the “I” button is pressed, or
• after Modbus register 4000 is set to 0.
Baud Rate
Sets the baud rate for Modbus (RS-485)
communications.
00
9,600 baud (default)
01
19,200 baud
Stop Bits
Sets the number of stop bits required to match the
controlling
communications
equipment
(e.g.,
building management system, etc.).
01
1 stop bit (default)
02
2 stop bits
Parity
Sets Modbus parity option.
00
None (default)
01
Odd parity
02
Even parity
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Parameter
Description
Analog Output Scaling
Allows the user to select the full-scale PPM value
that represents maximum analog output (e.g., 20
mA) for scaling the analog output. Adjustment range
is from 100 PPM to 3500 PPM. Default = 3500
PPM. (The setting cannot be adjusted above 3500.)
Use the Up and DOWN buttons to set the desired
full scale value. All outputs will be scaled to the
indicated full scale value.
NOTE: Alarm values are not scaled, but are
absolute values. Setting a smaller full scale does
not correspondingly scale the alarm setting.
NOTE: When the ppm level is greater than the
programmed analog output Full Scale ppm (P.-16),
the analog output will go to a 10% over range state
(indicating that the concentration is too high for the
analog output to achieve). For example, for a 1-5 V
setting the analog output would go to 5.5 V, for
4-20 mA it would go to 22 mA and so on.
NOTE: The analog output signal range is from 100 ppm to
the default value of 3500 ppm, which is scaled across the
actual output range selected by the analog output type
parameter P.-03. The upper PPM limit is programmable using
analog output scaling parameter P.-16. This parameter sets
the full scale PPM value creating a PPM range across which
the analog output is scaled. See Figure 15 for more details.
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Figure 15. Analog Output Scaling Options
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Parameter
Description
Gas Test Mode
Places the gas detector in gas test mode.
00
Disabled (default)
01
Enabled
When enabled, the display continuously cycles
through the following:
•
•
•
CAL is displayed briefly.
Next, the gas group number or gas type
(based on product code) is displayed.
Then four dashes (----) are displayed.
After gas is applied and the 75 PPM squelch level is
exceeded, the live concentration replaces the four
dashes.
See section 6.4 if using Gas Test Mode to initiate
the calibration procedure.
NOTE: To prevent false alarms, all outputs are
suspended while Test Mode is active. The only live
indication is the 4-digit display.
Once the gas test mode is enabled to perform a gas
test or calibration, the unit will automatically go
offline for a ten minute period after the parameter
list is exited. (This allows time for the test gas to
clear before the unit becomes active)
If no activity occurs for ten minutes, the unit exits
the gas test mode.
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Parameter
Description
Diagnostics Menu
Parameter 18 provides access to the self diagnostic
information. The LED display shows “DIAG” until
the Enter button is pressed. Use the UP and
DOWN buttons to scroll through the list of diagnostic
attributes.
A.-01
Current fault condition
A.-02
Last fault
A.-03
Days in service
A.-04
Days since last adjust/test
A.-05-A.-07
Factory Use Only
A.-08
Detector temperature in °C
A.-09
Temperature rate of change
A.-10-A.-17
Factory Use Only
To aid in troubleshooting, the operator may choose
to reset the gas detector to its default state by
holding both the UP and DOWN buttons for 5
seconds while in the Diagnostics Menu. All settings,
including the alarm setpoint, gas adjustments, the
selected gas curve, calibration data, the Modbus
address, etc. revert to specific default values after a
reset.
IMPORTANT: Calibrations on either gas-specific or
broadband models are lost after a reset. This
returns the gas detector to an uncalibrated
condition. See parameter P.-17 for information on
how to recalibrate the gas detector.
See Section 8 for a complete list of codes and
details on the reset option.
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Parameter
Description
Response Filtering
This parameter is used to turn filtered output ON
(01) or OFF (00).
The default setting is ON (01). The Modbus and
analog output are filtered so that responses below
75 ppm are squelched. If the display mode (P.-09)
is set to ON (01) the display shows 0 for any signal
level below 75 ppm.
Some installations may wish to monitor the small
analog output changes that may be created by the
detector environment. Turning filtering OFF (00)
allows these small variations around the minimum
analog output (e.g., 4 mA, 1V, etc.) to be
transmitted via Modbus and the analog output
terminals.
NOTE: The detector display is OFF when filtering is
OFF (P.-09 is disabled).
NOTE: Whenever filtering is OFF the detector
display will turn ON for 10 minutes if the detector is
re-zeroed (see Section 4.3). This is intended to aid
maintenance testing. The analog outputs continue
to transmit the full, unfiltered range, and the alarm
setpoint remains active.
5.3. Completing Setup
To complete the setup after all parameters are set as needed, simply
press and hold the information button () for 5 seconds to exit the
Parameter list. The gas detector is now actively monitoring its
surroundings.
NOTE: If no buttons are pressed for 2 minutes, the
MGS-250 exits setup mode automatically.
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Section 6.
Functional Tests and Adjustments
6.1. Introduction
To comply with the requirements of EN378 and the European F-GAS
regulation, gas detectors must be tested annually. However, local
regulations may specify the nature and frequency of this test.
CAUTION: Check local regulations on calibration or testing
requirements.
CAUTION: The MGS-250 contains sensitive electronic
components that can be easily damaged. Neither touch nor
disturb any of these components
IMPORTANT: Bacharach recommends annual checks and
adjustment using calibration gas. Calibration gas adjustment
frequency may be extended based on application, but should
never exceed 2 years.
CAUTION: In applications where life safety is critical,
calibration gas adjustment should be done quarterly (every
3 months) or on a more frequent basis. Bacharach is not
responsible for setting safety practices and policies. Safe
work procedures including calibration policies are best
determined by company policy, industry standards, and local
codes.
CAUTION: Failure to test or adjust the unit in accordance
with applicable instructions and with industry guidelines may
result in serious injury or death. The manufacturer is not
liable for any loss, injury, or damage arising from improper
testing, incorrect adjustment, or inappropriate use of the unit.
IMPORTANT: Before testing the gas detectors on-site, the
MGS-250 must have been powered up and allowed to
stabilize.
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IMPORTANT: After initial installation, the MGS-250 should
be gas tested to ensure proper operation.
IMPORTANT: The testing and/or adjustment of the unit must
be carried out by a suitably qualified technician, and must be
done:
•
•
in accordance with this manual
in compliance with locally applicable guidelines and
regulations.
Qualified operators of the unit should be aware of the
regulations and standards set down by the industry/country
for the testing or calibration of this unit. This manual is only
intended as a guide and, insofar as permitted by law, the
manufacturer accepts no responsibility for the calibration,
testing, or operation of this unit.
The frequency and nature of testing or calibration may be
determined by local regulation or standards.
EN378 and the F-GAS Regulation require an annual check in
accordance with the manufacturer’s recommendation.
6.2. Bump Testing vs. Adjusting Detector Response
There are two concepts that need to be differentiated.
•
•
bump test
gas detector response adjustment
A bump test exposes the gas detector to a gas. The operator then
observes the gas detector’s response to the gas. The objectives are
two-fold:
•
•
establishes if the gas detector is reacting to the gas
determines if all of the detector outputs are working correctly
There are two types of bump test.
•
•
quantified:
non-quantified:
A known concentration of gas is used.
A gas of unknown concentration is used.
Adjusting gas detector response exposes the gas detector to a
calibration gas as well (like a quantified bump test), but additionally sets
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the actual gas detector response level (via parameter P.-17) to ensure
that the gas detector activates at the specified gas concentration.
Refer to the following sections for addition information on bump testing
and gas detector response adjustment.
CAUTION: Before you carry out the test or adjustment:
•
•
•
Advise occupants, plant operators, and supervisors.
Check if the gas detector is connected to external
systems such as sprinkler systems, plant shut down,
external sirens and beacons, ventilation, etc. and
disconnect as instructed by the customer.
For bump test or calibration the MGS-250 should be
powered up and fully stabilized per Section 4.
6.3. Bump Testing
IMPORTANT: Notify others that testing is underway. During
bump testing the alarm outputs are active, and will trigger
whatever response is intended. It is the operator’s
responsibility to ensure that such actions are acceptable and
can be performed safely.
After installation and parameter setup (see Section 5), the units should
be bump tested. Expose the gas detector to test gas. The gas selected
should be a high enough concentration to put the system into alarm and
light the LED display.
With a bump test you can see the functions of the gas detector:
•
•
•
the LED display will light and show the detected PPM
concentration once the alarm setpoint is reached
the relay and audible alarm will function as configured including
any delays set (ON or OFF).
the output (0-10V, for example) will show the gas level
Ideally bump tests are conducted on-site in a clean air atmosphere.
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Step
Bump Testing Using Calibration Gas Cylinders
1
Remove the Splash Shield accessory if one is used.
2
Connect the regulator to the test gas port using 3 mm or 1/8”
inside diameter tubing (see below).
3
Expose the gas detector to gas from the cylinder. Monitor
the LED display reading. Refer to the specifications section
for acceptance criteria.
Figure 16. Using Calibration Gas
6.4. Adjustment Using Calibration Gas
Adjustment Using Calibration Gas requires a gas cylinder with the
appropriate gas and concentration. Note that Bacharach offers a
calibration kit that consists of a calibration gas cylinder and a flow
regulation valve with flexible non-absorbent tubing.
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NOTE: For improved accuracy and response, the gas
detector should be protected from excess drafts while
performing the adjustment. Excess air circulation may dilute
the applied calibration gas and lead to lower than expected
response.
Step
Adjustment Using Calibration Gas Cylinders
1
Connect the regulator to the test gas port using 3 mm or 1/8”
inside diameter tubing.
2
Enable parameter P.-17 Gas Test Mode (see Section 5).
When enabled, the display continuously cycles through the
following:
• CAL is displayed briefly.
• Next, the gas group number or gas type (based on
product code) is displayed.
• Then four dashes (----) are displayed.
After gas is applied and the 75 PPM squelch level is
exceeded, the live concentration replaces the four dashes.
NOTE: The analog outputs, relay activity, and RS-485 ppm
reporting are suspended in Gas Test Mode to prevent false
alarms.
3
Expose the gas detector to gas from the cylinder. Monitor
the 4 digit LED display reading.
4
Wait for the ppm reading to stabilize. This should take
approximately 4-6 minutes. Minor changes (less than 5 ppm
in 10 seconds) are considered stable readings. Compare the
response value with the calibration gas concentration.
5
Adjust the gas detector displayed value by using the UP or
DOWN buttons to increase or decrease the value shown.
Adjust until the reading is within ± 2% of the calibration gas.
For example, if the calibration gas is 1000 ppm, the gas
detector is adjusted properly when the displayed reading is
between 980 and 1020 ppm.
6
Press the Enter button to store the new adjustment. Turn off
the calibration gas and remove the tubing from the calibration
port.
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Step
Adjustment Using Calibration Gas Cylinders
7
If no further changes to the other parameters are required,
press and hold the  button for 5 seconds to exit the
Parameter list. Upon exiting the parameters list, the gas
detector will enter offline mode for a period of 10 minutes.
This allows time for the calibration gas to dissipate after
testing. During offline mode, the gas detector suppresses all
outputs. The display reads “oFFL” (offline) during 10 minute
timeout.
NOTE: All calibration gas mixtures have a blend tolerance.
The tolerance will limit the actual adjustment accuracy that is
achievable.
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Section 7.
Modbus Communications
7.1. Introduction
The MGS-250 gas detector can be configured to communicate on an
RS-485 network using Modbus-RTU protocol. Before configuring the
gas detector for Modbus communications, be sure your network
connection is complete and your network termination switches are set
appropriately. Refer to Chapter 3 (Wiring and Configuration) for details.
This section details the MGS-250 parameters that can be accessed via
registers of the Modbus-RTU (“Modbus”) protocol. Generally (with the
exception of some of the communications parameters), parameters you
can access and/or configure from the front panel of the MGS-250 can
also be accessed and/or configured via a Building Management System
(for example) on the same Modbus network.
7.2. Communications Settings
There are 255 selections available to be set electronically, from
addresses 1 to 255 inclusive. Modbus data with a zero in the address
field is received by all detectors (regardless of the address selected) to
enable the master device to broadcast simultaneously to all the
detectors.
Refer to the specifications section (page 16) for information on RS-485
network communications parameters such as data bits, stop bits, etc.
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7.3. Analog Input Registers
Analog input registers are read only and use function code 04.
Table 14: Analog Input Registers
Reg
50
Description
Range
Units
P.-##
1000
Concentration gas level
0-100
% FS
--
1001
Concentration gas level
0-65,535
ppm
--
1002
Reserved
1003
Full scale detector level
1004
Alarm set-point (% full scale)
1005
Gas detector timer
1006
Node address
1007
Software version
1008
Reserved
--
1009
Reserved
--
1010
Reserved
--
1011
Reserved
--
1012
16-bit fault code
-0-65,535
ppm
--
0-100
%
--
0-65,535
hours
--
1-247
none
P.-10
none
--
0-65535
none
--
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7.4. Analog Output Registers
Analog output registers are readable (using function code 03) and
writable (using function code 06).
Table 15: Analog Output Registers
Reg
Description
Range
Units
P.-##
75-3500
ppm
P.-02
2000
Alarm setpoint
2001
Alarm ON delay (Alarm flag
register 3000 is set to 1)
0-15
min
P.-04
2002
Buzzer mute time
0-59
min
P.-12
2003
Alarm OFF delay
0-15
min
P.-05
2004
Relay action
0=NO
1=Failsafe
none
P.-06
2005
Relay latching enable
0=Disable
1=Enable
none
P.-07
2006
Buzzer enable
0=Disable
1=Enable
none
P.-08
2007
Display mode
0=Off
1=On
none
P.-09
2008
Analog output type
0=0-5 V
1=1-5 V
2=0-10 V
3=2-10 V
4=4-20 ma
none
P.-03
2009
Baud rate
0=9600
1=19200
none
P.-13
2010
Stop bits
1 or 2
none
P.-14
none
P.-11
2011
Gas curve number
1 to 3
(broadband
unit) or gas
type (gas
specific)
2012
Analog output full scale ppm
(R/O)
100 – 3500
ppm
P.-16
2013
Parity
0=None
1=Odd
2=Even
none
P.-15
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7.5. Input Status Flags
Input Status Flags are readable (using function code 02).
Table 16: Input Status Flags
Reg
Description
Range
P.-##
3000
Alarm flag (0 or 1=Alarm)
0-1
--
3001
Relay state (0 or 1=energized)
0-1
--
3002
Detector fault (0 or 1=fault)
0-1
--
3003
Red LED state (0 or 1=ON)
0-1
--
3004
Green LED state (0 or 1=powered
on)
0-1
3005
Reserved
3006
Start up (0=normal operation
1=warming up)
3007
Reserved
--
3008
Reserved
--
---
0-1
--
7.6. Output Status Flags
Output Status Flags are readable (using function code 01) and writable
(using function code 05).
Table 17: Output Status Flags
Reg
Description
4000
Buzzer flag (0 or 1=ON)
4001
Test required (If operating for
>1 year). (1=requires testing)
52
Range
P.-##
0=Off
1=On
--
0=Okay
1=Test
--
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Section 8.
Troubleshooting
8.1. Fault Codes
To comply with the requirements of EN378 and the European F-GAS
regulation, gas detectors must be tested annually. However, local
regulations may specify the nature and frequency of this test.
The MGS-250 features sophisticated internal status monitoring and will
indicate whether a fault condition exists, both on the front display (F.-XX,
with XX being the fault number) and over the Modbus communications
network.
There are two classes of fault conditions: critical and non-critical.
general, non-critical faults occur…
In
…when environmental conditions exist that are
outside the product’s specified operating range, or if
an installation error has occurred (wrong wiring, for
example).
The gas detector will typically continue to monitor its surroundings
(except for fault F.-08), and may report inaccurate readings and false
alarms.
Correcting non-critical faults is a matter of waiting for the environmental
conditions to return to a more typical condition, correcting wiring
mistakes, or in some cases, relocating the gas detector. For example,
placing the gas detector near a forced air heater may cause temperature
faults. The non-critical fault range is F.-01 to F.-08. Critical faults
indicate…
…a functional problem that results in the gas
detector no longer monitoring its surroundings for
refrigerant.
The fault number is displayed and the power LED is turned off, indicating
that the gas detector is offline. The critical fault range is F.-09 to F.-16.
If any of these faults occur, first try to clear the faults by cycling power to
the sensor. The easiest way to do this is by removing the sensor from
the base and reattaching. If the fault returns after cycling power, the gas
detector should be removed from service and replaced.
Additionally, the faults are stored as a hex number and can be accessed
in the Diagnostics menu P.-18. The associated hex codes are listed next
to the Fault Code in Table 18. Refer to Diagnostics Menu P.-18 in the
next section for additional information.
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Table 18: Fault Codes
Description
Fault Code
Hex
Code
Possible Causes
Gas Detector
Temperature
Fault
0x0001
Gas Detector temperature
reports > 55° C or < -35° C.
Gas Detector
Temperature
Rate of
Change Fault
0x0002
Temperature rate of
change exceeds ~1°C/min
for more than 15 minutes.
RS485 RX
Fault
0x0004
Message too long for
receive buffer.
RS485 CRC
Fault
0x0008
Transmission is corrupted
(computed CRC doesn’t
match transmitted CRC).
Open Loop
Fault
0x0010
Possible wiring,
connection, and/or
termination issue exists.
When analog output type is
4-20ma and loop is open,
use 18-24AWG shielded
twisted pair with 120 ohm
characteristic impedance
for Modbus connections.
Modbus Fault
0x0020
Modbus message was
truncated or timed out
early.
PPM Overrange Fault
0x0040
PPM exceeds 9999. This
may indicate a very large
gross leak. If no leak is
present, it indicates a gas
detector error.
Input Voltage
Fault
0x0080
Input supply power to the
MGS-250 is out of range
(i.e., 24V ±20%).
IMPORTANT: If this fault is
active, the gas detector is
offline and not monitoring.
Correct the input supply
voltage to restore normal
operation.
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Description
Fault Code
Hex
Code
Critical Faults
:
Possible Causes
Critical fault. Cycle power
to the sensor and see of
the fault clears. If not, the
gas detector should be
removed from service and
replaced.
:
8.2. Diagnostics Attributes (P.-18)
Use this option to review the built-in diagnostic attributes. Access the
parameter list (see Section 5) and select P.-18. Press the Enter button to
access the diagnostics, and then use the UP or DOWN button to select
each attribute. The following information is available.
Table 19: Diagnostic Attributes
Attribute
Description
Displays the current fault condition code in hex
format:
0000
= no faults are active
XXXX
= HEX number
See Table 18 for the HEX format cross reference.
Displays a hex format code that corresponds to any
faults that occurred since the internal fault record
was last erased. See Table 18 for the HEX format
cross reference. The records may be erased by
pressing the ENTER button.
Displays the number of days that the MGS-250 has
been in service. The value of this attribute rolls over
after 9999.
Displays the elapsed time (in days) from the last gas
adjustment or test. This value is automatically reset
to 0000 after completing a gas adjustment via Test
Mode P.-17. (Note that the new adjustment is
stored using the Enter button.) The value may be
reset to 0000 by pressing the ENTER button.
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MGS-250 Manual
Attribute
:
Description
Reserved
Displays the sensor temperature in °C.
Displays the sensor’s approximate rate of
temperature change per half minute interval (°C
change over 30 seconds).
:
Reserved
8.3. Resetting MGS-250 to Default Values
The gas detector may be reset to its default state, if needed, to aid in
troubleshooting. All settings, including alarm setpoint, gas adjustments,
selected gas curve, calibration data, Modbus address, etc. revert to
specific default values after a reset. The broadband sensor option (P/N
6401-0500) resets to gas group 1. Gas specific products (P/Ns 64010501 through 6401-0514) are reset to the R134a gas curve.
IMPORTANT:
Calibrations on either gas-specific or
broadband models are lost after a reset. This returns the gas
detector to an uncalibrated condition. See parameter P.-17
for information on how to recalibrate the gas detector.
Before performing this operation it is advisable to write down all the
parameter settings, so they can be re-programmed.
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Step
Description
1
Access diagnostics menu P.-18.
2
Press and hold both the UP and DOWN buttons for 5
seconds. This will cause the following to occur:
• All the LED segments will then light for 3 seconds
• The gas detector resets to the default settings
• The gas detector beeper sounds for 3 seconds.
3
After 3 seconds the user is returned to the parameter list at
parameter P.-18.
4
The gas detector may now be re-programmed for further
troubleshooting if needed.
8.4. Other Symptoms
Other common wiring problems can also cause the gas detector to
malfunction. Check below for additional conditions that will cause gas
detector issues.
Table 20: Other Symptoms and Possible Causes
Symptom
Possible Cause(s)
Green power LED
off
Check power supply. Check wiring.
Alarms in the
absence of a leak
If you experience alarms in the absence of a leak, try
setting an alarm delay.
Perform a bump test to ensure proper operation.
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MGS-250 Manual
Section 9. Replacement Parts and Accessories
The following items are available as replacement parts.
NOTE: All modules come ready to mount to the original
mounting base provided.
Table 21: Replacement Parts and Accessories
Part Number
Description
0051-2320
6400-0014
6400-0015
6400-0016
6400-0017
6400-0018
6400-0019
6400-0020
6400-0021
6400-0022
6400-0023
6400-0024
6400-0025
6400-0026
6400-0027
6400-0028
6400-0029
6490-9000
Calibration Gas Regulator, 1.0 LPM, 5/8"-18 UNF fitting
Mounting Base Kit (with Mounting Hardware)
1
Gas Detector Module, Broadband
1
Gas Detector Module, R22 Calibrated
1
Gas Detector Module, R123 Calibrated
1
Gas Detector Module, R134a Calibrated
1
Gas Detector Module, R404a Calibrated
1
Gas Detector Module, R407a Calibrated
1
Gas Detector Module, R407c Calibrated
1
Gas Detector Module, R407f Calibrated
1
Gas Detector Module, R410a Calibrated
1
Gas Detector Module, R422a Calibrated
1
Gas Detector Module, R422d Calibrated
1
Gas Detector Module, R427a Calibrated
1
Gas Detector Module, R507 Calibrated
1
Gas Detector Module, HFO1234YF Calibrated
1
Gas Detector Module, HFO1234ZE Calibrated
Installation and Operation Manual
6900-0001
Splash Shield Kit (Accessory): Provides additional
protection for wash down or impact. Includes mounting
hardware for attaching to walls.
NOTE: The gas detector response time will lengthen when
the splash shield is used. The installer is responsible for
determining whether the response time is suitable for the
application.
1 – Replacement gas detector modules do not include the mounting base (order P/N 6400-0014)
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DECLARATION OF CONFORMITY
The manufacturer of the
products covered by this
declaration:
Bacharach, Inc.
621 Hunt Valley Circle
New Kensington, PA 15068
Year conformity is
declared:
2013
Product(s):
Refrigerant Gas Monitor/Transmitter
Model(s):
MGS-250
The undersigned hereby declares that the above referenced products are in conformity
with the provisions of the following standard(s) and is in accordance with the following
directive(s).
Directive(s):
2004/108/EC
Electromagnetic Compatibility (EMC) Directive
2006/65/EC
Low Voltage Directive (LVD)
Standard(s):
EN 50270:2006
Electromagnetic compatibility – electrical apparatus for the
detection and measurement of combustible gases, toxic gases
or oxygen
EN 55011:2007
Limits and methods of measurement of electromagnetic
disturbance characteristics of industrial, scientific and medical
(ISM) radio frequency equipment
IEC 61010-1:2010
EN 61010-1:2010
Safety requirements for electrical equipment for
measurement, control, and laboratory use – Part 1: General
requirements
Signature:
Name:
Title:
Date:
Aaron Kennison
Engineering Manager
3 July 2013
The technical documentation file required by this directive is maintained at the corporate
headquarters of Bacharach, Inc.
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MGS-250 Manual
Murco - A Bacharach Company
114a George’s Street LOWER
Dun Laoghaire • Co Dublin • IRELAND
Phone: +353 1 284 6388 • Fax: +353 1 284 6389
www.murcogasdetection.com • sales@murco.ie
World Headquarters
621 Hunt Valley Circle, New Kensington, Pennsylvania 15068
Phone: 724-334-5000 • Toll Free: 1-800-736-4666 • Fax: 724-334-5001
Website: www.MyBacharach.com • E-mail: help@MyBacharach.com
60
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