MRLDS-CO2 Gas Detector
Manual
026-1312 Rev 1
Emerson
1065 Big Shanty Road NW, Suite 100
Kennesaw, GA 30144 USA
770-425-2724 • www.emerson.com
Table of Contents
1 OVERVIEW ....................................................................................................................................... 1
1.1. GENERAL INFORMATION ................................................................................................................... 1
1.2. TECHNICAL SPECIFICATIONS............................................................................................................. 2
2 INSTALLATION AND WIRING..................................................................................................... 3
2.1.
2.2.
2.3.
2.4.
2.5.
2.6.
2.7.
GENERAL PLACEMENT GUIDELINES ................................................................................................. 3
COMPONENTS AND ACCESS OVERVIEW............................................................................................ 3
MACHINERY ROOMS ......................................................................................................................... 5
REFRIGERATED SPACES .................................................................................................................... 6
CHILLERS .......................................................................................................................................... 6
AIR CONDITIONING (DIRECT SYSTEMS VRF/VRV) ......................................................................... 6
REMOTE SENSOR HEAD INSTALLATION............................................................................................ 7
3 HOUSING DIMENSIONS ................................................................................................................ 8
4 OPERATION AND STABILIZATION ......................................................................................... 10
5 CONFIGURATIONS....................................................................................................................... 11
5.1. OVERVIEW ...................................................................................................................................... 11
5.2. ADJUSTING THE ALARM RELAY SETPOINT ..................................................................................... 11
6 FUNCTIONAL TESTS AND CALIBRATION ............................................................................ 12
6.1.
6.2.
6.3.
6.4.
6.5.
INTRODUCTION................................................................................................................................ 12
BUMP TESTING................................................................................................................................ 13
CALIBRATION OVERVIEW ............................................................................................................... 15
CALCULATING CALIBRATION VOLTAGE ......................................................................................... 15
CALIBRATING INFRARED (IR) SENSORS ......................................................................................... 15
7 TROUBLESHOOTING................................................................................................................... 16
Table of Contents • v
1
Overview
1.1. General Information
The MRLDS-CO2 (P/N 809-1020) is a fixed gas detector that detects the presence of CO2
refrigerant. The gas sensor can be used on a stand-alone basis or integrated into Controls or Building
Management Systems (BMS).
The MRLDS-CO2 can be used:
• In new buildings/areas that require continuous monitoring with high tech gas sensor transmitters.
• To add gas detection solutions to an existing system.
Typical detection applications include the detection of:
• Refrigerant gases
• Combustible gases
• Toxic gases and/or volatile organic compounds.
Figure 1-1 - MRLDS-CO2 Sensor Board (EC, IR, and SC)
General Information
Overview • 1
1.2. Technical Specifications
Specifications
Description
Power Supply
12-24 VDC/VAC; 50-60 Hz; 2 W max.
Power Consumption (12V); 136 mA (IR)
Monitoring LEDs
Power: Green LED
Audible Alarm
Buzzer, enabled/disabled
Relay Outputs
1 relay rated 1 A @ 24 VAC/VDC; Delay: 0, 1, 5, or 10 minutes
IP Rating
IP66
Temperature Rating
Humidity Rating
Dimensions/ Weights
per Enclosure Type
(see Note below)
Approvals
Alarm: Red LED
Sensor
IR and SC (all)
IP66 Housing
-40° to 122°F (-40° to 50°C)
0-95% non-condensing
Housing
Dimensions
Weight
IP66
6.89” x 6.5” x 3.29”
175 x 165 x 82 mm
1 lb 6 oz
629 g
w/ Splash Guard
6.89” x 8.9” x 3.29”
175 x 225 x 82 mm
1 lb 9 oz
700 g
CE; UL/CSA/IEC/EN 61010-1; EN 55011
Table 1-1 - MRLDS-CO2 Technical Specifications
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026-1312 Rev 1
2
Installation and
Wiring
WARNING: Explosion hazard! Do not
mount the MRLDS-CO2 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 MRLDS-CO2 contains
sensitive electronic components that can
be easily damaged. Do not touch or
disturb any of these components.
CAUTION: For AC-powered
configurations, ensure that the AC
neutral supply is not used as the ground
reference for the analog outputs.
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
by a marked, suitably located and easily
reached switch or circuit-breaker as
means of disconnection.
Connect monitor power and signaling
terminals using wiring that complies with local
electrical codes or regulations for the intended
application.
NOTE: This instrument can be equipped
with a semiconductor sensor for the
detection of refrigerant, combustible and
VOC gases. Semiconductor sensors are
not gas specific and respond to a variety of other
gases including propane exhaust, cleaners, and
solvents. Changes in temperature and humidity
may also affect the sensor’s performance.
2.1. General Placement
Guidelines
NOTE: The MRLDS-CO2 should be
installed plumb and level and securely
fastened to a rigid mounting surface.
Sensors must be located within the
appropriate wire lengths from the central control
unit (if used).
In all cases the sensor supplied is designed for
maximum sensitivity to a particular gas. However,
in certain circumstances false alarms may be
caused by the occasional presence of sufficiently
high concentrations of other gaseous impurities.
Examples of situations where such abnormalities
may arise include the following:
• Plant room maintenance activity
involving solvent or paint fumes or
refrigerant leaks.
• Accidental gas migration in fruit ripening/
storage facilities (bananas - ethylene,
apples - carbon dioxide).
• Heavy localized exhaust fumes (carbon
monoxide, dioxide, propane) from
engine-driven forklifts in confined spaces
or close to sensors.
Setting the alarm delay is recommended.
2.2. Components and
Access Overview
NOTE: Only use three wires to connect
the controller to the MRLDS-CO2. If
there is a fourth wire, use this to double
up on the 0V connection between the
controller and the MRLDS-CO2. The 0V for the
supply voltage and the 0V for the 4-20 mA output
are common. The wiring is the same for the
electro-chemical, semi-conductor, and infrared
models. The controller wiring is the same for all
controllers.
There is a five-minute power-up delay to
allow the sensor to stabilize. Refer to Figure 2-1
and for internal components wiring.
General Placement Guidelines
Installation and Wiring • 3
Figure 2-1 - EC or IR Sensor Components and Wiring
4 • MRLDS-CO2 Gas Detector Manual
026-1312 Rev 1
Components
Description
Enclosure Access
To open the standard sensor enclosure, turn the cable clamp 1/2 turn
counter-clockwise to loosen the internal nut, depress the clip on top of the
enclosure and open. Reverse to close. Note: For the IP66 enclosure, use the four
bolts on the front cover.
Power
12-24V AC/DC, connect at positions 0V and +V at connector block CN1.
• For AC: Jumper A is on, D is off. (See Figure 2-1).
• For DC: Jumper A is off, D is on. (Default Factory Setting is AC.)
Use two wires, typically 18 AWG (minimum).
Output
Connect the other two wires of the cable to terminal block CN2 positions 0V and
V or I for voltage or current, respectively.
• Connect 4-20mA at CN2 positions 0V and I
• Connect voltage output at CN2 positions 0V and V
Relay Setpoint
P1 sets the trip point for the relay and audible alarm using the 0- 5V scale
(measure at test points 0V and alarm test point TP1). Default factory setting is
50% of the range.
Time Delay
A time delay for the operation of the relay and audible alarm can be selected using
jumpers JP5 and JP6. Default factory setting is zero.
Audible Alarm
The audible alarm can be disabled using jumper JP3. Default factory setting is
enabled.
Table 2-1 - MRLDS-CO2 Components and Access Overview
2.3. Machinery Rooms
There is no absolute rule in determining the
number of sensors and their locations. However, a
number of simple guidelines will help to make a
decision. Sensors monitor a point as opposed to an
area. If the gas leak does not reach the sensor, no
alarm will be triggered. Therefore, it is extremely
important to select the sensor location carefully.
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, storage rooms or pipelines.
The most common leak sources are valves, gauges,
flanges, joints (brazed or mechanical), filling or
draining connections, etc.
Machinery Rooms
• When mechanical or natural ventilation is
present, mount a sensor in the airflow.
• In machinery rooms where there is no
discernable or strong airflow, the options
are:
- Point Detection, where sensors 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.
- Perimeter Detection, where sensors
completely surround the area or
equipment.
• For heavier-than-air gases such as
halocarbon and hydrocarbon refrigerants
such as R404A, propane, and butane
sensors should be located near ground
level.
• For lighter-than-air gas (for example,
ammonia), the sensor needs to be located
above the equipment to be monitored on a
bracket or high on a wall within 12 in (300
Installation and Wiring • 5
mm) of (or on) the ceiling – provided
there is no possibility of a thermal layer
trapped under the ceiling preventing gas
from reaching the sensor.
NOTE: At very low temperatures (for
example, refrigerated cold store),
ammonia gas becomes heavier than air.
• With similar density or miscible gases (for
example, CO or CO2), sensors should be
mounted about head height (about 5 ft
[1.5 m]).
• Sensors 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 high-speed jet and not be detected
by the sensor.
• Make sure that pits, stairwells, and
trenches are monitored since they may fill
with stagnant pockets of gas.
• If a pressure relief vent (PRV) pipe is
fitted to the system, it may be a
requirement to mount a sensor to monitor
this vent pipe. It could be positioned about
6 feet (2 m) above the PRV to allow gas
clouds to form.
• For racks or chillers pre-fitted with
refrigerant sensors, these should be
mounted so as to monitor the
compressors. If extract ducts are fitted the
airflow in the duct may be monitored.
2.4. Refrigerated Spaces
In refrigerated spaces, sensors should be
located in the return airflow to the evaporators on
a sidewall (below head-height is preferred), or on
the ceiling, not directly in front of an evaporator. In
large rooms with multiple evaporators, sensors
should be mounted on the central line between two
adjacent evaporators, as turbulence will result in
airflows mixing.
2.5. Chillers
In the case of small water- or air-cooled
enclosed chiller units, mount the sensor so as to
monitor airflow to the extract fans. With larger
models also place a sensor inside the enclosure
under or adjacent to the compressors.
In the case of outdoor units:
• For enclosed air-cooled chillers or the
outdoor unit for variable refrigerant
volume and variable refrigerant flow
(VRV/VRF) systems, mount the sensor so
as to monitor airflow to the extract fan.
With large units also place a sensor inside
the enclosure under or adjacent to the
compressors.
In the case of non-enclosed outdoor units:
• If there is an enclosed machinery section,
mount a sensor there.
• In the case of units with enclosed
compressors, mount sensors in the
enclosures.
• Where there are protective or acoustic
panels, mount the sensor low down under
the compressors where it is protected by
the panels.
• With air-cooled chillers or air-cooled
condensers with non-enclosed condenser
sections, it is difficult to monitor leaks in
the coil sections effectively. With some
designs it will be possible using an airflow
sensor to monitor airflow to the start-up
fans in the front or rear sections.
• If there is a possibility of refrigerant leaks
into a duct or air-handling unit, install a
sensor to monitor the airflow.
Weatherproof sensors should be used for
unprotected outdoor applications.
2.6. Air Conditioning
(Direct Systems VRF/
VRV)
For compliance with EN378, at least one
detector installed in each occupied space being
considered and the location of detectors chosen in
relation to the refrigerant, and also be located
6 • MRLDS-CO2 Gas Detector Manual
026-1312 Rev 1
where the refrigerant will collect from the leak. In
this case refrigerants are heavier than air and
detectors should have their sensors mounted low;
for example, at less than bed height in the case of
a hotel or other similar Category Class A spaces.
Ceilings or other voids, if not sealed, are part of the
occupied space.
NOTE: Monitoring the ceiling voids in a
hotel room would not strictly comply
with EN378.
DO Mount In-Room Sensors:
• At less than the normal height of the
occupants. For example, in a hotel room
this is less than bed height (between 8 and
20 inches [200 and 500 mm] off the floor).
• Away from drafts and heat sources like
radiators, etc.
• To avoid sources of steam.
DO NOT Mount Sensors:
• Under mirrors.
• At vanity units.
• In or near bathrooms.
To clean, the faceplate should be lightly
dusted.
NOTE: Do not spray the MRLDS-CO2
with cleaning or polishing aerosols.
Remote Sensor Head Installation
2.7. Remote Sensor Head
Installation
If you do not wish to surface mount the
MRLDS-CO2, a brushed stainless steel faceplate
is available. The remote sensor is mounted in an
electrical back box (1.7 in) or (44 mm) deep to
which the vented faceplate is fitted.
CAUTION: To avoid component mixup, do not remove sensor boards from
multiple units at the same time.
Alternatively, label them or match the
serial number on the main PCB and the remote
sensor PCB when reinstalling.
1.
Remove the connector from the sensor
PCB to feed the cable through the
housing.
2. Immediately refit the connector to the
sensor board in the back of the box.
The MGS and remote sensor must be
kept together as they are calibrated
together and are a matched pair.
To clean, the faceplate should be lightly
dusted.
NOTE: Do not spray the MRLDS-CO2
with cleaning or polishing aerosols.
Installation and Wiring • 7
3
Housing Dimensions
Figure 3-1 - IP66 Housing with Splashguard
8 • MRLDS-CO2 Gas Detector Manual
026-1312 Rev 1
Figure 3-2 - IP66 Housing with Remote Sensor Head
For Dimensions and Mounting Locations, see Figure 3-1.
NOTE: For the EXd Remote Sensor
Head and 16.4 ft. (5 m) cable, the thread
varies based on the model.
Remote Sensor Head Installation
Housing Dimensions • 9
4
Operation and
Stabilization
the process can take up to 24 hours or more. Again,
you may monitor the 0-10V output to follow the
progress.
On powering up, the MRLDS-CO2 will sense
for the presence of gas after an initial warm-up
delay of five minutes. The green LED will flash at
one-second intervals during the warm-up.
In an alarm condition:
• Green LED stays on and the red LED will
be on.
• Audible alarm operates (if not disabled
and after delay, if option selected).
• Relay output activates (after a delay, if
this option was selected).
• V or I output changes proportionally with
gas concentration.
In a fault condition:
• Green LED will be off and the red LED
will be on.
• Voltage or current fault output will
activate:
- 2mA on the 4-20mA output
- 0.5V on the 1-5V output
- 1.0V on the 2-10V output
Sensor Type
Stabilization Time
Electrochemical (EC)
20-30 seconds
Output
1-3 minutes
Relay Setpoint
2 minutes
Table 4-1 - Typical Time for Various Sensor Types
On power up, the electrochemical sensor
outputs a signal voltage normally below the set
alarm level. Semiconductors output over the + max
scale, i.e., > 5V. Both move towards zero as they
stabilize.
If sensors have been in long-term storage or
the detectors have been turned off for a long
period, stabilization is much slower. However,
within 1-2 hours, sensors should have dropped
below the alarm level and be operational. You can
monitor progress exactly by monitoring the 0-10V
output. When the output settles around zero the
sensor is stabilized. In exceptional circumstances
10 • MRLDS-CO2 Gas Detector Manual
026-1312 Rev 1
5
Configurations
5.1. Overview
Function
Description
Time
Delay
Available on the audible alarm and
relay to avoid false alarms. This is set
with jumpers. The default delay is 0
minutes. You may wish to set to 15
minutes during start up and/or
construction if you may have volatile
organic compound (VOC) fumes,
paint, etc. in the rooms. See
Figure 2-1 for setting the jumpers.
Audible
Alarm
The units have an internal audible
alarm. You can disable this by using
the jumper, but the default setting is
“enabled” in compliance with
EN378. See Figure 2-1 for setting
the jumpers.
Output
Decide which output is required:
4-20mA, 1-5V, 0-10V, relay outputs,
etc. See Figure 2-1 for setting the
jumpers.
Alarm
Point
Voltage
Alarm
Point
Voltage
=
=
Alarm Value
100
ppm
X
X
5V
Max Range
5V
1000 ppm
= 0.5V
So the alarm relay setting is 0.5 Volts.
Table 5-1 - MRLDS-CO2 Functions
5.2. Adjusting the Alarm
Relay Setpoint
This process is the same for all versions using
Pot P1 and test points 0V and REF1.
Adjusting the Alarm Relay:
1. Locate Pot P1 and use it to adjust the
setpoint at which the relay activates.
2. Monitor the output between test points
0V (negative) and REF1 (positive) until
the correct setting is reached. See
example below.
Example: For a sensor range of 0-1000 ppm,
calculate the voltage to set the relay at 100 ppm.
Overview
Configurations • 11
6
Functional Tests
and Calibration
6.1. Introduction
To comply with the requirements of EN378
and the European F-GAS regulation, sensors 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 MRLDS-CO2 contains
sensitive electronic components that can
be easily damaged. Do not touch or
disturb any of these components.
NOTE: The MRLDS-CO2 is calibrated
at the factory and is not required to be
calibrated at the time of installation.
NOTE: If the MRLDS-CO2 is exposed
to a large leak it should be tested to
ensure correct functionality by
electrically resetting the zero setting and
carrying out a bump test. See procedures below.
NOTE: Annual checks and gas
calibration is recommended. Sensor
replacement every three years or as
required is also recommended.
Calibration frequency may be extended based on
application, but should never exceed two years.
NOTE: In applications where life safety
is critical, calibration should be done
quarterly (every three months) or on a
more frequent basis. Emerson Retail
Solutions 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.
12 • MRLDS-CO2 Gas Detector Manual
WARNING: Failure to test or calibrate
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 calibration, or inappropriate
use of the unit.
NOTE: Before testing the sensors
on-site, the MRLDS-CO2 must have
been powered up and allowed to
stabilize.
NOTE: The testing and/or calibration 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.
Suitably 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.
NOTE: For improved accuracy and
response, the instrument should be
zeroed and calibrated in the
environment in which it is being
installed.
There are two concepts that need to be
differentiated:
• Bump test - Exposing the sensor to a gas
and observing its response to the gas. The
objective is to establish if the sensor is
reacting to the gas and all the sensor
outputs are working correctly. There are
two types of bump test:
026-1312 Rev 1
- Quantified - A known concentration
of gas is used.
- Non-Quantified - A gas of unknown
concentration is used.
• Calibration - Exposing the sensor to a
calibration gas, setting the “zero” or
standby voltage to the span/range, and
checking/adjusting all the outputs, to
ensure that they are activated at the
specified gas concentration.
NOTE: Procedures for bump test and
calibration vary depending on the
sensor technology used and the gas in
question.
NOTE: Do not pressurize the sensor.
NOTE: For semiconductor sensors, you
MUST use calibration gas in a balance
of air (not N2).
CAUTION: Before you carry out the test
or calibration:
• Advise occupants, plant operators, and
supervisors.
• Check if the MRLDS-CO2 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.
• Deactivate alarm delays if selected at
JP5, JP6 as per Figure 2-1.
• For bump test or calibration the
MRLDS-CO2 should be powered up for
24 hours. The instrument should be fully
stabilized per Section 4.
NOTE: After a semiconductor or
electrochemical sensor is exposed to a
substantial gas leak, the sensor should
be checked and replaced if necessary.
NOTE: To test the audible alarm and/or
relay function, check if the delay is set to
zero and expose to gas. You can mute
the audible alarm by removing jumper 3.
Bump Testing Using Calibration Gas Cylinder:
6.2. Bump Testing
After installation, the units should be bump
tested. Expose the sensors to test gas (NH3, CO2,
etc.). The system will alarm when the test gas ppm
value is above the alarm level. The gas should put
the system into alarm and light the red LED. The
delay prevents the audible alarm from sounding
and the relay from switching (if delay is set).
With a bump test you can see the functions of
the sensor - the red LED will light, the relay and
audible alarm will function, and the output
selected (0-10V, for example) will show the gas
level. Ideally bump tests are conducted on site in a
clean air atmosphere.
1.
Remove the
enclosure lid of the
gas detector (not in
an exhaust area).
2.
Connect a voltmeter
to monitor sensor
response (in Volts
DC). Monitor the
response between
pins 0V and VS.
3.
Expose the sensor to gas from the cylinder.
You can place the entire MRLDS-CO2 into a
plastic bag or use a plastic hose/hood to direct
gas to the sensor head. A response of above
80% is acceptable.
NOTE: Prior to carrying out a bump
test, check and adjust the zero setting as
described in the Calibration section.
Bump Testing
Functional Tests and Calibration • 13
.
Bump Testing Using Calibration Gas Cylinder:
Figure 6-1 - Gas Cylinder and Test Hardware
1.
Make sure that both the ampoules and the
calibration beaker are clean and dry.
2.
Unscrew the beaker hold screw and place the
ampoules so that it sits in the base of the
beaker (see Figure 6-2).
3.
Tighten the
wing-nut-screw onto
the ampule without
breaking it.
4.
Remove the
enclosure lid of the
gas detector.
5.
Connect a voltmeter
between pins 0V and
VS to monitor sensor
response (in Volts
DC).
6.
Place the beaker over the sensor head using
the multi sensor adaptor to fit the sensor, or, if
an EXd, IP66 or Remote sensor head version,
screw the beaker on the remote sensor head
M42 thread or M35 thread adaptor. It should
be as tight fitting as possible to allow
maximum gas exposure.
7.
Tighten the wing-nut screw onto the ampoule
until it shatters allowing the gas to diffuse in
the beaker. It should be left in place for
approximately five minutes.
8.
The voltage output will increase. This
confirms that the sensor is responding. A
response equivalent to at least 50%
(typically) of the test gas will confirm that the
system is in order if tested with the unit’s
specified span gas.
9.
Remove the beaker from the sensor. Carefully
remove any ampoule remains from the gas
detector and beaker.
Gas ampoules are convenient and inexpensive
alternatives to using gas cylinders for bump
testing.
14 • MRLDS-CO2 Gas Detector Manual
026-1312 Rev 1
Voltage =
800 ppm X
5V
1000 ppm
= 4V
So the output voltage signal should be
adjusted to 4V.
Figure 6-2 - Gas Ampoules for Bump Testing
6.3. Calibration Overview
There are two adjustments required: zero and
span. They are monitored at 0V and VS using a
0-5V scale. If the sensor range is 0-1000 ppm, then
5V=1000 ppm.
A calibration kit is available that consists of a
calibration gas cylinder, a flow regulation valve
with flexible non-absorbent tubing and vented
calibration hood.
Tools required:
• Gas cylinder with the appropriate gas and
concentration.
• A voltmeter (crocodile clips
recommended).
• Screwdriver (depending on housing).
6.4. Calculating Calibration
Voltage
6.5. Calibrating Infrared (IR)
Sensors
To calibrate Infrared (IR) Sensors:
1. Locate Pot VR203, which is used to
adjust the zero point.
2. Monitor the output between 0V
(negative) and VS (positive).
3. Expose the sensor to pure 99% nitrogen
or until output is stable (approximately
three minutes).
4. Adjust Pot VR203 to 0V or slightly
positive (0.01 V is acceptable).
5. Locate Pot VR202, which is used to
calibrate the range (span) of the sensor.
6. Monitor the output between 0V
(negative) and VS (positive).
7. Expose the sensor to calibration gas and
allow to stabilize (approximately three
minutes).
8. Adjust pot VR202 to the voltage
calculated in Section 6.4., Calculating
Calibration Voltage.
Sensor outputs are linear. As long the gas
cylinder is of known concentration, it can be
calibrated to any desired range.
Example: For a sensor range of 0-1000 ppm
and a cylinder of the target gas at 800 ppm:
Voltage =
Target Gas
Value
Calibration Overview
X
5V
Sensor Range
Functional Tests and Calibration • 15
7
Troubleshooting
Symptom
Possible Cause(s)
Green and Red light off
• Check power supply. Check wiring.
• MRLDS-CO2 was possibly damaged in transit. Check
by installing another MRLDS-CO2 to confirm the fault.
Red light on, green LED off
(indicates a fault)
• The sensor may be disconnected from printed circuit
board. Check if the sensor is properly inserted into
board.
• The sensor element has been damaged or has reached
end-of-life and needs to be exchanged. Contact Emerson
Retail Solutions for instructions and support.
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.
Table 7-1 - Troubleshooting MRLDS-CO2
16 • MRLDS-CO2 Gas Detector Manual
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The contents of this publication are presented for informational purposes only and they are not to be construed as warranties or guarantees,
express or implied, regarding the products or services described herein or their use or applicability. Emerson Climate Technologies Retail
Solutions, Inc. and/or its affiliates (collectively “Emerson”), reserves the right to modify the designs or specifications of such products at
any time without notice. Emerson does not assume responsibility for the selection, use or maintenance of any product. Responsibility for
proper selection, use and maintenance of any product remains solely with the purchaser and end-user.
026-1312 Emerson is a trademark of Emerson Electric Co. ©2017 Emerson Climate Technologies Retail Solutions, Inc. All rights reserved.
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