Dwyer Instruments CMT200 Installation and operating instructions

Model CMT200 Carbon Monoxide Transmitter
Specications - Installation and Operating Instructions
Bulletin AQ-CMT200
The Model CMT200 Carbon Monoxide Transmitter provides a eld selectable
current or voltage output that is proportional to the gas concentration in underground
parking garages, vehicle maintenance facilities, or mechanical rooms. A eld
replaceable, electrochemical sensor provides accurate readings for up to 4 years
with proper calibration. Field calibration can be done by using Model GCK-200CO-
2000CO2 calibration gas, Model A-507A calibration adapter, and the on board span
and zero potentiometers.
CMT200
CMT200-R
SPECIFICATIONS
Sensor: Field replaceable electrochemical, 4 year typical lifespan.
Range: 0 to 200 ppm.
Output Drift: <5% per year in air.
Coverage Area: 5000 to 7000 sq. ft. typical.
Accuracy: ±2% FS at the time of calibration.
Temperature Limits: -4 to 122°F (-20 to 50°C).
Storage Temperature: For best sensor life, 32 to 68°F (0 to 20°C).
Humidity Limits: 15 to 90% RH constant; 0 to 99% RH intermittent.
Response Time: <45 seconds to 90% of nal value.
Calibration: 15 turn span and zero adjustment potentiometers.
Housing: UV resistant polycarbonate.
Output: Jumper selectable 4 to 20 mA (loop powered) or 2 to 10 V (load must be
>50 KΩ).
Power Requirements: Current Output: 18 to 28 VDC; Voltage Output: 18 to 28 VDC/
VAC, reverse polarity protected.
Electrical Connection: Removable terminal block, add two PG11 and one PG 16
knockouts for conduit tting.
Weight: 0.28 lb (0.11 kg).
Agency Approvals: CE.
Ø1-5/64
[27.317]
Ø3-1/4
[82.713]
1-31/32
[50.196]
1-37/64
[39.891]
3-9/64
[79.781]
2-21/64
[59.073]
Disconnect power supply before installation to prevent electrical
shock and equipment damage. Make sure all connections are in
accordance with the job wiring diagram and national and local electrical codes. Use
copper conductors only.
WARNING
Use electrostatic discharge precautions (e.g., use of wrist straps)
during installation and wiring to prevent equipment damage.
Avoid locations where severe shock or vibration, excessive
moisture or corrosive fumes are present.
Do not exceed ratings of this device; permanent damage
not covered by warranty may result. The 4 to 20 mA wiring
congurations are not designed for AC voltage operation.
CAUTION
CAUTION
CAUTION
2-15/64
[56.75] 3-45/64 [94.06]
3-1/8 [79.38]
4-17/32
[115.09]
5-7/64
[129.78]
21/64
[8.33]
1-5/64
[27.38]
®
DWYER INSTRUMENTS, INC.
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.
Phone: [phone]
Fax: [phone]
www.dwyer-inst.com
e-mail: [email protected]

WIRING
Use maximum 18 AWG wire for wiring terminals. Refer to Figure 1 or Figure 2 for
wiring information. The terminal block is removable for ease of installation.
4 to 20 mA Output
Before wiring for 4 to 20 mA output, check that the jumper P1 is connected so that the
jumper is on the two pins furthest from the terminal block as shown in gure 1. 4 to
20 mA output may be powered by 18 to 28 VDC. The transmitter is reverse polarity
protected. The load must not exceed the maximum loop resistance, Rmax, listed on
the next page. The load and power supply should be connected according to Figure 1.
Max Loop Resistance
For 4 to 20 mA Outputs
The maximum allowable loop resistance depends on the power supply voltage.
Maximum loop voltage drop must not reduce the transmitter voltage below the 18 VDC
minimum. Maximum loop resistance can be calculated with the following equation. Vps
is the power supply voltage.
Rmax = Vps – 18
20 mA
Some receivers, particularly loop powered indicators, may maintain a xed loop
voltage to power the device. This voltage drop must also be subtracted from the power
supply voltage when calculating the voltage margin for the transmitter. The following
equation takes this into account. Vrec is the receiver xed voltage.
Rmax = Vps – 18 – Vrec
20 mA
2 to 10 VDC Output
Before wiring for 2 to 10 VDC output, check that the jumper P1 is connected so that
the jumper is on the two pins closest to the terminal block as shown in gure 2. 2 to
10 VDC output may be powered by 18 to 28 VAC or VDC. The transmitter is reverse
polarity protected. The load must be greater than 50 KΩ. The load and power supply
should be connected according to Figure 2.
P1
+
+
-
-
POWER
SUPPLY
RECEIVER P1 JUMPER SE
T
FOR CURRENT
VOLTAGE OUTPUT - WIRING AND P1 SETTING
SPAN ZERO
3 2 1
Figure 2
Figure 1
P1
+
+
-
-
P1 JUMPER SE
T
FOR CURRENT
CURRENT OUTPUT - WIRING AND P1 SETTING
POWER
SUPPLY
RECEIVER
SPAN ZERO
3 2 1
INSTALLATION
• The transmitter should be mounted at normal breathing height, approximately 5 to 6
ft above the oor.
• The unit may be mounted in the horizontal or vertical position. It should be
mounted in an area that is shielded from direct contact with the elements or direct
sunlight.
• Mount in an area that will prevent the sensor from having any direct contact with
water.
• The unit should be placed in an area that will give an average of the air quality. Do
not place the unit so it will receive direct engine exhaust. Prolonged exposure
to direct engine exhaust may damage the sensor.
MOUNTING
1. Twist the lid a quarter turn and pull the lid from the base housing.
2. Remove the desired conduit tting knock out and install conduit tting (not
provided).
3. Position the transmitter where it is to be mounted and mark the mounting hole
located in the center of the housing base.
4. Drill or punch out marked locations.
5. Place the transmitter on the wall and align the mounting hole. Install the
transmitter using the included screw and washer through the mounting hole.
6. Set the jumper selection for current or voltage output.
7. Proceed with the wiring according to diagrams in gures 1 and 2.
8. Replace the cover.
The electrochemical sensors should be stored in an environment
with a minimum humidity level of 20% RH. If the sensor dries out,
replacements will not be covered under warranty, but they can be revived by allowing
them to stabilize in an environment above 40% RH for 10 days. Once revived, they
need to be recalibrated before use.
These are general guidelines. Local laws or ordinances will take
precedence.
NOTICE
NOTICE
CALIBRATION
Calibration of the Model CMT200 requires an A-507A calibration adapter, model GCK-
200CO-2000CO2 calibration gas, a multimeter, and a small at head screw driver.
1. Turn off power to the transmitter.
2. Remove the lid from the housing by twisting it a quarter turn and pulling off.
3. Replace the receiver shown in gure 1 or 2 with a multimeter and restore the
power to the transmitter.
4. Attach the tubing from the zero calibration gas to the A-507A calibration adapter.
5. Securely attach the A-507A to the CMT200 as shown in gure 3.
6. Allow the calibration gas to ow at a rate of 0.5 to 1.0 slpm for at least 3 minutes.
7. Adjust the zero potentiometer (blue) until the output reading on the multimeter
reads 4 mA or 2VDC (depending on output selection).
8. Repeat steps 4 through 6 using the span calibration gas.
9. Adjust the span potentiometer (grey) until the output reading on the multimeter
reads 20 mA or 10 VDC (depending on output selection).
10. Turn off the power to the transmitter.
11. Replace the multimeter with the receiver as shown in gures 1 and 2 and
restore the power to the transmitter.
12. Remove the A-507A calibration adapter.
13. Replace the lid on to the transmitter.

Sensor Replacement
A replacement sensor is available from Dwyer Instruments, Inc. Order part number
A-505 for a replacement CO sensor.
1. Turn off power to the transmitter and remove the terminal block from the circuit
board.
2. Remove the two screws in the circuit board mounting bracket shown in Figure 4.
3. Gently slide the circuit board and sensor out of the sensor guard.
4. Remove sensor by gently pulling the sensor straight out of its sockets.
5. Install the new sensor by gently pressing the pins of the sensor into the sockets in
the circuit board.
6. Slide the sensor and circuit board back into the sensor guard and align the
mounting holes on the circuit board brackets with the holes on the housing.
7. Reattach the circuit board bracket to the housing and the terminal block to the
circuit board.
8. Go through the calibration procedures in the calibration section.
MAINTENANCE/REPAIR
Upon nal installation of the Model CMT200 Transmitter, no routine maintenance is
required with the exception of calibration. As with all electrochemical type gas sensors,
routine calibration is required. It is recommended that units be re-calibrated at 6 month
intervals, to maintain the published accuracy, or as required by local ordinances or
other requirements. The units will maintain 5% accuracy if they are re-calibrated at 12
month intervals.
Except for sensor replacement and calibration, the Model CMT200 is not eld
serviceable and should be returned if repair is needed (eld repair should not be
attempted and may void warranty). Be sure to include a brief description of the
problem plus any relevant application notes. Contact customer service to receive a
return goods authorization number before shipping.
Figure 3 Figure 4
CMT200
CMT200
CMT200-R
CMT200-R
Zero adjustment
Zero adjustment
Span adjustment
Span adjustment
Circuit board
mounting
bracket screw
Circuit board
mounting
bracket screw
If the span potentiometer on the Model CMT200 cannot restore the
output to 20 mA, the sensor will need to be replaced.
When replacing the sensor, reset each potentiometer position to
the middle of the range before adjusting the calibration.
NOTICE
NOTICE
This symbol indicates waste electrical products should not be disposed
of with household waste. Please recycle where facilities exist. Check with
your Local Authority or retailer for recycling advice.

©Copyright 2019 Dwyer Instruments, Inc. Printed in U.S.A. 4/19 FR# 444080-00 Rev. 7
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DWYER INSTRUMENTS, INC.
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.
Phone: [phone]
Fax: [phone]
dwyer-inst.com
e-mail: [email protected]