Carbon Monoxide Transmitter
Installation Manual
IN-CMD5B1-01-01
May 2, 2017
Page 4
The sensor must be continuously powered for at least 1/2 hour prior to calibration.
For local display, an ammeter can be placed in series of the output. Disconnect the signal wire from the OUT terminal of the
CO sensor. Connect the + lead of the ammeter to the OUT terminal of the CO sensor and connect the COM lead of the
ammeter to the removed signal wire. Set ammeter to porper setting to read a 20 MA signal.
Calibrate the sensor first in clean air with no CO gas present. Simply adjust the ZERO pot on the sensor board until a 4 mA
output is obtained.
Then attach the gas supply. Turn the regulator on/off knob fully off and attach it to the 250 ppm gas bottle and firmly tighten
it by hand. Moisten the sponge and squeeze out any excess water. Place the sponge in the cap so that it will not touch the
sensor but does not plug the hole in the side of the cap. Attach the cap to the fixture over the sensor. Slowly turn the valve
knob on the regulator to let the gas begin flowing.
The regulator will restrict the flow rate to the specified 200 ml/min and the sponge will ensure the gas is in the right humidity
range. Wait for 5 minutes and then adjust the SPAN pot on the sensor board until the output reads 250 ppm. Close the valve
on the tank and take the cap off from the sensor. Calibration is complete.
If the gas cap is too loose on the fixtures, simply place a wrap of electrical tape around the cap to tighten it up.
Once calibration is complete, remove ammeter and reconnect signal wire to OUT terminal of the CO sensor.