23
Testing the 4-20mA current loop
1.
Connect the 2000 ppm cylinder of carbon dioxide to the regulator.
2.
Check the pressure gauge. If there is 25-psi or less the cylinder should be replaced.
3.
Place the cap from the regulator over the CO2 sensor. Turn on the regulator to start the gas flow.
4.
The Fan relay should activate according to the settings.
5.
The Alarm relay should activate according to the settings.
6.
The 4-20 mA output should ramp up from 4mA in clean air to 20mA at 2000 ppm. See 4-20 mA diagram on page 8.
Note:
If the 4-20mA output does not ramp up within 2 minutes, there are four possibilities:
a.
Gas cylinder is empty, check the pressure gauge. Replace the gas cylinder if 25-psi or less.
b.
Unit needs to be re-calibrated (automated background calibration and re-test).
c.
Detector is in need of servicing (return unit to factory for servicing).
d.
Detector has 4-20 mA option set to “OFF”. Set 4-20mA option to “On” and repeat the test.
7.
Remove the gas from the sensor. Re-assemble the CD-12 (make sure the LED is aligned with the front case hole). You are
done.
