Testing The 4-20Ma Current Loop; Manual Calibration - Cd-12Mc Only - Macurco CD-12H Mode D'emploi

6. Remove the gas from the sensor after Test. Proceed to Test the 4-20mA output or replace the top cover.
4.4.3

Testing the 4-20mA current loop

1. Connect the 5000-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 CO
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 5000 ppm. See
Note: If the 4-20mA output does not ramp up within 2 minutes, there are four possibilities:
a. The 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. The detector is in need of servicing (return unit to the factory for servicing).
d. The 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-"x" (make sure the LED is aligned with the front case hole). You are
done.
4.4.4 Manual Calibration – CD-12MC ONLY
Note: For optimum calibration results the unit should be in the clean air and be in a low ambient air flow.
1. Remove the Philips screw on the front of the CD-12MC. Remove the front cover.
2. Open the FCK. Connect the 400-ppm gas cylinder to the regulator.
3. Check the pressure gauge on the regulator. If you have 25-psi or less you will need to replace the gas canister. Check the
expiration date on the cylinder, if it has passed the expiration date the cylinder should be replaced.
4. Assemble regulator, hose, and Calibration Hood and place the hood over the CO
5. On the detector press the Menu / Next button three times to get to the CAL menu. Press Enter / Test button
6. With the display showing "400" press Enter / Test button. The display will begin flashing "400" and "____".
7. Turn on the regulator to start the gas flow and wait with the gas applied continuously.
sensor. Turn on the regulator to start the gas flow.
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4-20 mA diagram.
sensor.
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