Field Calibration Procedure - Macurco TX-12-AM Instructions D'utilisation

4. The Fan relay should activate according to the settings.
5. With the display function turned "On" and the gas concentration reaching the Alarm Relay setting, (20 ppm, for example) the
display will flash back and forth between "ALr" and "20". The buzzer will sound indicating "Alarm" if the buzzer is turned "On".
With the display function turned off the display does not show the gas concentration, but will show "ALr" when the Alarm relay
is activated.
Note: If the Alarm relay fails to operate 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 (go through recalibration and re-test).
c. Detector is in need of servicing (return unit to factory for servicing).
d. Detector has Alarm relay set to disable (diS) or higher than 20. Set Alarm relay to 20 ppm and repeat the test.
6. Remove the gas from the sensor after Test. Proceed to Test the 4-20mA output or replace the top cover. Alarm relay test is
complete.
Testing the 4-20mA current loop
1. Connect the 25 ppm cylinder of Ammonia to the regulator.
2. Check the pressure gauge. If there is 25-psi or less the cylinder should be replaced.
3. Place the test hood from the regulator over the gas 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 8 mA at 25 ppm. See 4-20 mA diagram on page 7.
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 (go through recalibration 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 TX-12-AM (make sure the LED is aligned with the front case hole). 4-20
current loop test is complete.

FIELD CALIBRATION PROCEDURE

Note: For optimum calibration results the unit should be in clean air and be in a low ambient air flow.
Zero the Sensor
1. Ensure that the ambient air has less than 0.1 ppm NH3 before proceeding with Zeroing the sensor. Remove the Philips screw
on the front of the TX-12-AM. Pull the front cover of the unit off.
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