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

Testing the 4-20mA current loop
1. Connect the 25 ppm cylinder of Hydrogen Sulfide 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 12.5 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-HS (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 H2S before proceeding with Zeroing the sensor. Remove the Philips screw
on the front of the TX-12-HS. Pull the front cover of the unit off.
2. To select Calibration Zero Mode (000), from normal mode, press the Next button three times to get to CAL or Calibration
Mode.
3. Then press the Enter button to get to "000" - Calibration Zero Mode.
4. Press the Enter button and the display will read the current gas level alternating with 000 (blinking) indicating zero calibration
in progress (max 165 sec).
5. If the process is successful, the display will read 0 alternating with PAS (blinking) Zero Calibration complete.
6. If the process was not successful the display will read the current gas level alternating with FAil (fail) (blinking). If this occurs,
repeat steps 2 through 4. If the sensor fails to zero twice contact Technical Assistance: 1-877-367-7891.
Note: The display may just go back to 000 if the process is unsuccessful because the sensor response is too negative or if gas is
present.
7. To return to Normal Mode press Enter and then press Next until "End" is displayed. Press Enter to return to Normal Mode.
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