Macurco OX-12 User Instructions page 22

1. Connect the 17.0% v/v cylinder of oxygen to the regulator.
2. Check the pressure gauge. If there is 25psi or less the cylinder should be replaced.
3. Place the test hood over the gas sensor. Turn on the regulator to start the gas flow.
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, (19.5% v/v, for example) the
display will flash back and forth between "ALr" and "19.5". 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 has Alarm relay set to disable (OFF). Set Alarm relay to 19.5% v/v and repeat the test.
d. Detector is in need of servicing (return unit to factory for servicing).
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 17.0% v/v cylinder of oxygen 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 decrease from 17.4 mA in clean air (20.9% v/v) to 14.9 mA at 17.0% v/v. See 4-20 mA diagram on
page 8.
Note: If the 4-20mA output does not decrease 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 has 4-20 mA option set to "OFF". Set 4-20mA option to "On" and repeat the test.
d. Detector is in need of servicing (return unit to factory for servicing).
7. Remove the gas from the sensor. Re-assemble the OX-12 (make sure the LED is aligned with the front case hole). 4-20 current
loop test is complete.
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