22
9. If the control equipment display requires adjustment consult the
operating manual for the equipment.
10.Remove the gas and allow the sensor to completely settle before re
checking the zero setting.
11.Close the junction box of the detector ensuring that the lid is securely
tightened, and the grubscrew is secured.
12.The detector is now operational.
3.1b Commissioning procedure
– oxygen type only
1. Follow steps 1 to 5 given in 3.1a above.
Zeroing the detector
2. Remove the amplifier PCB cover and move the LINK on the amplifier
board from ‘RUN’ to ‘SET ZERO’. Adjust the ‘ZERO’ pot on the
amplifier until the DVM reads 40 mV. Check that the control equipment
display reads zero.
Calibrating the detector
3. With normal clean air present at the detector, replace the LINK to ‘RUN’
on the amplifier board, adjust the ‘CAL’ pot until the DVM reads 174 mV,
(20.9% O
2
). Leave the LINK in ‘RUN’ position and refit the PCB cover.
4. If the control equipment display requires adjustment consult the
operating manual for the equipment.
5. Follow steps 11 and 12 given in 3.1a above. The detector is now
operational.
3.2 Routine maintenance
The operational life of the sensors depends on the application, frequency
and amount of gas being seen. Under normal conditions (6 monthly
calibration with periodic exposure to CAL gas) the life expectancy of the
toxic sensors is 23 years. Oxygen sensors must be replaced every two
years.
Site practices will dictate the frequency with which detectors are tested.
Crowcon would recommend that detectors be gas tested at least every 6
months and recalibrated as necessary. To recalibrate a detector follow
the steps given in 3.1 above. The calibration frequency should be
increased in environments subject to extreme heat and/or dust, and
where gas is frequently present.
The sinter should be inspected regularly, and replaced if it has become
contaminated. A blocked sinter may prevent gas from reaching the
sensor.
3. Operation
Xgard Type 2
