Crowcon Xgard Bright, Installation, Operation And Maintenance Instructions

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Operation
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English
3.8 Sensor replacement
The operational life of sensors depends on the application and amount of gas
to which the sensor has been exposed. Under normal conditions (6 monthly
calibration with periodic exposure to test gas) the typical life expectancy of
sensors is as follows:
• Oxygen sensors: 2 years.
• Electrochemical toxic gas sensors: 2-3 years.
• Pellistors: 3-5 years.
• IR sensors: 10+ years.
• MPS sensors: 5+ years
Pellistors can suffer from loss of sensitivity when there is a presence of poisons
or inhibitors such as silicones, sulphides, chlorine, lead or halogenated
hydrocarbons. Crowcon use poison resistant pellistors to maximise operational
life, however in applications where such compounds are present we recommend
the use of IR sensors which are immune to such poisons and inhibitors.
Toxic and flammable gas sensor modules should be replaced when they fail
to calibrate or show a very low response to test gas. Oxygen sensors must be
replaced every two years.
To replace a sensor module:
1. Switch off and isolate power to the detector.
2. Loosen the grub-screw and unscrew the sensor retainer.
3. Carefully withdraw the sensor module by grasping the top and bottom of
the moulding.
4. Fit the replacement sensor (having checked that the part number matches
that stated on the detector junction box label). Take care to align the
locating pins correctly with the slots in the
Xgard Bright enclosure.
5. Re-fit the sensor retainer having first inspected the sinter to make sure that
it has not become contaminated. Contaminated sinters must be replaced
as any blockages may prevent gas from reaching the sensor. Ensure the
grub-screw is re-secured.
6. Zero and calibrate the new sensor.
Warning: Xgard Bright sensor modules are NOT compatible with
Xgard sensor Modules.