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3.2 Routine maintenance
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 the operational life of
Xgard
. In applications where such
compounds are continuously present we recommend the use of
Crowcon’s fixed point infrared flammable gas detectors, which are
immune to such poisons and inhibitors. Please contact Crowcon for
further details.
The operational life of the pellistors depends on the application and
amount of gas to which the pellistor has been exposed. Under normal
conditions (6 monthly calibration with periodic exposure to CAL gas) the
life expectancy is 35 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.
The sinter should be inspected regularly, and replaced if it has become
contaminated. A blocked sinter may prevent gas from reaching the
sensor.
When performing maintenance on
Xgard
, ensure that the sensor retainer
and junction box lid Orings are present and in good condition to maintain
the ingress protection of the product. See the ‘Spare parts and
accessories’ section for the part numbers of replacement Orings.
3. Operation
Xgard Type 5
