Crowcon T4 - Pellistor Sensors

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2.6.3 Pellistor sensors
Pellistor sensors (or catalytic beads) are specically designed to sense explosive gases. The
detecting element consists of small “beads” of catalyst loaded ceramic whose resistance changes in
the presence of gas.
2.6.4 Pellistor saver mode
Pellistor sensors can suffer degradation if powered while exposed to ammable gas concentrations
greater than 100% LEL, and also if exposed to high levels of H
2
S or silicones.
To reduce degradation T4 employs a Pellistor saver mode.
When the ammable gas exceeds the pellistor saver threshold, the
detector will turn off the sensor for a minimum period of 200 seconds
À.
When pellistor saver mode is activated the user must immediately
move to a clean air environment.
After the dened period the sensor can be re-activated by a single
click of the operator button
Á once the instrument is in a clean air
environment.
After a stabilisation time (
Â), if the gas level still exceeds the threshold
then the sensor will be turned off and the cycle starts again.
While in saver mode and the subsequent stabilise time, the gas level displayed on the LCD screen
will indicate over range. As the sensor has been exposed to a gas level sufcient to cause a sensor
over-range T4 should be gas tested to ensure no lasting damage has occurred.
À
Á
Â
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