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qazxsw123 · 16th Apr 2018, 6:36 pm

the sensor is a heated wire, in a bridge cct. the resistance of the wire changes when the gas is passed over it thus altering the bridge and changing the display on the meter. they take a load of U2 1.5v batts. the switch and meter will have a batt test position. the sensor is damaged by the petrol vapour that leaves a coating on the wire. there was a filter unit to be inserted in the sensor line if petrol contamination was expected. and yes when a petrol tank in a garage leaks it finds its way into the cable ducts.

you should be able to test it using the gac cooker, just turn it on for a second and then test the air around it.

16th Apr 2018, 6:36 pm	#11
qazxsw123 Triode Join Date: Nov 2016 Location: Frinton on Sea, Essex, UK. Posts: 45	Re: GPO Indicator Gas No5 the sensor is a heated wire, in a bridge cct. the resistance of the wire changes when the gas is passed over it thus altering the bridge and changing the display on the meter. they take a load of U2 1.5v batts. the switch and meter will have a batt test position. the sensor is damaged by the petrol vapour that leaves a coating on the wire. there was a filter unit to be inserted in the sensor line if petrol contamination was expected. and yes when a petrol tank in a garage leaks it finds its way into the cable ducts. you should be able to test it using the gac cooker, just turn it on for a second and then test the air around it.