Question 10 of 30
Combustible gas indicators operate by drawing an air sample into the instrument
over an electrically heated platinum filament
where it is mixed with nitrogen
where it is ignited by a sparking device
where its specific gravity is measured **Correct answer : over an electrically heated platinum filament**
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Answer & Explanation
The correct answer is Option A: over an electrically heated platinum filament.
Combustible gas indicators (explosimeters) utilize a Wheatstone bridge circuit. An air sample is drawn over an electrically heated platinum filament; the combustion of flammable gas on the filament increases its temperature and resistance, which is then measured and displayed as a percentage of the Lower Explosive Limit (LEL).