A combustible gas indicator will operate...

Question 1 / 270705eccef9ebacbc34ba4d465ef

Question 1 of 270705eccef9ebacbc34ba4d465ef

A combustible gas indicator will operate correctly ONLY when the __________.

Question 1 of 27070

A combustible gas indicator will operate correctly ONLY when the __________.

🔍 Key Concepts

• Combustible gas indicator purpose – what it actually measures in an atmosphere • Explosive limits (LEL vs UEL) – lower vs upper explosive limits for flammable gases • Role of oxygen – whether the instrument (and an explosion) needs a certain oxygen percentage to work

💭 Think About

• Think about when a gas/air mixture can actually burn or explode: what range of concentration is required relative to the lower and upper explosive limits? • Consider whether a combustible gas indicator is designed to work in a space with no oxygen at all, or if it requires some oxygen present. • Ask yourself if normal atmospheres always have some CO₂ in them — would a typical instrument be designed to require a compartment completely free of CO₂?

✅ Before You Answer

• Be clear on the difference between Lower Explosive Limit (LEL) and Upper Explosive Limit (UEL) and which one is typically used for calibration and readings. • Verify in your notes whether a combustible gas indicator will still function correctly in oxygen-deficient atmospheres. • Consider whether CO₂ is normally present in air and whether its presence alone would stop the instrument from working.

Question 1 of 27070

A combustible gas indicator will operate correctly ONLY when the __________.

hydrocarbon content of the atmosphere is less than the Upper Explosive Limit

atmosphere is deficient in oxygen

compartment to be tested is free of CO₂

All of the above

Question 1 / 270705eccef9ebacbc34ba4d465ef

Question 1 of 270705eccef9ebacbc34ba4d465ef

A combustible gas indicator will operate correctly ONLY when the __________.

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Question 1 of 27070

A combustible gas indicator will operate correctly ONLY when the __________.