CHEMCO Exit Exam • Set 5 Question 15 of 30

While using a combustible gas indicator, if the hydrocarbon content of the atmosphere exceeds the U.E.L., the needle of the indicator will

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Direct Answer

Option D: move to the maximum reading and immediately return to zero

When a combustible gas indicator detects a hydrocarbon concentration exceeding the Upper Explosive Limit (UEL), the instrument typically registers a maximum reading and then immediately returns to zero, indicating a dangerously rich atmosphere, as per ISGOTT.

All Options

remain at zero without moving

move to the maximum reading and stay there

move halfway up the scale

move to the maximum reading and immediately return to zero (Correct Answer)

Detailed Explanation & Context

Relevant Framework: STCW 2010 Manila Amendments • DG Shipping E-Learning & Exit Exam Standards • Advanced Training for Chemical Tanker Cargo Operations (CHEMCO).

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