Tankerman · Cargo Properties — Vapor Density
Petroleum cargo vapors have a vapor density greater than 1, which means they:
- ARise and disperse upward quickly
- BCannot be detected
- CAre heavier than air and collect in low, poorly ventilated spaces✓ Correct
- DAre lighter than air
Explanation
Because hydrocarbon vapors are denser than air, they sink and pool in low areas—the bottom of tanks, cofferdams, pump rooms, and on deck in still air—where they form flammable/toxic concentrations. Ventilation and gas testing target these low points.
Authority: ISGOTT
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