Tankers carrying cryogenic cargoes, such as LNG, are fitted with gas detector systems alarmed at 30% of the lower explosive limit. If the gas detector alarms sounds, this means __________.

Correct Answer: Option A — a flammable vapor concentration exists at the sample point, but it is too lean to burn

A Lower Explosive Limit (LEL) alarm at 30% indicates that flammable hydrocarbon vapors are present in the sampled atmosphere, but their concentration is well below the threshold required to sustain combustion.