When pumping sour crude, which gas should be tested for prior to entering the cargo pump room to repair a leaking pump?

Correct Answer: Option C — Hydrogen sulfide

Sour crude contains high concentrations of hydrogen sulfide (H2S), a highly toxic and lethal gas. Before entering a pump room or enclosed space where sour crude has been handled, testing for H2S is mandatory to prevent fatal exposure, as it can be detected at low levels but quickly paralyzes the senses.