SafetyQuestion 691 of 700
When atmospheric testing is performed before entering a permit-required confined space, in what ORDER should the atmosphere generally be tested?
a.Toxic gases first, then oxygen, then flammable
b.Flammable first, then toxic, then oxygen
c.Oxygen first, then flammable/combustible gases, then toxic contaminants
d.The order does not matter as long as all three are tested
Explanation
Correct: test oxygen first (because many combustible-gas meters need adequate oxygen to read correctly), then flammable/combustible gases and vapors, and finally toxic contaminants. Starting with toxics or flammables can give false readings if oxygen is off. The order does matter for accurate, safe results, so 'order does not matter' is incorrect.
Law Reference: Cal/OSHA Title 8 CCR §5157Practice all 700 questions free — no signup required.
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