Tankerman · Cargo — Flammable Range
A vapor mixture that is 'too rich to burn' contains:
- AVapor below the lower flammable limit (LFL)
- BVapor above the upper flammable limit (UFL)✓ Correct
- CExactly the stoichiometric concentration
- DNo hydrocarbon vapor at all
Explanation
Above the upper flammable limit there is too much fuel vapor and too little oxygen to ignite — the mixture is 'too rich.' Below the LFL it is 'too lean.' Only between LFL and UFL will the mixture burn.
Authority: Tank Vessel Operations — Flammability
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