Tankerman · Inert Gas — Tank Atmosphere
A cargo tank is considered safely inerted for carriage when the oxygen content of the tank atmosphere is maintained below approximately:
- A5% by volume✓ Correct
- B11% by volume
- C15% by volume
- D21% by volume
Explanation
Tanks are kept inerted with oxygen below about 5% by volume (well under the ~11% that supports combustion of hydrocarbon vapor), held at positive pressure to prevent air ingress.
Authority: SOLAS Chapter II-2; ISGOTT
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