Tankerman · Gauging — Closed / Restricted
On a tanker handling toxic or volatile cargo, closed gauging is used because it:
- AAdds oxygen to the tank
- BRequires opening every tank hatch
- CMeasures the level without opening the tank to atmosphere, preventing vapor release and crew exposure✓ Correct
- DWorks only on empty tanks
Explanation
Closed gauging (fixed/portable level systems that read through a vapor-tight fitting) lets the tankerman measure ullage and temperature without venting cargo vapor to the deck or exposing personnel — required for toxic cargoes and for inerted tanks whose positive pressure must be preserved.
Authority: ISGOTT; SOLAS/IGC/IBC
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