Tankerman · Cargo Pumps — Centrifugal Priming
A centrifugal cargo pump loses suction (vapor locks) near the end of discharge because:
- AThe cargo becomes too dense
- BIt pumps better with no liquid
- CCentrifugal pumps are self-priming at all levels
- DIt cannot pump vapor; as the level drops it draws gas, so a stripping system or eductor finishes the tank✓ Correct
Explanation
Centrifugal pumps move liquid efficiently but lose prime when they begin to draw vapor at low tank levels. The last of the cargo is removed by a positive-displacement stripping pump or an eductor that can handle the liquid/vapor mixture, leaving minimal remaining-on-board.
Authority: Cargo pump operating references; ISGOTT
Practice the full Tankerman bank
Free spaced-repetition quizzing across 2550 USCG exam questions — it schedules your reviews so the ones you miss come back until they stick.
Related Tankerman questions
- Transfer — PIC
During a cargo transfer on a tank vessel, the Person-In-Charge (PIC) is primarily responsible for:
- Transfer — DOI
Before a transfer of oil or hazardous material begins, the PICs of the transferring and receiving facilities must complete and agree on a:
- Safety — Inert Gas
The purpose of an inert gas system on a tanker is to:
- Safety — Inert Gas
A cargo tank is generally considered properly inerted when the oxygen content is held at or below:
- Safety — Flammability
A hydrocarbon vapor/air mixture will burn only when its concentration is:
- Safety — Static
To prevent a static-electricity ignition hazard during loading of a static-accumulating cargo, the tankerman should: