You suspect a problem with the centrifugal fire pump on your ship, and begin to slowly close the discharge valve. Your suspicion is confirmed when the __________.

Correct Answer: Option D — discharge valve is closed off and there is no change in the discharge pressure

Centrifugal pumps are dynamic machines; if the discharge valve is closed and the pressure remains unchanged, the impeller is likely slipping or the pump has lost its prime. A properly functioning centrifugal pump will exhibit a significant rise in discharge pressure (shut-off head) when the discharge valve is closed.