Your centrifugal ballast pump is producing a pressure less than the designed discharge pressure. What could be the cause?

Correct Answer: Option C — Worn wearing rings.

Worn wearing rings increase the internal clearance between the impeller and casing. This allows high-pressure discharge fluid to recirculate back to the suction side, effectively reducing the pump's net discharge pressure and overall volumetric efficiency. This is a classic symptom of internal wear in centrifugal pump systems.