Excessive air leakage into the suction side of a centrifugal pump would be indicated by which of the following operational problems?

Correct Answer: Option A — The pump delivers full capacity when started, but gradually slackens off to an abnormally low flow.

Air leakage into the suction side creates a gas-bound condition. Initially, the pump may move fluid, but as air accumulates in the impeller eye, the discharge flow gradually decreases. This phenomenon, often called air binding, prevents the pump from maintaining its prime and results in the observed loss of capacity.