During a pump capacity test, a pumper should deliver what percentage of its rated capacity at 250 psi for 10 minutes?

• A. 25%
• B. 100%
• C. 50%
• D. 75%

Answer: (C)

At high discharge pressure, a pump can deliver less flow because the head the pump must overcome reduces its output along the pump curve. A capacity test at 250 psi is checking that the pump can still operate reliably when pushed to a substantial head for a sustained period. The standard expectation is that the pump will be able to deliver about half of its rated capacity even at that elevated pressure, and it should do so for 10 minutes to verify thermal stability and mechanical reliability. So delivering around 50% of rated capacity at 250 psi ensures the pump has enough flow to be useful while staying within safe operating limits under sustained high-pressure conditions. The other options would either require unrealistically high flow at high head or too little flow to meaningfully test performance.