During the 50% pump capacity test, what percentage of rated capacity should be delivered?

• A. 60%
• B. 70%
• C. 80%
• D. 50%

Answer: (D)

The key idea here is testing the pump under a partial-load condition. In the 50% pump capacity test, you operate the pump at half of its rated capacity. This verifies that, when flow is reduced to 50%, the pump can still meet the required discharge pressure and that the pump’s controls and performance behave correctly across a partial-load operating point. It checks the governor response, efficiency, and system pressure stability at lower flow, which is a common real-world scenario.

The other options describe higher load levels (more than half of rated capacity) and are not what this specific test is assessing, so they don’t fit the procedure.