In the 50% pump capacity test, the net pressure is applied for how long?

• A. 5 minutes
• B. 10 minutes
• C. 15 minutes
• D. 20 minutes

Answer: (B)

The main idea is to test how the pump behaves under a partial-load condition. In this test you run the pump at about half of its rated capacity and apply net pressure on the discharge side to see if the system can hold a steady pressure without drifting, leaking, or overheating.

Ten minutes is used because it’s long enough to reveal slow leaks, packing gland issues, or heat buildup that could cause pressure to drift or fail, yet short enough to avoid unnecessary wear. If the pressure remains steady within acceptable limits for the full ten-minute period, the pump and its packing, valves, and piping are considered able to operate reliably at 50% capacity.