Which are signs of a pump executing improperly and how would you troubleshoot?

• A. High discharge pressure
• B. Cavitation noise only
• C. Low discharge pressure, cavitation (noise), surging, leaks; troubleshoot by checking prime, leaks, valve positions, and pump speed (RPM)
• D. Leaks only

Answer: (C)

Signs of improper pump operation show up as a drop in discharge pressure, cavitation noise, flow instability such as surging, and visible leaks. Low discharge pressure usually means the pump isn’t developing enough head due to suction issues, throttled flow, air entering the system, or an incorrect speed. Cavitation noise happens when local pressure at the impeller falls below vapor pressure, creating bubbles that collapse and damage the pump; this is commonly caused by insufficient suction head, leaks, blockages, or operating at a speed/flow that the system can’t support. Surging indicates the pump and system aren’t on a stable operating point, often from mismatched valve settings or an improper speed setting. Leaks drain pressure and introduce air, further degrading performance.

Troubleshooting by first ensuring the pump is properly primed removes air from the suction path and restores the needed suction pressure. Checking for leaks in the suction and discharge lines eliminates sources of air ingress and pressure loss. Verifying valve positions ensures the system resistance seen by the pump matches its design, preventing choking or improper flow. Confirming the pump speed (RPM) ensures the operating point aligns with the system head and desired flow, avoiding under- or over-speed conditions that drive cavitation or surging. These checks directly address the observed symptoms and help restore proper pump performance.