How would you identify potential suction entrainment entering the pump and what actions would you take to mitigate it?

• A. Listen for air or loss of prime; tighten suction connections, repair leaks, re-prime, and ensure water source is uninterrupted.
• B. Observe a rising water level, and open discharge valve.
• C. Increase engine RPM to overcome entrainment; ignore leaks.
• D. Submerge the pump to prevent air entry.

Answer: (B)

Suction entrainment is when air gets pulled into the pump through the suction line, breaking the prime and causing unstable flow. A clear way to detect this is to watch for changes in the pump’s water level on the suction side: a rising water level can indicate air pockets forming as the pump struggles to pull water.

To mitigate it, vent the system by opening the discharge valve slightly. This allows trapped air to escape and helps water begin to flow steadily, which assists in re-priming the pump. Once water flow through the line is continuous and the prime is restored, close the discharge valve and verify the suction side is sealed and the water source remains uninterrupted. If needed, re-prime fully and recheck for leaks in the suction connections.

Listening for air or assuming a fix by increasing engine speed doesn’t address the air in the suction directly, and submerging the pump doesn’t solve the entrainment issue.