A common cause of pump cavitation is which of the following?

• A. The discharge line is blocked
• B. The suction line is clogged
• C. The motor is running hot
• D. The impeller is oversized

Answer: (B)

Cavitation happens when the pressure at the pump inlet falls below the liquid’s vapor pressure, causing tiny vapor bubbles that collapse as they move into higher-pressure areas. A clogged suction line lowers the flow into the pump and reduces the pressure at the eye of the impeller, cutting into the available suction head. That drop in inlet pressure makes cavitation much more likely. So, the suction line being blocked is the common cause because it directly undermines the pump’s ability to draw in fluid with sufficient pressure.

Blocking the discharge line raises backpressure on the outlet side, which doesn’t drive cavitation. A motor running hot indicates overheating or overload, not cavitation. An oversized impeller changes flow and head but doesn’t inherently create the low inlet pressure needed for cavitation.