Pump cavitation can be caused by which condition?

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

Answer: (A)

Cavitation happens when pressure inside the pump drops below the liquid’s vapor pressure, causing tiny vapor bubbles to form. On a water distribution pump, the suction side dictates how much pressure is available at the eye of the impeller. If the suction line is clogged, flow into the pump is restricted and suction pressure falls, which can drive the pressure below the liquid’s vapor pressure and trigger cavitation. A motor running hot is an electrical/thermal problem for the driver, not a direct cause of low suction pressure in the fluid. A worn impeller changes flow characteristics and efficiency but doesn’t by itself create the low suction pressure needed for cavitation. A blocked discharge line raises back pressure on the discharge side and can reduce flow, but cavitation is driven by a drop on the suction side, not an overpressure on the discharge side.