Which condition can lead to cavitation in a pump?

• A. Too cold and too viscous
• B. Too hot, too light or too much flow, anything to cause vapor pressure to go up
• C. Low ambient humidity
• D. Under-inflated tires

Answer: (B)

Cavitation happens when the pressure in the pump falls to or below the liquid’s vapor pressure, so tiny vapor bubbles form and then collapse as they move into higher-pressure regions. The likelihood of cavitation rises when the liquid’s vapor pressure is higher, which occurs as the liquid gets hotter. So heating the fluid makes cavitation more probable because the pump has to overcome a higher vapor-pressure threshold to keep the liquid in a non-vapor state.

Also, high flow can contribute by creating larger velocity and pressure drops on the suction side or at the impeller eye. That local pressure dip can push the operating point into the region where it’s below the vapor pressure, facilitating bubble formation. So a condition that elevates vapor pressure (being too hot) or that promotes local pressure drops (too much flow) can lead to cavitation.

In contrast, being too cold or too viscous generally lowers vapor pressure and increases resistance, making cavitation less likely; unrelated factors like humidity or tire inflation don’t affect the pump’s cavitation tendency.