Cavitation occurs when local pressure drops below what?

Cavitation occurs when local pressure drops below what?

• A. The ambient pressure
• B. The liquid's saturation temperature
• C. The liquid's vapor pressure
• D. The system pressure

Answer: (B)

Cavitation starts when the local pressure drops below the liquid’s vapor pressure at the current temperature. Vapor pressure is the pressure at which liquid and vapor are in equilibrium for a given temperature; if the surrounding pressure falls below that value, the liquid locally boils and vapor bubbles form. The other options aren’t the threshold for this phase change: ambient or system pressure aren’t the thermodynamic limit, and the saturation temperature is a temperature reference, not the pressure level that triggers cavitation. In practice, keeping the local pressure above the liquid’s vapor pressure (accounting for temperature) prevents cavitation.

Cavitation starts when the local pressure drops below the liquid’s vapor pressure at the current temperature. Vapor pressure is the pressure at which liquid and vapor are in equilibrium for a given temperature; if the surrounding pressure falls below that value, the liquid locally boils and vapor bubbles form. The other options aren’t the threshold for this phase change: ambient or system pressure aren’t the thermodynamic limit, and the saturation temperature is a temperature reference, not the pressure level that triggers cavitation. In practice, keeping the local pressure above the liquid’s vapor pressure (accounting for temperature) prevents cavitation.