Question

Cavitation in the pump occurs when 
1. Vapor pressure of liquid is greater than local pressure of liquid inside the pump
2. Vapor pressure of liquid is lower than local pressure of liquid inside the pump
3. Vapor pressure of liquid is lower than that of atmospheric pressure
4. local pressure of liquid inside the pump is greater than atmospheric pressure

Answer 1

Correct Answer - Option 1 : Vapor pressure of liquid is greater than local pressure of liquid inside the pump

Explanation:

Cavitation:

• It is the formation of gas bubbles of a flowing liquid in a region where the pressure of the liquid falls below its vapour pressure i.e. Vapor pressure of liquid is greater than local pressure.
• It is the phenomenon of formation of vapour bubbles of a flowing liquid in a region where the pressure of the liquid falls below the vapour pressure of the fluid and sudden collapsing of these bubbles in the region of higher pressure.
• In centrifugal pumps, the cavitation may occur at the inlet of the impeller of the pump or at the suction side of the pumps, where the pressure is considerably reduced.
• Hence if the pressure at the suction side of the pump drops below the vapour pressure of the liquid then the cavitation may occur.