How is cavitation related to Vapour pressure?
Cavitation occurs in a pump when the temperature and pressure of the liquid at the suction of the impeller equals the vapor pressure. It can happen at low pressures and normal operating temperatures.
At what pressure does cavitation occur?
Cavitation may occur when local static pressure in a fluid reach a level below the vapor pressure of the liquid at the actual temperature. According the Bernoulli Equation this may happen when a fluid accelerates in a control valve or around a pump impeller.
What is cavitation pressure?
Cavitation is a phenomenon in which the static pressure of a liquid reduces to below the liquid’s vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. This results in surface fatigue of the metal causing a type of wear also called “cavitation”.
What is Thomas cavitation number?
Thoma’s Cavitation Factor: It is an equation which is used to measure the cavitation in a hydraulic pump installation. It is denoted by the symbol ‘σ’. NPSHA (Net positive suction head available) is the difference between the absolute head at the inlet of the pump and the vapour pressure head.
What happens when pressure drops below vapor pressure?
Because cavitation occurs in the pump when the fluid pressure drops below its vapor pressure. If the pressure is below the vapor pressure, it will flash to vapor—not because of a temperature change, but because of a pressure change.
How do you measure cavitation?
Practical methods of assessing cavitation can be divided into two basic classes: The direct measurement of ultrasonic energy producing cavitation within a finite volume. The indirect measurement of cavitation energy by observing the effects of cavitation. This can be either within a finite volume or over a finite area.
What is cavitation index?
The cavitation index is the ratio of the pressure differential between the equipment inlet pressure and the fluid vapour pressure to the pressure differential pressure across the equipment.