When the pressure P1 at the inlet of the split case pump is equal to or less than the saturated vapor pressure PV of the liquid at the same temperature, the liquid vaporizes, and the bubbles rapidly condense or rupture under the action of high pressure to generate an impact with extremely high pressure and high frequency. The pump body vibrates strongly and emits noise, and the liquid flow, head (outlet pressure) and efficiency are significantly reduced. This phenomenon is called cavitation of a split case centrifugal pump.
Operation of the pump in the middle (energy conversion): Before the pump starts, the pump casing is filled with the liquid to be transported; after starting, after the start, the impeller is driven by the shaft to rotate at a high speed, and the liquid between the blades must also rotate. Under the action of centrifugal force, the liquid is thrown from the center of the impeller to the outer edge and obtains energy, leaving the outer edge of the impeller at high speed into the volute casing.
In the volute, the liquid decelerates due to the gradual expansion of the flow path, and part of the kinetic energy is converted into static pressure energy, and finally flows into the discharge pipe at a relatively high pressure and is sent to a place where it is needed. When the liquid flows from the center of the impeller to the outer edge, a certain vacuum is formed at the center of the impeller. Since the pressure above the liquid level of the tank is greater than the pressure at the inlet of the pump, the liquid is continuously pressed into the impeller. It can be seen that as long as the impeller rotates continuously, the liquid is continuously sucked in and discharged.
