Working Principle of a Clear Water Centrifugal Pump

Clear water centrifugal pumps operate by using a motor to drive the rotation of an impeller, transporting liquid through the action of centrifugal force. To balance axial thrust, most pumps feature wear rings on both the front and back of the impeller, as well as balance holes in the impeller's rear shroud. The axial sealing system-comprising a gland, a lantern ring, and packing material-prevents air ingress or excessive leakage. When the impeller has balance holes, the cavity containing the soft packing connects to the impeller's suction inlet; since a vacuum at the inlet could easily draw air in along the shaft sleeve surface, pressurized water from the pump chamber is routed through a small hole in the pump cover to the lantern ring to maintain the seal. The pump is directly driven by the motor via an extended flexible coupling, and the direction of rotation is clockwise when viewed from the drive end.

Self-priming clear water centrifugal pumps utilize a pump casing design featuring axial liquid recirculation; the casing consists of a suction chamber, a liquid storage chamber, a volute chamber, recirculation ports, and a gas-liquid separation chamber. Upon startup, the impeller draws in and mixes the liquid stored in the suction chamber with the air from the suction pipeline. Driven by centrifugal force, the liquid-entraining the gas-flows toward the outer edge of the volute chamber, forming a high-speed rotating liquid ring at the impeller's periphery. The gas-liquid mixture enters the separation chamber through a diffuser; as the flow velocity drops, the gas separates and is discharged through the pump outlet, while the degassed liquid returns to the storage chamber to re-enter the impeller and continue the cycle. This process repeats until all air is evacuated from the suction pipeline, completing the self-priming operation.

Multistage clear water centrifugal pumps employ multiple impellers operating in series to incrementally increase liquid pressure (head). Their operation is likewise based on centrifugal force generated by impeller rotation; however, their structural design requires special consideration to balance the significantly higher axial forces inherent in multistage pumps.