Construction of Centrifugal Pump

Construction of centrifugal pump is considered on the example of a monoblock design with air-cooled motor.

The spiral housing, made in the form of a diffuser, houses the impeller with radially curved blades. The impeller is mounted on the motor shaft and secured with a tightening screw.

The pump housing, with a flange and tightening bolts, is connected to the motor housing and forms a single unit with it. For air cooling of the motor, a flywheel is attached to the end of the shaft opposite the impeller, enclosed in a protective cover.

Centrifugal pumps with three-phase connection to the power grid are equipped with asynchronous motors with a short-circuited rotor. Depending on the number of poles, the motor can have the following speeds:

Materials

The pump shaft is made of stainless steel, the impeller is made of steel or stainless steel, and in low-power pumps, they are made of composite materials.

The casing of the centrifugal pump is cast from cast iron, bronze or stainless steel. To protect against corrosion, the casing is coated with cathodic electrophoretic paint, which has good impact-resistant properties and scratch protection.

Shaft Seals

The sealing between the shaft and the pump casing is provided by a mechanical seal or a sliding end-face seal.

A sliding end-face seal consists of two polished graphite or silicon rings mounted on the pump shaft and pressed against each other by a spring. One ring is movable and rotates together with the pump shaft, while the other is fixed in the casing. A thin layer of water is formed between the polished surfaces of the rubbing rings, which simultaneously provides lubrication and cooling.

A mechanical seal is a stuffing box wound around the shaft and fixed with a compression nut. The mechanical seal is made of Kevlar, Twaron, PTFE, or synthetic yarn.

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