Centrifugal pumps are composed of many parts, which can be roughly divided into three types according to the working state of each component at work: rotating parts, fixed parts and handover parts.

1. Impeller

The impeller is the core component of the pump, which allows the water to gain kinetic energy and flow. The impeller is composed of blades, covers and hubs, and when selecting impeller materials, in addition to considering the mechanical strength under the action of centrifugal force, the wear resistance and corrosion resistance of the material should also be considered. Most impellers are currently made of cast iron, cast steel and bronze.

Impellers can generally be divided into two types: single-suction impeller and double-suction impeller. Single-suction impeller.

2. Pump shaft

The pump shaft is used to rotate the pump impeller. Common materials are carbon steel and stainless steel. The pump shaft should have sufficient torsional strength and sufficient stiffness, and its deflection should not exceed the allowable value. The impeller and shaft are connected by keys. The key is the connection of the rotating body, the centrifugal pump generally uses a flat key, this key can only transmit torque without fixing the axial position of the impeller, in the large and medium-sized water pump in the axial position of the impeller is usually used shaft sleeve and the nut of the parallel bushing to position.

3. Pump casing

Its water crossing part requires good hydraulic conditions. When the pump and pump station design calculate the impeller work, along the volute gradient section, the flow rate is gradually increased, in order to reduce hydraulic loss, in the centrifugal pump design should make the water flow speed along the volute progressive section is a constant. After the water is discharged from the volute, it flows into the pressurized water pipe through the conical diffusion tube. The function of the conical diffuser tube on the volute is to reduce the speed of the water flow, so that part of the flow rate head is converted into a pressure head. The material selection of the pump casing, in addition to considering the corrosion and wear of the medium to the overflow part, should also make the housing have sufficient mechanical strength as a pressure-resistant vessel.

4. Pump casing

The pump casing consists of several parts, and its inner cavity forms the impeller chamber, the suction chamber and the pressurized water chamber. The shape and size of the pump casing depends on the impeller construction form and size and the shape and size of the suction chamber and pressurized water chamber determined by the hydraulic design. The pump casing mainly has two types: end-cover pump casing and split pump casing, and the end-cover pump casing is divided along the radial plane perpendicular to the pump axis line to form a pump body and pump cover, mostly used for single-stage pumps