02 What Is The Difference Between Multistage Centrifugal Pump And Single-stage Centrifugal Pump?

02 What is the difference between multistage centrifugal pump and single-stage centrifugal pump?


What is construction difference between multistage centrifugal pump and single-stage centrifugal pump? What's the difference between centrifugal pump and metering diaphragm pump? 


The single-stage centrifugal pump includes pump body, pump cover, motor device with output shaft, pump shaft, bearing seat, impeller, mechanical seal and mechanical seal gland structure components installed in the pump body. The key feature is that there is a device between the output shaft of the motor and the pump shaft called the counter clamp coupling, or the device installed on the bearing seat called the help support pump shaft Guide bearing. The clamp type coupling is connected with the rigidity of the motor output shaft and pump shaft. When the motor output shaft and pump are connected, the length of the space between the shafts is convenient to dismantle the mechanical seal and the mechanical seal gland. It is not necessary to remove the motor and pump cover when repairing or replacing the mechanical seal.


The multistage pump is mainly composed of stator, rotor, bearing and shaft seal

1. The stator part of multistage pump is mainly composed of suction section, middle section, discharge section and guide vane, and each section is clamped by tightening bolts to form a working room. D-type pump generally inhales horizontally and spits vertically upward; when it is used for oilfield water injection, the inlet and outlet of the pump are all vertically upward. The inlet and outlet of DG multistage pump are vertical upward.

2. The rotor part of multistage pump is mainly composed of shaft, impeller, balance plate and shaft sleeve. The axial force is balanced by the balance plate.

3. The bearing of multistage pump is mainly composed of bearing body, bearing and bearing gland. The bearing is lubricated with grease or thin oil.

4. The multistage pump shaft seal adopts the soft packing seal, which is mainly composed of the seal body, packing and water retaining ring on the water inlet section and the tail cover. The water seal water of type D pump comes from the pressure water in the pump. DG type pump water seal water comes from external water supply.

5. The rotating pump of multistage pump is directly driven by prime mover through elastic coupling. Viewed from the end of the prime mover, the pump is a clockwise rotating D and DG type pump, which is a horizontal single suction multistage segmental centrifugal pump. For conveying clear water (containing less than 1% impurity and less than 0.1mm particle size) or other liquids with physical and chemical properties similar to water. D-type pump is suitable for mine drainage, oilfield water injection, factory and city water supply and drainage, etc. According to the corrosiveness of medium, the oil field water injection pump adopts different materials. The temperature of DG type pump is less than 105 ℃, which is suitable for all kinds of boiler feed water.


The installation of more than two pumps is called multistage centrifugal pump, so the single-stage pump is only installed with one impeller. In the installation method, this is the biggest difference with metering diaphragm pump.