What is the difference between a multi-stage centrifugal pump and a single-stage centrifugal pump

1. What is a single-stage centrifugal pump

The single-stage centrifugal pump is a mixture of fluid and liquid, or suspended particles and gas or liquid. It enters at the entrance of the root of the blade shaft, and relies on the rotating blade to obtain a centrifugal force, and then generates high pressure and flows out from the pressure relief outlet. These media delivery devices


A single-stage centrifugal pump includes a pump body, a pump cover, a motor device with an output shaft, the pump shaft, bearing housing, impeller, mechanical seal and mechanical seal gland structural components installed in the pump body. The key feature is that it contains There is a device between the output shaft of the motor and the pump shaft called a wafer coupling, or a device installed on a bearing seat, called a guide bearing that supports the pump shaft.
The described wafer coupling has a rigid connection with the motor output shaft and the pump shaft. When the motor output shaft and the pump, there is a space between the shafts to easily remove the mechanical seal and the mechanical seal gland. length. It is not necessary to remove the motor and pump cover when repairing or replacing the mechanical seal.

2. What is a multistage centrifugal pump

The multi-stage centrifugal pump is a collection of two multiple pumps with the same function. In terms of the structure of the fluid channel, its performance is that the medium pressure relief port of the previous stage and the inlet of the next stage can communicate with each other. At the inlet of such a number of levels, the pressure relief port and the inlet are all figured out. In this way, the series structure forms a multi-stage centrifugal pump. The function of setting a multistage centrifugal pump is to increase the set pressure.

Horizontal-Multistage-Pump (4)

The multi-stage pump is mainly composed of four parts: stator, rotor, bearing and shaft seal:

1. The stator part of the multi-stage pump is mainly composed of the suction section, the middle section, the discharge section and the guide vane. There are tension bolts to clamp each section to form a working room. The D-type pump generally sucks in horizontally and discharges vertically upward; when it is used for water injection in oil fields, the inlet and outlet of the pump are vertically upward. The outlet and inlet of the DG multi-stage pump are vertically upward.
2. The rotor part of the multi-stage pump is mainly composed of shaft, impeller, balance disc and shaft sleeve. The axial force is balanced by the balance plate.
3. Multi-stage pump bearings are mainly composed of bearing bodies, bearings and bearing glands. The bearings are lubricated with grease or thin oil.
4. The shaft seal of the multi-stage pump adopts soft packing seal, which is mainly composed of the sealing box body, packing and water retaining ring on the water inlet section and the tail cover. D type pump seal water comes from the pressure water in the pump. The sealing water of DG type pump comes from external water supply.
5. Multi-stage pump rotation. The pump is directly driven by the prime mover through an elastic coupling. Looking at the pump from the prime mover side, the pump rotates clockwise. D and DG pumps are horizontal single-suction multi-stage centrifugal pumps. For transporting clean water (with impurities less than 1%, particle size less than 0.1mm) or other liquids with physical and chemical properties similar to water. The medium temperature of D-type pump is less than 80℃, suitable for mine drainage, oil field water injection, factory and urban water supply and drainage. Oil field water injection pumps use different materials according to the corrosiveness of the medium. The medium temperature of the DG pump is less than 105℃, which is suitable for all kinds of boiler feed water.

3. What is the difference between a multi-stage centrifugal pump and a single-stage centrifugal pump?

The difference between multi-stage centrifugal pumps and single-stage centrifugal pumps lies in the number of impellers. The multi-stage centrifugal pump is characterized by high pressure and low flow. Single-stage centrifugal pumps have only one impeller, which is characterized by low pressure and large flow.

First, a single-stage pump refers to a pump with only one impeller

Second, the multi-stage pump has two or more impellers, and the highest head can exceed the head of a single-stage centrifugal pump; when the multi-stage pump has a single-stage pump head, it is necessary to add a two-stage motor. By increasing the number of impellers to match the four-stage motor, the service life of the pump and the noise of the unit can be reduced, but the maintenance of multi-stage pumps is a bit more difficult than single-stage pumps.

Third, when the actual head of the pump does not exceed 125 meters, multi-stage pumps are generally more expensive according to the area of ​​the pump studio and the price of the pump, and multiple reasons should be considered. Single stage should be selected. The pump is still a multistage pump.

Fourth, because the single-stage centrifugal pump has only one impeller on the pump shaft, and the multi-stage centrifugal pump has many impellers connected in series on the pump shaft, the multi-stage centrifugal pump is installed on the same shaft by the impeller of two or more stages. Let’s work together. The output of the front impeller enters the input of the rear impeller. Each layer of impeller blades is called a first stage.

2020-08-18T15:53:06+08:00August 18th, 2020|

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