1. Classified according to the number of working impellers
Single-stage pump: that is, there is only one impeller on the pump shaft.
Multi-stage pump: that is, there are two or more impellers on the pump shaft.
2. Classified by work pressure
Low-pressure pump, medium pressure pump, high-pressure pump
Three, according to the impeller water inlet method to classify
Single-side water inlet pump: also called single-suction pump, that is, there is only one water inlet on the impeller;
Double-side water inlet pump: also called double-suction pump, that is, there is a water inlet on both sides of the impeller.
Four, according to the position of the pump shaft to classify
Horizontal pump: The pump shaft is in a horizontal position.
Vertical pump: The pump shaft is in a vertical position.
Basic structure of centrifugal pump
Features of single-stage single-suction centrifugal pump:
The single-stage single-suction centrifugal pump is reliable, simple in structure, easy to manufacture and process, convenient in maintenance, and strong in adaptability. It is a widely used centrifugal pump. One end of the pump is supported by a bearing in the bracket, and the other end with the impeller cantilever out of the bracket.
According to the different split positions of the pump body and the pump cover, it can be divided into two structures: front opening and rear opening. The advantage of the rear-opening pump is that during maintenance, the bracket and the impeller can be taken out by loosening the stop nut of the bracket, and it is not necessary to disassemble the inlet and outlet pipelines of the pump.
Structural features of double-suction centrifugal pump:
1. Beautiful appearance, good stability and easy installation. The motor can be on the left or right end as required. The double-suction centrifugal pump has a split structure in the pump casing. During maintenance, only the pump cover needs to be lifted, and the rotor parts can be removed for maintenance operations without disassembling the pipeline, which is very convenient.
2. The shaft seal adopts mechanical seal or packing seal. Can guarantee no leakage for a long time. The impeller sealing ring can be replaced after it is worn out, which reduces operation and maintenance costs.
3. The optimized design of the double-suction impeller reduces the axial force to a minimum, is hydraulically symmetrical, and has no axial force (in theory). Since the double-suction impeller has two suction ports, each inlet only needs to bear half of the flow, so the flow rate is relatively low, and the impeller is not easy to cavitation.
4. High efficiency, large flow and high lift. However, it is large and heavy, so it is generally not suitable for mobile operations. It is mostly used in factories, mines, urban water supply and drainage, etc.
Structural features of multi-stage centrifugal pumps:
The multi-stage pump uses several impellers to work in series, so the head is high. Divided into two forms of segmented multistage centrifugal pump and split multistage centrifugal pump.
The segmented multi-stage centrifugal pump has good performance, large flow and head range, and is widely used in petrochemical production. The pump body is a vertically split multi-section structure, composed of a first section, a tail section and several middle sections, which are connected as a whole by four bolts.
There are multi-stage impellers in the middle of the pump shaft, and each impeller is equipped with a guide wheel to guide the flow. Both ends of the shaft are supported by bearings and placed in the bearing body. The shaft sealing device is symmetrically arranged on the protruding part of the pump shaft at the first and last sections of the pump.
Since the impellers are arranged on the shaft in one direction, each stage of the impeller has an axial force, so the total axial force after the stepwise addition is very large, a dynamic balance disc must be installed behind the last stage of the impeller to parallel the axial force . The segmented multistage centrifugal pump is easy to manufacture, and each section of the pump body can be processed separately, but the structure is more complicated and it is difficult to assemble and disassemble.