In accordance with the principle of the pump pump can be divided into power pumps, positive displacement pumps and other types of pumps. 1. Centrifugal pump classification Centrifugal pump basic performance parameters for the flow Q (m3 / h, L / h), head H (m), allowable cavitation margin △ hr (m), speed n (rev / min), shaft power N and efficiency η. These pumps are simple in construction and light in weight, delivering clear water at temperatures up to 80 ° C and liquids that are physically and chemically similar to water. 2. Axial flow pump classification Axial flow pumps are mostly single stage, can be divided into fixed blade and adjustable blade two. 3. Vortex pump classification Centrifugal pump compared with the same impeller diameter and speed, the vortex pump lift higher than the centrifugal pump 2 to 4 times, but its efficiency is low, usually only 20% to 50%. Vortex pump fluid clean, low viscosity, non-solid particles. 4. Reciprocating pump classification reciprocating pump with electric pump, direct acting pump, diaphragm pump, metering pump four. 5. Screw pump classification Screw pump is characterized by small fluctuations in flow and pressure, low noise, long life, self-priming capability, simple structure and compact. A single screw pump, twin screw pump and three screw pump points. 6. Gear pump classification Gear pump structure is simple, easy to manufacture, reliable, easy maintenance, self-priming, but the flow and pressure pulsation and noise larger. Gear pump is suitable for conveying a variety of liquids without solid particles, the viscosity of the transport liquid range is very wide, high pressure liquid can be transported. 7. Liquid ring pump classification Liquid ring pump is a fluid conveying fluid machinery. Liquid ring pump working fluid often water, sulfuric acid, oil and so on. Liquid ring vacuum pump commonly used in vacuum evaporation, drying, water pump and so on. Liquid ring compressor is mainly used for pressure delivery of gas, ethylene, chlorine, oxygen and so on. 8. Vacuum pump classification Many types of vacuum pump, reciprocating with empty pump, rotary vacuum pump, Roots vacuum pump and jet vacuum pump.