Pump selection principle 1, so that the type and performance of the selected pump in line with the device flow, head, pressure, temperature, cavitation flow, suction stroke and other process parameters. 2, must meet the characteristics of the media requirements. Pumps that deliver flammable, explosive toxic or valuable media require dependable shaft seals or leak-free pumps such as magnetically driven pumps, diaphragm pumps, shielded pumps, pumps that deliver aggressive media, convective components require corrosion-resistant materials , Such as AFB stainless steel corrosion pump, CQF plastic magnetic drive pump. Pumps containing solid particulate media are required to have a wear-resistant material for the convection components and flush with a cleaning fluid if necessary. 3, high mechanical reliability, low noise, small vibration. 4, the economic should take into account the equipment costs, operating costs, maintenance costs and management fees the lowest total cost. 5, centrifugal pump with high speed, small size, light weight, high efficiency, large flow, simple structure, infusion without pulsation, stable performance, easy operation and maintenance features such as convenience. Therefore, in addition to the following circumstances, the centrifugal pump should be used as far as possible: When there are measurement requirements, the choice of metering pump head is very demanding, the flow is small and not suitable for small flow High-lift centrifugal pump can be used when optional reciprocating pumps such as cavitation When the requirement is not high, the vortex pump can also be used. The lift is very low. When the flow rate is very high, the axial pump and the mixed flow pump can be used. Medium viscosity (greater than 650 ~ 1000mm2 / s), consider the use of rotor pump or reciprocating pump (gear pump, screw pump) medium 75% gas content, the flow is smaller and the viscosity is less than 37.4mm2 / s, the choice of vortex Pump. On the occasion of frequent or inconvenient irrigation pump should be used with self-priming performance, such as self-priming centrifugal pump, self-priming vortex pump, pneumatic (electric) diaphragm pump.