Mainly used to transport liquids such as water, oil, acid and alkali liquid, emulsion, suspension emulsion and liquid metals, can also transport liquid, gas mixtures and liquids containing suspended solids.Performance parameters of the pump main performance parameters of the pump flow and head, in addition to shaft power, speed and necessary cavitation margin. Flow per unit time is the output of liquid through the pump outlet volume flow rate generally used; head is the unit weight of the carrier liquid from the inlet to the outlet of the energy increment for the pumps, the energy increment is mainly reflected in the pressure to increase the Therefore, instead of lift is usually expressed as pressure increment. Pump efficiency is not an independent performance parameters, it can be other performance parameters such as flow, head and shaft power calculated by formula. Conversely, the known flow rate, head and efficiency, shaft power can be obtained. Various performance parameters of the pump there is a certain interdependence between the changes in relationships can be tested by the pump were measured and calculated parameter values, and painted to represent the curve, the curve is called the pump characteristic curve. Each pump has a specific characteristic curve provided by the pump manufacturer. Usually given curve in the factory on the performance also marked the recommended section, called the scope of the work of the pump. The actual operating point pump curves and pump from the pump device to determine the intersection curve. Selection and use of the pump, the pump operating point should be to fall within the scope of work to ensure the functioning of economy and safety. In addition, the same pumping liquids of different viscosity, the characteristic curve will change. Typically, pump manufacturers curve given by most is the transmission characteristic curve of clean cold water. For the power pump, with the liquid viscosity increases, lift and lower efficiency, shaft power increases, so sometimes the viscosity of industrial liquid heating to viscous smaller to improve transport efficiency.