Usually by the working principle pump displacement pumps , power pumps and other types of pumps , such as the jet pump , water hammer pumps, solenoid pumps, gas lift pump . According to the structure can be divided into single-stage pumps and multistage pumps ; -use can be divided into boiler feed pumps and metering pumps ; according to the nature of transmission fluid can be divided into water pumps, oil pumps and mud pumps .
Positive displacement pumps rely on the operating member in the pump cylinder for reciprocating or rotary motion , the working volume increases and out alternately in order to achieve suction and discharge of liquid . The operating member for reciprocating displacement pump known reciprocating pumps, rotary movement of the rotary pump is called . The former process in the same suction and discharge pump cylinder alternately, by the suction and discharge valves to be controlled ; the latter through the gears , screw, vane leaf rotors or rotation of the operating member such as , forcing fluid from the inlet side to the discharge side . Positive displacement reciprocating pumps at a certain speed or frequency of the flow is constant , almost does not change with pressure ; reciprocating pump flow and pressure pulsations have a greater need to take appropriate measures to abate pulsation ; rotary pumps generally no or only a small ripple pulsation ; self- priming capability , the pump can be started after pumping air into the liquid in the pipeline .
When starting the pump discharge line valves must be fully open ; reciprocating pump for high pressure and low flow ; rotary pump for small flow and high pressure ; reciprocating pumps suitable for pumping clean liquids or liquid mixtures. In general, the volumetric efficiency of the pump higher power pump . Power pump impeller by the rapid rotation force of the liquid , the mechanical energy transmitted to the liquid , it can increase the kinetic energy and pressure , and then through the pump cylinder , the majority of the kinetic energy is converted to pressure energy transfer is achieved . Also known as power pumps vane impeller pump or pumps.