Positive displacement pump relies on elements in the pump cylinder reciprocating or rotary motion, working alternately increase and decrease volume to achieve suction and discharge of liquids. Components for reciprocating pump with reciprocating positive displacement pump, rotary movement known as the Rotary pump. The former alternating suction and discharge processes at the same pump cylinder and the suction valve and discharge valve control; the latter is through the gears, screw, leaf-shaped components such as rotor or vane rotary action, forcing liquid discharged from the suction side moved to the side.

Volume type pump in must speed or reciprocating times Xia of flow is must of, almost not with pressure and change; reciprocating pump of flow and pressure has larger pulse, need take corresponding of cut pulse measures; Rotary pump General no pulse or only small of pulse; has since sucking capacity, pump started Hou that can pumping except pipeline in the of air inhalation liquid; started pump Shi must will discharge pipeline valve completely open; reciprocating pump applies Yu high pressure and small flow; Rotary pump applies Yu small flow and high pressure ; Reciprocating pumps are suitable for clean liquids or gas-liquid mixture.