Positive displacement pump is to rely on working elements in the pump cylinder for reciprocating or rotary motion, so that work volume alternately increase and decrease, in order to achieve liquid inhalation and discharge. The reciprocating motion of the working elements of the positive displacement pump called the reciprocating pump for rotary motion known as rotary pump. The former suction and discharge process alternately in the same pump cylinder, and by the suction valve and the discharge valve to control; the latter through the gears, screws, leaf rotors or vanes and other working elements of the rotation, forcing liquid from the inhalation Side to the discharge side. Volumetric pump at a certain speed or reciprocation frequency is constant, with almost no change in pressure; reciprocating pump flow and pressure pulsation, the need to take appropriate measures to reduce pulsation; rotary pump generally pulsatile or only small Pulsation; with self-suction capacity, the pump can be started immediately after the suction pipe to suck the liquid in the air; start the pump must be completely open the discharge pipe valve; reciprocating pump for high pressure and low flow; rotary pump for small and medium flow And higher pressure; reciprocating pump suitable for conveying clean liquid or gas-liquid mixture. In general, positive displacement pumps are more efficient than powered pumps. Powered pumps rely on the impellers' ability to rapidly rotate the impeller to transfer mechanical energy to the fluid to increase its kinetic energy and pressure, and then through the pump cylinder to convert most of the kinetic energy to pressure energy for delivery. Power pump, also known as impeller pump or vane pump. Centrifugal pumps are the most common type of power pumps. Power pump at a certain speed has a limited head lift, head with flow and change; work stable, continuous delivery, flow and pressure pulsation; generally no self-absorption capacity, the need to pump the first filled with liquid or pipe pumping To work in vacuum; suitable for a wide range of performance; suitable for conveying a very small viscosity of the cleaning liquid, specially designed pump can transport mud, sewage and water transport solids. Power pumps are mainly used for water supply, drainage, irrigation, process liquid delivery, power storage, hydraulic transmission and jet propulsion.
