Reciprocating pump is a positive displacement pump, is to rely on the piston pump cylinder reciprocating motion to change the work volume, so as to achieve the purpose of conveying liquid. Piston is an example to illustrate the working principle of the reciprocating pump. Piston pump mainly by the piston in the pump cylinder reciprocating motion to inhale and remove the liquid. When the piston starts to move to the right from the extreme left end position, the volume of the working chamber gradually expands and the pressure in the chamber decreases. The fluid opens the suction valve and enters the space left by the piston until the piston moves to the extreme right end. The water absorption process. When the piston moves from the right end to the left end, the fluid filled with the pump is squeezed, the water suction valve is closed, and the pressure valve is opened and discharged. This process is called as the pressure-pumping process of the pump. Pistons continue reciprocating motion, the pump suction and water pressure on the continuous process of alternating. This pump features: Pump pressure can be infinitely high, the flow has nothing to do with the pressure, with self-absorption capacity, flow uneven. This pump is suitable for small flow, high pressure infusion system.