First, the structure of reciprocating pump and working principle The main components: pump cylinder, piston, piston rod and inhalation valve, discharge valve. Working principle: When the piston moves from left to right, a negative pressure is formed in the pump cylinder, then the liquid in the sump enters the pump cylinder through the suction valve. When the piston moves from right to left, the liquid in the cylinder is squeezed, the pressure increases, and it is discharged by the discharge valve. Pistons reciprocate, each suction and discharge a liquid, called a work cycle; this pump is called a single action pump. If the piston from time to time, each inhalation and discharge of liquid twice, known as double-acting pump. Pistons move from one end to the other end, called a stroke. Second, the reciprocating pump flow and pressure head The reciprocating pump flow has nothing to do with the pressure head, and pump cylinder size, piston stroke and reciprocation frequency. The theoretical flow of a single-acting pump is QT = Asn. The actual flow of the reciprocating pump is smaller than the theoretical one and decreases with the increase of the pressure head due to the leakage. Reciprocating pump head and pump flow and pump geometry has nothing to do, but by the pump mechanical strength, the power of the prime mover and other factors. Third, the reciprocating pump installation height and flow control Reciprocating pump start without filling liquid, because the reciprocating pump has self-suction capacity, but the vacuum suction height also depends on the installation area of ​​the atmospheric pressure, the nature of the liquid and the temperature changes , So the reciprocating pump installation height also has certain limit. Reciprocating pump flow can not be discharged with the valve on the pipeline to adjust, but should be used by the bypass pipe or change the reciprocation of the piston to change the piston stroke to achieve. Before starting the reciprocating pump, the valve in the discharge line must be opened. The reciprocating pump's piston is connected to the prime mover by the connecting rod crankshaft. The prime mover motor, steam engine can also be used. Reciprocating pumps for high-pressure head, small flow, high-viscosity liquid delivery, but not for transporting corrosive liquids. Sometimes directly driven by the steam engine, delivering flammable, explosive liquids.