High Pressure Piston Pump

       

HIGH PRESSURE WATER PUMP

An important feature of the piston pump is that the volume capacity of pump depends on pump speed. So long as pump is rotating the same volume of liquid that goes in must come out. Unlike a centrifugal pump where restriction or increased head creates reduced flow a piston pump has a very flat flow performance curve no matter how high the pressure goes. This is why blockage can be dangerous and why safety devices such as unloader valves must be incorporated into system.

        As the plunger moves back, water is drawn into pump cylinder cavity through inlet check valves. When plunger moves forward, the inlet valves close, forcing water to travel through a series of outlet valves and to the discharge port of pump.

        Most plunger pumps are either duplex or triplex. Two-piston pumps have higher pulsations and are harder on system components and the operator. Triplex are the most common used for pressure washers as they result in smoother flow.

      Newer higher speed pumps also result in less pressure fluctuations and require less starting torque; however, they result in faster wear, have less suction lift capability and sometime noise is high pitched and can be irritating.

       Unfortunately since pump is the core of the pressure washer it is generally blamed for any system failing. However, generally 90% of pressure washer problems are not the cause of the pump. Most can be attributed to system restrictions or component wear such as nozzle, etc. Pump starvation of liquid is probably the leading cause of premature pump failure. Inlet line restrictions does not allow adequate water to enter pump resulting in cavitation. Cavitation is when air mixes with water causing small explosions to occur when pressurized which will tear away at packing or piston surface.