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Positive Displacement Pump Buyers Guide
A positive displacement pump makes a fluid move by trapping a fixed amount and forcing (displacing) that trapped volume into the discharge pipe. Some positive displacement pumps use an expanding cavity on the suction side and a decreasing cavity on the discharge side. Liquid flows into the pump as the cavity on the suction side expands and the liquid flows out of the discharge as the cavity collapses. The volume is constant through each cycle of operation.
Positive displacement pumps, unlike centrifugal or roto-dynamic pumps, theoretically can produce the same flow at a given speed (RPM) no matter what the discharge pressure. Thus, positive displacement pumps are constant flow machines. However, a slight increase in internal leakage as the pressure increases prevents a truly constant flow rate.
A positive displacement pump must not operate against a closed valve on the discharge side of the pump, because it has no shutoff head like centrifugal pumps. A positive displacement pump operating against a closed discharge valve continues to produce flow and the pressure in the discharge line increases until the line bursts, the pump is severely damaged, or both.
Below you will find manufacturers representatives who handle a wide array of Positive Displacement Pumps.
For specific manufacturer please use the Pumps By Manufacturer section on the top navigation bar.
John Brooks Company
Positive Displacement Pumps
Positive displacement pumps from John Brooks Company feature positive displacement lobe pumps, sanitary positive displacement pumps and rotary gear positive displacement pumps from Tuthill, Shertech, and Pulsafeeder.