Equipment reference
Positive-displacement pumps
These pumps move liquid by repeatedly enclosing and displacing a volume. The displacement mechanism, fluid and pressure protection determine the suitable duty.
Enclose, then displace
Rotary designs include gear and screw mechanisms; reciprocating designs include pistons and diaphragms. At a given speed, displacement largely sets the flow, while leakage, compressibility and filling conditions affect the actual delivery.
Pressure protection
Discharge resistance determines the pressure the pump must overcome. A blocked outlet can cause a rapid pressure rise. Specify suitable relief or other independent pressure protection, its setpoint and discharge route as part of the installation design.
Fluid and mechanism
Viscous fluids, accurate dosing or sensitive products can favour particular displacement designs; no design suits every such duty. State viscosity at working temperature, solids, chemical compatibility, required dosing accuracy and allowable shear or pulsation.
Wear and delivery
Compare delivered flow against speed, pressure and fluid condition. Changes may indicate incomplete filling, wear or leakage. Service limits and replaceable elements depend on the actual gear, screw, diaphragm, piston or tube design.