Pump types and performance data

Abstract

Centrifugal pumps are turbomachines used for transporting liquids by raising a specified volume flow to a specified pressure level. The energy transfer in turbomachines is invariably based on hydrodynamic processes for which characteristically all pressure and energy differences are proportional to the square of the circumferential rotor speed. By contrast, positive displacement pumps (e.g. piston pumps) essentially deliver the same volume V_stroke at each stroke independently of flow velocity or rotor speed n. The flow rate then becomes Q = n×V_stroke; the pressure rise results solely from the imposed back pressure.