An impeller is a rotating component equipped with vanes or blades used in turbomachinery Flow deflection at the impeller vanes allows mechanical power (energy at the vanes) to be converted into pump power output.
In accordance with EUROPUMP TERMINOLOGY and DIN 24250, a distinction is made between counter-clockwise and clockwise impellers, as viewed in inlet flow direction.
Depending on the fluid flow pattern in multistage pumps and the impellers' arrangement on the pump shaft, impeller design and arrangements are categorised as: single-stage, multistage, single-entry, double-entry, multiple-entry, in-line (tandem) or back-to-back arrangement.