Mechanical efficiency

Mechanical efficiency (η_m) is described as the ratio between the power input (P) minus the mechanical power loss (P_L.m) and the power input itself:

Power loss refers primarily to the friction loss in pump bearings (e.g. plain and rolling element bearings) and shaft seals.

It typically consumes 0.5 to 2 % of power input, whereby this figure generally becomes smaller the more powerful the centrifugal pump.