What Is Pump Efficiency and Its Formula?

   Pump efficiency refers to the ratio of the pump’s effective power to its shaft power.

Effective Power (Ne)Effective power refers to the power actually used to convey the fluid, calculated as the product of the pump head, flow rate and fluid specific weight (weight flow rate).The formula is:Ne=γQHUnit: kilowatt (kW)

Conversion factors:

1 kW=10275 metric horsepower

Shaft Power (N)Shaft power, also referred to as centrifugal pump input power, denotes the power transmitted from the prime mover to the pump shaft.Unit: kilowatt (kW)

Efficiency Formula (η)

When the flow rate Q is in liters per second (L/s):η=NNe=102NγQHWhere:

γ = fluid specific weight, unit: t/m3

Q = flow rate, unit: L/s

H = pump head, unit: m

N = shaft power, unit: kW

When the flow rate Q is in cubic meters per hour (m3/h):η=NNe=102×3.6NγQHWhere:

γ = fluid specific weight, unit: t/m3

Q = flow rate, unit: m3/h

H = pump head, unit: m

N = shaft power, unit: kW