Pump Power Calculator: Calculate Hydraulic and Shaft Power for Pumps

 Hydraulic Pump Power

The ideal hydraulic power to drive a pump depends on

• the mass flow rate the
• liquid density
• the differential height

- either it is the static lift from one height to an other or the total head loss component of the system - and can be calculated like

P_h(kW) = q ρ g h / 3.6×10⁶

        = q p / 3.6×10⁶                                  (1)

where

P_h(kW) = hydraulic power (kW)

q = flow (m³/h)

ρ = density of fluid (kg/m³)

g = acceleration of gravity (9.81 m/s²)

h = differential head (m)

p = differential pressure (N/m², Pa)

The hydraulic Horse Power can be calculated as:

P_h(hp) = P_h(kW) / 0.746                                  (2)

where

P_h(hp) = hydraulic horsepower (hp)

Or - alternatively

P_h(hp) = q_gpm h_ft SG / (3960 η)                              (2b)

where

q_gpm = flow (gpm)

h_ft = differential head (ft)

SG = Specific Gravity (1 for water)

η = pump efficiency

Example - Power pumping Water, SI Units

1 m³/h of water is pumped a head of 10 m. The theoretical pump power can be calculated as

P_h(kW) = (1 m³/h) (1000 kg/m³) (9.81 m/s²) (10 m) / (3.6×10⁶)

    = 0.027 kW

Example - Power pumping Water, Imperial Units

600 gpm of water is pumped a head of 110 ft. The efficiency ofthe pump i s 60% (0.6) and the specific gravity of water is 1. The pump shaft power can be calculated as

P_h(kW) = (60 gpm) (110 ft) (1) / ((3960) (0.6))

    = 27.8  hp

Shaft Pump Power

The shaft power - the power required transferred from the motor to the shaft of the pump - depends on the efficiency of the pump and can be calculated as

P_s(kW) = P_h(kW) / η                                     (3)

where

P_s(kW)  = shaft power (kW)

η = pump efficiency

Online Pump Calculator - SI-units

The calculator below can used to calculate the hydraulic and shaft power of a pump:

q - flow (m³/h)

ρ - density of fluid (kg/m³)

g - gravity (m/s²)

h - differential head (m)

η - pump efficiency

Online Pump Calculator - Imperial units

The calculator below can used to calculate the hydraulic and shaft power of a pump using Imperial units:

q - flow capacity (gpm)

 γ - specific weight of fluid (lb/ft³)

g - gravity (ft/s²)

h - differential head (ft)

η - pump efficiency

• Specific weight of water is 62.4 lb/ft³
• Check the relation between Density, Specific Weight and Specific Gravity
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Related Mobile Apps from The Engineering ToolBox

• Pump Calculator App

- free apps for offline use on mobile devices.