Hydraulic Oil Pumps - Horsepower Required

Horsepower required by hydraulic pumps

A practical formula for calculating horsepower required by a hydraulic pump

hydraulic pump

can be expressed as

PHP = q p / 1714        (1)

where

PHP = horsepower (HP)

q = required pump capacity (gpm)

p = required pressure (psi)

  • 1 gpm (US) =6.30888x10-5 m3/s = 0.227 m3/h = 0.06309 dm3(litre)/s = 2.228x10-3 ft3/s = 0.1337 ft3/min = 0.8327 gpm (UK)
  • 1 psi (lb/in2) = 144 psf (lbf/ft2) = 6,894.8 Pa (N/m2) = 6.895x10-3 N/mm2 = 6.895x10-2 bar
  • 1 hp = 745.7 W

hydraulic pump horsepower graph

Example - Hydraulic Pump

Power required by a a pump with 20 gpm capacity and 1500 psi pressure can be calculated as

 PHP = (20 gpm) (1500 psi) / 1714

    = 17.5 HP

Efficiency

Note that the equation above can be used for a 100% efficient pump - which in the practial life is never true. An overall efficiency of 80 - 95% is common. 

The equation above (1) can be modified to 

PHP = q p / ((μ / 100) 1714)        (2)

where

μ = overall efficiency (%)

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