Horsepower required by a hydraulic pump can be calculated as
P HP = q p / 1714 (1)
P HP = horsepower (HP)
q = flow (gpm)
p = required pressure (psi)
- 1 gpm (US) =6.30888x10 -5 m 3 /s = 0.227 m 3 /h = 0.06309 dm 3 (litre)/s = 2.228x10 -3 ft 3 /s = 0.1337 ft 3 /min = 0.8327 gpm (UK)
- 1 psi (lb/in 2 ) = 144 psf (lb f /ft 2 ) = 6,894.8 Pa (N/m 2 ) = 6.895x10 -3 N/mm 2 = 6.895x10 -2 bar
- 1 hp = 745.7 W
Example - Hydraulic Pump
The horsepower required by a a pump with flow 20 gpm and 1500 psi increase in pressure can be calculated as
P HP = (20 gpm) (1500 psi) / 1714
= 17.5 HP
Note that the equation above is for a pump with 100% efficiency - which in the practial life is never true. An overall efficiency of 80 - 95% is common.
The equation above (1) can be modified to
P HP = q p / ((μ / 100) 1714) (2)
μ = overall efficiency (%)
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