Motor Reference Guide: Pump & Fan Power Equations

July 17, 2015

Need a quick guide to pump & fan power equations as they relate to fractional horsepower motors? We’ve created this just for you.

Power – Fans & Blowers

P = Qp / 229u

  • P = Power (hp)
  • Q = Flow rate (cfm)
  • p = Pressure (psi)
  • u = Efficiency

Power – Pumps

P = QHS / 3960u

  • P = Power (hp)
  • Q = Flow rate (gpm)
  • H = Head (ft)
  • S = Specific gravity of fluid
  • u = Pump efficiency

Specific Gravity of Fluids

Liquid

Specific Gravity

Temp °C
Acetone 0.79 20
Alcohol 0.79 20
Benzene 0.90 0
Carbon Disulfide 1.29 0
Ether 0.74 0
Gasoline 0.67 –
Glycerin 1.26 0
Kerosene 0.82 –
Mercury 13.6 –
Milk 1.0 –
Castor Oil 0.97 15
Cotton Oil 0.93 16
Olive Oil 0.92 15
Sea Water 1.04 15
Turpentine 0.87 –
Water 1.0 4

 

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