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Handy Method to Estimate Pump Power Requirement


In this post I want to share a handy method to estimate pump power requirement. Pump power is a function of these parameters:

  • Flow rate
  • Delivered pressure
  • Pump efficiency
Parameters affecting pump power requirement
Parameters affecting pump power requirement

If the flow rate in US gallon per minute (USgpm) and delivered pressure is in psi, then use the equation below to estimate pump power:

          Pump Power Requirement (HP) = Flow rate (GPM) x ∆P / (1715 x Eff)

Where:

∆P = delivered pressure (discharge minus suction), psi

Eff = pump efficiency

If the flowrate in m3/h and delivered pressure is in bar, then use the following equation:

          Pump Power Requirement (kW) = Flow rate (m3/h) x ∆P / (36.01 x Eff)

Where:

∆P = delivered pressure (discharge minus suction), bar

How to determine pump efficiency?

The pump efficiency will depend on the type of pump used and the operating conditions. In this post, I shared how to estimate pump efficiency as a function of head and flow rate. For preliminary purpose, the following graph can be used to estimate pump efficiency of centrifugal pump.

Centrifugal Pump Efficiency [2]
Centrifugal Pump Efficiency [2]
In this spreadsheet I shared above pump power calculation. I hope you find this useful.

Reference:

  1. Branan, Carl, Rules of Thumbs for Chemical Engineers, Gulf Professional Publishing, 2005.
  2. Sinnot, R.K., Chemical Engineering Design Volume 6, Elsevier Butterworth-Heinemann, 2005.
  3. Feature image by Denny Müller on Unsplash