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
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)
∆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)
∆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.
In this spreadsheet I shared above pump power calculation. I hope you find this useful.