 # 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

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.