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How to Calculate NSPH of Pump with Examples and Illustrations

NPSH of pump (net positive suction head) should be calculated/predicted in the beginning of pump sizing. The purpose is to check if the pump will work appropriately. Liquid pressure will lower right in inlet of pump impeller. If pressure reduction is lower than vapor pressure, liquid phase will change to vapor phase. The impeller rapidly collapses vapor bubbles which cause cavitation and damage.

In this post I will share you how to calculate NPSH available, which is net positive suction head calculated based on system arrangement. The value of NPSH available (NPSHA) shall be greater than NPSH required (NPSHR), which is a function of pump and to be specified by pump manufacturer.

NSPH of pump is calculated as follow:

NPSH available (ft, m) = absolute pressure (ft, m)vapor pressure (ft, m) –  line loss (ft, m) ± elevation difference (ft, m) (more…)

Centrifugal Pump Sizing Spreadsheet

Since past two days, people still celebrate new year, so office activity has not started yet. That means I actually still in holiday too. But I want to update this blog while enjoying my holiday. I cannot (or in a mood) to create full article. So, instead sharing full article, in this post, I want to share you centrifugal pump sizing spreadsheet.

I created pump sizing spreadsheet for my first LNG project. The inspiration came from Pump Sizing Calculation from CheCalc. But I made it better.

I think you should download this spreadsheet because it offers better features that online calculation fro CheCalc. 

  • The spreadsheet is simple. You just input the data in dark yellow highlight
  • Pump sizing is calculated based on rated flow rate. If you want to size based on normal flow rate, input 0 in percentage of rated flow rate
  • Pressure drop components is comprehensive, including pipe loss, fitting loss, and equipment loss
  • Pump data results is comprehensive, including:
    • Suction pressure
    • Discharge pressure
    • Differential pressure
    • Differential head
    • Hydraulic power
    • Pump BHP
    • Rated power (calculated)
    • Rated power (selected) : based on commercial output motor power
    • NPSHA
    • NPSHR
    • Shut in pressure

Stop reading! Start downloading! Hope you find this useful!

Download Pump Sizing