Pump calculations

how to calculate the pump performance curve vales for Volume flow rate, RPM, Head pressure, pump power, impeller diameter for centrifugal pump. This can be applied to pumps within HVAC industry such as chilled water pumps.

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Pump calculations how to calculate pump speed, head pressure, rpm, volume flow rate, impeller diameter

In this article we learn how to perform pump calculations in both imperial and metric units to assess pumping performance following the change of flow rate, pump speed, head pressure and power. These formulas are common practice rules of thumb and provide theoretical values to which actual values will likely differ. YouTube video tutorial at the bottom of the page.

To calculate the new flow rate of a pump from an increase or decrease in pump speed RPM, the following formula and calculation can be used.

How to calculate pump flow rate from an increase or decrease in pump speed RPM
Calculate pump flow rate from an increase or decrease in pump speed RPM

To calculate the new flow rate of a pump from an increase or decrease in impeller diameter, the following formula and calculation can be used.

How to calculate pump flow rate from a change in impeller diameter
Calculate pump flow rate from a change in impeller diameter

To calculate the new pump speed RPM from an increase or decrease in flow rate, the following formula and calculation can be used.

How to calculate pump speed RPM with an increase or decrease in flow rate
Calculate pump speed RPM with an increase or decrease in flow rate

To calculate the new pump head pressure from an increase or decrease in pump speed RPM, the following formula and calculation can be used.

How to calculate head pressure for an increase or decrease in pump speed rpm
Calculate head pressure for an increase or decrease in pump speed rpm

To calculate the new pump head pressure from an increase or decrease in flow rate, the following formula and calculation can be used.

how to calculate pump head pressure for an increase or decrease in flow rate
Calculate pump head pressure for an increase or decrease in flow rate

To calculate the new pump head pressure from an increase or decrease in pump speed rpm, the following formula and calculation can be used.

how to calculate head pressure for an increase or decrease in pump speed rpm
Calculate head pressure for an increase or decrease in pump speed rpm

To calculate the new pump impeller diameter to suit a change in pump flow rate, the following formula and calculation and be used.

how to calculate new pump impeller diameter to suit a change in flow rate
Calculate new pump impeller diameter to suit a change in flow rate

11 COMMENTS

  1. how to avoid capitation at submersible vertical turbine pump,
    how minimum level water from pump submersible to avoid capitation.

  2. Hiii evans,

    Can you please tell me the direct relationship between pump capacity, head, impeller speed and impeller dia.

    Best regards,
    AJAY K

  3. how can you calculate a pump requirement for a water pumping system in the following arrangement

    flow rate of 17 L/min, viscosity of water , 38m of 1/2” ID piping with a 10m lift and also include joints and explain how you might calculate looses in those joints.

    Answer in bar

  4. I am sorry, but the calculations for head pressure from increase/decrease flow rate, doesn’t really make sense, if your flow rate goes down, your head is supposed to go up… Unless I am missing anything here…

  5. Dear all
    I need pump calculation sample way if i have 5 hp pump and use water for three floors so please clarify.
    thanks all my friends

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