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Calculate The Power Required To Generate Hydraulic Pump Flow

The role of a hydraulic pump is to provide sufficient pressure to overcome the operating pressure of a system to move hydraulic fluid at a required pump flow rate. To achieve the required flow and to ensure you have a suitable pump, you would need to calculate what operating pressure the system will need to be.

There are three categories of efficiency to consider when looking at hydraulic pumps and their pump flow rates;  Volumetric EfficiencyThis is determined by dividing the actual flow that is delivered to by the pump at a given pressure by the theoretical flow. The theoretical flow is calculated by multiplying a hydraulic pump’s displacement per revolution by its driven speed. For example; if a hydraulic pump has a displacement of 100cc/rev and is driven at 1000 RPM its theoretical flow will be 100 litres/minute.  Mechanical/Hydraulic EfficiencyThe hydraulic efficiency can be determined by dividing theoretical torque required to drive it by actual torque required to drive it. If there is an efficiency of 100%, this means if the hydraulic pump was delivering flow at zero pressure, no force or torque would be required to drive it.  Overall EfficiencyThe product of volumetric and mechanical/hydraulic efficiency. This is used to calculate the drive power required by a hydraulic pump at a given pump flow and pressure. Ideally the hydraulic power needed to drive a pump depends on these three things:

  •  The mass flow rate
  •          Liquid density
  •          Differential height

 Key Formulas to use: KW = L/MIN X BAR ÷ 510BAR = KW X 510 ÷ L/MINL/MIN = KW X 510 ÷ BARHP (Horse Power) = KW ÷ 0.75  Flowfit have a vast range of hydraulic gear pumps and accessories to choose from. 

For more information about our services or for advice from our experts, please don’t hesitate to give the Flowfit team a call on 01584 879 033 or e-mail us at

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