Centrifugal pump minimum required flow
What is the minimum flow of a pump ?
Why a recirculation is important and why to ensure a minimal flow
How to calculate the required minimum flow of a pump ?
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|1. What is a minimum
flow for a pump
|2. How to calculate
a centrifugal pump minimal flow
1. What is the minimum flow for a pump ?
Due to the rotation of the impeller, energy is transferred to the
fluid in a centrifugal pump. Part of this energy is actually
dissipated in heat. If the flow through the pump is too low, the fluid
temperature may increase and reach the saturation temperature at the
pressure within the pump, leading to cavitation
and damages of the pump. It is therefore necessary to ensure a minimal
flow through a centrifugal pump. This minimum flow can be done thanks
to a recirculation.
2. How to calculate a centrifugal pump minimal flow ?
The minimum flow to ensure with a centrifugal pump can be calculated
the following way :
q = Cp.P.sg / 2.95
q = Minimum flow rate through the
pump in m3/s
P = Pump power in W
Cp = Liquid specific heat capacity
sg = Liquid specific gravity
Note : this gives an estimation of
the minimal flow to avoid cavitation, however even with this flow,
other kind of damages can happen to a pump if run long time in these
conditions (bearing, impeller...), it is therefore recommended to
check the value calculated with the pump manufacturer.