Centrifugal Pumps - Minimum Flow
Minimum continuous flow to prevent flashing in centrifugal pumps.
Catastrophic failures may occur in centrifugal pumps if the liquid within the pumps starts to vaporize. A minimum flow through the pump must be maintained to prevent flashing within the casings. The heat transferred from the motor must be removed to keep the fluid below its saturation temperature at the actual pressure.
If 15 oF is accepted as a temperature rise in the pump casing - the minimum water flow through the pump can be estimated to
q = PBHP / 2.95 cp SG (1)
q = minimum flow rate (gpm)
PBHP = power input (BHP)
cp = specific heat of fluid (Btu/lb oF)