Centrifugal Pump Formula:
Pump
Efficiency to KW or KW to Pump Efficiency
Power at the Pump shaft KW = flowrate(Q) x Head(H) x Specific Gravity (SG)/367 x Efficiency of Pump
Head to
Pressure or Pressure to Head conversion:
Head (H) = 10.2 x Pressure (P)/Specific Gravity (SG)
NPSH available
at pump suction = NPSH available
= 10.2x (Suction
Pressure – Vapor pressure)/Specific Gravity(SG)
Motor input
current to Power or Motor power to current
Power(P) KW = square root of 3 x Voltage(V) x Current((I) x Power factor(PF) x Efficiency /1000
Mass Flow
to Volumetric Flow or Volumetric flow to Mass flow
= Flowrate(Q)
= Mass flowrate(M) / Specific Gravity(SG)
Specific
speed is a unit less an index used to predict desired pump performance and the
general shape of a pumps impeller. It is the speed of a geometrically similar
pump which would deliver unit quantity (1 M3/sec) against a unit Head (1 Mtr).
Specific
Speed = Ns = RPM(N) x Square root of Flowrate(Q)/Head(H)¾
For multi
stage pump, Head per stage = Total Head/ Nos of stage
For double
suction impeller pump flow, Q = half of total flow Q/2
