Centrifugal Pump Formula

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 of Pump: 

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