Centrifugal Pumps and Influence from Viscosity

When a liquid flow through a pump, hydrodynamic losses depends on fluid viscosity

When a more viscous fluid is handled by a centrifugal pump

  • brake horsepower requirement increases
  • the head generated is reduced
  • capacity is reduced
  • efficiency of pump is reduced and the Best Efficiency Point - BEP - is moved

Centrifugal pumps and influence of fluid viscosity

The head, flow and capacity with fluids with other viscosities than used in the original documentation can be modified with coefficients.

Flow

qv = cq q                                (1)

where

qv = flow compensated for viscosity (m3/h, gpm)

cq = viscosity flow coefficient

q = original flow according pump curve (m3/h, gpm)

Head

hv = ch h                               (2)

where

hv = head compensated for viscosity (m, ft)

ch = viscosity head coefficient

h = original head according pump curve (m, ft)

Efficiency

μv = cμ μ                             (3)  

where

μv = effciency compensated for viscosity

cμ = viscosity efficiency coefficient

μ = original efficiency according pump curve

Power - SI units

Pv = qv hv ρv g / (3.6 106  μv)                            (4)

where

Pv = power compensated for viscosity (kW)

ρv = density of viscous fluid (kg/m3)

g = acceleration of gravity (9.81 m/s2)

Power - Imperial units

Pv = qv hv SG / (3960 μv)                              (5)

where

Pv = power compensated for viscosity (bhp)

SG = specific gravity of viscous fluid

Related Topics

  • Pumps - Piping systems and pumps - centrifugal pumps, displacement pumps - cavitation, viscosity, head and pressure, power consumption and more
  • Viscosity - Documents giving viscosity of different kind of chemical species at varying conditions

Related Documents

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