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Slurry Pump
WH14AAAAAA0EN_04D.DOC JAN 04-W08
Desccription of operation
2/4
Q
F
F
BEP
When the pump operates at
best efficiency point, uniform
pressure is obtained in the
casing which in its turn
eliminates radial forces on
the impeller. When the pump's flow
capacity is not utilized,
uniform pressure in the
pump casing will not be
obtained and this results in
a radial force
F on the
impeller.
The magnitude of the radial
force F is greatest when the
pump runs against closed
valve = 0 flow. The force
subsequently diminishes up
to
BEP where it is close to
zero. At flows above BEP the
force changes direction.
Figure 4.2-1 Best efficiency point
When the pump is not operating at BEP the bearings will have a shorter service life on
account of shaft deflection. In addition, the differential pressure over the impeller gives rise
to the transport of slurry between the impeller and the inlet liner, causing rapid wear of the
liner.
4.3 Hydraulic effects of operation at, and outside, BEP
Impeller vane inlet Pump casing nose
1 2
Figure 4.3-1 Operating at best efficiency point
1. The slurry's inflow angle coincides with the impeller's vane angle and no erosive
vortices occur.
2. The slurry's flow angle harmonizes with the angle of the pump casing nose and no
erosive vortices occur.