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The Practical Pumping Handbook ....... ; ......................................

Figure 7.2: Multi-stage pump (Reproduced with permission of Flowserve Corp)

In the horizontal, end suction pump, both bearings are located on one
side of the impeller, so that the impeller is mounted on a cantilevered
extension of the shaft. Most multistage pumps have one bearing on
each end of the shaft with the impellers located between them. In most
instances, the radial bearing is situated at the coupling end of the shaft,
with the thrust bearing at the outer end.

The same is also true of the double-suction pump in spite of the fact
that this style is considered in axial hydraulic balance owing to the inlet
flow impacting both sides of the impeller. However, this balance can be
detrimentally affected by unequal wear on the wear rings, or the flow of
liquid into the two suction eyes may be different because of an
improper suction piping arrangement. Consequently, a thrust bearing is
still required on the double suction pump.
Bearings are mounted in a housing attached to the pump casing. The
housing contains the lubricant and can also provide additional means of
controlling the operating temperature of the bearings within acceptable
limits. This is frequently achieved with a jacketed area in the housing
through which cold water is circulated. It is particularly important in
the case of high ambient temperatures around the pump, or when the
product is being pumped at an elevated temperature.

7.2 Bearing loads

The life of a bearing is dependent on the loads it must carry and the
speed of rotation of the pump. In addition to the physical forces

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