Page 135 - Centrifugal Pumps Design and Application

9

Vertical

Pumps

by Erik B. Fiske
BW/JP International, Inc.
Pump Division

This chapter discusses radially split bowl pumps that are typically
mounted vertically. In older literature these pumps are often, but improp-
erly, referred to as vertical turbine pumps. This pump type is unique in
that designs with optimum efficiency can be obtained over the full spe-
cific speed range, normally with values from 1,500 to 15,000. In the up-
per specific speed range, the pumps are referred to as axial flow or pro-
peller pumps. The impeller profile changes with the specific speed as
shown in Figure 9-1.
The hydraulic performance parameters, including efficiency, compare
favorably with centrifugal pumps of the volute and diffuser type. How-
ever, except for highly specialized designs, vertical pumps are seldom
used for high speed applications above 3,600 rpm.
Vertical pumps can be designed mechanically for virtually any applica-
tion and are the only suitable configurations for certain applications such
as well pumping. They are commonly used for handling cryogenic liq-
uids in the minus 200°F to minus 300°F range as well as for pumping
molten metals above 1000°F. The radially split bowl design lends itself to
safe, confined gasketing. For high pressure applications, typically above
1,0(30 psi discharge pressure, an outer pressure casing can be employed,
similar to that which is used for double-case, horizontal pumps. Except
for conventional well pumps, the mechanical design for the majority of
vertical pumps is customized in accordance with the application require-
ments. This requires close cooperation between the pump manufacturer
and the architect/engineers responsible for the pump mounting structure
and system piping.
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