Page 232 - Centrifugal Pumps Design and Application

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Double-Case

Pumps

by Erik S. Fiske
BW/IP international, Inc.
Pump Division

Double-case pumps are also known as double-casing, barrel-case, or
barrel-type pumps. They are used for temperatures and pressures above
the range of single-case horizontally split, or diffuser-type multi-stage
pumps, and pressures above the capabilities of radially split process
pumps. The following are typical temperature and pressure limitations
for centrifugal pumps. Horizontally split multi-stage pumps, such as
those illustrated in Figures 6-1 and 10-13 are limited to operating temper-
atures of 400°F [1]. They can be designed for discharge pressures up to
4,000 psi, but often are limited to lower pressures by user specifications.
Radially split process pumps are suitable for temperatures up to 800 °F
Radially split double-suction, single-stage process pumps cover operat-
ing conditions up to 500 psi discharge pressure. Two-stage process
pumps cover conditions to 1,000 psi. Double-case pumps are typically
applied for operating conditions above these limits.

Configurations

Pump Casing

Double-case pumps got their name from being constructed with two
cases: an inner case assembly that contains the complex shape of the sta-
tionary hydraulic passages and an outer case (barrel) that acts as the pres-
sure boundary for the pumped fluid. The inner case assembly is sub-

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