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Centrifugal Pumps Design and Application 2nd ed - Val S. Lobanoff, Robert R. Ross (Butterworth-Heinemann, 1992)

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12<br />

by Erik S. Fiske<br />

BW/IP international, Inc.<br />

Pump Division<br />

Double-Case<br />

<strong>Pumps</strong><br />

Double-case pumps are also known as double-casing, barrel-case, or<br />

barrel-type pumps. They are us<strong>ed</strong> for temperatures <strong>and</strong> pressures above<br />

the range of single-case horizontally split, or diffuser-type multi-stage<br />

pumps, <strong>and</strong> pressures above the capabilities of radially split process<br />

pumps. The following are typical temperature <strong>and</strong> pressure limitations<br />

for centrifugal pumps. Horizontally split multi-stage pumps, such as<br />

those illustrat<strong>ed</strong> in Figures 6-1 <strong>and</strong> 10-13 are limit<strong>ed</strong> to operating temperatures<br />

of 400°F [1]. They can be design<strong>ed</strong> for discharge pressures up to<br />

4,000 psi, but often are limit<strong>ed</strong> to lower pressures by user specifications.<br />

Radially split process pumps are suitable for temperatures up to 800 °F<br />

Radially split double-suction, single-stage process pumps cover operating<br />

conditions up to 500 psi discharge pressure. Two-stage process<br />

pumps cover conditions to 1,000 psi. Double-case pumps are typically<br />

appli<strong>ed</strong> for operating conditions above these limits.<br />

Pump Casing<br />

Configurations<br />

Double-case pumps got their name from being construct<strong>ed</strong> with two<br />

cases: an inner case assembly that contains the complex shape of the stationary<br />

hydraulic passages <strong>and</strong> an outer case (barrel) that acts as the pressure<br />

boundary for the pump<strong>ed</strong> fluid. The inner case assembly is sub-<br />

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