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

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Chemical <strong>Pumps</strong> Metallic <strong>and</strong> Nonmetallic 293<br />

Figure 15-9B. Partially scallop<strong>ed</strong> open impeller.<br />

Casings<br />

Casings for the ANSI chemical pumps have centerline discharge <strong>and</strong><br />

suction both in the horizontal <strong>and</strong> vertical pumps. This makes it easier for<br />

laying out the piping in a system as well as r<strong>ed</strong>ucing the nozzle loading.<br />

This is because the centerline nozzle eliminates the moment arm from the<br />

centerline of the casing to the centerline of the nozzle that exists with<br />

tangential discharge (Figures 15-10A <strong>and</strong> 15-1 OB).<br />

On the horizontal casing, the centerline discharge results in a cutwater<br />

being approximately 30° off the centerline allowing the casing to be self<br />

venting. The casings are design<strong>ed</strong> so that the rotor can be remov<strong>ed</strong> from<br />

the back without disturbing the suction <strong>and</strong> discharge piping. The gaskets<br />

of the casing are atmospheric confin<strong>ed</strong> so that the internal pressure cannot<br />

push the gasket out, as could occur with a Ml, flatface gasket. The<br />

flanges are 150 ASME flatface with an option of a rais<strong>ed</strong> face for steel<br />

<strong>and</strong> alloy material casings. There is the option of 300 Ib. flanges for both<br />

the suction <strong>and</strong> the discharge on the steel <strong>and</strong> alloy casings. In the chemi-

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