24.01.2016 Views

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

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Impeller <strong>Design</strong> 33<br />

Step 8: Estimate NPSHR.<br />

From Figure 3-6:<br />

Step 9: Determine volute parameters,<br />

To finalize the impeller design, we must consider any mechanical<br />

limitations of the pump casing. <strong>Design</strong>ing the impeller alone is not sufficient<br />

as we must see how it physically relates to the volute area,<br />

cutwater diameter, volute width, etc,<br />

• Volute area. Figure 3-7 shows a number of curves for volute velocity<br />

constant K 3 . These represent the statistical gathering efforts of a<br />

number of major pump companies. Figure 3-8 shows the average of<br />

these curves <strong>and</strong> is recommend<strong>ed</strong> for estimating volute area.<br />

The calculat<strong>ed</strong> volute area is the final area for a single volute pump.<br />

For double-volute pumps, this area should be divid<strong>ed</strong> by 2, <strong>and</strong> for<br />

diffuser type pumps it should be divid<strong>ed</strong> by the number of vanes in<br />

the diffuser casing.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!