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A Refresher On Pump Cavitation And Npsh

There have been numerous articles on the subject item and most standard textbooks in chemical engineering provide quite a detailed description on what pump cavitation and NPSH is. Despite all the literature available on the subject, the debate related to pump cavitation and NPSH continues which is evident from the numerous postings related to the subject in "Cheresources" forum.

The fact that many chemical engineers raise queries related to cavitation and NPSH indicates that whatever information they have gathered is in bits and pieces and are not able to get their hands on some comprehensive article or book regarding the subject. This blog entry is a humble effort to try to cover the subject to the extent that it proves a refresher to most chemical engineers who have some knowledge of the subject.

As I have mentioned earlier in my blog entries I am not a researcher, I am a compiler. I love to compile information from sources which I find easy to understand. In this regard, I have liberally picked up material from a book which has in my opinion treated this subject in exhaustive detail and with great clarity. The name of the book is "Pump Characteristics and Applications" by Michael Volk.

There are illustrations and tables in my explanation of the subject of cavitation and NPSH which cannot be reproduced as text here. Hence, the whole subject is provided as an attached word file. Please refer the attachment accompanying this blog entry.

I would love to hear the comments from the members of "Cheresources" regarding this blog entry.


Download attachment: Refresher on Cavitation and NPSH

See also, article on cavitation from Mukesh Sahdev here:
Centrifugal Pumps: Understanding Cavitation

It si good stuff for young engineers in consultacy .
I have one question on control valve pressure drops.
During basic engineering stage ( i.e, when we don't have exact elevation and isometrics available) how do we specify the control valve pressure drops??

Your question is not related to NPSH and cavitation. However, the answer is:

For liquid service during the initial stage of design consider 30% of the system dynamic losses (excluding control valve) or 0.7 bar (10 psi) whichever is higher.


Thanks !

Sep 20 2011 08:02 AM
Thanks Ankur sir...


Thanks Mr. Ankur

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