NPSHr and Impeller Diameter Increase 1

[planck121]

I am wondering if there is an equation that relates the NPSHr on a pump to the impeller diameter increase. So what happens to the NPSHr when you say increase the diameter on an impeller.

Thanks

 

[ione]

https://pump-zone.com/pumps/centrifugal-pumps/performance-curves-and-npsh-tests.html

 

[Artisi]

To answer your question - No - there is no equation.
However, assuming you are talking about increasing the impeller diameter of a impeller which has previously be reduced, then flow and head will increase, but not knowing the reason behind the increase can not say what the effect will be on the installed performance. If flow thru the pump increases then it stand to reason that NPSHr will increase and likely that NPSHa will be reduced.

More detail would be required as would a pump performance curve to give a considered reply.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[SNORGY]

ione:

Thank you for that excellent link.

I did have some doubts, but my first reaction was that I would expect little to no change in NPSHR if the same flow was to be maintained - but at a different head - via the impeller change. I can see from this link that this would have been incorrect.

I'll keep this one...thanks.

Regards,

SNORGY.

 

[planck121]

Thanks everyone for responding. The link is very helpful.It certainly clarifies the fact that NPSHr actually increases with reducing impeller diameter (alleast losely speking) and that it would be a failed effort to try to calculate it as per standard equations. Testing seems to be the only way to be able to determine the NPSHr for a given impeller diameter.

Thank You again