Pump Curve Operation

[sinbj1]

Can I expect to see shaft deflection for a standard centrifugal pump operating to the far right of the pump curve? If so, what would the mechanism for which the excessive radial forces would be generated? I would expect to see signs of clasical cavatitation as the NPSHr increases as flow increases but what about shaft deflection?

 

[SNORGY]

According to Chesterton et al, at least, you will have some amount of shaft deflection when you are either left or right of BEP, since either case will produce unbalanced side loads on the shaft.

 

[Artisi]

Google "pump shaft deflection" plenty of info. to satisfy your concerns.

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.)

 

[TenPenny]

The short answer is yes, if you are not AT BEP, you will have shaft deflection.

 

[BigInch]

Shaft deflection creates high bearing stresses, vibration and seal wear.

"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek

 

[Artisi]

In real life, I would be less worried about shaft deflection at "run-out" compared to operating at CV. Operating well right of BEP introduces other problems, cavitation, mis-match of flow onto the impeller blade, possibly with pre-rotation, noise and vibration, possible seal damage, bearing overloads etc. You haven't indicated what size pump you are talking about, if it was a 0.5kw unit I wouldn't be concerned in the slightest about operation well right of BEP, on the other hand if it is a 1000kw unit when I would be very concerned.

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.)