PUMP CURVES 1

[turbA]

hi everyone!

We are currently operating a six-stage pump that has been in operation for possibly 20 years. During this time, the internals have been continuously repaired and I think the impeller size has changed.

If the head obtained from the pump is the same, can the original pump curve still be used to assess where the pump is currently operating or do we have to obtain a new curve? In other words, what factors affect the pump curve?

Thank you!

 

[pmover]

if impellers have been changed and are not hydraulically identical to original design, then the original pump performance curves should not be utilized.

short of obtaining oem performance curves & while not familiar with pump system as a whole, it may be a simple process to gather actual opera data and create a curve for existing pump. if historical data is available for the current pump configuration (i.e. impeller, etc.), you might then be able to conduct a performance analysis, but be aware of potential differences.

regarding factors in pump curves, process fluid, rpm, impeller geometry, case geometry, etc. to name a few.

good luck!
-pmover

 

[scalleke]

If there have been changes to the parts that you mention then the original curve is no longer valid.

Either have the pump retested or test and determine the curve on site.

Best Regards.

Scalleke

 

[api9th]

hi brothers
acc.to API 9th edition ,if pump shaft cotains more than i%chromium &speed is more than 20m/s then it should be hard chromium coated to prevent wire wooling.
does one of you come across such problem ?
rgds
api9th

 

[smckennz]

Hi turbA
if you can do a shutoff head, and have a second head point with a measurable/known flow, you should have a reasonable idea of whats going on if you plot on the old curve.
Normally with old reworked pumps, the curve drops a bit faster; I would allow 80% of new flow at measured head if the application is not critical.

Cheers

Steve