Question:
There are often cases where the centerlines of the suction and discharge from a given pump are not on the same level. Some cases can be more significant than others. When the manufacturers create their curves, are they accounting for this change in elevation in the data?

Answer:
The Hydraulic Institute standard asks the manufacturers to restate the total head relative to the centerline of the pump. So, if the manufacturer has gages at the suction and discharge flanges, they are supposed to adjust for the location of these gauges relative to the centerline.
 
That being said, there is no guarantee that all manufacturers make this adjustment correctly. If, for example a manufacturer were only using a discharge gauge in their test, they would be mixing up total head with total discharge head which would overstate the pump’s actual performance.
 
If you have any doubts, the best bet is always to contact the manufacturer of the pump you are considering for your application to verify what method they use to gather their data.


Guest Expert:
This Ask an Engineer answered by Pump Consultant, Michael Volk, P.E. President of Volk & Associates, Inc. Author of the reference, Pump Characteristics and Applications, Second Edition, published by CRC Press.

To read more about Michael Volk, click here.