## July 04, 2008

### Pump Efficiency - Quick Way to Calculate

Pump efficiency have always been a problem to determine, especially when no pump information is available. Here is a small equation which can be used to estimate an approximate value without power measurement.

I see this equation more useful for getting the flow information which is generally not available while head & power can be measured.

The formula is useful to make decisions for improvements in pumping system.

The equation is

Eff = 80 - 0.2855 * F + 0.000378 * F * G - 0.000000238 * F * G^2 + 0.000539 * F^2 - 0.0000000639 * (F^2) * G + 0.0000000004 * (F^2) * (G^2)

Where F = Developed head in Feet - F should be 50 to 300 feet
G = Flow in GPM - G should be 100 to 1000 GPM

So if you know flow & head, you can calculate approx efficiency & then can confirm this with power consumption. OR if you dont know flow then use iteration method to calculate flow based on actual power consumption.

Thus it is very useful for all process engineers who need to improve their pumping system. This formula can definitely guide them in making proper decision on replacing or repairing the pumps.

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Anonymous said...

Nice,
What about the flow less than 100GPM.

I got the below formulae from the other online blog for flow less than 100GPM

http://webwormcpt.blogspot.com/2008/05/tips-pump-efficiency-estimation-without.html

profmaster said...

I will not prefer to consider any empirical equation for efficiency as the flow geometry & forces inside the pump changes significantly below 100 GPM. So the errors might be larger.

However I do not see any problem in using this equation as preliminary guideline but one must be carefully consider them based on past experience.

David said...

Hi i just discovered this site and found it pretty interesting.

Howerver i would like to know where this formula is taken from.
I'm dealing into pump business and tryied it to compare with some data that i have and seem pretty much accurate.

As for our business we manufacture pump and get the efficiency by submitting the pump to a multitude of test.

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