Reading Pump Curve (Total Head Axis)
Reading Pump Curve (Total Head Axis)
(OP)
Dear all,
The total head (m/ feet) for a given pump curve, is it always in pressure atmosphere or pressure gauge?
Eg. reference the pump curve Total Head H in Page 8. No atmosphere or gauge is stated. So which is it, A or G?
http://w ww.gouldsp umps.com/d ownload_fi les/ic/bic family.pdf
Is there an industry norm that I am not aware of?
The total head (m/ feet) for a given pump curve, is it always in pressure atmosphere or pressure gauge?
Eg. reference the pump curve Total Head H in Page 8. No atmosphere or gauge is stated. So which is it, A or G?
http://w
Is there an industry norm that I am not aware of?





RE: Reading Pump Curve (Total Head Axis)
RE: Reading Pump Curve (Total Head Axis)
This is similar to the pressure drop down a pipeline - which is also a differential and therefore is not specified as absolute or gauge.
Of course a point pressure at the pump discharge or anywhere along a pipeline can be specified either as absolute or gauge, but not when we are looking at differentials.
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Engineering & Risk Analysis Software
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RE: Reading Pump Curve (Total Head Axis)
But when I read the corresponding gpm vs. H, the reported value in the technical datasheet could not be reconciled with the curve.
Datasheet:
Vendor pump data was reported with suction = 1.2 barA, differential head = 103m =~ 10bar.
Discharge would then be 11.2 barA.
Curve:
At duty gpm, Total Pressure head H read off was 11 bar.
(Il)logical conclusion, the curve of total head H was reporting discharge pressure? Else, should have obtained 12.2 bar A discharge (=11 bar differential head + 1.2barA = 12.2barA)
RE: Reading Pump Curve (Total Head Axis)
RE: Reading Pump Curve (Total Head Axis)
It is one of those instances where a difference of 1 bar makes a difference to the calculation (theoretically).
Else, I may just have shrugged it off..
RE: Reading Pump Curve (Total Head Axis)
Also presumably the density of your fluid is close enough to water to allow your conversion from 103 to 10 bar ?
RE: Reading Pump Curve (Total Head Axis)
For example, if the pump can generate X metres it is X metres at SG 1 or SG 3 or SG 0.7.
RE: Reading Pump Curve (Total Head Axis)
RE: Reading Pump Curve (Total Head Axis)
Thanks for your advices.
FYI, it is water (condensate at 85 deg. C) that I am looking at. Sorry it was not stated earlier.
I called the Pump Manufacturer directly to discuss the pump curves, and was offered the possible explainations (which I will re-confirm with the Vendor):
1. to check the actual impeller installed
2. the Vendor may have used an actual curve from a previous project to submit to me
3. Motor speed in the pump curve maybe different from the data in the datasheet
However at a later date I will review the pump performance test data to verify.
Thank you all for your inputs.
RE: Reading Pump Curve (Total Head Axis)
Points 1 & 2 seem reasonable comment but point 3 doesn't make a lot of sense unless of course you are talking about the difference between say 2 pole and 4 pole speeds, if you are talking about a few percent difference in running speed resulting from slipage then it doesn't account for much in the way of head.