For two pumps operating in parallel, with discharge pipe of 365 mm, connected to a header of 599 mm dia. Is it possible to have header pressure greater than pump discharge pressure.... please elaborate using relations
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Pump Discharge Pressure
#1
Posted 30 September 2014 - 01:24 PM
#2
Posted 30 September 2014 - 02:00 PM
Hi,
If two identical parallel pumps are working at the same time, the header pressure would be a little bit lower than the discharge pressure of the each pump...
#3
Posted 30 September 2014 - 09:50 PM
calibrate your PG/PT... they always confuse you with their values. Even I got confused once in similar case!
#4
Posted 30 September 2014 - 11:44 PM
Hi ,
I think you got the answers . The relation you may refer to is the application of Bernoulli Theorem between discharge point and header .
Breizh
#5
Posted 01 October 2014 - 05:59 AM
Anwar,
Do you mean that, both the pumps are running (flow is doubled) and discharge pressure shown by PG is more than that of as per pump curve?
Please refer below links.
http://www.mcnallyin...-html/15-01.htm
http://www.engineeri...rial-d_636.html
https://www1.eere.en.../pdfs/38945.pdf
In parallel (or series) or not, pumps will follow pump curve.
Regards.
Ajay S. Satpute
#6
Posted 01 October 2014 - 02:51 PM
I agree with Breizh that the Bernoulli Theorem needs to be considered. Because I am feeling lazy I will refer you to a reply I gave recently to a similar question rather than writing it all out again. See http://www.eng-tips.....cfm?qid=371053
The difference in your case is that it seems that the two pumps are running simulateously so the volumetric flow rate in the header is twice what it is in each pump discharge. The header has an area of 2.7x the area of each of the pump discharges so the increase in flow rate and the increase in area almost cancel each other out. Depending on how the discharge pipes are connected into the header (eg, stub-in connections, pipe reducers, tapered reducers) and the losses incurred there, the pressure in the header could be slightly higher or lower than in the discharge pipes.
#7
Posted 02 October 2014 - 12:53 PM
#8
Posted 03 October 2014 - 12:30 AM
Is your header underground and the pressure is measured in a under ground pit? In that case there will gain of elevation and if the friction losses are negligible the header might show pressure higher compared to pressure immediate at discharge.
And hence, as Breiz stated "-Bernoulli Theorem between discharge point and header."
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