Pumps in parallel with different discharge pipework
Pumps in parallel with different discharge pipework
(OP)
Hi All,
In many references I have come across regarding use of pumps in parallel, all examples and theory covers a situation where the discharge of the second pump's pipework is identical to the first pump's pipework, up until their point of rejoining.
However, in reality, this sometimes isn't the case/can't be the case - there might be a need for more bends on the second pump's discharge and some more pipework, for example, before the common point of rejoining.
In my theory courses, I have learned to develop a system curve with just one pump in operation. So my question is, how do I show such a case of the additional pipework and fittings that are required in the second pump's case on the "system curve"? Or am I going to need two "system curves" for each pump - but then how is the overall system represented?
In many references I have come across regarding use of pumps in parallel, all examples and theory covers a situation where the discharge of the second pump's pipework is identical to the first pump's pipework, up until their point of rejoining.
However, in reality, this sometimes isn't the case/can't be the case - there might be a need for more bends on the second pump's discharge and some more pipework, for example, before the common point of rejoining.
In my theory courses, I have learned to develop a system curve with just one pump in operation. So my question is, how do I show such a case of the additional pipework and fittings that are required in the second pump's case on the "system curve"? Or am I going to need two "system curves" for each pump - but then how is the overall system represented?





RE: Pumps in parallel with different discharge pipework
Patricia Lougheed
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RE: Pumps in parallel with different discharge pipework
If you only have fixed speed units, do as vpl says. If you have variable speeds, you'll have to do as many curve combinations as you can make from some set of discrete operating points chosen from your speed range. Its much better to use a pipeline simulation program in that case.
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Pumps in parallel with different discharge pipework
RE: Pumps in parallel with different discharge pipework
If anyone additionally has any recommended websites with an example problem, it would be greatly appreciated - as they say, a picture is worth a thousand words!
RE: Pumps in parallel with different discharge pipework
RE: Pumps in parallel with different discharge pipework
of the composite curve, the parallel pump operation could be very sensitive and/or unpredictable.
RE: Pumps in parallel with different discharge pipework
RE: Pumps in parallel with different discharge pipework
Keith Cress
kcress - http://www.flaminsystems.com
RE: Pumps in parallel with different discharge pipework
RE: Pumps in parallel with different discharge pipework
Kind regards
RE: Pumps in parallel with different discharge pipework
CAUTION!
AFT Fathom is a sophisticated pipe flow analysis program designed for qualified engineers with experience in pipe flow analysis and should not be used by untrained individuals. AFT Fathom is intended solely as an
aide for pipe flow analysis engineers and not as a replacement for other design and analysis methods, including hand calculations and sound engineering judgment. All data generated by AFT Fathom should be independently verified with other engineering methods.
AFT Fathom is designed to be used only by persons who possess a level of knowledge consistent with that obtained in an undergraduate engineering course in the analysis of pipe system fluid mechanics and are familiar with standard industry practice in pipe flow analysis.
By all means learn your fluid dynamics by using this software as a tool. Recognise the limits of boundary conditions. Use other resources such as books and websites. www.mcnallyinstitue.com & www.pipingdesign.com etc.
Download tools from the pump suppliers such as Sulzer, Goulds, ITT Fluids, Flowserve etc etc