Pumps connected in Parallel

[ullas2711]

Hi All,
I have installed two submersible pumps of same make and specification in a tank and connected the discharge of both of them to a common header. I want to know what will be the pressure at the header if the pump discharge pressure is 2 bar. Whether the pressure in the header remain 2 bar itself or will it increase?
Thanks in advance.....

 

[petrochemical87]

Are you running them in parallel?
centrifugal pumps connected in parallel will produce the same head and hence the dicharge pressure for both pumps will be the same. Assuming there are no elevation changes the header pressure can never be greater than the indivisual pump pressure.

 

[ullas2711]

Yes I am running them in parallel

 

[petrochemical87]

I am not quite sure what you want to achieve with your pumping system.
Do you wish to increase the header pressure?
Is 2 bar the discharge pressure when one pump is running?
Do you wish to run both pumps to increase the header pressure?
Please provide more details.

 

[JJPellin]

The flow and pressure will be determined by the point where the combined pump curve intersects the system curve. The most likely outcome will be an increase in both flow and pressure. Draw the curves.

Johnny Pellin

 

[Artisi]

To answer your question, the pressure in the header will be 2 bar less any losses due to friction from the pumps to the header and any change in elevation from the pump discharge to the point of measurement.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[gerhardl]

...also important to know for best possible pump result: connection and pipeline layout including dimensioning of pipelines and placement of checkvalves.

Two pumps in parallell can give as a result the one pump giving higer pressureresistance for the other, than for the first. Result: uneven load, wear and pumped amount. [But total pressure not more than 2 bar)

 

[bimr]

Pumps are connected in parallel to increase the capacity (gpm or m3/hr) of the system.

The pumps will pump where they each intersect the system curve. Please note of the following:

[ol 1]
[li]With two pumps running they intersect at a higher head and a greater capacity than if one pump was running.[/li]
[li]With two pumps running, the higher system head will cause each pump to reduce its capacity a little bit.[/li]
[/ol]

 

[DubMac]

Draw the curves!
When selecting pumps suitable for parallel pumping, I think of two important considerations:
1. Make sure none of the performance curves are "drooping", i.e. head never decreases moving towards shutoff.
2. Curves should be somewhat "steep", i.e. minimum 10% head rise to shutoff from BEP.

 

[123engr]

If your pumps are connected in parallel position, the pressure at the header will be the same as the discharge head.i.e. 2 bar.

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