Friction loss in split piping system

[aRom]

I would like some help regarding calculating losses in a split piping system.
The pump has a duty of 200 L/s, from the discharge it splits into two pipes, they re-join 120m down the pipeline.
When calculating the friction losses, do i split the flow and calculate the losses based on 100L/s per pipe then combine those losses for the total losses in the pipework?

Many thanks in advance

 

[katmar]

If the two pipes are the same diameter and length, and have the same fittings, then you can assume that the flow is split equally. If the pipes are not identical then you have to guess a pressure drop between the points where they split and re-combine and use that to calculate the flow through each of the pipes separately. If the combined flow calculated for the two pipes is not 200 L/s then guess a new pressure drop and try again.

Katmar Software - AioFlo Pipe Hydraulics

http://katmarsoftware.com

"An undefined problem has an infinite number of solutions"

 

[LittleInch]

I agree with katmar.

The only thing that is fixed the same is the pressures at the nodes where the two pipes join and recombine., i.e. pressure drop between the two nodes has to be identical for both pipes. It's the flow in each pipe which changes to match the pressure drop.

If the pipes are same length but different sizes the flow will be split (ID1/ID2)^4

More or less.

The difference in flow between even say a 10" and 8" pipe is huge.

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[hydrae]

If the fluid is water at normal pressures and temperatures,
then there are several programs that can do the calculation based upon the H-W formula
one if which is EPAnet which is free from EPA.gov.

Hydrae

 

[GeoEnvGuy]

Epanet allows you to change the fluid properties. Easy to model simple problems once you get the hang of it.

 

[bimr]

One doesn't combine the head loss when working with parallel pipes. Use the head loss for one of the pipes.

 

[LittleInch]

And then adjust the split of flow in each pipe until the head loss is the same.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.