Manifold Design Guidelines 1

here are some references that are useful for determining the flow unbalance in manifolds/ headers ( as I listed in a earlier thread):

Bajura, RA "A model for flow distr...: trans ASME 98-A-4,473-479 Oct 76

Acrivos, A Chem Eng Sci V10 p112 1959

Keffer, JF J Fluid Mech 15 p 481 & , 1963

Bajura, RA, Jones, EH J trans ASME V93 ser A no 1 pp 7-12 Jan 71

Ahn, H KSME Int J 12(1):87-95 feb 98

Hager,WH P I Mech Eng C-J Mech 201(6):439-448 1987

Greskovi, EJ , Obara, J T Ind Eng chem proc DD 7(4):593 1968

A science citation search of newer articles that reference these papers may provide more modern techniques, such as using FLUENT etc 3D CFD to simulate the flow in the headers.

I have attached an example of how natural gas services are sized when branches are involved. You might use this as a guide in your problem. You can extend this methodology for use with more than two branches.

Thanks for these references. I notice that the term "momentum recovery" pops up in the discussion of the pressure change in the header. Is this simply the fact that at the end of the header the velocity decreases which increases the static pressure, or is there something more elaborate going on here?

The general piping design rule of thumb is, up to three branches, equalized flow splitting is not required. Four and above, equalized flow splitting is required.

eadwine:

Equalized flow splitting? Could you please elaborate?

skuntz,

"Equalized flow splitting"-setting up pipe layouts so that flow is equalized in each branch. For example, three branch, one header three seperate branchs that are identical so that pressure drop is the same. Four or more branches, Main hdr, two branches, then two more branches on each of the first two branches-piping arrangements identical in order to equalize pressure drop the branch arrangements and so equalize flow.

three branch: | | |
| | | all branches require identical
Flow >____________ layouts and fittingw to
equalize pressure
drops

four or more branchs: | | | |
| | | |
_____ _____
| |
| |
Flow >_____________________


I hope this primitive sketch gives you the picture and idea of how to set up 'equalized flow splittting & distribution.

eadwine-

I see now, thank you. Here is the real problem we a tackling at my company. We need to pump a gas through 10 separate lines from a single pump. Each line is 1/8 inch ID and 3/16 inch OD. The outlet of the pump is 1/4 NPT. Volume to be pumped through the main line is 5 liters/min. I need to figure out how to distribute the flow.