2 replies to this topic

[BABU]

Appreciate if anyone could comment on the following:

1. What is the difference between 'Junction' and 'Manifold' in PIPEPHASE?
2. Under what conditions each should be used?
3. Which is best suitable for steady state simulation?

Thanks in advance

Regards
Babu

[Adriaan]

1. What is the difference between 'Junction' and 'Manifold' in PIPEPHASE?
2. Under what conditions each should be used?

1.) In my experience a MANIFOLD is used to connect multiple things (hence the name) to a source or drain. For most applications the manifold is larger than the piping connected to it, thus acting as a buffer a little bit (in air systems the manifold is often installed vertically with a drain at the bottom).

In a piping JUNCTION only a few pipes are connected directly (having more than three in any one junction is rare for mechanical - technical reasons, consecutive T junctions are normally used if more pipes need to be connected) together (no larger section).

2.) The placement and orientation of [and choice between] a manifold or junction depends on several factors; the media involved, the minimum and maximum flow required, the step-difference in flow (in sizing the manifold, to prevent waterhammer for example) and mechanical-technical considerations.

The drawback of using a manifold is that it almost by definition creates a dead zone so for substances that need continuous flow (to prevent sedimentation, separation, condensation, fermentation) consecutive pipe junctions might be needed (or alternatively some way to clean the manifold). One nice advantage of using a manifold is that it is a lot easier to identify different lines as the connections (and usually valves) form a neat series. Said dead zone can be a disadvantage but also an advantage (see the air system manifold comment above) .

[BABU]

Sub: 'Junction' and 'Manifold' in PIPEPHASE

Thank you dear Adriaan

I am interested in fuel gas cross country pipeline network. I wish to know what is the best practice - ie. to use the 'Junction' or 'Manifold' in the pipeline network model? I guess it is easy to develop the network by using the 'Junction'. 'Manifold' has more long term benefits. ie if it is required to stop flow through a particular pipeline, then it is easy in Manifold, but in Junction, we have to physically delelte the line.

Another query is related to Pipe Inside Roughness. The default 'absolute' value is 1.8e-003 in. I wish to know what is the typcial value for pipelines 30 - 40 years old?