concentric or eccentric fittings

Darin(in Michigan)

I knew the answer but was looking for backup. My boss is a plumber but there isn't much steam here. More FA and HW. If I could get a response to the velocity question I would really appreciate it. I'm quite curious.

Darin(in Michigan)

Eccentric reducer or leave the old one?

Does anyone know if a concentric reducer will cause water hammer? Does the velocity of the steam increase as the steam is forced into the smaller hole? Is it safe to say this could cause water hammer? Thanks much

bob young

only use if needed

going in the direction of flow you must use an eccentric or you will have a pocket where condensate will trap. the fitting's purpose is to keep reduction of diameter on the same elevation plane to maintain grade. steam piping is all about proper piping techniques and pitch. every piece of the puzzle is installed with a ruler & level

Brad White_9

Bob is correct

and I would add "flat on bottom". Flat on top will create a pocket which can trigger water hammer.

Brad White_19

Somehow I missed that part

about the velocity question. Answer is YES.

Whenever a volume of moving fluid at a given velocity is forced across less area, the velocity will increase in proportion to the area (roughly speaking).

I say "roughly" in that there are modest turbulence factors at the transition and a film factor at the pipe wall, but heck you do not care about that and neither do I

Tony Conner_2

If...

... the flow is the same, the velocity will increase in the smaller line. But the only reason there should be a reduction in line size is if the flow is smaller past that point. If things have been designed correctly, the velocity should be about the same.

The thing to remember about steam lines is that you DO NOT want pockets of condensate laying in them. In addition to the obvious - everything needs to be sloped so it will drain - there are considerations like globe valves with the stems vertical, and concentric reducers in horizontal lines. You can use concentric reducers on steam lines if they're installed in vertical runs.

Brad White_19

Thanks, Tony

Your answer is more practical than the basic physics I addressed and got back onto the track of the orignal question. You are right in that as part of the design, the velocities should be about the same and best of all, no water sitting in the pipe!

Brad

Darin(in Michigan)

Thanks guys

God do I love this website:))