duct step reducer

[pesy]

What is the technical name of a concentric duct reducer/increaser that has a step (shown below), not a taper? Where can you buy them? I found an old 6x4, but I'm looking for a 6x5. The reason I'm looking for this is that I want to increase from a 5 to a 6 without taking up any additional length.

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Pesy

 

[KenRad]

In the piping world, we would just call this a bushing. I'm not sure what to call it in the duct world, but I believe that you'll have a hard time finding one.

What is your application? There may be a better solution. A typical round duct 6" x 5" reducer would be about 7" long. Even a step reducer will have some length -- what's your limit?

---KenRad

 

[CRG]

Make one, this is trivial for a sheet metal shop. Or, get a 6” cap and put a 5” tap in the end.

 

[lilliput1]

What is the CFM airflow and in which direction is it going. I can give you pressure drop for the transition you like & alternates.

 

[pesy]

The step reducer has an installed length of about 1/2". That's it. That's because both the 5" and 6" nubs overlap with the connecting pieces. Sorry about my diagram, it got messed up when I posted it.

It is basically a 6" cap with a 5" hole with a 5" dia x 1" long duct attached.

The issue is not flow, it is more of an assembly issue where I am trying to use existing parts. I have a 6" duct that ends at point A, and a new, 5" duct at point B, that is 1" from point A. Previously, I had a 6" duct at point B and connected A to B with a flexible hose....So to answer KenRad's question: I have 1".

Any 5x6 increaser with a 1" length (plus overlap onto the 5" & 6" ducts) will work. I was trying to find a standard, in-stock item to do the job--I'd rather not make a custom part. They must exist, because I have one in my hands--just not the right size. I don't know where it came from, I found it in a bin of old parts.