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duct step reducer

duct step reducer

duct step reducer

(OP)
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

RE: duct step reducer

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

RE: duct step reducer

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

RE: duct step reducer

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

RE: duct step reducer

(OP)
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.

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