DC Pipe Sizes

[Anthony Whitesell]

I think I'd like to go with S&D PVC for my new setup, especially since it would be the easiest to make my own gates with. I have a few unknowns to figure out. Like, what sizes does S&D PVC come. I'm sure there is 4" and 6". Anything smaller is useless, what about larger? 7"? 8"?

I have another concern as well. The inlet to the new DC is square and they supplied me with a square to 7" round coupling, if I go to PVC after that, how well do the sheetmetal fittings marry with S&D PVC. Is it too big, too small, or just right?

[Dan Friedrichs]

I believe the ASTM 2729 S&D pipe (the lightest stuff, best choice for DC ducting) only comes in 3", 4" and 6".

Even if you could find 7" or 8", I think the prices of the fittings would kill you...

[Jim Becker]

The various plastic options tend to even numbers outside of occasionally being available in 3" as Dan mentioned. Don't hesitate to do a hybrid system if you want/need to have 7"/8" from your DC inlet to at least the first branch. Personally, I favor metal ducting, but I can appreciate both choices.

[Anthony Whitesell]

That's what I'm thinking of, but I wonder how well the pipe and fittings match. I'm thinking of a sheetmetal main with PVC gates, if they fit together.

[Jim Andrew]

It would be easier to adapt from metal to plastic when you go to 6", and you might have to innovate. Like maybe you need to make a bushing, or crimp the end of the metal. You can use the rubber transitions as well that are made for sewer connections to existing pipe.