DC - Metal or PVC? 1 4" main or 2?

[travis howe]

Hey all...I'm sure this is out there somewhere but not finding it this morning.

I understand the potential risks of PVC over metal however, performance wise is there much of a difference if any? I'm not picturing why pvc wouldn't have the same performance as metal.

Second question is I have a 2hp delta and the intake is like 10-12" across with 3 separate 4" openings. Should I find something to replace the intake to a single 6" or maybe use 2 of the 4" and connect to one 6"? Not sure where to find something like that (replacing the entire thing w/ one 6")

My run is basically out of the DC up 10 feet and straight 18feet where most all the runs to the tools being w/in a few feet of each other. At some point I may have a need for piping going a different direction, so maybe the 4" would be enough to run one tool at a time?

[Chuck Isaacson]

I would find something to take it to a single 6" main. Ideally, you would want to run 6" as far as you can. Then switch to 4" right at the machine.

[John Jendro]

I went with PVC. I had metal HVAC ducts on an earlier system and the PVC is so much smoother that I believe it has to be pulling the air more efficiently. I'm not sure what potential risks of going with PVC you think you well have. (There aren't any.)

As far as the intake goes, I would take off the the intake port and make it one 6 inch opening and make your main line 6 inches as close to your machines as you can. I would only go down to 4 inches if I couldn't retro the connection with the tool.

[glenn bradley]

+1 on PVC but, that's a Ford/Chevy argument that will never die so you will hear lots of stuff. You mention a large opening reduced to three 4" openings. Is this a 50-761 or the like? I too would try to get to 6" main and carry it as far as is reasonable. I run 4" flex off a 6" main as much as 6 or 7 feet (after a blast gate) to a tool but I keep it as short as is comfortably workable.

Another thing I have seen done with that configuration of a machine is to flip the motor assembly; the whole thing, so the motor is below and the outlet leads up. Bags are switched too of course. The possibility of this will depend on your machine but it avoids the 90* (or worse, a U-turn) coming out of the bottom of the machine.

[travis howe]

It's the older 50-851 model. I've found some factory manifolds to replace this that are either 3 5inch or 2 5inch, haven't found anything to 6".

I did measure it though and the entire opening is only 8" not 10 so hopefully I can find a 8" to 6".

[glenn bradley]

HVAC reducer at the BORG can probably solve this for you.

[Dan Friedrichs]

I understand the potential risks of PVC over metal however, performance wise is there much of a difference if any? I'm not picturing why pvc wouldn't have the same performance as metal.

There are no risks to using PVC. PVC will probably have better performance than metal, as the inside walls are smoother.

I see you're also in the Denver area - just so you know, there is a Horizon Irrigation store at I-70 and Chambers that carries ASTM 2729 6" S+D pipe for a reasonable price (I think it's ~$11 for 10'). They'll try to charge you about double that if you don't have an account, but they'll quickly agree to sell it at the wholesale price if you ask nicely.

Finally, I attached a picture showing how I got a 6" port on my DC. Maybe you can do something similar? I just unscrewed the plate, and replaced it with a plywood disc that has a 6" metal fitting in the center (hidden underneath the duct tape )

[Chris Jackson]

Travis...Home Depot or Lowe's (and possibly ACE) will carry what is called a 6" to 4" No Hub coupling. It's essentially a rubber coupling to join to pieces of PVC pipe...this will work very well as a 6" to 4" single line reducer. Now, as a pump engineer by trade I'll tell you 6" header pipe with 4" drops to your machines is the best way to go from a flow and pressure drop standpoint. However, if like me your objective is not to get every last micron of dust form the air, but rather to get decent chip and majority dust removal from your tools then 4" will be fine depending on the size and speed of your collecter fan (impeller diameter). I currently have a 2hp collector with a 12.5" impeller, and run one 4" branch of PVC at approxmately 10' in length and another at around 12' in length...I isolate whichever header I am not using via blast gate. This seems adequate for me...as I also have an overhead box type air filter running all the time.

Hope that helps.

Take a look at some photos of my setup here.

http://www.sawmillcreek.org/showthread.php?t=134174