DC piping

[Lee Schierer]

What Ben said! Tons of "discussions" on the Forum.

I've read many people saying there's no problem with static buildup in PVC and many who say there is and run a drain wire for protection. If you don't believe in the potential for static buildup in "plastic" pipe, just place your arm next to the hose on your shop vac while it's running. Air moving through plastic creates static. It might never create an explosion hazard, but?????

Yep, I had that static too for about the first week I used my shop vac, now it is gone. The same thing happens with new pvc pipe until it gets some dust on it. New pvc pipe off the rack is full of static, it goes away in less than a week of use. My DC system is over 10 years old and the static charge on the pipes after planing a dozen boards won't even wiggle the hairs on your arm. No ground wires inside or out.....

[Bill Blackburn]

There's a pic of 30ga being sucked flat on the Oneida site.
.

I swapped out my sch 2929 pvc for 30ga metal from the Borg when I replumbed shop as I wanted less weight up on ceiling. Also the fittings are everywhere here - pvc was hit-miss depending on day. I used 6" metal that came in 4' sections. Run a 2hp PSI dc http://www.pennstateind.com/store/DC2000B.html , and not had any issues on collapsing. I'd read and saw a thread on someones pipe collapsing and that had me nervous and was reason I went pvc first time around. Funny thing tho - that is the only documented collapse out there and a lot of us use this stuff. A really big cyclone and choked down metal and no doubt it could happen I imagine. Not real world scenario for many of use in our shops I believe.
At least that be my .02 and I'm holding to it.

[Chris Damm]

I have using PVC for years with no problems. Forget the glue or screws! If you need to hold it together use foil faced tape, it is easy to cut when you need to change (and you will) your system

[Ken Fitzgerald]

GENTLEMEN...................

1. John Keeton posted photos here at the Creek of his collapsed 30 gauge pipe that he experienced he first installed his DC system.

2. Did it ever dawn on you that if I have more CFM and HP in my DC than you do, my system could collapse 30 gauge pipe and your wimpy system couldn't? The point is not all DC systems are the same and some might collapse 30 gauge pipe. If the manufacturer recommends NOT using 30 gauge metal pipe, there might be a reason why and it might be prudent to follow their recommendations.

[Jim O'Dell]

I didn't glue connections either. But after the connections were put together and in place, I did put some caulk on the seam edge with my finger tip. Easy to cut and take apart if need be. Jim.

[John Harden]

Did someone say they glued up their PVC connections? I must have missed that.

I can't think of any reason to ever do that in above ground installations. Screwing them together will hold them tight so they don't pull apart, even on vertical runs. A bead of silicone caulk around the connection point will make it air tight and in no way "glues" the joint together. It just peels right off when you need to pull it apart.

If you prefer duct tape, I also agree with the recommendation for the foil type made for HVAC. The outer "fabric" doesn't get brittle and seperate from the adhesive like typical duct tape will over time.

Regards,

John

[Troy John]

will abs work the same as pvc?
sorry for the lame questions, Im new to this stuff and dont want to create a
hazard for me or my family?
Is there some where that states the flow numbers for different size piping?
Finaly does it do me any good to hook a 6" hose to a machine with a 4"
outlet or is it only as good as its weakest point?

Thanks for helping the amature

[Bill Arnold]

... If the manufacturer recommends NOT using 30 gauge metal pipe, there might be a reason why and it might be prudent to follow their recommendations.

Amen, Ken!

I followed Oneida's recommendation about 26ga on my wyes, 7", 6" and part of my 5" duct. My only deviation was part of the 5" and all of the 4" is 30ga that I bought from a local HVAC distributor. Early in my installation, I checked a section of 30ga 4" with full flow through it, then closed the gate and it never moved. I would not have used anything lighter than 26ga for the larger diameters but 30ga is working fine on my 5" and 4" sections.

[John Keeton]

There's a pic of 30ga being sucked flat on the Oneida site.
.

Mitchell, I haven't seen the pic, but I suspect it is mine. I provided Oneida the pics and gave them permission to publish them. Do you have a link? I would be interested in seeing how they handled it.

Did it look like this?

[Chris Livingston]

I haven't even been able to find 6" PVC or ABS here in Portland. I was initially looking for some for one section of my DC and couldn't find it. Plus HD doesn't have air ducting anymore (at least here they don't) and they looked at my like I was crazy when I asked about 6" PVC.

Went with snap together 26 gauge metal ducting in 5' lengths. They cost about $11 for each 5' section.

[Dan Friedrichs]

I haven't even been able to find 6" PVC or ABS here in Portland. I was initially looking for some for one section of my DC and couldn't find it. Plus HD doesn't have air ducting anymore (at least here they don't) and they looked at my like I was crazy when I asked about 6" PVC.

Went with snap together 26 gauge metal ducting in 5' lengths. They cost about $11 for each 5' section.

Did you try Horizon Irrigation (they appear to have a location in Tigard)? The Horizon near me has ASTM2729 6" PVC for ~$15/10'.

[Chris Livingston]

Dangit, never thought about irrigation companies. I'll give them a shot for some short lengths I need. Thanks

[glenn bradley]

One issue with PVC is if you glue it together during install. If you need to make modifications to your DC piping then it's a pain to saw apart and re-attach. Modular piping has an advantage in this regard.

My ASTM-2729 is all slip-fit and airtight. Its actually a bit of a struggle to get a joint separated if modifications are required. I did use a short self drilling screw (too short to enter the airway) as a belt-and-suspenders item where the blast gates slip in.

I had no issue with static till the air turned dry. If my install didn't require me to touch one of the airways as I pass, I wouldn't have bothered. But, for a few bucks I bought some insulated, stranded, copper wire (no it doesn't need to be bare . . . think about it). I attached one end at the cyclone, wound it about 1 turn per foot using wire nuts anywhere I though I might want to detach a joint (3 total).

At the far end I crimped an alligator clip to the wire. I scrubbed a spot on the slab with alcohol in an out of the way place, applied some metallic HVAC tape molding a little flap into the middle and clipped the alligator clip to that. No static since. Cost = <$10.