DC piping

[Troy John]

Am I safe to run PVC or ABS plastic pipe for my dust collection?
I have been told that plastic pipe builds static and will spark or arc,
yet I know of people running it without trouble.
Whats the trick to make it work? Thanks

[Ben Hatcher]

There's no trick. Use the forum's search function and read through the countless posts on this topic.

The short short version is that PVC will build up static but that the conditions needed for that static to cause an explosion are nearly impossible to replicate in a home hobby shop. If you're a belt AND suspenders kind of guy, go with metal. If you like to play the odds, **edit odds of an explosion are about as high as you winning the lottery TWICE* pvc can be a lot cheaper.

[Bill Arnold]

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?????

[Jim O'Dell]

I've been running PVC for 2 years now and no problems. I get very little static build up, and have never been shocked from the pipe, though it will raise the hair on my arm at times when the humidity is real low. Some people go to great lengths to try to discharge the static, but I truly believe it is a waste of time and money for a hobby shop. Commercial heavy use, I'd bet code would say you must use metal ducts. Jim.

[Greg Portland]

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.

[John Keeton]

I have never put any stock in the explosion hazard with PVC. With all that has been written, I have yet to see a specific documented incident in a home workshop. There have been industrial situations in a heavily dust laden air situation, with a large volumn of air, but NOTHING ever reported in a home shop. Pretty good odds given all of the DC sytems.

That said, when I installed my DC system, I priced everything, and the cheapest, by far, that I could do my install was with HVAC metal snaplock from a local supplier. It was a bit more work, but I doubt much. The stuff is lightweight, and I merely taped all connections and applied silicone to all elbow joints. I have no leaks that I am aware of and I get extremely good performance.

One caution - you MUST use 26 gauge pipe. Trust me, DO NOT use 30 gauge or you will be replacing your ductwork!!;)

[zayd alle]

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.

True, Greg. To avoid that problem -- especially since my shop layout wasn't final -- I just dry-fitted the joints and caulked the seams. The dry joints are tight, nothing moves and no leaks.

Zayd

[John Coloccia]

I don't worry much about the static except I did ground it at the SawStop end. I heard a rumor that a large static discharge from the DC piping was able to set off the brake. Just a rumor, but it makes sense to me, so it's now grounded at the SawStop end. It won't stop a spark but it'll give it a good path to ground and away from everything else, hopefully. I don't personally believe that a hobbiest shop could make the tremendous amount of fine dust, in a sustained manner, which is nescessary for an exposive atmostphere. Maybe I'm 100% wrong but it just seems very hard to imagine. That's just my opinion, though.

I ran PVC, by the way, and Dry fit everything with a screw through the coupler when I was happy. If I find a particularly leaky joint, I duct tape it (of course!).

[Denny Rice]

True, Greg. To avoid that problem -- especially since my shop layout wasn't final -- I just dry-fitted the joints and caulked the seams. The dry joints are tight, nothing moves and no leaks.

Zayd

You can also do as I did. I dry fitted the PVC together but instead of gluing the system together I used 1 1/2" self tapping screws at all the joints. This gives you the ability to make fine adjustments while hanging large and small pipe sections, once you are happy with the system, go back and apply a small bead of silicone at all the joints. When building your system you can also save a LOT of cash by building your own blast gates, I built 6" blast gates for less money than I could purchase 4" gates from several retailers. Hope this helps. You can also get a lot of cool ideas from Bill P's website

[Nick Lazz]

You do not need glue for PVC. I used S&D2729. My whole system is dry fit and the joints are tight enough. No leaks. No screws either except in a few vertical drops. There is a study that was done on the PVC debate that I think is linked to the Bill Pentz site. A lot of good information. Bottom line, PVC is safe to use.

[John Harden]

I have never put any stock in the explosion hazard with PVC. With all that has been written, I have yet to see a specific documented incident in a home workshop.

+1000 This has been discussed so many times it is downright tiresome.

I've used PVC for nearly 15 years here in bone dry Southern California.

For the folks who claim otherwise, I'd ask them to point to an instance of a home shop fire caused by a plastic ducted dust collection system.

They can't because there have never been any. The burden of proof rests with them.

Given the thousands of installations across the country, if the threat were real, you'd see suburban homes going up in flames, two or three a week. ;)

Nothing to see here. Move along folks.......

Regards,

John

[Bill Leonard]

Assuming you are truly concerned (needlessly) regards static build up in your PVC, consider the fact that the ground wire must be inside not outside the pipe. Grounding the outside does nothing to discharge the static inside where the dust is. PVC is an insulator, therefor, the static build up is only discharged through the ground on the surface exposed to the ground wire.

[Cliff Holmes]

Assuming you are truly concerned (needlessly) regards static build up in your PVC, consider the fact that the ground wire must be inside not outside the pipe.

This won't do any good, either. It is impossible to drain the static charge from PVC. PVC is an insulator, the static will not travel across it to a ground wire more than a fraction of an inch. The only way to ground PVC is wrap the interior with a conductor, e.g. a metal lining.

And yes, this is a needless concern. You'd be much better off building a meteor shield for your shop, because you're vastly more likely to be hit by a meteor than get a static-induced dust explosion in a home DC system.

[Curt Harms]

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.

Don't glue it. A lot of mine is simply pushed together as tight as I could get it. The joints that might move I wrapped with Duct tape. Another option is to put 2 or 3 short screws through both pieces of PVC. As far as a fire/explosion hazard, I'm more concerned about a bit of metal striking the metal D.C. impeller and creating a spark then settling into a nice bed of kindling:eek:. The only time I've ever had significant static in my shop was using a Fein vacuum to vacuum a D.C. canister filter out. THAT operation created some static.

[Mitchell Andrus]

One caution - you MUST use 26 gauge pipe. Trust me, DO NOT use 30 gauge or you will be replacing your ductwork!!;)

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

[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?
http://www.sawmillcreek.org/attachment.php?attachmentid=86642&stc=1&thumb=1&d=1208386587 (http://www.sawmillcreek.org/attachment.php?attachmentid=86642&d=1208386587)

[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 (http://www.sawmillcreek.org/attachment.php?attachmentid=116473&d=1240537596) into the middle and clipped the alligator clip to that. No static since. Cost = <$10.