Dust Collection

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DO NOT use PVC duct for dust collection

10/17/17       
Damien Member

DO Not, Do not, Do not! I tried using 4 and 6 inch PVC tube and fittings for the dust collection system in my first shop 15 years ago. everything had been running fine on a mix of metal and flex collector hose, until a shop partner moved out and took many parts with him. I bought a few new machines and decided to redo the DC system using PVC hard pipe to save money.... it seemed like it was working, but we soon noticed that even if shut down all the ports except for the one machine we were using the system was inept. we took everything apart looking for clogs--no clogs-- then after noticing that as soon as we turned the system on, if you stood close to one of the pipes, your hair would reach out to it from static, I took everything apart and ran bare grounding wire through everything and to the machines. But alas.... it didn't matter what I thought up (I even foil taped the exterior of one run and grounded that), eventually we had to admit that as soon as the system came on it essentially would statically charge itself to the point of disabling the movement of dust through the pipes---OR at least that's what we (2 non-engineering background woodworkers) decided was the case before tearing it all out, plumbing it with spiral duct, and never having that problem again.

BANG LLC

10/19/17       #2: DO NOT use PVC duct for dust collec ...
Mark B Member

You probably wont get much fuss here but if you toss this grenade out on a hobby forum you'll be in for a long ride.

We have metal and only one short run of plastic (in a trough that must be plastic so it can be sealed and glued and is tolerant of moisture in the trough.

Ive been in countless shops that are plumbed completely in plastic, many of which have no static wire inside or outside the pipe and they would all likely take issue with your claims as they had all been running like that for years and were all profitable.

My guess is you had other issues going on that exacerbated the static issue.

Glad you found a solution that works for you.

10/19/17       #3: DO NOT use PVC duct for dust collec ...
chris

thats why it is good to work with a company like air handling systems who advertise on this site.
very knowledgeable.

10/20/17       #4: DO NOT use PVC duct for dust collec ...
Damien Member

To Mark B... agreed, it was 15 some years ago and to us it was a bit of a hokus-pokus sort mystery so instead of continuing down the guess and check time-hole it was becoming, we ditched the idea and went with a known method... which brings up the constant topic of "are you really saving yourself money by trying to do things with cheap materials if it takes more time and might not work vs spending more on materials and getting things done?" (I shouldn't even mention that question--it already hijacks enough forum responses elsewhere--but it was just one of those times that demonstrates the rule). But out of curiosity, are those shops you know of done entirely in plastic plumbed with the corrugated plastic dust collection hose, or did they plumb with hard Schedule 40 PVC like we tried?

Dust Forum Thread

10/21/17       #5: DO NOT use PVC duct for dust collec ...
Geoffrey Wirth  Member

Website: Possessionwood.com

I am using a 5hp cyclone with schedule 40 pvc drain pipe. It has the advantage of being cheap, easy to use, and available locally. It has been working great for about five years. My understanding is that it's not possible to ground column of air and dust. We have not had any static issues. If my system was larger I would be more concerned with containing a potential explosion. I think I would add another small dust collector instead of a single large unit. If I could stop moving machinery around it would be easier to set up a spiral duct system.

10/21/17       #6: DO NOT use PVC duct for dust collec ...
rich c.

I thought I was going to read about someone finally having a fire so the myth about PVC being a spark hazard could be proven. Not so huh? Mythbusters spent a lot of time trying to confirm the myth about a static spark. They even turned the pipe into a Van de Graaff generator and could not get an explosion in the pipe.

10/24/17       #7: DO NOT use PVC duct for dust collec ...
Curt Corum

It was never really a case of the dust catching fire inside of the pipe moving at 4,000 fpm. It is the static discharge from the pipe that can be the ignition source for a combustible dust explosion or a room full of volatile fumes from spray painting. That is what Mythbusters should have tested. It would have been pretty easy to achieve. Open electrical can even be an ignition source in these instances. All that being said, it is also critical to use proper air flow fittings to get the best performance from the dust collector. Curt

10/24/17       #8: DO NOT use PVC duct for dust collec ...
rich c.

Here's a link to an annotated description of the episode. It's called exploding cannon. What's open electrical? I designed explosion proof electrical systems for turbine natural gas compressors early in my life. If you are implying an open electrical box could cause ignition, I highly doubt it. It would take a switch that sparks to be an issue. It would take a spark, and then the exact correct mixture of oxygen and fuel. Explosion proof fixtures do not eliminate the possibility of explosion. What they do provide is containment and prevent transmission of any explosion that occurs inside the electrical system.

Mythbusters

10/29/17       #9: DO NOT use PVC duct for dust collec ...
JR Rutter

Regardless of material, you do need to actually design a duct system to some extent so that it flows well. Air handling has some good design guidelines in their catalog, and there is more info readily available elsewhere. Fan curves, duct diameters, elbow radius, machine connections - it all matters, especially if you run multiple machines at a time.


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