Dust Collection - Explosions

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Forum topic by BobKat posted 03-04-2011 05:03 AM 4073 views 0 times favorited 30 replies Add to Favorites Watch
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9 posts in 2782 days

03-04-2011 05:03 AM

Topic tags/keywords: question resource

Has anyone ever had or heard of a dust explosion or fire in a home woodshop dust collection system as a result of static discharge? I’m trying to determine how to install a collection system in my new shop and I’m confused with all the different opinions about PVC vs metal ductwork. There’s a lot of warnings out there about not using PVC due to the potential of an explosion, but there is no specific examples of an issue (at least that I could find). Is the issue real or a myth?

30 replies so far

View ajosephg's profile


1878 posts in 2984 days

#1 posted 03-04-2011 05:07 AM

This has been widely sliced and diced on Lumberjocks.

The need for grounding home woodshop dust collection systems to prevent fire/explosions due to static discharge is basically an urban legend.

-- Joe

View TheWoodNerd's profile


288 posts in 2614 days

#2 posted 03-04-2011 05:10 AM

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671 posts in 2114 days

#3 posted 03-04-2011 05:13 AM

From the research I gathered from a post I made a few years back . No . It takes way to many variables for this to occur. Go with joe.

Now the rest will ring in and say differnet.

-- Who can I block now???????????????????????

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Rick Dennington

5107 posts in 2617 days

#4 posted 03-04-2011 05:21 AM

I’ve had a dust collector in all 3 of my shops…all with Scheudle 40 Thin Wall PVC, and in 26 years of having d.c., I’ve never had a dust fire or explosion, and have never grounded my systems…..I’m with my bud, Joe….urban legend…...

-- At my age, an "all--nighter" is not having to get up and pee...!!!

View BobKat's profile


9 posts in 2782 days

#5 posted 03-04-2011 05:37 AM

Thanks Guys – I appreciate your input

View knothead's profile


162 posts in 3371 days

#6 posted 03-04-2011 06:15 AM

You all are absolutely correct, this topic has seen more than it’s share of discussion. To anyone that might be concerned about static it would be very little effort or expense to simply ground your system and just be done with it. one ground, say, for every 8 feet of plastic pipe all ganged together and then connected to the metal frame of the DC (Provided it is plugged into a properly grounded receptacle) should do the trick.

Just 2 cents worth


-- So Much Wood - So Little Time! --

View woodnick3's profile


3 posts in 2064 days

#7 posted 03-04-2011 08:45 AM

I have used 6 inch schedule 40 sewer pipe for 15 years in the two shops I have built. The pipe was naturally grounded because I put it under the slab before poring the concrete. I have a 2.5 hp cyclone dust collector and have never had any problems with it being able to pull the dust and chips from my machines, and you don’t have alot of duct work hanging in your shop.


View Greedo's profile


470 posts in 2383 days

#8 posted 03-04-2011 08:57 AM

it’s a myth, a commercial one! my dc system is all pvc, i have tried to get schocked by the tubes but never had any reaction, in fact i can feel static, and even get small discharges only from the flexible tubes that came with my stationary tools wich connect them to the dust collection system! even the hose of my Festool shop vac gives me discharges when my naked arm touches it while sanding!

View Les 's profile


201 posts in 2113 days

#9 posted 03-04-2011 02:13 PM

I have used pvc for years, it did get a lot of static build up on my drum sander pipe because it is so fine I guess. I have a roll of bare stranded wire, about # 14. I grounded one end to the sander, ran the wire inside the 4” dust line, and tied the other end to the bare wire inside a nearby receptacle. Problem solved. I wasn’t concerned about explosion, just didn’t like the static build up.


-- Stay busy....Stay young

View TheWoodNerd's profile


288 posts in 2614 days

#10 posted 03-04-2011 04:53 PM

To those who are suggesting “why not ground, it’s cheap/easy”: You CANNOT ground an insulating material. All you can do is drain the charge from a tiny area right around the wire. Unlike conductive materials like metal, insulators are perfectly happy with unbalanced charges on their surface, the static will not “flow” to the ground wire. To truly get rid of the the static, you have to basically wrap the entire duct in metal.

Some anecdotal evidence suggests that as the PVC gets a health coating of dust inside it’s far less likely to take on a static charge from the dust, which would explain why people who’ve wrapped a wire around their duct “don’t have static anymore”. It’s not draining the charge, the charge never generates.

Grounding wires are an exercise in futility.

-- The Wood Nerd --

View airhand's profile


1 post in 2063 days

#11 posted 03-04-2011 04:57 PM

I have been following the combustible dust issue from the industry side. Here is some background info on the topic.

It is important to look at the difference between a classic fire triangle (fuel – dust; ignition – spark; oxygen – air) and a dust explosion pentagon which adds (dispersion – dust suspension; and confinement). YES a spark can cause an explosion. Imperial Sugar, which had the large dust explosion, thought they were doing the right thing. They had sugar dust in the air (dispersion) coming off conveyor belts which moved the sugar. They added an enclosure around the flow of sugar to contain it, since it was being suspended in the air on conveyor belts, hence they added the “confinement” to the dust explosion pentagon. and YES dust is explosive (wood dust the size of fairly course sand or in this case sugar).

Have I ever heard of a home shop exploding no (but I wouldn’t want to be the first) as there is a laundry list of very small to commercial and industrial sized woodworking shop that have exploded. The thing is the dust explosion pentagon doesn’t care what size shop you have if you have the five components (fuel, ignition, oxygen, dispersion, confinement) you have the formula for an explosion. And it doesn’t take much to cause a large explosion (1/32” of wood dust – thickness of a dime). Just look on youtube for videos where less than a cup full of dust makes a huge explosion. Where is confinement in your shop – most likely the dust collector and where can a spark come from? Not only static electricity from pvc but also from picking up a nail that hits the inside of the cyclone. So it is not just a static issue – which can be serious as well – just look at the NFPA regs 664 and 654.

Yes this is a serious issue. The first line of defense is good housekeeping. For example don’t blow dust off your projects with an air gun and create suspended dust which will settle on ceiling joists. Imperial Sugar experienced secondary explosions when the first explosion shook the building which disturbed the dust which settled on the ceiling beams, the release of this explosive dust created the secondary explosions.

Full disclosure, we have been in the dust collection business for 60 years. We have always been aware of the issue and have done much research when this whole issue came up after the Imperial sugar explosion. I have spoken on this issue and even attended a meeting with OSHA. However from a macro level I am very concerned with the potential OSHA regs as I don’t want them to be so strict they create an economic burden on small shops. There are also NFPA regs on the topic as mentioned above. And my business will not benefit if the regulations are so strict that companies literally go out of business because they can’t afford to meet them.

View JJohnston's profile


1614 posts in 2714 days

#12 posted 03-04-2011 05:37 PM

I often get nuisance static shocks from mine. It’s at the ends, either at the collection port, or around the top of the drum under the cyclone. Any way to prevent these?

-- "A man may conduct himself well in both adversity and good fortune, but if you want to test his character, give him power." - Abraham Lincoln

View TheWoodNerd's profile


288 posts in 2614 days

#13 posted 03-04-2011 06:15 PM

You can wrap aluminum duct tape around those points and ground that to get rid of the nuisance.

-- The Wood Nerd --

View TJU's profile


72 posts in 2079 days

#14 posted 03-04-2011 06:39 PM

From what I understand it is not a matter of static electricity build up in the shop. You can get a spark from many different sources, the pvc pipe being the main culprit. We don’t get dust explotions in home shops because home dust collection systems don’t move enough volume of concentrated dust to fuel the explosion. If you want to read a scientific paper about it here is a good one.


-- Although the voices aren't real they have some pretty good ideas.

View DLCW's profile


530 posts in 2077 days

#15 posted 03-05-2011 11:26 PM

The one area where the “no grounding required” method doesn’t work is if you have modern, computer controlled, machinery in your shop that is susceptible to RFI (radio frequency interference). Every time there is a little static discharge it create an EMP (electro-magnetic pulse). Humans won’t feel this to much but the amount of RFI in the air can cause communications disruptions between computers and equipment. CNC’s are susceptible to this and your DC systems need to be well grounded to shunt all the static to ground.

Other woodworking equipment is not susceptible to this so it shouldn’t be a problem.

-- Don, Diamond Lake Custom Woodworks - - "If you make something idiot proof, all they do is make a better idiot"

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