I use a 14-gal shop-vac hooked up to my table saw, router, planer, etc. to collect the sawdust and it’s working well enough until I can afford a real dust-collector.
However, I’ve read that there could be a problem with static electricity causing a fire with the sawdust? Is this true? Has this actually happened to anybody here?
Toolfanatic (a.k.a. The man formerly known as “Toolfreak”)
Replies
For what it's worth, I've never heard of a real case of this happening. I watched an episode of "Mythbusters" where they heard the myth of explosions from fine dust of all sorts being ignited by a spark. They performed multiple experiments, specifically with wood dust, and couldn't make a fire, or explosion.
Given all that, I'm still a whimp when it comes to fire prevention. Best suggestion? At the end of the day, empty the shop vac outside anyway. It's just good prevention.
I suppose that it's theoretically possible, but I've never heard of a documented case of this.................the urban legends seem plentiful, though - lol.
Back around 1971-2, I was sharing a shop with a couple of guys up in Fayetteville, when a young fellow emptied the contents from under the table-saw onto a bed of hot coals. He managed to close the lid, it was top load, before the explosion. That lid was cast iron, and after it hit a high ceiling then landed on the floor between us there were about 4 young weak kneed woodworkers needing to check their shorts.I took my band-saw off of the system when one night I was cutting something and noticed that my shop apron was standing straight out from the draft just an inch from the blade, but the scary part was the stream of sparks and dust being sucked into the pipe. The thrust bearing behind the blade was the cause of the sparks. It is set up with the axis fore and aft, with a plate where the back of the blade riding against the edge of the face, so there is a slight shearing action between the back of the blade and the edge of the disk. With that as an ignition source, in the stream of fine dust from a BS, nothing happened before I took it off, so I don't know what it takes, but I don't want to ever find out either.
The woodstove explosion was most likely a gas explosion, not a dust explosion. A smoldering fire, which could have been caused by smothering the coals with sawdust, will produce a very flammable gas that will ignite explosively under the right conditions. I've seen this happen a few times.
John W.
John, You are right, I didn't think that anyone might think that I was implying that would have any relevance to the shop vac / static topic. I don't even know why I thought about it, or wrote it down. I guess it could be one more of those hazards that someone heating with wood may not know about.
I'll stick my big old nose in here...DUST can explode for almost any reason... Just ask the grain elevator operations that had to put all kinds of safety devices and sensors all over the place.. To lazy to look it up now but some link I found had number of deaths from dust explosions per year.. WAY down since OSHA got involved in it...I think I posted in here about a fire I caught in my shop Vaccume.. I do not think it was caused by static.. Probably spontaneous combustion...I do not think it is a real problem.. I now empty my vacuume outside into a closed metal trash can that is outside away from the house.. I figgure better safe than sorry..HOWEVER.. Long ago I did see a small vacuume cleaner explode..
Xerox tech. cleaning a copier of toner/mix... There is Iron in the Mix (what the toner is added to) and causes ALOT of static...
Dust from most any substance, in the right combination of concentration and particle size, can explode if exposed to a spark or flame. I worked on the reconstruction of an animal feed manufacturing plant a couple years ago that had a dust explosion; it took down a good portion of the building and unfortunately one of the workers was killed.
I don't have any data to back this up, but I suspect that sawdust generated in a small shop is usually not fine enough or in large enough quantities to cause a problem as long as you clean it up regularly.
Ahhhh, but corn flour now... DAMHIKT
Not to worry ...........
There was a thread her sometime back in which someone posted a study done on dust collection systems from an MIT professor, who himself is a hobbyist woodworker.
He said there has never been a documented incident of a fire started by static electricity in a dust collection system -- which would include a shop vac.
His evidence was good enough to cause me not to worry about it.
Maybe somebody can pull up the link to that thread.
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"It is what we learn after we think we know it all, that counts."
John Wooden 1910-
Most fires in dust collection systems are caused by the intake of metal parts such as screws or nails that cause a spark when hitting a metal impeller. This is one reason why cyclone systems are safer since the heavy objects drop out before the impeller. I would have no concerns of explsoions caused by static discharge.
I think it more likely that a vacuum can pick up an ember from a burning cigarette or a spark from one of the tools which then smolders inside the container till it catches on fire.
A spark caused by static electricity is most unlikely in places of high humidity (like Houston). Down here you can scuff yoor feet all day on a carpet without getting a static electric build up.
PlaneWood by Mike_in_Katy (maker of fine sawdust!)
PlaneWood
Far as I know, the only static problem you'll encounter in the real world is occasional zing to yourself.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Another proud member of the "I Rocked With ToolDoc Club" .... :>)
"Occassional zing" she says, LOL. You can get quite a whack. It ain't the whack tho, that's gonna hurt, it's whatever part of you hits some imobile object when you jump, LOL.
Tool guy: In the National Electric Code, I spent most of my working life as an electrician, there are many references to dust hazards. Some are the various dust's explosive and fire potentials on its own and some are about the dust collecting on and insulating heat producing items till the temperature gets dangerous. There is also a situation where if the dust sits long enough on something warm it ''carburizes'' which makes it much more likely to burn. Static is also mentioned but I don't remember it as it relates to wood dust. Mostly for flammable liquid transfer where the vapor is very flammable, explosive even. The national authority on this is the NFPA or National Fire Protective Association. They have information available and probably will answer some questions via their web site. Hope this helps, KDM
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