airborne sawdust combustion?

[Kaizen]

I was doing a lot of table saw work the other night. My saw is a hybrid cabinet saw and I had the 4" dust collector on the whole time. Also due to 5 degree night I had on my 110k btu trash can propane heater. I noticed after a few hours the air had a lot of dust in it from sawing. I know grain towers can explode due to this and was wondering if I was putting myself at risk with an open flame and a lot of dust?

 

[Caman]

Yup, it can also happen with paper, and other flamable dusts at the right concentration.

http://www.lni.wa.gov/safety/hazardalerts/SawmillDustExplosions.pdf

.What causes dust explosions?
The 5 basic elements needed for a combustible dust explosion are:
 An accumulation of fine, powder-like combustible dust. Accumulations as thin as a paper clip, or even thinner can pose risk depending on physical characteristics.*
 Dispersion of the dust into the air in sufficient amounts.
 Confinement of the dust cloud inside a room, machine, or other space.
 Oxygen in air.
 An ignition source such as a flame, hot work, spark, electric arc, or static discharge.
*Per NFPA 664, Standard for the Prevention of Fire and Dust Explosions in Wood Processing and Woodworking Facilities.
Dust explosions often occur in series. For example, the pressure wave from an explosion inside a piece of process machinery can shake dust accumulations loose from ceiling beams and other surfaces outside of the machine, suspending dangerous dust into the air and leading to a second, more devastating blast. The destructive forces from an explosion can kill or injure workers and bystanders, cause fires, send out flying debris, and destabilize building structures.

 

[info2x]

Almost anything if fine enough is an explosive powder.

 

[RunninOnEmpty]

I've heard of factories going up in flames from chips of metal like titanium catching on fire as well. A lot of things can catch fire particularly when in small pieces. The chance of it happening depends on the specific type of dust, concentration, proximity to your heater, any filters in the heater, etc.

 

[MFolks]

People who cut metal on miter and tablesaws, can also have a fire ignite, from sawdust buildup. I've heard of vacuums, igniting/exploding,if the filters are clogged too.

 

[Kaizen]

this site has a huge following. has anyone here had or heard of this happening in a woodshop like I described?

 

[Stuart in MN]

It's possible, but the amount of airborne dust required for an explosion is probably more than you're normally going to see in a home shop. However, determining just how much dust is enough is the tricky part, and certainly you don't want to find out through personal experience. If you follow the link posted earlier it leads to some other links that have some information about concentration levels.

The main thing is to regularly sweep up sawdust, and to use ventilation if you're doing a lot of cutting at one time. An air cleaner may be worth looking into - you can buy them (here's one example: http://www.rockler.com/how-to/woodshop-air-filtration/ ) or there are plans out there online for building your own, they're basically a fan in a box with some filters on it.

I was once involved in the investigation/reconstruction of a grain facility that exploded; it was not a pretty sight (the whole front wall of the factory blew out and one worker was killed), but they had huge amounts of dust piled up along with some non-code wiring.

 

[Fishplate]

I know grain towers can explode due to this and was wondering if I was putting myself at risk with an open flame and a lot of dust?

14 people killed, 42 injured when sugar exploded.

http://en.wikipedia.org/wiki/2008_Georgia_sugar_refinery_explosion

Dust can be bad news.

 

[pima67]

Back in my U.S. Army explosives demolition training, we were told how to level a building using a few pounds of explosives by first setting off a small explosion that raises dust and then igniting the dust.

 

[67carl]

Next time you're in a restaurant that has a candle on the table lightly sprinkle some of the powdered creamer from one of those little packets on the flame. Like a sparkler! The Mythbusters did it, but on a much larger scale:

I worked in a sugar factory for a short time. They had two massive silos to store the processed sugar in that were cone shaped on the bottom. Over time the sugar would pile up on the sloped wall and they would have to lower someone down from the top to shovel it off. They wore bunny suits and had to use copper shovels so they wouldn't inadvertently cause a spark. Spark = BOOM! With sugar dust.

 

[404]

this site has a huge following. has anyone here had or heard of this happening in a woodshop like I described?

No. The question has come up before on forums even before the web. On an industrial scale it does happen. On a home scale it does not. If there was a home incident we would never hear the end of it.

 

[srmofo]

Possible? Sure
Probably? Very unlikely
I might be concerned with starting a fire with an open flame but not am out right explosion

But it's the same reason some people run a grounding wire through their dust collecting pipes.

 

[bdkw1]

this site has a huge following. has anyone here had or heard of this happening in a woodshop like I described?

Kind of......

As a prank, we screwed the bathroom door shut on one of our least favorite fellow employ's. My buddy then blew a dust pan full of very fine sawdust under the door with an air hose. He then fallowed up with a can of carb cleaner and a lighter. There was a extremely large thump from behind the door. The explosion poped both the guys eardrums. It went off a little better than planed.

So, yes, I have witnessed a sawdust explosion.

 

[zeeke]

Yup, it happened in our wood working shop when I was in High school. Back in the early 80's.

 

[G_P]

People who cut metal on miter and tablesaws, can also have a fire ignite, from sawdust buildup. I've heard of vacuums, igniting/exploding,if the filters are clogged too.

Aluminum powder is one part of the explosive used in M80's. The finer the powder, the bigger the bang. Metals are also quite hard to put out when they get to burning.

I've had so much sawdust in the air in my shop that visibility was limited and it never blew up and my furnace is down there.

 

[1320stang]

I used to work for a commercial store fixture manufacturer. They would shut the shop down every year right before Christmas for 2 weeks and clean the shop, even the rafters.

In the late 80's I worked in Albuquerque building custom adobe homes. We'd typically set up a table saw in the garage for trim and such. We'd sweep the building out and clean it pretty good prior to sealing the brick floors and painting walls and clearing trim and wood beams and ceiling. We'd typically build a small pit and burn our cutoffs and trimmings. I'd swept up under the table saw and had a 5 gallon bucket that was almost full of sawdust and a few 2x cutoffs. I walked over the small fire and from about 5 feet away tossed the contents into the fire. The ensuing fireball was so big that co-workers said all we saw was a 20' fireball with the lower part of 2 legs sticking out and so quick that I didn't react to it until it was gone. They said I looked like Wiley Coyote still standing there with the bucket in the tossing position after the fireball was gone, THEN I started running around in a circle waving my arms frantically. The non-English speaking co-workers had great fun repeating that story back at the shop. Lost my eyebrows and arm hair and singed the hair on my head, but other than being embarrassed, I was uninjured.

 

[K'ledgeBldr]

The explosion that started safety standards-

http://www3.gendisasters.com/illinois/8352/litchfield-il-flour-mill-explosion-mar-1893

 

[Kaizen]

Thanks guys. With warmer weather coming and my exhaust fans i'll be less concerned. Definitley getting a air filter for .

 

[Onewolf]

Kind of......

As a prank, we screwed the bathroom door shut on one of our least favorite fellow employ's. My buddy then blew a dust pan full of very fine sawdust under the door with an air hose. He then fallowed up with a can of carb cleaner and a lighter. There was a extremely large thump from behind the door. The explosion poped both the guys eardrums. It went off a little better than planed.

So, yes, I have witnessed a sawdust explosion.

So.... when are you eligible for parole?

 

[DekeT]

Kind of......

As a prank, we screwed the bathroom door shut on one of our least favorite fellow employ's. My buddy then blew a dust pan full of very fine sawdust under the door with an air hose. He then fallowed up with a can of carb cleaner and a lighter. There was a extremely large thump from behind the door. The explosion poped both the guys eardrums. It went off a little better than planed.

So, yes, I have witnessed a sawdust explosion.

I hope you pranksters spent a little jail time for that.

 

[sberry]

I can understand grounding collection pipe. It would have to be so thick a guy couldnt see in a room to get close to being an issue but dirty air will fug up a combustion system. Some use outside air.

 

[FTWingRiders]

Its possible with an open flame around, but unlikey at a home shop level unless its so thick you can't see the opposite wall.. bigger concern is breathing that stuff in. An overhead air filter is highly recommended. This is what I use..

http://www.grizzly.com/products/Hanging-Air-Filter-w-Remote/G0572

Or there are plenty of ideas to build your own on line. At least you should wear a cloth respirator when it gets thick.

 

[NUTTSGT]

UEL

LEL

Any concentration between those two is basically what you need to worry about, below the Lower Explosive Limit is normal day to day. Anything above the Upper Explosive Limit is too rich but you will need to be concerned when the concentration starts to lean out.

For a home shop, I really wouldn't worry about it, I'd be more concerned with setting off too many bug bombs in your home. Not that you need bug bombs but I believe there are more cases of homes exploding from that than home workshops with saw dust.

 

[Terranova]

Oh ****, that's funny, right there. I'm a sucker for a good wile e coyote reference. Glad you survived!

I used to work for a commercial store fixture manufacturer. They would shut the shop down every year right before Christmas for 2 weeks and clean the shop, even the rafters.

In the late 80's I worked in Albuquerque building custom adobe homes. We'd typically set up a table saw in the garage for trim and such. We'd sweep the building out and clean it pretty good prior to sealing the brick floors and painting walls and clearing trim and wood beams and ceiling. We'd typically build a small pit and burn our cutoffs and trimmings. I'd swept up under the table saw and had a 5 gallon bucket that was almost full of sawdust and a few 2x cutoffs. I walked over the small fire and from about 5 feet away tossed the contents into the fire. The ensuing fireball was so big that co-workers said all we saw was a 20' fireball with the lower part of 2 legs sticking out and so quick that I didn't react to it until it was gone. They said I looked like Wiley Coyote still standing there with the bucket in the tossing position after the fireball was gone, THEN I started running around in a circle waving my arms frantically. The non-English speaking co-workers had great fun repeating that story back at the shop. Lost my eyebrows and arm hair and singed the hair on my head, but other than being embarrassed, I was uninjured.

 

[Hammer03]

I had a circular saw shoot a 4 foot flame in college while ripping several sheets of MDF in a closed garage (trying to avoid annoying the neighbors). By the 5th or 6th sheet, it was pretty thick air, not that I knew better or that my paper filter mask wasn't doing anything for me... The cord on my very very old circular saw had seen better days and the strain relief had completely disappeared.

Somewhere, something decided it had had enough, and let out a burp. That let us know it was time to take a break and open the door for some fresh air in a hurry... Now I know better.

 

[6768rogues]

If the shop has a large accumulation of dust, usually the first explosion ignites the dust in the air making the dust on the structure fall off. Then the secondary explosion levels the building. With a home shop, you would have to have an unusually large accumulation of dust to make that happen. You would probably get one loud bang from dust in the air.

 

[Kevin54]

this site has a huge following. has anyone here had or heard of this happening in a woodshop like I described?

Not exactly with airborne dust, but in my hometown, there was a cabinet maker that used a wood burner in his workshop and he tossed a shovel full of sawdust into the woodburner and it exploded, catching part of his shop on fire.

My largest fear of airborne dust is if you don't wear a mask of some sort, you can get a lung infection. I went for over 9 months and numerous CT Scans and PET test, bronchoscopy for tissue samples, all for the doctors to tell me I had a large cancerous tumor on my right upper lobe of my lung. They wanted to remove the tumor, a third of my lung, and if it was wrapped around a rib or two, they would have removed the ribs along with it.

I tried to tell each and every doctor that I DID NOT have cancer and that I was cutting MDF in the garage, and when I was done, I swept it up, then took the leafblower and blowed the rest of it outside. I didn't have a mask on. All it started out with was a scratchy throat that two days later turned into a hell of a non stop cough. The doctors took away almost a year of my life.

So I take extra precautions when cutting wood unless I am outside cutting it.

 

[Kaizen]

Not exactly with airborne dust, but in my hometown, there was a cabinet maker that used a wood burner in his workshop and he tossed a shovel full of sawdust into the woodburner and it exploded, catching part of his shop on fire.

My largest fear of airborne dust is if you don't wear a mask of some sort, you can get a lung infection. I went for over 9 months and numerous CT Scans and PET test, bronchoscopy for tissue samples, all for the doctors to tell me I had a large cancerous tumor on my right upper lobe of my lung. They wanted to remove the tumor, a third of my lung, and if it was wrapped around a rib or two, they would have removed the ribs along with it.

I tried to tell each and every doctor that I DID NOT have cancer and that I was cutting MDF in the garage, and when I was done, I swept it up, then took the leafblower and blowed the rest of it outside. I didn't have a mask on. All it started out with was a scratchy throat that two days later turned into a hell of a non stop cough. The doctors took away almost a year of my life.

So I take extra precautions when cutting wood unless I am outside cutting it.

geez kev I never trust doctors. they think they know everything. I normally have a respirator on but as it was cold in the shop I was having condensate in the mask and couldn't breath so had to take it off. I agree now no one is smoking 2 packs of Marlboros every day we definitely notice how fine dust is really bad.

 

[BioNerd]

I wear a respirator because it gives me asthma to breathe in airborne saw dust. It wasnt like this before but after 5 years in a shop I developed it. Specially cedar, redwood, oak.

The guy who showed us how to make windows and doors, worked for many years in that shop. He used those paper masks only.
He died from lung cancer and in his last days he stressed a lot for us to wear respirators and ventilate the shop.

 

[Lippyp]

Even flour can explode. I used to sell office furniture and I had a flour mill as a customer, you had to hand in any matches and lighters to the gate guard before you were allowed onto the site.