Sawdust Hots

[bandmiller2]

I know sawdust can heat in a pile and I've heard the horror stories but have any of you personally had a sawdust pile near the ignition point.??I  have about a five yard pile and stick my hand in it and not even warm. Frank C.

[customsawyer]

When they come and grind my slabs there is a big pile of mulch. As they scoop it up to put on the trucks it will have steam coming off of it but it has never started a fire. Sometimes it will sit there for six months or so before they get it all loaded.

[drobertson]

No, not on this end,

[WDH]

When I saw this title, I thought that you might have been running around on your sawmill  .

[POSTON WIDEHEAD]

Being a Wildland Firefighter with a Dozer to fight wildfires, I have been to many mulch and sawdust piles that have started by spontaneous combustion.

Generally for this to happen, it takes a lot of mulch or sawdust with a lot of weight to really get this to happen. A lot of factors are involved such as moisture content, type of fuel chips, the right amount of oxygen, etc. They're sometime impossible to put out being the combustion point is so deep into the pile.

[Chuck White]

It seems to me that there is one state here in the North East that has a limitation on sawdust, and your sawdust pile can't be over 3 feet high!

[barbender]

I used to work at a wild rice processing plant, and there were huge piles of hulls from about 50 years of processing. Those would spontaneously combust at times, it would be so far down inside you could barely tell it was burning except for a bit of smoke that would seep through. The DNR would make the company get an excavator out and open the piles up. There would be tunnels of fire down about 10 feet, it looked like it could be hell I don't think they ever got those out completely :

[Paper Maker]

   I've seen the bark piles at the paper mill where I work smolder and burn from spontaneous combustion several times. We would spread it out with 966 loader, wet it down, and burn it in the boiler. Sometimes the piles will smoke for weeks.

[justallan1]

I've seen a couple sawdust piles burning from spontaneous combustion at large commercial mills and I know on one it was pretty much smoldering and when it got a good hole to let air in it would go like a giant torch or something out of a movie. The closest I could come to describing it would be like seeing volcanoes on tv. They would take equiptment  and try to plug it so it could burn itself out gradually instead of setting the whole place on fire.

Allan

[Ron Wenrich]

We've had a couple of bark piles catch on fire.  In each case it was winter time, the piles were high, and we were driving on top of the pile to dump the bark.  We stopped driving on the piles, and we never had a problem after that.  We also didn't get anaerobic decomposition problems.  That's when you get the rotten egg smell. 

As for sawdust, I've had piles as high as 15' and never had a problem.  We also have blown sawdust into trailers for many years.  Never had a problem in a tight container on a hot day.  In the wintertime, sawdust would freeze on the sides of the trailer.  The insides would be steamy hot.

I also went to a guys yard that was a sawdust dealer.  He had a pretty high mountain of dust and it never caught on fire, that I know of.  He even had dust that had urea in it.  That stuff got hot overnight, but didn't ignite. 

Seems to me that the common denominator is compression.  The wintertime scenario may have something to do with the temperature difference inside the pile to the outside and you get thermal up drafts which fan the flames.  Its not a dramatic in the warmer months.

[bandmiller2]

Thanks guys, so what I've gleaned from this post is my dinky loose sawdust pile is no threat. Frank C.

[Magicman]

Yes it can happen.  Several weeks after I left a portable saw job, the sawdust pile, bark, etc. combusted and burned most of the customer's lumber which was stickered nearby.

[delvis]

I have a friend who is also a sometimes customer and he takes most of the sawdust I make to use for horse bedding.  Shavings are too expensive for the old hay burners.  I don't worry about the sawdust pile combusting because of the turn over in the pile.  What I worry about is sawdust around the engine igniting when we've gone home for the night. 

We use the leaf blower to blow the entire mill done and especially around the head.  We also use the leaf blower to cool the muffler down to the point where we can put the covers on.  Along with the fire extinguisher we have on hand, hopefully we'll be able to avoid any fires.

[justallan1]

Seems to me that the common denominator is compression.  The wintertime scenario may have something to do with the temperature difference inside the pile to the outside and you get thermal up drafts which fan the flames.  Its not a dramatic in the warmer months.

I think Ron is very much correct on this.
The last ranch I worked for would chop corn (husks, stalks and all) for silage. You take the corn, dump it in a pit or pile and continuously drive a big 8 wheel tractor over it to pack it. The whole idea is to let it basically ferment rather than rot. Fermenting makes its own heat.
When I would get into the pit in the winter with the loader it would let off bunches of steam and was good and warm.
I've never put the two together, thanks Ron.

Allan

[YellowHammer]

I've seen hay bales burn but didn't know sawdust could too.  I'll have to be more careful not to let my pile get too big.  The last time Google Earth satellites did a flyover, my sawdust pile was big enough for me to use as a landmark   ;D
I guess that won't happen again :D
YH