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A Rare But Real Danger


OldMarine

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I had a large canvas bucket that I keep my chain hoist in and over the course of the years it had become worn and grease impregnated so I bought me a new one. I had the old one in a bucket so I could add it to the trash for my weekly pickup for the last two days.


I came out of the house after feeding the critters a bit ago and WHADDAYAKNOW?


I had a flaming bucket of greasy canvas. The grease wasn't a problem until I confined it in the bucket and locked in the heat allowing spontaneous combustion to occur. It's not just the comps that can burn you down but the trash as well!


Paper goods with any oxidizer and just a smidgen of grease also have the potential to self ignite if confined so empty those shop trash cans daily!

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Jeez...ya hear about that happening. Good thing you caught it. Ironically and terribly...the FD and all were down my road Monday. Not me this time. Neighbor’s house went UP. Bad... started in the attic/fireplace chim they figger. No one was hurt tho thank God.

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OM,

I often work in oil / grease producing plants, and it is always forbidden to put greasy towels in trash cans (we have to bring them to a special area, where they immerge it in water or something like this).

 

I always thought to myself "come on, you make too much of it! What the hell could be the chemical reaction to increase temperature so rapidly???"

 

UNTIL I red your post today....

 

Safety first. Chemistry tells us to stay humble. Thanks for this post.

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IF i am correct , depending on what the oil you were using , lets use linseed oil for an example . If you keep rags that are soaked in linseed oil , they can polymerize and the polymerization cause lots of heat and can spontaneously catch fire over time .
correct me if i am wrong here , but that is my explanation for what might have happened

 

Stay Safe and Stay Green

 

~Steven

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Sulfurstan, it's not ONLY 'oil'. Petroleum oils don't do that. As Steven indicated, it's "drying oils", of which almost all are vegetable oils.

 

They oxidize, harden, and liberate heat during the process.

 

The old "oily rags" mantra came from painting, which in the now fairly-distant past used (almost exclusively) boiled linseed oil as the vehicle for paints. Rags wetted with it would continue to oxidize (and harden, just as paint does) and liberate heat as they did so.

 

Some paints still use synthetic oils similar to linseed oil, and those vehicles can still present the same dangers.

 

But 'motor oil' doesn't. Neither does 3-in-one oil. The effect is limited to those oils that 'cure' as they're exposed to oxygen.

 

Lloyd

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Between Lloyd, our uniform delivery guy and my knowledge of the stuff permeating the bag we've come to the consensus that it was the vegetable oils in the bag material that caused combustion and the petroleum only provided extra fuel for the fire. I'll toss the next one straight in the burn barrel!

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Now it is clear to me:

I omit to specify in my previous post that the plants I was talking about are not only producing mineral (petroleum based) products, but also vegetable based products: they produce kind of special blends of lubricants etc.

So that's why the rule of thumb there is "no greasy oily towels in the trash", you never exactly know what's on your towels!

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Yep... I don't know if I mentioned it here or on another site, but there are some greases for "food safe" applications that use clear mineral oil as the lubricant (petroleum, and not subject to the 'drying'), and vegetable oil-based soaps as the thickening/gelling agent.

 

Those greases can (and do) oxidize over long periods of time. If they were distributed thinly in a rag, that likely would accelerate the process.

 

Lloyd

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