Fire Danger

[BigBoy1]

I'm a member of a makers space and we have wood and metal working shops. As a result of using wood finishes, a small fire resulted from spontaneous combustion of oily rags. The safety "dogs" are now searching all of the areas looking for oil products. Before they get to the machine shop, I want to get ideas/opinions/facts of the cutting and machining oils used. Do these oils present any kind of spontaneous combustion problems if rags use to soak them up are left around? I'm concerned if there is a chance these oils can cause a fire or are only the wood finishes the type of materials which will cause spontaneous combustion fires. Appreciate any help. Thanks.

[SteveM]

We were brought up with "oily rags - fire danger!!!!" without any context.

From what I understand, the oils that can do this are "drying oils". As they dry, they generate heat. The best example of this is linseed oil, which is why your fire was started in the wood finishing area.

I've never heard of motor oil doing this, although I'm not going to say it's not possible.

I have a metal can that is actually a benchtop parts washer, and when I have an oily rag, I stick it in there. Every once in a while, I dump them in the outside garbage. There are actual containers for that purpose, although my guess is that they are not cheap (half the price or more is probably the manufacturer passing along the liability insurance bill).

Steve

[John Hasler]

Only "drying" (i.e., polymerizing) oils such as linseed and tung oil spontaneously combust. You have to pile the rags up to get them to do it.

Telling them this won't help, though. They will quote an "expert" as asserting that all oily rags are dangerous.

[GlennW]

I keep and oily rag can, one of those triangle shape red cans with the flip up lid, near where I am working. It gets dumped into a 55 gal steel drum with a heavy lid that is supplied by the environmental waste people that I use.

When I have an inspection from the Fire Marshall or EPA it makes them smile.

[liveaboard]

I try to keep solvents out of the machine shop area, but of course there's always oils + greases.
Welding cables, 220 + 380v wires, and torch hoses jostle for floor space with bits of sharp metal shavings.

I suppose I should have a fire extinguisher in there, maybe even running water would be a plan.

[armscor 1]

Years ago I used fish oil on my old Ford Fairlane to prevent rust and cleaned up with cotton rags, dumped them in the garbage bin, a few hours later my Son alerted me that the bin was on fire, quickly put it out.
Fish oil and cotton you have guaranteed spontaneous combustion!

[curtis cutter]

In my decades of doing fire inspections/investigations, I found that shop fires USUALLY occur in those shops that basic cleanliness and code compliance are not a high priority. Stuff piled all over is like a recipe for a fire. Rags, of any type, when dirty should be kept in proper metal containers. Simply a spark skitting across the floor and into light debris is a frequent culprit. Shoddy electrical work and extension cords that are not rated for the amperage being asked for.

When a fire occurs, it is frequently a chain of events that contribute and support it.

[mcostello]

I had seen somewhere that everything that was once living had the potential to spontaneously combust. Sawdust, coal and rock dust come to mind.

[Bill Shields]

bails of hay all stacked up.....will burn for weeks....

[pete]

Dust has to be within a fairly narrow mixing range of itself and the oxygen in the air plus have an ignition source. That ignition source can for some materials be as little as a static discharge that builds up and creates enough enough heat within the spark to cause that ignition. In the open pit mines I worked at huge amounts of rock dust were just part of the processing. Since most types of rock dust won't burn at any normally obtainable temperatures it's not really a problem. I have seen the after effects of two buildings blown up due to coal dust for the first and wheat dust for the second. It's pretty impressive seeing how much damage can be done just from that dust. And yes wet hay stacked or bailed up in large amounts can spontaneously ignite. Due to the higher moisture content the material starts to rot, that causes heat and if it can't escape a fire can be the result. So the farmers have learned the hard way to dry there hay real well before bailing it.

I doubt most cutting and lubrication oils used in a metal shop would cause any issues with spontaneous combustion. None of the repair shops at the mines I worked at seemed concerned about oily or greasy rags being a problem. Today that doesn't matter. Everyone seems more concerned about CYA first than using fact based research before making up the rules. My guess is that Maker Space has insurance, ask one of there insurance adjusters what's required. That's who you really need to keep satisfied or that insurance policy isn't worth the paper it's written on. Anything else is just best guesses.

[BigBoy1]

Thanks for all of the replies. It is as I suspected that cutting and lubrication oils are not going to be a potential spontaneous combustion source if disposed properly. I think I can keep the safety "dogs" at bay if neatness is practiced - rags are cleaned up each day and put into proper containers.

[John Hasler]

Hay has to be in a fairly narrow moisture range to ignite. Unfortunately every once in a while someone manages to hit that range.
I've made thousands of tons of hay and never had a fire. The fire hazard is not the only reason to dry hay. If it's too wet it becomes very moldy and cannot be fed.