"Greg D." wrote in message
...
Hi,

I'm currently writing an article for a canadian woodworking magazine
about fire hazards in a typical workshop. The article will discuss
passive and active measures to take to avoid or extinguish fire.

I would like to make a test with rags soaked with oil and see how long
it would take before it catches fire. I'm wondering which oil is
generating the most heat (tung oil, linseed oil, danish, etc.) and how
long it takes, based on your experience (if you had any), to get the
smoke or an actual flame.

I would also be interested in knowing any experiences with dust
collector fires. There is obviously static electricity but I prefer to
hear about any kind of "accidents" that might have happened and sent a
spark in your dust collector to later on, catch fire. Again, I would
be interested in knowing how long it takes before you do get the smoke
to figure out something's wrong. I know it can be a couple hours.

Feel free to add any other fire hazards you've come across that I may
just overlook at the moment.

Thanks,


Greg D.

P.S.: There is obviously the chemical storage which are also a
concern.

For some reason I woke up this morning thinking about this discussion (mind
works in mysterious ways). I realize it's a bit late but here goes.

Most people seek to avoid spontaneous combustion so I think you'll find
little real experience with it among woodworkers, and certainly none at the
level that you're looking for--most of us who have had one experience with
it consider that enough for a lifetime and don't continue to make the same
mistakes of storage that would let us gather enough anecdotal data to be
able to compare different finishes.

That said, I'm not sure your question really has an answer. The time to
combust depends on too many variables. To take a couple of extremes, hang
an oil-soaked rag on a clothesline and toss a bunch of wadded up rags into a
barrel of oil. Neither will combust no matter how long you leave them. The
rag on the clothseline has plenty of oxygen, but it also has a lot of
surface exposed to free convection--that keeps it cool enough to not
combust, or even get perceptibly warmer than an adjacent dry rag. The rags
in the oil barrel aren't exposed to oxygen at all, so they don't heat.

To get spontaneous combustion you need a lot of oily surface exposed to air,
but also need to have that air trapped so that it acts as an insulator and
you need enough thickness of insulation to hold in the heat. How soon it
happens depends on how oily the rags are and in what quanntity and how
tightly wadded--too oily and it won't happen, not oily enough and it won't
happen, too tightly wadded it won't happen, not tightly enough it won't
happen, not _enough_ of it wadded up and it won't happen and in the range in
which it will happen there's a range from "barely goes" to "goes right
quick".