Where would you find more information about the dangers of combustion
of dust or vapors in the workshop.
I have a natural gas furnace in the workshop which has a constant-on
pilot light. I would think that the concentration of dust would have
to be extremely thick before an explosion would ignite, but I do want
to be safe.
Vapors from inflammible liquids can easily cause an explosion under
If you use Google to search the rec.woodworking archives you will
find the issue of dust explosions in a home workshop rather hotly
My conclusion is that you would be hard pressed to produce dust
fast enough to cause an explosion but if dust accumulates
somewhere and goes airborn en masses, say for example on top of
something that gets tipped over toward the furnace then you could
get a high enough concentration to get a whoomf. That'd be like
throwing a handful of sawdust onto an open flame, it most definately
I do recall reading, but do not recall where, an account of an
actual fire by one woodworker. He observerd a short wall of flame,
only a couple of inches high, move from the ignition source accross
the room. Not an explosion, just a fire, the flame front moved
slowly enough that he was able to beat it to the stairs. Evidently
the dust concentration near the floor (and only near the floor) was
high enough to support combustion.
Then again, maybe he was working some sort of exotic wood with
a toxin that causes halucinations.
There are other issues as well like dust being blown through the
ducts or accumulating and growing moldy getting parts of the
furnace dirty so it doesn't burn efficiently. Inefficient burning
means more CO. Is the furnace flueless?
The "hotly debated issue" of dust explosions was about static
electricity from dust collection causing them. The OP's question was
about ignition from a natural gas pilot - a completely different and
very real concern. It definitely has the energy to ignite something,
if there is sufficient fuel and air.
My humble opinion is that management of the dust in a similar manner as
you would for health should be sufficient.
I use an open flame propane heater and it has never "caught fire" from the
dist but I've intentionally kicked up enough to see tiny glowing particles
when the fan blows them through the flame. Not much of a concern under
Fumes though, can go whooooooosh real fast.
My Hugely unscientific test:
I have a small radiant heater perched on top of a 20# propane cylinder. I
took a handful of sawdust and blew it into the heater. It flared when it
hit the red hot screen. Didn't even "poof". I figured that was way more
sawdust in the air then I would ever generate, so I'm not too worried about
I don't use gasoline in the shop, so I am not too worried about vapors, but
if there was any concentration at all, I'd turn off the heat.
I too have a propane fueled torpedo heater, Never have I noticed any
possible ignition from any of the dust I throw out. And as a matter of fact
Mythbusters (on Discovery) actually did a sequence on just this scenerio.
They built a blastproof cabinet, put in an ignition source several I
believe. They put in so much saw dust and it barely flashed. The only thing
that developed flame was a fume source.
I used to have a open flame propane heater next to my bandsaw before I had a dc.
all it did was burn the sawdust. you really need a cloud to get anything. if you
had that much of a cloud you could not work in the shop.
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