Date: Sun, 5 Dec 2010 10:33:09 -0800
Reply-To: Alistair Bell <albell@SHAW.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Alistair Bell <albell@SHAW.CA>
Subject: Re: Vanagon engine fire or mishap in Roanoke, Va
In-Reply-To: <20101205100322.64RSQ.268514.imail@eastrmwml31>
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I've just heard the same Car Talk reference as David did, saying that
an oil leak on exh. was more likely to cause fire than a gas leak.
Its an unnerving assumption to make though.
I say that David does need to set up a hot plate and drip fluids onto
it. Video of expt. would be required :)
I've always been impressed at the whump of ignition when using
gasoline to light brush piles (we seem to generate a ton of that
stuff here on the "farm", and yes, we really do want a big chipper).
Diesel is so much safer to use, but sometimes the neighbour and I (he
is a bad influence) fool around. Even on cold days the gasoline
vapours spread further than I imagine.
Its all very silly, juvenile, and fun. But it does make you realise
what potential bomb you're sitting on.
On a related note, the only jury duty I have done was a trial of a
couple of dolts who torched their car after a joy ride (including
detour onto golf course) and the fire started a minor forest fire.
The crown had an expert witness who showed a video of his re-
enactment of how the defendants started fire in the car (Camaro?). It
was surprising how long it took from fire on the driver's seat to the
gas tank igniting. The engine caught fire quite a time after the
interior was ablaze, then the front tires caught, and some time after
the gas tank cap popped (heat from interior and rear tires I guess)
and gasoline vapour whooshed out and that caught fire. It never did
explode, just flared like an oil well.
alistair
On 5-Dec-10, at 7:03 AM, Dave Mcneely wrote:
Perversely, it is the high volatility of gasoline in this situation
that prevents the flame up, at least according to a physical organic
chemist I once knew. He claimed that when the amount of gasoline was
relatively small and ventilation was good, the vapors formed quickly
and wafted away before ignition could occur. Of course, his day job
was developing the stuff that makes disposable diapers, menstrual
pads, and so on absorbent. It is likely that right at the hot
surface, little or no fuel is present, and only inches away the
temperature is below ignition point. Oil remains on the surface to
be heated and ignited.
Seems to me that our only list chemist is Alistair, whose expertise
seems to be more in the line of microbial work. But being a good
scientist, he might have some insight. Alistair?
As I said before, I am not willing to perform the test except with
such a small amount of fuel that I might not consider it
representative of real world conditions.
--
David McNeely
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