Hi, Brian,
You were so careful to translate "petrol" into "gasoline" for our Americam
brethren, yet totally overlooked your use of a word, which without
translation, conjures up an altogether different picture, viz:
"...incandescent end of a lit fag. " To us Brits, this means the glowing
end of a lit cigarette, but across the puddle, it could be read as the
extremely angry end of a burning homosexual.
No offense, just a thought and my warped sense of humour.
Peter
Brian Ellis <[log in to unmask]> 21/10/2002 10:25 PM
Sent by: TechNet <[log in to unmask]>
Please respond to "TechNet E-Mail Forum."; Please respond to Brian Ellis
To: [log in to unmask]
cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
Subject: Re: [TN] Flammability
Doug
Your question is not odd, at all. There is a lot of incomprehension
about flammability and flash points and you are quite right to raise the
question. The flash point of both these hydrohalogenated solvents and
most other hydrohalogenated ones is not measurable by any of the
standard ISO methods (open cup, TAG closed cup, Pensky-Martens etc.)
under normal conditions. This does not mean they will not burn. They
both have lower and higher explosive limits in a fairly narrow range. If
you spray them, for example, onto a printed circuit fairly
energetically, the rebounding will cause a mist to form and this can
explode, if ignited, if the proportions in air are right, at any
temperature.
To answer your direct question, if you have a bucket of the stuff and
you throw a lit ciggy into it, the ciggy will certainly be extinguished
and no fire can result, no matter the temperature of the solvent. That
does not mean a thing. There is every chance that if you do the same
with a bucket of alcohol or even petrol (gasoline for you), it will do
the same, even if it is a dozen degrees or more over its flash point.
Why? Because there is relatively little energy available in the
incandescent end of a lit fag end to heat the vapour sufficiently while
it is transiting through the zone where the vapour/air mix is right.
Don't try it though, because there are many variables that can upset the
equation! :-(
The important point that you have missed out is that no one should be
smoking anywhere near where any halogenated solvent is deployed, not
because of the fire hazard, but simply because he/she can kill
him/herself. Inhaling even a very small quantity of solvent vapour
through a lit cigarette will fill the lungs with an extremely toxic mix
of phosgene (for chlorinated solvents, carbonyl bromide for brominated
and so on), hydrohalic acid and carbon monoxide. The first good puff
will cause a good high, the second may be even better and the third
could easily end in a coffin or, at the best, permanent lung lesions.
Just to complete the picture, perhalogenated solvents (e.g., carbon tet
and perchloroethylene) do not have explosive limits. In fact, carbon tet
used to be used extensively as a sprayable fire extinguisher and it is
possible that I may not be alive today if carbon tet had not been used
to douse an engine fire in a passenger plane I was in in 1952. (Yeah! I
can hear you! Why the hell was that plane equipped with an extinguishing
system! :-) ) Perhalogenated solvents can still kill smokers faster than
cancer.
Please don't hesitate to ask if you need any more info on solvents.
Best regards,
Brian
[log in to unmask] wrote:
> Good morning all,
> In my quest to ask the oddest question of the day:
>
> If you threw a lit cigarette into a beaker of either trichloroethylene or
> 1,1,1-trichloroethane, would the liquids catch on fire? What would be
the
> critical parameter in determining this? Flash point?
>
> Doug Pauls
> Advanced Operations Engineering
> Rockwell Collins
>
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