Peter.Hore@dhs.vic.gov.au wrote:
>
> Warning Warning Warning???
>
> About 4 years ago at a car club meeting we were warned about a particular
> acid that is given off when some types of modern automotive plastic are
> burned, in for instance, a car fire.
>
> It seems that when this acid starts to eat into your fingers/hand/whatever,
> it cannot be stopped except by amputation. There was a fancy name for the
> acid which I cant remember.
> Does anyone know if this is true or just bulls**t?
Sounds like a bit of a scare story.... Here's the chemistry, as I
understand it. The acids you refer to are _concentrated_ hydrofluoric
and _concentrated_ phosphoric acid. Neither of these is present in the
smoke or residue of burned automotive plastic. However, if the fire is
put out by water, some of the compounds in plastics can create _dilute_
acids. Concentrated phosphoric acid will eat you, and doesn't stop at
bone--bone is a complex mineral-based tissue high in phosphorus
compounds, so phosphoric acid likes it. Hydrofluoric acid would probably
only be present in the residue of fluoroelastomers (o-rings in the a/c
system, etc.), and their quantity in an automobile is small.
What is produced, in noticeable quantities, is chlorine gas from burning
vinyl (poly vinyl chloride)--when doused with water, this produces weak
hydrochloric acid (same thing as in your stomach acids). The principal
problem with this is that it usually saturates the underlying metal, and
starts considerable corrosion. The only other noticeable plastics in
cars today are ABS and DKE. ABS has some sulfur compounds in it, which
could create weak sulfuric acid in the presence of water, and DKE is an
acrylic alloy. As well, most wiring today has some sort of sheathing
made of PVC, and some have fluorocarbon skins over the sheathing, so
that is another potential source of hydrofluoric acid, but still quite
small.
All these acids must be dissolved in water (in an ionic state) at fairly
high concentrations to be truly dangerous. I stripped the interior of a
burned Chicago Transit Authority bus in 1994 and suffered no ill
effects--and there are lots of plastics and wiring in the interior of
one. A nasty job, but not a life-threatening one, by any means.
Cheers.
--
My other Triumph runs, but....
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