Re: Burning papers (fwd)

[Jim Choate <ravage@ssz.com>]

Forwarded message:

> Date: Mon, 26 Jan 1998 19:05:54 +0100 (MET)
> Subject: Re: Burning papers (fwd)
> From: nobody@REPLAY.COM (Anonymous)

> As usual Jim, your posting is prolific but your science is lacking.

Ad hominims, opinions, and no proof...

> bind to whatever it comes in contact with (usually oxygen).  The only way
> cyanide could escape in gaseous form is as HCN, however this cannot happen
> because the hydrogen has a lower activation energy for combining with
> oxygen, and thus the reaction is starved of free hydrogen by the time the
> carbon begins to burn.  Various other nitrogen compounds are produced,
> such as NOx, but this is true of all combustion and not limited to plastic.

I have forwarded to the list a single safety standard for plastics and fires.
It *specificaly* mentions HCN, so apparently it not only can happen but does
often enough they want to test for it on a national level. There are many
more out there and as I said before, if you contact your local fire dept.
they can provide you with documentation as well.

> A more likely (and deadly) result, which you did not mention, is sulfur
> dioxide.  Most plastics don't contain sulfur, but rubber products may.

Sulfur dioxide is present and does pose a threat, fortunately it's a rather
short termed threat and treatable. Sulfur dioxide turns into sulphuric acid
in the water of the body. Not to mention it burns up the oxygen in formation.
The biggest threat with the acids that are produced in a fire is to your
possessions. They soak this stuff up and then when the firemen put the fire
out they use water which creates acids. These acids effect the components of
your possessions over an extended time.

> Sulfur dioxide combines with water to produce H2SO3 and H2SO4 (sulfuric
> acid) which is quite toxic if inhaled.

Depends on the molarity. It is nowhere near as toxic as cyanide on a per
part basis.

> Most smoke inhalation deaths result for particles clogging the lungs rather
> than gases.  Cats have a tendency to hide when they feel threatened or
> injured, an instinct which often imperils them in a burning building.

Actualy most smoke inhalation deaths occur because of lack of oxygen and the
elevated temperatures. The actual clogging process would take much longer
than the 2-3 minutes most smoke deaths take to occur.

As to cats hiding, they tend to hind *under* furniture which is actualy the
*safest* place to be, the clearest air is next to the floor. It was also
where my cats were found, in the living room under the couch where the smoke
very clearly never got below about shoulder height - it stains the walls
quite well. The fire didn't even make it into that part of the house, it
stopped in the next room. The fire itself burned for less than 20 minutes
total because the neighbor saw it about 5 minutes after the person who
accidently set it off had left. The fire station was on the next block.
It was very quick. The firemen were very careful to explain to me exactly
why the cats died, gases from the plastics (HCN was specificaly mentioned)
and the temperature of the air (they estimate over 350F). While not enough
to cause spontaneous combustion it is more than enough to cook the lungs.
The air was hot enough that several plastic bags holding wargame materials
within 1 ft of the floor were melted but the paper materials were not even
scorched. This would further indicate that the damage was done by the
temperature of the gas and not direct flame or smoke.

> Also remember that computers have materials in them other than plastic, for
> example lead and other heavy metals.  Batteries and electrolytic capacitors
> are also sources of many toxic materials.

The leads on most components are an aluminum compound (my background is EE)
and they typicaly don't start to burn until well over 800F, aluminum itself
burns at 600. Since typical tip temperatures in soldering (lead eutecticts
only - not indium composites) are in the 600 to 700 it is clear that pure
aluminum would not be desirable. So they mix tin and other compounds with 
it.

As to electrolytics, the liquid plastics that make up the dielectrics are
very toxic and most certainly give off xCN compounds when burned.

Just for the record, Lead (the element) is not generaly used in modern
electronics except in a eutectic solder mix for connections. I have several
computers that were burned in the fire and the majority of the solder on the
pcb's was *not* evaporated. In most cases it wasn't even melted even though
the case was completely gone (2 A1000's that work fine though the cases were
completely destroyed by the temperature of the air, not fire).

> In short, it's not the plastic that's toxic, it's all the other crap (ink,
> dye, glue, solder, batteries, dielectric, etc)

Malarky.


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