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RE: Toroid Design
> -----Original Message-----
> From: Tesla List [mailto:tesla-at-pupman-dot-com]
> Sent: Saturday, December 26, 1998 7:22 PM
> To: tesla-at-pupman-dot-com
> Subject: Re: Toroid Design
>
>
> Original Poster: "Robert W. Stephens" <rwstephens-at-headwaters-dot-com>
>
> Tesla List wrote:
> >
> > Original Poster: "Coiler" <mycroft-at-access1-dot-net>
> >
> > >
> > > There are two part spray foams available as industrial products
<snip>
> In the case
> > of createing polyisocyanate, (rigid foam)you combine Polyol and
Isocyante,
> which combine
> > in a rather highly exothermic reaction. Care must be taken to avoid
> > spontanious(sp?) combustion. I would be concerned with anything
> over about
> > 8"
> > in thickness. Granted, the burn is very slow, more like a smoldering,
> > smoking
> > mess, but it does produce rather nasty toxic fumes.
<snip>
> So, will this stuff work in this application, or what?
>
> Robert W. Stephens
Assuming you are aware of the caveats mentioned above, yes, it should work.
We used it to make a roofing system in sealed containers. This was the
polyol-isocyanate... I don't know what they have now.
You really must be careful however, as it is a fairly toxic soup. Depending
on the particular mix, the temperature rise can be as much as 300 deg. F.
Since it is a wonderful insulator (the main reason the stuff is used) the
core temp can rise above that, and trigger combustion. If you intend to
fill someting larger than 8", get the slow setting type, or be willing to
fill
by doing 2 or more pours. Use in a well ventalated area - the reaction
releases flourocarbons and formaldehyde among other things. Seriously
discuss
these facts with your supplier.
When I was spraying this stuff (paying my way through college) we used a 3
stage
organic rated face mask, and changed the first 2 stages about every 4 hours,
and
the carbon stage every day. Granted, it was airborne mist, but do be
careful.
Also, be aware that unlike the spray stuff from home depot, this stuff will
blow open seams if overfilled, the expasive power of it is amazing.
Michael Baumann
Coiler, Homebrewer, Nerd. mycroft-at-access1-dot-net