Craig Clark on fri 12 apr 02
to
fire method
I don't know who originally started this thread, but, to whom it may
concern, let me share a brief story about a fire that resulted in the
complete loss of one of the civil engineering buildings at the University
that I attended.
To make a long story short, research was being done on long term
exposure of a particular cement beam to cycles of heating, freezing and
thaw. The idea being to mimic mother natures change of the seasons.
The beams, there were two dozen of them, were suspended in large boxes.
The boxes were made of three quarter inch plywood. The "heating" device was
a spot light in each box. The bulbs themselves were hot to the touch. They
were several inches (in the top) from the plywood. The stress tests went on
for several months without any trouble until one night........ the building
was gutted in the fire. Total loss.
What I learned from the fire inspector who went through the scene was
that the combustion point of wood, especially laminated woods like plywood,
may be lowered through prolonged gradual heating and resultant dryness. The
phenominon, as explained to me, was called porosity (dealing with wood here
not glazes.) He stated that the combustion point could be lowered as low as
300 degrees Farenheight. Don't know is he was right or not. That's just what
the fire inspector said. The source of the blaze was traced to the light
bulb which was enough to get things going do to the porosity.
This brings me to my point. If the kiln has been sitting on the floor,
or transfering much heat to the floor, over an extended period of time then
the wood beneath it has probably become increasingly porous. Be aware of
this. I realize that soft brick doesn't conduct that much heat but this
phenominon is still something to be aware of.
I would suggest putting the kiln on a metal stand up off the floor with
insulation beneath the feet and plenty of air flow. This will minimize the
heat that is transfered. You ought to be able to do the touch test
underneath the footprint of the kiln when it's going full tilt boogie.
Craig Dunn Clark
619 East 11 1/2 st
Houston, Texas 77008
(713)861-2083
mudman@hal-pc.org
----- Original Message -----
From: "Stephen J Lewicki"
To:
Sent: Friday, April 12, 2002 8:25 AM
Subject: Re: Kiln Question / This Forum
> I would say no - which is not to say you might not get away with it.
> Monitoring temperatures is one issue - and that is certainly prudent.
> However, there is another major issue - time. The heat of the kiln over
> time will tend to dry out the wood and lower its spontaneous combustion
> temperature until one day - boom! I know of a major million dollar fire
> caused by a kiln improperly installed on a wood floor. Just insulating the
> heat from the wood, I don't think, is enough. Maybe (and I am NOT an
expert
> on this issue - just putting in my two cents) it might work if you had
> insulation and an air space under the insulation. I think perhaps you
> should seek out the advice of a competent fire chief.
>
> Stephen J Lewicki
> President
> L&L Kiln Mfg
>
>
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Chris Jones on fri 12 apr 02
to fire method
Hello all........
An added experience of mine is from the pottery where I worked. We fired a
60 c.foot sprung arch gas kiln outside covered by a tin roof that was
supported naturally by a "2x4" frame. The top of the kiln was covered with
kaowool blankets and not terribly hot to the touch and the roof was at least
4' above the kiln. However, the beams of the roof were blackened and charred
as if they were in direct contact of the fire. That happened over several
years, and was due to the same factor as the bulb in the box. Some woods,
especially pine, can actually combust at lower than 300 degrees according to
the local firemarshal. I learned this after witnessing a fire in an attic on
a newly constructed condo with a fireplace. The chimney had a gap in the
mortar which blew hot gasses on to a roof beam and eventually ignited the
home. Be safe, be cautious.
On another note, I used to fire my bisque in electric kilns at night,
outside. I awoke to the acrid smell of an electrical fire. Come to find out,
the plug on the kiln had heated up to the point of ignition and burned up my
whole power cord. I was lucky to not sleep as deeply as normal that night. I
now check the connections regularly.
Thank you,
Chris Jones
Visit www.jonespottery.net
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