mel jacobson on mon 15 aug 05
i have a wooden building for my kiln.
it has been a part of my studio/kiln for many years.
i am very concerned about safety.
i have wooden exposed joist members near my stack.
so:
i have a full 4x8 sheet of non/flammable material behind my kiln.
mounted a half inch from the wall/air gap.
i spray my ceiling with a mist of water before every firing.
soak it all down.
i use a garden mister during the firing and keep the ceiling damp.
i spray every two hours...and you can tell it works as the water
does not soak in...it stays on the surface for about twenty minutes.
my kiln roof is covered with a blanket of kaowool. if i lose a brick...not
to worry.
i have painted the joists with `fire paint`. that is a paint with
kaowool fibre. suppose to retard fire to 800 degrees F.
i keep four fans running across the ceiling during firing.
i have a sucking fan in the ceiling above the kiln.
i have a large exhaust fan in the back wall...behind the kiln.
it is on a rheostat so i can control the amount of air.
i am watching the kiln during the entire firing. i keep an alarm clock
set for one hour checks. am very faithful with the timer.
i do believe that air movement is the most important single factor
in firing large gas kilns in any room. air in, air out.
it is the dead hot space that will ignite. and, firing after firing without
thinking about that space. wham..fire. dry as old paper.
after my kiln is done firing, before i go to bed...i soak the ceiling again
with water. keep the fans on all night.
that is why i always start my kilns at 5 a.m. it gives me alone time
with the kiln during the warm up period.
it means that the kiln will be done in the late afternoon...and i have
all evening to watch it...fire down....and not worry.
it is the firing until 2 a.m. /being exhausted, and forgetting small
safety factors that cause accidents.
diligence is the key. i have seen far too many potters loading kilns
at night...and turning them on...it seems like a macho/i am wonderful
and can stay up all night mentality. stupid i call it.
i have for thirty years, followed a system of firing.
load the kiln at 3-4 p.m. close up the kiln...turn on a small
gas burner with thermocouple safety shut off.
leave the damper in 90 percent. let the kiln warm slowly.
melt the wax, get the water out of the kiln.
when i get up a 4-5 a.m. the kiln is at 500F. i use a torch
to clear the stack...warm it. make sure the heat is going up.
then i turn on one burner for twenty minutes..then the second
burner....both on high. get her going.
make sure all systems are in proper place.
work in the studio all day while the kiln is firing.
diligent.
i also take the plugs out of my electric kilns every year and clean them
with emery. make things bright and shiny. check all connections.
always feel your wires during electric firings....make sure they are not
hot.
mel
from mel/minnetonka.mn.usa
website: http://www.pclink.com/melpots
http://home.comcast.net/~figglywig/clayart.htm
for gail's year book.
Louis Katz on mon 15 aug 05
Wiring near kilns.
One of my grad students had her house burn to the ground last friday.
They had replaced most of the wiring in the last six months. The old
wiring caught apparently. Everyone is fine, two dogs were lost. My
student is upset but doing well.
My house was built in the 40's. I smelled smoke one day and found it at
a light fixture. Turned the power off to the house ripped down the
fixture. The insulation on the wires fell off into powder. Turned out
it was a compact flourescent that had smoked. But it showed me a
problem with the wiring in my attic. I now have all of the lighting
circuits replaced. The wires in the attic here in SoHo Texas were all
in desparate need. The wall outlet wires are next on my list, but they
are in good shape.
Ok so what does this have to do with the color of smoke in the kiln
room? I would be very carefull about wiring in a kiln room that gets
elevated temperatures and make sure the insulation is holding up
particularly at staple points and on electric kiln circuits.
Joel Meyers came up to the Illinois State University Glass lab one
morning and noticed smoke coming out of vent. The lab was in an old
garage, wood......
Anyhow the exhaust fan had gone out and the garage had heated up. He
slowly opened a door (luck y it did not blow up) and got the
temperature down and the smoke out. Up in the rafters the wood had
started to turn black on the edges. plastic had melted in places around
the studio......
Exhaust fans stopping have been the cause of many mishaps.
A thermostatic alarm should not be too hard to build
Louis
John Baymore on mon 15 aug 05
Mel has it nailed pretty well there in that post about kiln roofs.
The cause of a kiln fires is about 99 percent "operator error".....either
in the firing process or in the original installation process. It is very
rare that a component of a kiln system in and of itself
catestrophically "fails".
Potter's tend to get rather complacent about fire over time. We work with
it and see it as a "friend". We forget the OTHER side. Ask a fireman
about fire... you'll likely get a bit different perspective .
And complacency breeds problems.
That being said....... I've been putting in kilns professionally for about
30 years now. I'd say that about 90-95 percent of them are/were housed
with wooden framing for the kiln enclosure. The percent of kiln fires in
those installations are (so far) ZERO. It is attention to detail, correct
installation, and giving the operator guidelines for operation that helps
with this. Metal is great... but it's not a "requirement".
As mel mentioned, ventilation and correct installation IS a requirement if
you don't use metal (and maybe if you do too). Metal lets you get away
with stuff.
I have housed MANY wood kilns in wooden structures over the years. It CAN
be done just fine. Look at the thatched roof structures over Japanese
wood kilns some with wooden beams literally inches from the kilns
themselves . (Yes... occasionally they DID catch fire.... but not as
often as you might think.)
COULD a wooden kiln building burn....... of course. If you need for some
reason to 100 percent rule out any fire in the kiln building ever.... of
course use all metal construction and put it FAR away from any other
wooden structures.
The real "danger point" in a fuel fired kiln istallation is the roof
penetration point for the chimney/vent. This is where the problems
typically start. Build that spot right... and you decrease the potential
for problems. If for some reson you have to use really close clearances
there......... research Van Packer zero clearance flue penetration
units ........ but get out your wallet .
And mel has it exactly right........ moving air in a kiln room is
crucial. Crucial for decreasing fire danger... as well as for not
breathing the crap coming out of the kiln. You have to disapate the heat
energy. Air movement does that pretty well.
The ignition point for wood decreases with repeated exposure to heat. So
a situation that was FINE in the original installation.... can catch fire
after 10 years of repeated heat exposure. Remember the title "Farenheight
451"? Don't take much to ignite a "paper thin" sliver of wood .
Anyone who has taken my annual summer noborigama woodfire workshop knows
the importance I put into the END of firing routine...... even after hours
of hot exhausting work with a nice soft bed calling.
All the excess wood that is CLEARLY not potentially hot or smoldering is
moved away from the kiln and put in secure racks. The entire area
surrounding the noborigama gets carefully raked with metal rakes. Any
errant coals that sneaked out get pushed up against the brickwork ... and
later soaked with watter. The stuff on the ground is raked in a manner
that assures any potential hot coals are separated from the wood supply
and the kiln structure. Then the entre area (including raked piles) gets
hosed down with a water spray until it is soaked. Every tarp and loose
combustable item is checked and tied firmly down. The wooden roof over
the kiln is sprayed with water. The chimney penetration point is SOAKED
with water.
The kiln chimney has a "cooler" opening that is opened to help drop the
temperature of the chimney at the penetration point as fast as is
possible. This is nothing more than a passive dampe port that is located
above the slab dampers that are used to seal the kiln after firing. Once
the kiln is sealed... this potrt is opened ... letting fresh air run
through the upper chimney and cool it. This is left open when we finally
go to bed.
This whole "shut down" procedure takes about an hour after the stoking
ends. While it is being done ... the slab damper is slowly getting closed
as the main coal beds slowly burn off... so as to not typically put the
kiln into reduction cooling too soon.
Anyway...... good post mel-san. "Required" reading.
best,
..............john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
JBaymore@compuserve.com
http://www.JohnBaymore.com
"Please use compuserve address for any direct communications."
Ingeborg Foco on mon 15 aug 05
Mel Said:
I have a wooden building for my kiln.
it has been a part of my studio/kiln for many years.
I am very concerned about safety.
I have wooden exposed joist members near my stack.
I have painted the joists with `fire paint`. that is a paint with
kaowool fibre. suppose to retard fire to 800 degrees F.
Mel, I also have a wood ceiling with exposed structural beams for a hip
roof. Two sides of the kiln area are screened with pressure treated lumber
the other two sides are concrete block .
After all of the discussion about fire paint some years ago, I spent the $
to purchase fire paint and had it shipped to Florida from California at no
small expense. I sprayed the fire paint all over the ceiling of the kiln
room including the ceiling above the two electrical kilns which are only
fired to bisque temp. I thought it was money well spent for piece of mind.
Recently, however, I noticed the fire paint bubbling and peeling off
throughout the entire ceiling not just above the gas kiln. It is most
upsetting to see it flaking off and I am now worried about the safety of my
roof. I just replaced the cover to the electrical plugs (where elec kilns
are plugged in) as the plastic covers just fell off. I guess it just gets
to darn hot in that room even though it is open to the outside on two sides.
I am at a loss as to what to do and while I never leave the building while I
fire, I worry about the roof heating up and catching on fire.
I have been thinking about having some type of sheet metal hood fabricated
to channel the heat and vent it out along with the stack. I still don't
know if that would really make a big difference. Any thoughts anyone?
Just passed my annual fire inspection two days ago and would hate to have to
call them to put out the flames.
Sincerely,
Ingeborg
the Potter's Workshop & Gallery
P.O. Box 510
3058 Stringfellow Road
St. James City, Florida 33956
239-283-2775
>>
Gordon Ward on mon 15 aug 05
I think a hood would be a good idea if it is getting that hot. Geil
kilns provides a full hood over their kilns plus what they call a
"flame bucket". It is a sheet metal structure that creates separation
between the flue pipe and ceiling/roof materials. it also extends
across the ceiling in an area around the flue opening. This is made of
sheet metal and lined with fiber insulation. They have done their
homework with this design. If you can find someone in the area with
one of these kiln installations, it might give you some ideas.
Gordon
On Aug 15, 2005, at 10:05 AM, Ingeborg Foco wrote:
> I have been thinking about having some type of sheet metal hood
> fabricated
> to channel the heat and vent it out along with the stack.
William & Susan Schran User on mon 15 aug 05
On 8/15/05 1:05 PM, "Ingeborg Foco" wrote:
> Recently, however, I noticed the fire paint bubbling and peeling off
> throughout the entire ceiling not just above the gas kiln. It is most
> upsetting to see it flaking off and I am now worried about the safety of my
> roof.
Is the roofing deck pressure treated wood? Could be the paint would not
adhere properly to pressure treated material.
>I have been thinking about having some type of sheet metal hood fabricated
>to channel the heat and vent it out along with the stack. I still don't
>know if that would really make a big difference.
A hood over the entire kiln would help to remove heat and fumes. An air gap
between the hood and stack would also be helpful.
--
William "Bill" Schran
Fredericksburg, Virginia
Debbie on mon 15 aug 05
What about using ITC to coat wood surfaces close to kiln heat?
Debbie (building a kiln room soon and soaking this all in)
> Subject: Re: kiln roof safety
> Recently, however, I noticed the fire paint bubbling and peeling off
> throughout the entire ceiling not just above the gas kiln. It is most
> upsetting to see it flaking off and I am now worried about the
> safety of my
> roof. >
June Kinsinger on mon 15 aug 05
I an not as experienced as everyone on this listserve but thougt I might share my solution. I purchased 3 panels of cement board that is used behind shower stall walls and have mounted them on a frame built of 2x4's for 3 sides of the kiln, I have felt these boards at max temp and they are just warm to the touch. Firing to ^6 and not had any problems at all. I also have a table up against the one side of the board for a work surface and nothing has been damaged at all. One wall has a receptical behind the board with a plastic cover that is level with the kiln top and it is still fine, no signs of melting at all.
Hope this helps someone,
June Kinsinger
Richmond, IN
-----Original Message-----
From: Ingeborg Foco
To: CLAYART@LSV.CERAMICS.ORG
Sent: Mon, 15 Aug 2005 13:05:35 -0400
Subject: Re: kiln roof safety
Mel Said:
I have a wooden building for my kiln.
it has been a part of my studio/kiln for many years.
I am very concerned about safety.
I have wooden exposed joist members near my stack.
I have painted the joists with `fire paint`. that is a paint with
kaowool fibre. suppose to retard fire to 800 degrees F.
Mel, I also have a wood ceiling with exposed structural beams for a hip
roof. Two sides of the kiln area are screened with pressure treated lumber
the other two sides are concrete block .
After all of the discussion about fire paint some years ago, I spent the $
to purchase fire paint and had it shipped to Florida from California at no
small expense. I sprayed the fire paint all over the ceiling of the kiln
room including the ceiling above the two electrical kilns which are only
fired to bisque temp. I thought it was money well spent for piece of mind.
Recently, however, I noticed the fire paint bubbling and peeling off
throughout the entire ceiling not just above the gas kiln. It is most
upsetting to see it flaking off and I am now worried about the safety of my
roof. I just replaced the cover to the electrical plugs (where elec kilns
are plugged in) as the plastic covers just fell off. I guess it just gets
to darn hot in that room even though it is open to the outside on two sides.
I am at a loss as to what to do and while I never leave the building while I
fire, I worry about the roof heating up and catching on fire.
I have been thinking about having some type of sheet metal hood fabricated
to channel the heat and vent it out along with the stack. I still don't
know if that would really make a big difference. Any thoughts anyone?
Just passed my annual fire inspection two days ago and would hate to have to
call them to put out the flames.
Sincerely,
Ingeborg
the Potter's Workshop & Gallery
P.O. Box 510
3058 Stringfellow Road
St. James City, Florida 33956
239-283-2775
>>
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Gordon Ward on mon 15 aug 05
A word of caution on fans in kiln rooms. It's a great idea to move the
air around inside as Mel has described, but take care in installing an
enormous exhaust fan. I did this once and it created negative pressure
in the room. It sucked the flames right out of the flame tubes going
into the kiln. Yes, it was a blaster.
Gordon
John Baymore on tue 16 aug 05
Hum.... I did a post on this a while ago just after Loius posted his
comment... and it apparently got lost in "Internet Bit Heaven".
Joel Meyers came up to the Illinois State University Glass lab one
morning and noticed smoke coming out of vent. The lab was in an old
garage, wood......
Anyhow the exhaust fan had gone out and the garage had heated up. He
slowly opened a door (luck y it did not blow up) and got the
temperature down and the smoke out. Up in the rafters the wood had
started to turn black on the edges. plastic had melted in places around
the studio......
Exhaust fans stopping have been the cause of many mishaps.
Great point there Louis.
Hot glass shops are a level of fire danger issue just a slight "notch
above" what we typically do......because typically they run 24/7 for long
uninterupted periods... and are typically unattended overnight...for night
after night after night. And the furnaces are running somewhat at
equilibrium temperature..... which means that the cold face of the walls
is typically hot. But....... most glass pot furnaces and glory holes are
smaller units than our kilns..... thankfully. And they tend to
get "throttled back" when they are in "overnight" mode.
When you absolutely DEPEND on a system for safe operation...... you really
SHOULD have some way of making sure that system is actually working... and
likely have a backup system available too. Critical components that, if
they fail, might cause catestrophic issues might take after the NASA
approach... have system redundency or some sort. If they can't be
redundant...... or can't alert the operator...... it should likely "abort"
the operation it is supporting.
Mel has it right again...... fanS. The "S" there can be important. If
you have one fan on a single source circuit...and that circuit or fan
fails..... you have no ventialtion at all. 100 % failure of your
necesssary system. But if you have 2 fans.... losing one is only now a 50
% failure of the system. That "buys you some time" to discover the
issue. And so on.
When I spec out kiln installations in places that are "institutional".....
(and often have inexperienced students around)......I usually set it up so
that there is an interlock between the exhaust fan(s) and the make up air
louver(s), and the combustion flame safety sustem. If the fans and the
air supply are not doing their thing... the kiln will not light...or it
will shut down.
This kind of seemingly complex setup is actually pretty simple to
accomplish. It just involves putting N.O. or N.C. switches in series with
the electrical circuit supplying the power to the main gas solenoid valve
(s). You can string together any number of "event monitors" in this way.
If you want to make sure a particular door is closed before the burners
are lit...... just put in a another switch .
If you use double pole switches...... you can also string indicator lights
and/or alarms remotely to inform you of the status of your various
monitored "events". So when that fan goes out....... the system starts
screaming at you.
I also typically recommend a hard wired digital display CO detector in
kiln rooms... and for gas kiln installations.... a flamable gas detector.
In the state of Massachusetts, it is also required by the State Fuel Gas
Board that there be an interlock on the effluent exhaust (chimney) that
prevents the burners from being started if the damper is not open. This
again is just another switch in series with the control circuitry.
BTW... if you are running natural gas into an interior kiln space... many
locales require explosion proof motors on fans and sparkless switches for
ventilation systems. And in many places any wiring for such stuff in kiln
rooms (including combustion flame safety systems) must be high temperature
rated wire run in metal conduit.
That all being said... if you beleive that your flame safety system is
completely protecting you..... I have a bridge for you to look
at .......cheap. .
The best safety system for kilns is the potter him/her self. Attentive
and never totally complacent about fire.
best,
.............john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
JBaymore@compuserve.com
http://www.JohnBaynmore.com
"Please use compuserve address for any direct communications."
Kathi LeSueur on tue 16 aug 05
Ingeborg Foco wrote:
>Mel, I also have a wood ceiling with exposed structural beams for a hip
>roof. Two sides of the kiln area are screened with pressure treated lumber
>the other two sides are concrete block .
>
>After all of the discussion about fire paint some years ago, I spent the $
>to purchase fire paint and had it shipped to Florida from California at no
>small expense. I sprayed the fire paint all over the ceiling of the kiln
>room including the ceiling above the two electrical kilns which are only
>fired to bisque temp. I thought it was money well spent for piece of mind.
>
>Recently, however, I noticed the fire paint bubbling and peeling off
>throughout the entire ceiling not just above the gas kiln........
>
>I have been thinking about having some type of sheet metal hood fabricated
>to channel the heat and vent it out along with the stack. I still don't
>know if that would really make a big difference.>>>>
>
My gas kiln is in a two car garage that was added on to the existing two
car garage that I use for a studio. I was very concerned about fire even
though the kiln was in the first garage for about seven years. The
addition was built with post and beam rather than trusses so that I
would have a clear span al the way to the peak. The whole inside is
lined with fire-resistant drywall. I had a 8' square hood fabricated
locally. It vents out through an opening at the peak of the garage. Any
furnace installer who does their own sheet metal fab should be able to
build one for you. I also installed two turbine vents in the roof to
take off any additional heat. This system has worked very well for me.
I'm still paranoid about fire. Keep an extinguisher and hose handy
through the whole firing and I'm thinking of installing a second layer
of drywall just to ease my mine. I've had this system in place for 15
years. BTW, my kiln is the Abernathy design. No chimney. Just an opening
at the bottom of the door with four forced air burners.
Kathi
Kathi
>
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