John Baymore on fri 3 nov 00
Hi all.
I'd like to thank everyone who took the time to respond to my quick littl=
e
informal survey about major problems with gas and electric kilns. I know=
how busy everybody is at this time of year and I appreciate the effort. =
Even though I was asking for reports of PROBLEMS.... many people went out=
of their way to email me and say that they have NEVER had a problem. =
Those responses were not included in the compiled data below, but they
helped put the level of the "problem" in perspective.
The good news........... aside from the lawyer drawing up the final
contractual agreement, the potter's coop that I was helping to
represent/defend has prevailed in their efforts to retain the use of thei=
r
gas kiln. In a quite intense and LONG meeting, verbal agreements were
reached with which both parties can live. In the end, the coops whole
kiln operation WILL be safer too. During negotiations, the data provided=
by this "survey" WAS utilized at one point in response to some of the
landlord's lawyers questions directed to me.
I promised to share the information I gained...... so here is a bit of
"food for thought". =
There were 43 total responses that listed a "major problem" (see original=
questions) with a gas or electric kiln. Thirty three involved electric
kilns and ten involved gas kilns. This would be somewhat expected, since=
there are more electric kilns in use than gas kilns.
This is a small response. With the potential large readership of the
original posting...... this possibly may indicate that "kiln disasters" a=
re
not all that common. Or it still could represent many other factors. =
=46rom my own expreiences as a professional kiln builder........ I'd lea=
n
gently toward the conclusion that kiln disasters are not the most burning=
safety issue in ceramics. =
The most instructive information comes from assessing the types of
incidents reported.
Of the 43 incidents reported, 20 specifically involved the failure of som=
e
sort of electronic automatic safety device to function properly. 18 of
these involved electric kilns and 2 were with gas kilns.
There were 7 reports of "fires" (scorching, flame, smoke, etc) occuring
that were external to the kiln (affecting building walls, etc.). All wer=
e
from electric kiln installations and ALL somehow involved the electrical
wiring or junction boxes. All the "fires" seemed to be pretty minor. No=
personal injury was reported.
There were 18 "meltdown" type incidents, 17 in electric kilns and one in =
a
gas kiln. In all cases, the damage appeared to be restricted to the kiln=
itself and/or the kiln contents. In some cases severe damage to the kiln=
was reported. Again, no injuries or structural damage to the building we=
re
reported.
The single gas kiln "meltdown" incident reported involved a high
temperature kiln constructed out of donated low duty refractories by an
inexperienced kiln builder...... so it really was a clear case of "pilot
error" .
There were 7 "explosive" type incidents reported....and as you would
imagine, all were with gas kilns. In this group, 3 of these kilns had no=
flame safety equipment, 2 experienced a failure of the flame safety syste=
m
to function correctly, and 1 did not specify if a flame safety system was=
present or not. The status of the flame safety on one unit was unknown.
One of these "explosive" incidents actually involved not gas and air....b=
ut
water and heat. An inexperienced kiln builder was involved once again, a=
nd
it was a steam explosion from combining a terribly underinsulated kiln
floor placed directly on a soaking wet, uncured concrete slab and the fir=
st
post-construction firing. Near peak of firing....bingo. This one was th=
e
"scariest" one listed . Pilot error once again.
In all cases except the wet concrete slab, the explosions that were
reported seemed to be pretty minor, with damage restricted to the kiln
itself and / or the contents. Some of these could be designated as "big
flashbacks" rather than "explosions". None of the kilns were
completely destroyed.... and seemed to require only repairs. The worst
repair job reported was the necessity of rebuilding an arch. In some cas=
es
not even the pots were destroyed. There was one case of personal injury
indicated, with 1st and 2nd degree burns. All explosions seemed to happe=
n
at "lightup".
On the question of what type of flame safety system is utilized on propan=
e
fired gas kilns........ there were 34 responses. Of these 28 utilized
thermocouples and BASO type valves, three had no flame safety system, 2
utilized ultraviolet detectors, and one utilized an approach that does no=
t
fit easy broad "classification"......... but was "high tech" and could so=
rt
of fall into the general UV detector category.
There is one thing that is reinforced by reading these stories that I
already have stressed in my kiln classes over the years....... and I'd li=
ke
to take this opportunity to stress to the CLAYART list. DO NOT believe
blindly in some automatic device to protect you, your family, your friend=
s,
your students, your pots, your home and studio, or your possessions from
harm. Automatic controls can fail. Use your brain ...... it is the most=
sophisticated "safety device" you can find.
To those who are using electric kilns............. those electric kiln
"meltdowns" were caused by the failure of the automatic shutoffs to
function correctly COMBINED WITH the assumption by the kiln firer that it=
WOULD shut off the kiln. They didn't! Electric kilns may APPEAR to be
sort of like a big toaster........ but they aren't. Don't go off and
leave them unattended. =
One reason that there may be so few real big disasters with "big dangerou=
s"
gas kilns is that the people firing them tend to pay far more attention t=
o
them than people tend to with "nice safe" electric kilns . ( To
clarify....... I am not saying here that gas kilns are inherently dangero=
us
and electric kilns are inherently safe...... but just that they tend to b=
e
PERCIEVED that way.)
Now another bit here that deals with COOPs and PARTNERSHIPS and the like.=
=
There is another thing that is quite obvious from dealing with this probl=
em
with this particular coop and the landlord. If you are involved in such
ventures........ make sure that you take the time at the OUTSET to figure=
out how things will be handled at some point "down the road" when one or
the other party in an agreement decides that they no longer like the
agreement. Get all the details in writing....and have that writing looke=
d
at by a lawyer. It would be cheap insurance to prevent nasty circumstanc=
es
developing..... and much higher costs later. It is easier and less costl=
y
to prevent such a problem than to fix it after the fact....if you even CA=
N
fix it.
Such things are business ventures....and should be treated as such. Even=
when at the outset everyone involved is friends and positve, and
"idealistic". Things can change. Depressing to think of when you are al=
l
"fired up" about a new venture. But you should try to anticipate all
likely possible future outcomes and prepare for them.
So.... thanks again to all who helped out.
Best,
........................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
603-654-2752 (s)
800-900-1110 (s)
JBaymore@compuserve.com
John.Baymore@GSD-CO.com
"DATES SET: Earth, Water, and Fire Noborigama Woodfiring Workshop =
August 17-26, 2001"
Wesley C. Rolley on fri 3 nov 00
John,
This was an excellent piece of reportage. It is what Clayart is all about.
Our town is going to put a "ceramics" room in a new community center that
was just approved by the "city" council and I will make sure that this is
passed on to them. When we are all focusing on the technical/aesthetic
issues of our craft, we need these guides for the problems of a business.
Wes Rolley
Wes Rolley
"Happiness is to be fully engaged in the activity that you believe in and,
if you are very good at it, well that's a bonus." -- Henry Moore
http://www.refpub.com
Hank Murrow on fri 3 nov 00
John Baymore wrote;
>
>I'd like to thank everyone who took the time to respond to my quick little
>informal survey about major problems with gas and electric kilns.
>There were 7 "explosive" type incidents reported....and as you would
>imagine, all were with gas kilns. In this group, 3 of these kilns had no
>flame safety equipment, 2 experienced a failure of the flame safety system
>to function correctly, and 1 did not specify if a flame safety system was
>present or not. The status of the flame safety on one unit was unknown.
>the explosions that were reported seemed to be pretty minor, with damage
>restricted to the kiln itself and/or the contents. Some of these could be
>designated as "big flashbacks" rather than "explosions". None of the kilns
>were
>completely destroyed.... and seemed to require only repairs. The worst
>repair job reported was the necessity of rebuilding an arch. There was one
>case of personal injury indicated, with 1st and 2nd degree burns. All
>explosions seemed to happen at "lightup".
******In 42 years of firing gas kilns I have witnessed or cleaned
up after
four "lighting events" which resulted in an explosion. All involved a
burner system
where the lighter checked one side of the kiln to see that the gas valve
was closed;
but assumed that the other side was closed also. The ritual that I teach
involves
turning off the air before turning off the gas, waiting one minute and
turning off
the gas at each burner, then turning off the main valve. I tell each
lighter that
they should check the kiln before firing to assure themselves that the
person before
them did so. Then and only then do they proceed to open main valve, light
the pilots,
then each burner valve, and finally, add in some air. This way there is
assurance
that there is never a dangerous mix of gas and air at lightup. i call it
the "Upstream/Downstream Method". One further preventative would be to make
sure the door was not completely sealed up at light-up. this would allow it
to vent without damaging anything. Of course noone should stand near the
door at light-up. I got approval for a student-built downdraft gas kiln at
Aspen H.S. by insisting that a one square foot block of fiber be fitted in
a corresponding hole in the back wall of the kiln adjacent to the chimney.
We tested this in the prescence of the entire school board by deliberately
creating a flashback condition. The fiber 'plug' blew out and hit the
chimney; but the stacked brick door and the stuff inside was undamaged. The
school board liked it so much that we repeated it twice more. Think they
were all pyromaniacs at heart, perhaps. Approval on the spot, happy kids, &
safe kiln.
>On the question of what type of flame safety system is utilized on propane
>fired gas kilns........
******One other safe operation feature specific to propane would be
a floor drain to allow accumulated propane, which is heavier than air, to
escape harmlessly out of the building. This feature is built into many hot
glass studios; but one hears it mentioned very seldom for pottery studios.
>There is one thing that is reinforced....... DO NOT believe
>blindly in some automatic device to protect you, Use your brain ...... it
>is the most
>sophisticated "safety device" you can find. One reason that there may be
>so few real big disasters >with "dangerous" gas kilns is that the people
>firing them tend to pay far more attention to
>them than people tend to with "nice safe" electric kilns.
******Thanks so much to everyone for their experiences; and to John
for doing a great job in building the file. great work! Hank in Eugene
Earl Brunner on fri 3 nov 00
Both "accidents" that I have had experience with were using
propane. I was slow getting my newspaper taper under the
kiln to the burners once and blew the soft brick door out
(on top of myself naturally). That was a fun mosaic, trying
to piece all the brick parts back together.
The other one occurred in the mid 70's in central Utah, A
group of people in a small town got together and stated
making slip cast planters for department stores. They had
an envelope kiln that was a couple hundred cubic feet. The
guy lighting the kiln (propane again) turned on the gas at
the tank, assuming the burners were off. They were in fact
wide open. When he tried to light it it blew up. The door
on the east side was found a block away in the school
playground. Fortunately no one received serious injury. The
kiln was destroyed though.
Neither kiln had safety equipment on them.
Hank Murrow wrote:
>
> John Baymore wrote;
> >
> >I'd like to thank everyone who took the time to respond to my quick little
> >informal survey about major problems with gas and electric kilns.
> >There were 7 "explosive" type incidents reported....and as you would
> >imagine, all were with gas kilns. In this group, 3 of these kilns had no
> >flame safety equipment, 2 experienced a failure of the flame safety system
> >to function correctly, and 1 did not specify if a flame safety system was
> >present or not. The status of the flame safety on one unit was unknown.
> >the explosions that were reported seemed to be pretty minor, with damage
> >restricted to the kiln itself and/or the contents. Some of these could be
> >designated as "big flashbacks" rather than "explosions". None of the kilns
> >were
> >completely destroyed.... and seemed to require only repairs. The worst
> >repair job reported was the necessity of rebuilding an arch. There was one
> >case of personal injury indicated, with 1st and 2nd degree burns. All
> >explosions seemed to happen at "lightup".
>
> ******In 42 years of firing gas kilns I have witnessed or cleaned
> up after
> four "lighting events" which resulted in an explosion. All involved a
> burner system
> where the lighter checked one side of the kiln to see that the gas valve
> was closed;
> but assumed that the other side was closed also. The ritual that I teach
> involves
> turning off the air before turning off the gas, waiting one minute and
> turning off
> the gas at each burner, then turning off the main valve. I tell each
> lighter that
> they should check the kiln before firing to assure themselves that the
> person before
> them did so. Then and only then do they proceed to open main valve, light
> the pilots,
> then each burner valve, and finally, add in some air. This way there is
> assurance
> that there is never a dangerous mix of gas and air at lightup. i call it
> the "Upstream/Downstream Method". One further preventative would be to make
> sure the door was not completely sealed up at light-up. this would allow it
> to vent without damaging anything. Of course noone should stand near the
> door at light-up. I got approval for a student-built downdraft gas kiln at
> Aspen H.S. by insisting that a one square foot block of fiber be fitted in
> a corresponding hole in the back wall of the kiln adjacent to the chimney.
> We tested this in the prescence of the entire school board by deliberately
> creating a flashback condition. The fiber 'plug' blew out and hit the
> chimney; but the stacked brick door and the stuff inside was undamaged. The
> school board liked it so much that we repeated it twice more. Think they
> were all pyromaniacs at heart, perhaps. Approval on the spot, happy kids, &
> safe kiln.
>
> >On the question of what type of flame safety system is utilized on propane
> >fired gas kilns........
>
> ******One other safe operation feature specific to propane would be
> a floor drain to allow accumulated propane, which is heavier than air, to
> escape harmlessly out of the building. This feature is built into many hot
> glass studios; but one hears it mentioned very seldom for pottery studios.
>
> >There is one thing that is reinforced....... DO NOT believe
> >blindly in some automatic device to protect you, Use your brain ...... it
> >is the most
> >sophisticated "safety device" you can find. One reason that there may be
> >so few real big disasters >with "dangerous" gas kilns is that the people
> >firing them tend to pay far more attention to
> >them than people tend to with "nice safe" electric kilns.
>
> ******Thanks so much to everyone for their experiences; and to John
> for doing a great job in building the file. great work! Hank in Eugene
>
> ______________________________________________________________________________
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>
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>
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--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
Diane Mead on sat 4 nov 00
All of my experiences with kiln mishaps were propane
(within the state of Georgia)
and there were never injuries.
Does it strike anybody else odd that elements that
are dangerous enough to be bombs did not harm
anyone involved? At the time it didn't
even think about the lack of great damage.
>From: Earl Brunner
>
>Both "accidents" that I have had experience with were using
>propane. I was slow getting my newspaper taper under the
>kiln to the burners once and blew the soft brick door out
>(on top of myself naturally). That was a fun mosaic, trying
>to piece all the brick parts back together.
>The other one occurred in the mid 70's in central Utah, A
>group of people in a small town got together and stated
>making slip cast planters for department stores. They had
>an envelope kiln that was a couple hundred cubic feet. The
>guy lighting the kiln (propane again) turned on the gas at
>the tank, assuming the burners were off. They were in fact
>wide open. When he tried to light it it blew up. The door
>on the east side was found a block away in the school
>playground. Fortunately no one received serious injury. The
>kiln was destroyed though.
>Neither kiln had safety equipment on them.
>
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