william schran on sat 19 feb 05
Began this morning firing the Olympic updraft that I retro fitted
with new burners for the first time. Darn thing really took off,
500°F in 10 minutes even with burners on low setting - guess it
thought I was doing a raku firing :-)
Anyway, at about 1800°F the kilns shuts down. First thought, pilot
blew out as the doors to the small shed were open and there was a bit
of wind. Kiln temp fell couple hundred degrees, re-lit pilot, re-lit
burners, shut shed door. Went back to studio (kiln is right outside
studio door), returned to check kiln 10 minutes later - had shut off
again. Hmmm... increased pressure to pilot, re-lit pilot then burners.
10/15 minutes later, kiln shuts down again... rats! Re-lit pilot &
burners, increased pressure to burners, kiln shut down again 10/15
minutes later.
Hmmm...I says, gotta be one of the safety controls. Here's what's
connected in the gas line from tank to kiln (propane): pressure
regulator on tank, pressure regulator in line (adjustable pressure,
9" - 14" - have adjusted this down because I thought the pressure too
much for safety controls), electric solenoid switch connected to Kiln
Sitter (max. 1/2 psi written on control), cut off valve, Baso switch
(also max 1/2 psi) with new pilot, but has older thermocouple (can't
see that end has burned off, but maybe an item to change) that is
attached to first burner, cut off valve (what I use to
increase/decrease pressure to burners, then the 3 - MR750 burners.
I'm considering: Changing the thermocouple, but I would think it
would have shut the kiln down sooner if it was defective. This would
be the least expensive.
Removing the electric solenoid & Kiln Sitter and see if that's where
the problem is.
Giving up on the low pressure set-up, removing the in-line regulator,
the solenoid and low pressure Baso - replacing with high pressure
Baso valve with pilot & thermocouple & an adjustable regulator.
An thoughts or advise before I decide to chuck it all and stick with
crystalline glazes in an electric kiln?
Thanks, Bill
Vince Pitelka on sun 20 feb 05
> Anyway, at about 1800=B0F the kilns shuts down. First thought, pilot
> blew out as the doors to the small shed were open and there was a bit
> of wind. Kiln temp fell couple hundred degrees, re-lit pilot, re-lit
> burners, shut shed door. Went back to studio (kiln is right outside
> studio door), returned to check kiln 10 minutes later - had shut off
> again.
Bill -
This sounds like classic thermocouple misalignment or a bad thermocouple.=
=20
Remember that there has to be flame directed at the thermocouple tip whil=
e=20
the main burners are working. Many people adjust the pilot and thermocou=
ple=20
so that the flame is just right when only the pilot is running, but then=20
when the main burners are lit, the whole flame dynamic can be changed. =
The=20
draft caused by the main burners can change the shape of the pilot flame =
so=20
that it is no longer adequately heating the thermocouple tip. Also, the=20
draft pattern can change as the kiln starts to heat up, so the problem mi=
ght=20
not arise until well into the firing. Even if the problem is just=20
misalignment, you definitely want to get a spare thermocouple. Take the =
old=20
one off and take it to your local gas company and they can sell you a new=
=20
one.
This is probably going to turn out to be something very simple, and altho=
ugh=20
it seems frustrating, as soon as you figure out you will be glad for the=20
experience.
Good luck -
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/=20
George Nagel on sun 20 feb 05
William, Can't really speak to the pilots, solenoids, thermocouples, etc. =
I got a used Olympic updraft and fire with propane. Guy I bought it from =
had used it for years and was going on to graduate school somewhere like Mi=
chigan or something (I live in Oregon). Anyway, he left me his set up he s=
aid worked great for him. About 15 ft. of copper tubing plumbed right into=
the burner ring. He said he used a 25lb propane tank and a standard regul=
ator, like they use for barbeque's etc. I tried it, it did work, very slow=
ly and trouble with reduction, but it worked. I replaced the set up with a=
250 lb. tank, first and second stage regulator. Second stage regulator is=
plumbed right into a new burner ring I got from Olympic (minus all the stu=
ff you mentioned.) No problem getting it to cone 10. Still learning how t=
o reguate the firing and the reduction. Talked to someone who does kiln de=
signs and has been a studio potter for years who advises the Olympics are v=
ery difficult to learn on because of their size and design. He recommended=
I move to a small downdraft kiln for economy of fuel and manageable firing=
.
I'm planning on doing that, but will continue with the Olympic until I get =
around to it. I'm getting some fair results, but believe he is probably ri=
ght about the difficulty managing the reduction. Oh yeh, he said another p=
roblem with them is that they cool to fast---not enough insulation. I agre=
e. Good luck. George
-----Original Message-----
From: william schran
Sent: Feb 19, 2005 8:12 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: frustration firing Olympic updraft
Began this morning firing the Olympic updraft that I retro fitted
with new burners for the first time. Darn thing really took off,
500=B0F in 10 minutes even with burners on low setting - guess it
thought I was doing a raku firing :-)
Anyway, at about 1800=B0F the kilns shuts down. First thought, pilot
blew out as the doors to the small shed were open and there was a bit
of wind. Kiln temp fell couple hundred degrees, re-lit pilot, re-lit
burners, shut shed door. Went back to studio (kiln is right outside
studio door), returned to check kiln 10 minutes later - had shut off
again. Hmmm... increased pressure to pilot, re-lit pilot then burners.
10/15 minutes later, kiln shuts down again... rats! Re-lit pilot &
burners, increased pressure to burners, kiln shut down again 10/15
minutes later.
Hmmm...I says, gotta be one of the safety controls. Here's what's
connected in the gas line from tank to kiln (propane): pressure
regulator on tank, pressure regulator in line (adjustable pressure,
9" - 14" - have adjusted this down because I thought the pressure too
much for safety controls), electric solenoid switch connected to Kiln
Sitter (max. 1/2 psi written on control), cut off valve, Baso switch
(also max 1/2 psi) with new pilot, but has older thermocouple (can't
see that end has burned off, but maybe an item to change) that is
attached to first burner, cut off valve (what I use to
increase/decrease pressure to burners, then the 3 - MR750 burners.
I'm considering: Changing the thermocouple, but I would think it
would have shut the kiln down sooner if it was defective. This would
be the least expensive.
Removing the electric solenoid & Kiln Sitter and see if that's where
the problem is.
Giving up on the low pressure set-up, removing the in-line regulator,
the solenoid and low pressure Baso - replacing with high pressure
Baso valve with pilot & thermocouple & an adjustable regulator.
An thoughts or advise before I decide to chuck it all and stick with
crystalline glazes in an electric kiln?
Thanks, Bill
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Lee Love on mon 21 feb 05
George Nagel wrote:
>An thoughts or advise before I decide to chuck it all and stick with
>crystalline glazes in an electric kiln?
>
>
George,
I can't remember who it was, maybe Pete Pinell. But he
converted his commercial updraft into a downdraft by making an exit in
the back and adding a stack there. Worked very well.
--
Lee in Mashiko, Japan http://mashiko.org
http://potters.blogspot.com/ WEB LOG
http://claycraft.blogspot.com/ Photos!
william schran on mon 21 feb 05
Vince wrote:>This sounds like classic thermocouple misalignment or a
bad thermocouple. Remember that there has to be flame directed at the
thermocouple tip while the main burners are working. Many people
adjust the pilot and thermocouple so that the flame is just right
when only the pilot is running, but then when the main burners are
lit, the whole flame dynamic can be changed.<
Vince - Thanks for the informed response.
My first thought was also the themocouple, though it was working fine
prior to my changing the burners. I did look at the pilot flame and
it looked like it was still directed at the thermocouple shortly
before the kiln shut down. But even so, it would be the least
expensive fix to start with.
I have a raku burner set up from Marc Ward at school that has the
same basic burner, pilot, thermocouple and I set the
pilot/thermocouple on the burner on my kiln the same as the raku
burner. But because the burner in my kiln is a bit closer to the
burner port, I should probably pull the pilot/thermocouple back a bit.
Bill
Bonita Cohn on mon 21 feb 05
Our 2 indoor kilns in San Francisco have all sorts of
safety features. The most sensitive is the one that
shuts off the kiln if the flame is blown away from the
sensor. we have intake fans that can blow the flame
away from the sensor, so we shield that sensor from
any breezes. We use various things: kiln shelf as a
wall, metal shelf along the side of ,iln as a wall, to
prevent a sudden breeze from blowing the flame away
from the sensor.
I know you shut your sudio door - perhaps the sensor
needs to be adjusted so the flame is closer to it.
Hope this makes some sense helps you figure it out.
Good luck, Bontia Cohn in San Francisco.
=====
Bonita Cohn
http://www.bonitacohn.com
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