Arturo Devitalis on sat 16 mar 96
Are there any better t han "plain-vanilla" Honeywell thermocouples out
there? TIA
--
Arturo DeVitalis
arto@uhura.cc.rochester.edu
bburruss@csn.net on sun 17 mar 96
>----------------------------Original message----------------------------
>Are there any better t han "plain-vanilla" Honeywell thermocouples out
>there? TIA
>--
>Arturo DeVitalis
>arto@uhura.cc.rochester.edu
What do you mean by "better" and "plain-vanilla"? There are lots of
different types of thermocouples. I certainly wouldn't call
platinum-platinum/10%rhodium a plain-vanilla thermocouple, but I wouldn't
want to pay for it either. The common pyrometers for ceramic kilns are
designed for chromel-alumel thermocouples. If you use a different alloy
combination you'd have to recalibrate the readout. I weld my own
chromel-alumel TC's and they work fine.
Bob
Nils Lou on sun 17 mar 96
Check with Axner's at NCECA--he has some good new stuff re pyrometers and
oxygen sensors--Lou
On Sat, 16 Mar 1996, Arturo Devitalis wrote:
> ----------------------------Original message----------------------------
> Are there any better t han "plain-vanilla" Honeywell thermocouples out
> there? TIA
> --
> Arturo DeVitalis
> arto@uhura.cc.rochester.edu
>
Bill Aycock on mon 18 mar 96
>----------------------------Original message----------------------------
>Are there any better t han "plain-vanilla" Honeywell thermocouples out
>there? TIA
>--
>Arturo DeVitalis
Arturo-
Are you refering to the thermocouple itself, or to the whole instrument? I
think Honeywell buys their thermocouples (or the wire to make them) and
makes most of their money off the read-out system, or on assembling the
parts into a neat package.
To me, a "plain-vanilla" thermocouple would be a simple Chromel-Alumel pair,
inserted into a protective ceramic tube and welded into a junction. The
connecting line and the read-out (dial or digital) are additional parts that
make the thermocouple useful as part of a pyrometer.
If your question was directed at finding a better way to measure temperature
in your kiln, try an optical pyrometer; they let you check any place you can
see through your peep holes.
They are fun. and expensive.
Bill- who recently acquired 3000 ft of very small Chomel-Alumel instrument
connecting wire, now stored on Persimmon Hill, (do you need to make a remote
kiln monitoring system ?)
Monaghan, Paul on mon 18 mar 96
Arturo,
Yes check out Omega Engineering, Inc; PO Box 4047; Stamford, Ct. 06907-0047;
1-800-826-6342. They have everything under the sun for measuring all types
of physical parameters. They will also send you an unbelievable set of free
tech manuals.
Paul Monaghan
----------
From: owner-clayart
To: Multiple recipients of list CLAYART
Subject: thermocouples
Date: Saturday, March 16, 1996 11:54PM
----------------------------Original message----------------------------
Are there any better t han "plain-vanilla" Honeywell thermocouples out
there? TIA
--
Arturo DeVitalis
arto@uhura.cc.rochester.edu
WardBurner@aol.com on tue 19 mar 96
Hi Arturo,
Been outa town, so I came in a little late on this thread. From your question
I think you're asking about thermocouples that are hooked to a safety valve
such as a BASO valve. The replys I read concerned sensing thermocouples for
pyrometers. Totally different animals. If you mean thermos that are hooked to
pyrometers, the advice I read was fine. But, I believe you are asking about
the K15 type thermo you can buy at the hardware for standing pilots. If
that's your question, the answer is yes, there are industrial thermos for
pilots that have a higher millivolt output and slightly more protected cold
juction. I know that may be technobabble and not mean much to you. I carry
Johnson Controls "Husky" thermos in 36" lengths with a 25-35 mV output. If
you are having recurring thermocouple burnouts, you may have other problems,
Feel free to give me a call or send me your address and I'll get a catalog to
you...
Marc Ward
Ward Burner Systems
PO Box 333
Dandridge, TN 37725
423.397.2914 voice
423.397.1253 fax
wardburner@aol.com
WILSHYN@cc.usu.edu on tue 19 mar 96
Arturo,
Were you refering to the type of thermocouples used to read the kiln temp.
or the ones that read the flame on your pilot and attach to your baso valve.
If you are refering to the first send me a personal message and
I will send you some information on the different types and
their best uses.
If you were refering to the second. Johnson controls makes what they
refer to as a HUSKY THERMOCOUPLE. They tend to out last the regular
ones. I have also seen ones refered to as Heavy Duty Thermocouples,
but I can't remember who makes them.
I hope this is what you were looking for.
Wil Shynkaruk
Utah State University
wilshyn@cc.usu.edu
Arturo Devitalis on wed 20 mar 96
I WAS referring to the basso valve thermocouples, but in haste failed to be
specific....so most of the postings related to the temp measuring
bi-metallic kind. I will chk Johnson controls in the Yellow pages and go
from there. Tks for you note....2 day Robin Hopper workshop ended today and
it was fine stuff...I highly recommend it
--
Arturo DeVitalis
arto@uhura.cc.rochester.edu
bryan on sun 20 dec 98
Are there any tricks to welding the type of wire that is used in a
thermocouple.
The ones I have came with very long leads, I could easily make another with =
the
scrap.
Thanks
Bryan Johnson
715-278-3408
adam-n-chris on mon 21 dec 98
as far as welding your thermocouples.........dont do it they will never work
again they come in diffent lenghts if it bothers you that much other wise
dont bother trying to cut them, a thermocouple is a bi metle switch that
reactes with heat.!!!!!!!!
-----Original Message-----
From: bryan
To: CLAYART@LSV.UKY.EDU
Date: Sunday, December 20, 1998 8:50 PM
Subject: Thermocouples
>----------------------------Original message----------------------------
>Are there any tricks to welding the type of wire that is used in a
>thermocouple.
>
>The ones I have came with very long leads, I could easily make another with
the
>scrap.
>
>Thanks
>
>Bryan Johnson
>
>715-278-3408
>
Fred Paget on mon 21 dec 98
It is tricky. The commercial thermocouples,if done correctly are welded in
an inert atmosphere. Overheating can degrade the wire. and welding gas and
the atmosphere in which the wire is welded can diffuse into the
thermocouple metal, changing its chararacteristics. The difficulty is
compounded by the very different nature of the two metals being
joined.Commercial thermocouples are welded on expensive machinery using a
capacitive -discharge technique to insure uniformity.
The above is from the OMEGA Temperature handbook.
Fred Paget
>----------------------------Original message----------------------------
>Are there any tricks to welding the type of wire that is used in a
>thermocouple.
>Bryan Johnson
-
From Fred Paget, in marvelous Marin County, California, USA
Earl Brunner on tue 22 dec 98
I don't see a problem with Bryan's question. SOMEBODY welded the original
thermocouple together. It can be done. And that was the question, Bryan
didn't say that he didn't know that the two metal rods are different alloys.
Obviously, he wouldn't be asking if he thought it was just a question of zapping
them with a welding rod. Uh, it's not just a question of zapping them with a
welding rod, IS it?
Earl Brunner
adam-n-chris wrote:
> ----------------------------Original message----------------------------
> as far as welding your thermocouples.........dont do it they will never work
> again they come in diffent lenghts if it bothers you that much other wise
> dont bother trying to cut them, a thermocouple is a bi metle switch that
> reactes with heat.!!!!!!!!
> -----Original Message-----
> From: bryan
> To: CLAYART@LSV.UKY.EDU
> Date: Sunday, December 20, 1998 8:50 PM
> Subject: Thermocouples
>
> >----------------------------Original message----------------------------
> >Are there any tricks to welding the type of wire that is used in a
> >thermocouple.
> >
> >The ones I have came with very long leads, I could easily make another with
> the
> >scrap.
> >
> >Thanks
> >
> >Bryan Johnson
> >
> >715-278-3408
> >
Gavin Stairs on tue 22 dec 98
At 03:06 PM 21/12/98 EST, bryan wrote:
....
>as far as welding your thermocouples.........dont do it they will never work
>again they come in diffent lenghts if it bothers you that much other wise
>dont bother trying to cut them, a thermocouple is a bi metle switch that
>reactes with heat.!!!!!!!!
....
>>in response to an original inquiry from Bryan Johnson:
....
>>Are there any tricks to welding the type of wire that is used in a
>>thermocouple.
....
I originally passed on this, figuring any number of people on this list
could supply the right answers. But this response... dear me.
A thermocouple is not a switch. It is in fact an electric generator that
works on heat. All metals contain free electrons. It is these electrons
which are responsible for most of what we feel as heat in the metal. The
hotter the metal, the faster the electrons bounce around inside the metal.
The electrons in different metals have different energy at the same
temperature. This is just a property of metals. Thermocouples exploit
this difference to produce a "diffusion current" across the metallic
junction between two dissimilar metals. In an open circuit, this diffusion
current produces a voltage difference across the junction which is
(approximately) proportional to the temperature at the junction. This
current actually cools the junction in proportion to the current. This
effect can be used to provide cooling with no moving parts: This is called
the Pelletier effect.
There are two types of thermocouples commonly used in ceramics work: the K
type has an operating range which stops just short of the cone 10 range.
It's made of a pair of base metal alloy usually referred to as
Chrome-Alomel. It is used to cone 10, and for all I know even higher, but
it is subject to degradation by oxidation and other high temperature
chemical effects. The other type in use is the type S (or its predecessor,
type R). This is a platinum couple made with almost pure platinum on one
leg and platinum with a 10-13% admixture of rhodium on the other leg. This
noble metal junction can be used to much higher temperatures, but is
subject to contamination at high temperature by less refractory metals from
the shielding housing and kiln atmospheres. For more on thermocouples, try
Most, if not all thermocouples used in pottery are welded. A thermocouple
will work with just about any kind of joint (welded, brazed, soldered, or
even just twisted together), but the welded joints are by far the most
durable. Especially at high temperatures, at which brazed and soldered
joints will reflow and eventually dissolve or fall apart, and twisted
joints will oxidized and become unreliable. So the welded joint is the
most common.
There is no real difficulty, but you really need the right equipment:
either a TIG welder or a shielded electric discharge machine. I suppose
you could do it with an oxy-hydrogen torch, with the right mixture. The
trick is to melt the two wires into a junction puddle without melting them
back too much, so the melt drops off. You also don't want to overheat so
that the melt forms a cavity on one or another of the wires. You want to
form a nice, constant diameter melt, in the case of an axial (butt) joint,
or a ball about the size of the two wires together in the case of a radial
(side by side) joint. Some preheating may help to control the melting, and
a little post heating to anneal. Do not keep the joint hot long enough to
recrystallize the metal, which will make the joint even more inhomogenous
that it already is, and promote disintegration in service. Be aware that
platinum melts at a very high temperature, and it might take you a bit of
practice to get a good weld.
The other point of interest is that the wire also ages in service, and it
may not be a good idea to reuse wire that has spent appreciable time almost
as hot as the junction that failed. If you do use old wire, cut off most
of the portion of the wire that was in the hot zone. If this takes away
too much wire, then consider purchasing your thermocouples in the form of a
bulk spool of wire, which would be much cheaper. In any case, you can use
the heat damaged wire for welding practice.
Gavin
===============================================
Gavin Stairs
Stairs Small Systems (S3)
921 College Street, # 1-A
Toronto, Ontario, Canada M6H 1A1
(416)530-0419
Don & Isao Morrill on tue 22 dec 98
At 15:14 12/21/98 EST, you wrote:
>----------------------------Original message----------------------------
> It is tricky. The commercial thermocouples,if done correctly are welded in
>an inert atmosphere. Overheating can degrade the wire. and welding gas and
>the atmosphere in which the wire is welded can diffuse into the
>thermocouple metal, changing its chararacteristics. The difficulty is
>compounded by the very different nature of the two metals being
>joined.Commercial thermocouples are welded on expensive machinery using a
>capacitive -discharge technique to insure uniformity.
>The above is from the OMEGA Temperature handbook.
>Fred Paget
>
>>----------------------------Original message----------------------------
>>Are there any tricks to welding the type of wire that is used in a
>>thermocouple.
>>Bryan Johnson
>
>
>-
> From Fred Paget, in marvelous Marin County, California, USA
>
>Dear Fred, Excuse me for jumping-in here. While there are many
sophisticated methods of joining T.C.s, it is rare for potters to be
concerned about th technology except as a matter of curiosity. Although I
have manufactured T.C.'s for everything from jet-engines to potting kilns,
I continue to simply clean both wires thoroughly and then twist them firmly
together. Ocassionally I have dipped the finished thermocouple in borax or
Sauereisen Cement as a protection. T.C. wire is not expensive. I believe I
bought 30 feet of #18 Chromel Alumel 30 years ago and still have 20feet
remaining. T.C.'s are no substitute for CONES.
don M.
Dan Tarro on tue 22 dec 98
Have you ever tried it? or are you going by what others have told you? It
does work. The values change, but if you are only looking to keep track
of the temp rise, it will do. Last time I used mild steel rod and I don't
expect it to last too long. Should really use stainless rod.
Dan Tarro
Oak Tree Stoneware
Ham Lake, Minnesota
On Mon, 21 Dec 1998 15:06:02 EST adam-n-chris
writes:
>----------------------------Original
>message----------------------------
>as far as welding your thermocouples.........dont do it they will
>never work
>again they come in diffent lenghts if it bothers you that much other
>wise
>dont bother trying to cut them, a thermocouple is a bi metle switch
>that
>reactes with heat.!!!!!!!!
>-----Original Message-----
>From: bryan
>To: CLAYART@LSV.UKY.EDU
>Date: Sunday, December 20, 1998 8:50 PM
>Subject: Thermocouples
>
>
>>----------------------------Original
>message----------------------------
>>Are there any tricks to welding the type of wire that is used in a
>>thermocouple.
>>
>>The ones I have came with very long leads, I could easily make
>another with
>the
>>scrap.
>>
>>Thanks
>>
>>Bryan Johnson
>>
>>715-278-3408
>>
>
___________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com/getjuno.html
or call Juno at (800) 654-JUNO [654-5866]
Dan / Joanne Taylor on tue 22 dec 98
Must disagree. Plainsman Clays here in Medicine Hat have welded many burned out
thermocouples and they work just fine thank you.
adam-n-chris wrote:
> ----------------------------Original message----------------------------
> as far as welding your thermocouples.........dont do it they will never work
> again they come in diffent lenghts if it bothers you that much other wise
> dont bother trying to cut them, a thermocouple is a bi metle switch that
> reactes with heat.!!!!!!!!
> -----Original Message-----
> From: bryan
> To: CLAYART@LSV.UKY.EDU
> Date: Sunday, December 20, 1998 8:50 PM
> Subject: Thermocouples
>
> >----------------------------Original message----------------------------
> >Are there any tricks to welding the type of wire that is used in a
> >thermocouple.
> >
> >The ones I have came with very long leads, I could easily make another with
> the
> >scrap.
> >
> >Thanks
> >
> >Bryan Johnson
> >
> >715-278-3408
> >
--
--------------------------------------------------------------------------------
Dan Taylor Ph: (403) 527-1002
1340 - 10th Ave. NE Fax: (403) 527-1032
Medicine Hat, Alberta email: dataylor@mlc.awinc.com
Canada T1A 6G3 "Today, well lived, makes every yesterday a dream of
happiness."
Euclid's Kilns & Elements on tue 22 dec 98
> Are there any tricks to welding the type of wire that is used in a
> thermocouple. The ones I have came with very long leads, I could easily
make another with the scrap. >
Hi Bryan,
The thermocouples we supply are spot welded. There is no foreign material
added.
Chris @
Euclid's Kilns and Elements
1-800-296-5456
Web Site: http://www.euclids.com
E-Mail: mail@euclids.com
adam-n-chris on wed 23 dec 98
as far as everybody worring the corrects words to describe a
themocouples......eat me..........i offered help the best that i could and
now i cheating hell for it!!!!!! that will help someone tring to help out
the next time! thanks for the hard time !
-----Original Message-----
From: Dan Tarro
To: CLAYART@LSV.UKY.EDU
Date: Tuesday, December 22, 1998 2:22 PM
Subject: Re: Thermocouples
----------------------------Original message----------------------------
Have you ever tried it? or are you going by what others have told you? It
does work. The values change, but if you are only looking to keep track
of the temp rise, it will do. Last time I used mild steel rod and I don't
expect it to last too long. Should really use stainless rod.
Dan Tarro
Oak Tree Stoneware
Ham Lake, Minnesota
On Mon, 21 Dec 1998 15:06:02 EST adam-n-chris
writes:
>----------------------------Original
>message----------------------------
>as far as welding your thermocouples.........dont do it they will
>never work
>again they come in diffent lenghts if it bothers you that much other
>wise
>dont bother trying to cut them, a thermocouple is a bi metle switch
>that
>reactes with heat.!!!!!!!!
>-----Original Message-----
>From: bryan
>To: CLAYART@LSV.UKY.EDU
>Date: Sunday, December 20, 1998 8:50 PM
>Subject: Thermocouples
>
>
>>----------------------------Original
>message----------------------------
>>Are there any tricks to welding the type of wire that is used in a
>>thermocouple.
>>
>>The ones I have came with very long leads, I could easily make
>another with
>the
>>scrap.
>>
>>Thanks
>>
>>Bryan Johnson
>>
>>715-278-3408
>>
>
___________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com/getjuno.html
or call Juno at (800) 654-JUNO [654-5866]
Don & Isao Morrill on wed 23 dec 98
At 14:15 12/22/98 EST, you wrote:
>----------------------------Original message----------------------------
>At 15:14 12/21/98 EST, you wrote:
>>----------------------------Original message----------------------------
>> It is tricky. The commercial thermocouples,if done correctly are welded in
>>an inert atmosphere. Overheating can degrade the wire. and welding gas and
>>the atmosphere in which the wire is welded can diffuse into the
>>thermocouple metal, changing its chararacteristics. The difficulty is
>>compounded by the very different nature of the two metals being
>>joined.Commercial thermocouples are welded on expensive machinery using a
>>capacitive -discharge technique to insure uniformity.
>>The above is from the OMEGA Temperature handbook.
>>Fred Paget
>>
>>>----------------------------Original message----------------------------
>>>Are there any tricks to welding the type of wire that is used in a
>>>thermocouple.
>>>Bryan Johnson
>>
>>
>>-
>> From Fred Paget, in marvelous Marin County, California, USA
>>
>>Dear Fred, Excuse me for jumping-in here. While there are many
>sophisticated methods of joining T.C.s, it is rare for potters to be
>concerned about th technology except as a matter of curiosity. Although I
>have manufactured T.C.'s for everything from jet-engines to potting kilns,
>I continue to simply clean both wires thoroughly and then twist them firmly
>together. Ocassionally I have dipped the finished thermocouple in borax or
>Sauereisen Cement as a protection. T.C. wire is not expensive. I believe I
>bought 30 feet of #18 Chromel Alumel 30 years ago and still have 20feet
>remaining. T.C.'s are no substitute for CONES.
>don M.
>
>P.S., It IS cost-effective in constructing hundreds of T.C.s to Heli-Arc
or spot-weld the junctions on Thermocouples subject to high temperatures
and long-time usage. MAterials like copper/copnic or copper/constantan are
low-temp junctions and are often silver soldered. Under continuous
usage,especially at even rated temperatures, junctions will fail. Scraping
the oxides away and then firmly twisting the wires together to form a
junction,is efficient and saves the the potter both time and money. donM.
Fred Paget on wed 23 dec 98
Don,
Yeah, I used to do that too. I was using dozens of type T thermocouples
at -60 to +200 deg. F. however and since they are copper and a copper
nickel alloy they could even be soft soldered. We were working well below
the melting point of soft solder. With the type K Chromel-Alumel couples
that potters use, the temperature is so high that they need to be welded or
else oxidation will form an insulating layer between the two wires.
I have an electric kiln that came with a really ugly weld job on the two
thermocouple wires. Looks like somebody used a torch on it. I checked it
against a type R platinum thermocouple using a Yokogawa instrument that is
accurate to 2 deg. at 2300 F and the badly welded type K is 30 degrees low
in reading.
I was going to recommend that a TIG welder might be used but then I got
out my Omega handbook to see what they had to say about making the joint,
There is not much in the handbook, only what I quoted.
Now Omega does make thermocouple assemblies among hundreds of other
things and some might say they have a vested interest in selling the
finished product, not in telling you how to make it yourself. As an
engineer of some 45 years experience in industry I think they are right in
cautioning that it is not easy to do it right.
With my Yokogawa digital meter and the type R thermocouple I can watch
the rate of rise and predict exactly when cone 10 is going over. This is
what the electric kiln controllers do but they need an accurate
thermocouple to work right. Oh how I wish somebody would make a kiln
controller that uses R or S thermocouples instead of only type K.
I think I will buy one of Euclid's spot welded thermocouples. It sounds
like they are doing it right.
Fred Paget
>>----------------------------Original message----------------------------
>> It is tricky. The commercial thermocouples,if done correctly are welded in
>>an inert atmosphere. Overheating can degrade the wire. and welding gas and
>>the atmosphere in which the wire is welded can diffuse into the
>>thermocouple metal, changing its chararacteristics. The difficulty is
>>compounded by the very different nature of the two metals being
>>joined.Commercial thermocouples are welded on expensive machinery using a
>>capacitive -discharge technique to insure uniformity.
>>The above is from the OMEGA Temperature handbook.
>>Fred Paget
>>
>>Dear Fred, Excuse me for jumping-in here. While there are many
>sophisticated methods of joining T.C.s, it is rare for potters to be
>concerned about th technology except as a matter of curiosity. Although I
>have manufactured T.C.'s for everything from jet-engines to potting kilns,
>I continue to simply clean both wires thoroughly and then twist them firmly
>together. Ocassionally I have dipped the finished thermocouple in borax or
>Sauereisen Cement as a protection. T.C. wire is not expensive. I believe I
>bought 30 feet of #18 Chromel Alumel 30 years ago and still have 20feet
>remaining. T.C.'s are no substitute for CONES.
>don M.
>
>------------------------------
-
From Fred Paget, in marvelous Marin County, California, USA
Stephen Mills on wed 23 dec 98
I the past I've persuaded thermocouple elements to work in modified form
by double twisting the ends together. The only problem is that because
they are made of two dissimilar metals, one starts to migrate to the
other when they are first joined (can't remember which goes to which!)
and that eventually makes them increasingly inaccurate. So there is a
good chance that a "reclaimed" element could give some pretty strange
readings! to say the least.
Steve
Bath
UK
In message , Earl Brunner writes
>----------------------------Original message----------------------------
>I don't see a problem with Bryan's question. SOMEBODY welded the original
>thermocouple together. It can be done. And that was the question, Bryan
>didn't say that he didn't know that the two metal rods are different alloys.
>Obviously, he wouldn't be asking if he thought it was just a question of zappin
>them with a welding rod. Uh, it's not just a question of zapping them with a
>welding rod, IS it?
>Earl Brunner
>
>adam-n-chris wrote:
>
>> ----------------------------Original message----------------------------
>> as far as welding your thermocouples.........dont do it they will never work
>> again they come in diffent lenghts if it bothers you that much other wise
>> dont bother trying to cut them, a thermocouple is a bi metle switch that
>> reactes with heat.!!!!!!!!
>> -----Original Message-----
>> From: bryan
>> To: CLAYART@LSV.UKY.EDU
>> Date: Sunday, December 20, 1998 8:50 PM
>> Subject: Thermocouples
>>
>> >----------------------------Original message----------------------------
>> >Are there any tricks to welding the type of wire that is used in a
>> >thermocouple.
>> >
>> >The ones I have came with very long leads, I could easily make another with
>> the
>> >scrap.
>> >
>> >Thanks
>> >
>> >Bryan Johnson
>> >
>> >715-278-3408
>> >
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
David Woodin on fri 25 dec 98
There are many controllers that will use a type R thermocouple but these are
industrial controllers and not as user friendly for potters and don't refer to
cones at all.
David
Don & Isao Morrill on fri 25 dec 98
At 10:54 12/23/98 EST, you wrote:
>----------------------------Original message----------------------------
>Don,
> Yeah, I used to do that too. I was using dozens of type T thermocouples
>at -60 to +200 deg. F. however and since they are copper and a copper
>nickel alloy they could even be soft soldered. We were working well below
>the melting point of soft solder. With the type K Chromel-Alumel couples
>that potters use, the temperature is so high that they need to be welded or
>else oxidation will form an insulating layer between the two wires.
> I have an electric kiln that came with a really ugly weld job on the two
>thermocouple wires. Looks like somebody used a torch on it. I checked it
>against a type R platinum thermocouple using a Yokogawa instrument that is
>accurate to 2 deg. at 2300 F and the badly welded type K is 30 degrees low
>in reading.
> I was going to recommend that a TIG welder might be used but then I got
>out my Omega handbook to see what they had to say about making the joint,
>There is not much in the handbook, only what I quoted.
> Now Omega does make thermocouple assemblies among hundreds of other
>things and some might say they have a vested interest in selling the
>finished product, not in telling you how to make it yourself. As an
>engineer of some 45 years experience in industry I think they are right in
>cautioning that it is not easy to do it right.
> With my Yokogawa digital meter and the type R thermocouple I can watch
>the rate of rise and predict exactly when cone 10 is going over. This is
>what the electric kiln controllers do but they need an accurate
>thermocouple to work right. Oh how I wish somebody would make a kiln
>controller that uses R or S thermocouples instead of only type K.
> I think I will buy one of Euclid's spot welded thermocouples. It sounds
>like they are doing it right.
>Fred Paget
>
>>>----------------------------Original message----------------------------
>>> It is tricky. The commercial thermocouples,if done correctly are welded in
>>>a>
Fred, Somehow it appears that continuance of the TC thread has opened a
kettle of bad fish. Certainly nothing either of us posted was insulting or
inflammatory.Ah,well.
No doubt many potters demand extreme accuracy in readings. We do
not.One learns to check the RELATIVE readings and to depend upon cones.
After 35 yrs at this game,I am like many auto mechanics: !pr.pliers.Bailing
wire and a monkey wrench take the place of all the fancy tools I have ever
purchased. By the way, what is the address of Yokogawa? While I am
familliar with FLUKE, Yoko gawa is a new one for me. I expect to go to
Japan,(for the 6th time) sometime in '99 and have lots of Japanese
relatives in engineering.etc. I'm sure They could obtain the digital meter
of which you have written.
While my memories of Marin sre limited to Kentfield 30yrs
ago,they are pleasant. Enjoy your holidays. Don & Isao
Fred Paget on sat 26 dec 98
Don, I guess you could say I am the exact opposite. I love tools and am
always looking for better ones. Never get too many. And I like instruments
that are accurate. It would be fair to say I am more of a technologist than
an artist.I use cones too.
The Yokogawa meter (Model UM04) came from Contemporary Kilns in Novato
CA. Right close here in Marin County.(They run an ad in CM). I don't know
where he got it but Yokogawa is a big Japanese industrial instrument
company and I am sure they must have a presence in the USA. I will try to
find a web site and address and put in the URL before I send this off.
The meter I have was around $350 and it is a panel meter. I had to go to
a local electronics store and buy a box to mount it in and provide a line
cord (it runs on 120 volts AC), switch, pilot light, fuse, and extension
cord and plug for the thermocouple. This meter has a switch so you can use
just about any kind of thermocouple in the right temperature range. Also it
has 2 alarm circuits that close a contact at any 2 set temperatures and
that can be used to shut off the kiln as an over temperature feature, but
you have to build the rest of a device to actually do it. You need a
solenoid valve in your gas line and an external power relay for a gas kiln,
or just a relay for an electric kiln plus a box to mount it in.
It is a real nice meter and appears to read to within 1 degree but they
only specify it to(0.1% of RDG.+2deg.) That is within about 5 degrees F at
cone 10
The platinum thermocouple that I have came from Contemporary Kilns also.
I think it was around $135. It came with an alumina tube and a mounting
junction box as one unit. It has a 1/2 inch pipe thread on the cool end of
the alumina tube and I have mounted a 1/2 inch flange on the outside of the
door near a peep hole where I put cones. There is a 3/8 inch hole under the
middle of the flange for the thermocouple tube. I just put the thermocouple
in the hole and give it a 360 degree turn to secure it in the thread. I
made it removable so I can use it in my electric kiln also to track crystal
glaze temperatures. That was why I bought it in the first place. At Carol
Sphar's crystalline glaze workshop at Mendocino Arts she had a similar
thermocouple and had us use it to keep the temperature constant
+ or - 10 degrees for four hours while the crystals were growing.
Fred Paget
> Fred, Somehow it appears that continuance of the TC thread has opened a
>kettle of bad fish. Certainly nothing either of us posted was insulting or
>inflammatory.Ah,well.
> No doubt many potters demand extreme accuracy in readings. We do
>not.One learns to check the RELATIVE readings and to depend upon cones.
>After 35 yrs at this game,I am like many auto mechanics: !pr.pliers.Bailing
>wire and a monkey wrench take the place of all the fancy tools I have ever
>purchased. By the way, what is the address of Yokogawa? While I am
>familliar with FLUKE, Yokogawa is a new one for me. I expect to go to
>Japan,(for the 6th time) sometime in '99 and have lots of Japanese
>relatives in engineering.etc. I'm sure They could obtain the digital meter
>of which you have written.
>Don & Isao
Yokogawa Electric Corp. 9-32, Nakacho 2 chome, Musashino-shi, Tokyo 180, Japan
Yokogawa Corporation of America
2 Dart Road, Shenandoah Industrial Park, Newman GA 30265 USA 404-253-7000
(http://www.yca.com/ )
-
From Fred Paget, in marvelous Marin County, California, USA
Stephen Mills on sat 26 dec 98
Thermocouples & Pyrometers only measure Temperature. Cones measure
accumulated heat-work, a very different thing indeed. If someone could
develop a gadget to TRULY replace the cone and do what it does, they'd
make a fortune and Ortons would be tearing their hair out!
In message , David Woodin writes
>----------------------------Original message----------------------------
>There are many controllers that will use a type R thermocouple but these are
>industrial controllers and not as user friendly for potters and don't refer to
>cones at all.
>David
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
James Blossom on sun 27 dec 98
Steve:
The very instrument you describe is easily built. It Would be called
an
integrating pyrometer, and consist of a themocouple hooked up to a
microprocessor which would add the heat per unit time to an accumulating
sum (the total heat work.) The result could be compared to a look-up table
in Read-Only-Memory to fit to true Orton numbers. Fortunatly, Skutt (or
whoever makes their controller for them) already does this in "cone mode"
Right-on about the difference between heat-work and temperature, tho.
J.B.
-----Original Message-----
From: Stephen Mills
To: CLAYART@LSV.UKY.EDU
Date: Saturday, December 26, 1998 11:15 AM
Subject: Re: Re Thermocouples
----------------------------Original message----------------------------
Thermocouples & Pyrometers only measure Temperature. Cones measure
accumulated heat-work, a very different thing indeed. If someone could
develop a gadget to TRULY replace the cone and do what it does, they'd
make a fortune and Ortons would be tearing their hair out!
In message , David Woodin writes
>----------------------------Original message----------------------------
>There are many controllers that will use a type R thermocouple but these
are
>industrial controllers and not as user friendly for potters and don't refer
to
>cones at all.
>David
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
Stephen Mills on mon 28 dec 98
Thanks James,
Trouble is I don't think those beasties have made it to this side of the
pond as yet, or if they have they've been pretty quiet about it!
Not easy to use in the middle of a field without a Gennie though :-)
Cheers
Steve
Bath
UK
In message , James Blossom writes
>----------------------------Original message----------------------------
>Steve:
> The very instrument you describe is easily built. It Would be called
>an
>integrating pyrometer, and consist of a themocouple hooked up to a
>microprocessor which would add the heat per unit time to an accumulating
>sum (the total heat work.) The result could be compared to a look-up table
>in Read-Only-Memory to fit to true Orton numbers. Fortunatly, Skutt (or
>whoever makes their controller for them) already does this in "cone mode"
>
>Right-on about the difference between heat-work and temperature, tho.
>
>J.B.
>-----Original Message-----
>From: Stephen Mills
>To: CLAYART@LSV.UKY.EDU
>Date: Saturday, December 26, 1998 11:15 AM
>Subject: Re: Re Thermocouples
>
>
>----------------------------Original message----------------------------
>Thermocouples & Pyrometers only measure Temperature. Cones measure
>accumulated heat-work, a very different thing indeed. If someone could
>develop a gadget to TRULY replace the cone and do what it does, they'd
>make a fortune and Ortons would be tearing their hair out!
>
>
>In message , David Woodin writes
>>----------------------------Original message----------------------------
>>There are many controllers that will use a type R thermocouple but these
>are
>>industrial controllers and not as user friendly for potters and don't refer
>to
>>cones at all.
>>David
>>
>
>--
>Steve Mills
>Bath
>UK
>home e-mail: stevemills@mudslinger.demon.co.uk
>work e-mail: stevemills@bathpotters.demon.co.uk
>own website: http://www.mudslinger.demon.co.uk
>BPS website: http://www.bathpotters.demon.co.uk
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
David Woodin on tue 29 dec 98
The easiest thing to do is get Orton's newer tables that have 3 different ramp
temperatures and just plot your own curve for different firing speeds. This
is very accurate and you can predict what temperature your cones will fall at
for any rate of temperature rise. Then it is easy to use digital pyrometers
or controllers.
David
Kenneth D. Westfall on wed 6 jan 99
The two wire are TIG welded and is not something a everyday buzz box stick
welder can tackle.
At 08:49 PM 12/20/98 EST, you wrote:
>----------------------------Original message----------------------------
>Are there any tricks to welding the type of wire that is used in a
>thermocouple.
>
>The ones I have came with very long leads, I could easily make another with =
>the
>scrap.
>
>Thanks
>
>Bryan Johnson
>
>715-278-3408
>
Kenneth D. Westfall
Pine Hill Pottery
R.D. #2 Box 6AA
Harrisville, WV 26362
pinehill@ruralnet.org
http://www.ruralnet.org/pinehillpottery
mel jacobson on tue 25 apr 00
i keep about 3-4 of them near my kiln.
it is the first thing i change if i am having
lighting problems.
i also have two of them hanging in my basement.
one for the hot water heater, one for my gas furnace.
after you have a plumber come just once, charge
you 100 bucks to change the thermocouple you won't
do that a second time.
thermocouples are almost always the first failure.
mel
minnetonka, minnesota, u.s.a
http://www.pclink.com/melpots (website)
Ron Roy on wed 26 apr 00
Just for a little contrast - I have the same 4 theremocouples that I
started with - thats 800 firings over 25 years. My burners are atmospheric
- Mark - could that be the reason? When I had them installed I made them
weld little draft shields right behind the couples so the flame would not
be blown away from them.
And yes - I have extras - for my burners and pyrometers.
RR
>----------------------------Original message----------------------------
>i keep about 3-4 of them near my kiln.
>it is the first thing i change if i am having
>lighting problems.
>
>i also have two of them hanging in my basement.
>one for the hot water heater, one for my gas furnace.
>
>after you have a plumber come just once, charge
>you 100 bucks to change the thermocouple you won't
>do that a second time.
>
>thermocouples are almost always the first failure.
>mel
>minnetonka, minnesota, u.s.a
>http://www.pclink.com/melpots (website)
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Stephen Mills on wed 26 apr 00
One of my jobs at Bath Potters Supplies is making burner kits which
include thermo-electric cut-offs. On the after-sales support side of
this activity my experience is that actual thermocouple failure is very
rare; what is far more common is the electrical contact at the valve end
working loose and as a result breaking down (it only generates about 2
amps after all). I suspect flame vibration as the cause for this.
Tightening up the connection (not too much) with a small spanner cures
this at no extra cost. Where the thermocouple does fail is where the
head has been adjusted INTO the flame path causing it to burn out. The
head needs only to be adjacent to the flame to perform its function, not
in it.
Steve Mills
Bath
UK
After the wettest spring for years I rather feel the webbed feet suit
me!
In message , mel jacobson writes
>----------------------------Original message----------------------------
>i keep about 3-4 of them near my kiln.
>it is the first thing i change if i am having
>lighting problems.
>
>i also have two of them hanging in my basement.
>one for the hot water heater, one for my gas furnace.
>
>after you have a plumber come just once, charge
>you 100 bucks to change the thermocouple you won't
>do that a second time.
>
>thermocouples are almost always the first failure.
>mel
>minnetonka, minnesota, u.s.a
>http://www.pclink.com/melpots (website)
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
Tel: **44 (0)1225 311699
Fax: **44 (0)870 0526466
vince pitelka on thu 27 apr 00
> Tightening up the connection (not too much) with a small spanner cures
> this at no extra cost. Where the thermocouple does fail is where the
> head has been adjusted INTO the flame path causing it to burn out. The
> head needs only to be adjacent to the flame to perform its function, not
> in it.
Steve -
You must have some very sensitive thermocouples over there. The inexpensive
ones we have here must be mounted with the tip part of the probe right in
the flame. If it is outside the flame it does not get hot enough and does
not generate the necessary current to energize the electromagnet in the Baso
valve.
Best wishes -
- Vince
Vince Pitelka
Home - vpitelka@dekalb.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
http://www.craftcenter.tntech.edu/
Marc Ward on thu 27 apr 00
In a message dated 4/26/00 1:24:40 PM, ronroy@pop.total.net writes:
<< - Mark - could that be the reason? When I had them installed I made them
weld little draft shields right behind the couples so the flame would not
be blown away from them. >>
yep. the cold junction of the thermocouple has been protected from excessive
blow-back and heat.
Marc Ward
Ward Burner Systems
PO Box 1086
Dandridge, TN 37725
865.397-2914 Voice
865.397-1253 Fax
wardburner@aol.com Email
wardburner.com Online Catalog
Stephen Mills on sat 29 apr 00
This might have something to do with the makeup of the Baso Valve;, the
ones I have seen are about twice the size of the UK single acting
equivalent and I guess would need a bit more oomph to keep them open
(though thinking over what Marc has to say it is obvious that the only
Baso's I've met have been low pressure ones). Having said that some of
the Techni double acting valves are about the same size as a Baso and
they're pretty sensitive as well. Again I find no need to have the tip
in the flame path.
Curious
ATB
Steve
In message , vince pitelka writes
>----------------------------Original message----------------------------
>> Tightening up the connection (not too much) with a small spanner cures
>> this at no extra cost. Where the thermocouple does fail is where the
>> head has been adjusted INTO the flame path causing it to burn out. The
>> head needs only to be adjacent to the flame to perform its function, not
>> in it.
>
>Steve -
>You must have some very sensitive thermocouples over there. The inexpensive
>ones we have here must be mounted with the tip part of the probe right in
>the flame. If it is outside the flame it does not get hot enough and does
>not generate the necessary current to energize the electromagnet in the Baso
>valve.
>Best wishes -
>- Vince
>
>Vince Pitelka
>Home - vpitelka@dekalb.net
>615/597-5376
>Work - wpitelka@tntech.edu
>615/597-6801 ext. 111, fax 615/597-6803
>Appalachian Center for Crafts
>Tennessee Technological University
>1560 Craft Center Drive, Smithville TN 37166
>http://www.craftcenter.tntech.edu/
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
Tel: **44 (0)1225 311699
Fax: **44 (0)870 0526466
David Woodin on fri 19 jan 01
All themocouples drift with time and that it why witness cones are used. As
far as the digital indicator goes it is unlikely to need calibration and will
stay within its published spec. If it doesn't you will know immediately
because it will most likely be a huge shift in calibration. Also the Fluke
and other digital indicators are usually type K and J thermocouple so be
careful which type you are switched to. The display will show type K or J
and deg F or C As far as using Type R or S themocouples yes this is what
industry would use for high temperatures. Potters normally don't have that
kind of money to spend and a type K in a protection tube will work fine. The
newer ones used by Skutt and others are incased in an inconel tube and when
the tip becomes corroded they fail immediately due to the fine gauge wire. If
you order from Omega make sure you get there low drift type K, which is 1/4"
in diameter protection tube and all. So $50 verses a delicate type R or S for
over $150 is something to consider.
David
Frederich, Tim on mon 22 jan 01
Type S thermocouples are very resistant to drift. We find almost no drift
when used here at Orton and have had Type S thermocouples last over 12
years. We sell a Type S (6 inch) thermocouple for $60. Not all controllers
can use a Type S so you should check with your manufacturer. If you need
more information please contact me.
Best regards,
Tim Frederich
Sherry Morrow on sun 28 jan 01
Tim,, I was catching up on my posts and saw yours about thermocouples. I've
been wanting to get one to use with my older cress kiln. Is this the type
that is hand held? Sherry Morrow
Brant Palley NMCLAY.com on mon 27 jan 03
Almost all the Thermocouples you can buy (under $50.00)are Type "K" and
can be used interchangeably. Use one about the same size. The Red side (+)
will attract a magnet. It should project a minimum of 3/4" into the kiln.
Brant Palley
New Mexico Clay
1-800-781-2529
1-505-881-2350
www.art-clay.com
www.nmclay.com
www.Silver-Clay.com
www.DuncanPaintStore.com
Ron Roy on tue 28 jan 03
If the lead wire from termocouple to meter changes it will affect the
reading - make sure to recalibrate with a glaze temperature cone when
replacing or changing the lenght of the wire and when you change
thermocouples.
Better still - never fire without at least one end of firing cone -
pyrometers drift and break - they are not reliable all the time - and never
will be.
RR
>Almost all the Thermocouples you can buy (under $50.00)are Type "K" and
>can be used interchangeably. Use one about the same size. The Red side (+)
>will attract a magnet. It should project a minimum of 3/4" into the kiln.
>
>
>
>Brant Palley
>New Mexico Clay
>1-800-781-2529
>1-505-881-2350
>www.art-clay.com
>www.nmclay.com
>www.Silver-Clay.com
>www.DuncanPaintStore.com
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Ruth F C Nicol on fri 12 sep 03
How do thermocouples behave when they begin to fail? I am trying to
fire a new-to-me Olympic torchbearer propane updraft. Two days ago the
burner began shutting off around 1800, an hour into reduction. I relit
it a couple of times but gave up when it continued to shut down again
after 10 minutes or so.
Later I wrapped the bulb end of the thermocouple in fiber blanket,
thinking it may be overheating due to back pressure from reduction, but
this didn't work.
Today, the problem started around 1400 degrees. I tried restarting it
several times - sometimes the ignition ring wouldn't even light while
holding the baso valve down. Or, it that lit, the burners would not
come on when the gas valve was opened. The ignition ring alone (no
burners) would not stay on by itself. The few times I got the burners
restarted, (things had to cool down quite a bit for that to happen)
everything would shut off within 2 or 3 minutes.
I'd like to say I resisted the temptation to clamp down the baso valve
but the reality is it would'nt have worked. If the thing didn't want to
light, no gas would flow at all while holding the valve down.
I'm hoping the problem is the thermocouple because that's an easy one.
Maybe it's something worse. Has anyone else been through this with
these kilns?
Thain in Ontario where it's still sunny and hot.
Steve Mills on sun 14 sep 03
Dear Ruth,
First thing to check: is the connection at the Baso end tight? I have
known them work loose. If that is not it try to move the tip of the
thermocouple nearer the flame. If it just won't work in any way, replace
it. When they fail, burner thermocouples just give up, there is no
gradual loss, it's all or nothing at all.
Steve
Bath
UK
In message , Ruth F C Nicol writes
>How do thermocouples behave when they begin to fail? I am trying to
>fire a new-to-me Olympic torchbearer propane updraft. Two days ago the
>burner began shutting off around 1800, an hour into reduction. I relit
>it a couple of times but gave up when it continued to shut down again
>after 10 minutes or so.
>Later I wrapped the bulb end of the thermocouple in fiber blanket,
>thinking it may be overheating due to back pressure from reduction, but
>this didn't work.
>Today, the problem started around 1400 degrees. I tried restarting it
>several times - sometimes the ignition ring wouldn't even light while
>holding the baso valve down. Or, it that lit, the burners would not
>come on when the gas valve was opened. The ignition ring alone (no
>burners) would not stay on by itself. The few times I got the burners
>restarted, (things had to cool down quite a bit for that to happen)
>everything would shut off within 2 or 3 minutes.
>I'd like to say I resisted the temptation to clamp down the baso valve
>but the reality is it would'nt have worked. If the thing didn't want to
>light, no gas would flow at all while holding the valve down.
> I'm hoping the problem is the thermocouple because that's an easy one.
>Maybe it's something worse. Has anyone else been through this with
>these kilns?
>
>Thain in Ontario where it's still sunny and hot.
--
Steve Mills
Bath
UK
Antoinette Badenhorst on fri 2 jan 04
Hi Guys.
Over the past few years I've been working with thermocouples in my
electric kiln that is made out of high fire wire ( guess it is the same
material that the elements are made out of, just much thicker). Two
wires are covered with segmented porcelain tubes and it split into a +
and - places in a square porcelain gadget (don't know what it is called)
and that connect with the electric wires in my kiln.
I used to use those years ago and had to replace them at least once
every 6 months. After I changed the thermocouples to what we used to
refer to as K- type thermocouples (in South Africa), I never had to
replace them again. They were covered with one solid porcelain tube.
At this stage it seems that there are not thermocouples like this K-type
available for my small 3.3 cub Bailey kiln and that made me wonder about
2 things:
1. Might there be some of these type thermocouples available
elsewhere in the USA and what might be the risk of trying them in my
kiln?
2. Since I have replaced several thermocouples by now, I have all
the materials available to make up my own thermocouples, except the
wire. How possible/impossible will it be to do that? I've noticed that
the front part of the thermocouple looks like 2 wires that are welded
together.
Just wondering..
Antoinette Badenhorst
105 Westwood Circle
Saltillo MS
38866
662 869 1651
www.clayandcanvas.com
william schran on sat 3 jan 04
Antoinette wrote:>
They were covered with one solid porcelain tube.
At this stage it seems that there are not thermocouples like this K-type
available for my small 3.3 cub Bailey kiln and that made me wonder about
2 things:
1. Might there be some of these type thermocouples available
elsewhere in the USA and what might be the risk of trying them in my
kiln?
2. Since I have replaced several thermocouples by now, I have all
the materials available to make up my own thermocouples, except the
wire. How possible/impossible will it be to do that?
I doubt that it would be less expensive to try and make your own
thermocouple after buying needed materials & tools. The porcelain
tube is the thermocouple protection tube that is desirable in high
fire oxidation and probably necessary in reduction firings.
You should be able to slide the thermocouple out of the protection
tube, measure the length of the thermocouple, and purchase a new one
that you'd slide back into the tube.
Bill
Earl Brunner on sat 3 jan 04
My understanding about making your own thermocouples is that the current
is created by the use of two different metals or alloys in the two leads
of the thermocouple. It was my understanding that it takes special
welding equipment and conditions to fuse the two together at the end. I
have heart that you can twist the ends together to achieve the proper
contact, but that it either doesn't work as well or last as long.
I think you can buy those porcelain tubes separately.
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of william
schran
Sent: Saturday, January 03, 2004 6:13 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Thermocouples
Antoinette wrote:>
They were covered with one solid porcelain tube.
At this stage it seems that there are not thermocouples like this K-type
available for my small 3.3 cub Bailey kiln and that made me wonder about
2 things:
1. Might there be some of these type thermocouples available
elsewhere in the USA and what might be the risk of trying them in my
kiln?
2. Since I have replaced several thermocouples by now, I have all
the materials available to make up my own thermocouples, except the
wire. How possible/impossible will it be to do that?
Antoinette Badenhorst on sun 4 jan 04
Hi everyone, thank you for all the info and advice on thermocouples. The
more I am involved in clay the prouder I am for being in this career.
Ceramic in general is not meant for empty heads. So often times when I
am throwing pots, I realize how much skill a potter needs in so many
different fields.
Thanks again.
Antoinette Badenhorst
105 Westwood Circle
Saltillo MS
38866
662 869 1651
Lynn Barnwell on fri 9 jan 04
Dear Ivor,
Thank you for your email. I think I understood most of it. To let you know
what I have, the kiln has three thermocouples and a Bartlett electronic
controller. I have changed thermocouples and elements in this Kiln and 2
others. I usually have consistent firings. I lost one thermocouple and
the kiln will still run on the other two but I put one industrial TC in that
my supplier shipped as a substitute as they were out of what I needed at the
last order. This thermocouple only enters 3/8" and my readings have been
off. (Checking readings between TCs started varying upwards of 100 degrees
F. Cone packs in the kiln at all three zones are showing a difference that
I have not been having. The bottom is getting the hottest with the middle
where the new TC is being coolest. I didn't know if it was the TC or
another problem. I have reordered TCs and will change out. If that is not
the problem I will call Bartlett.
Thanks again,
Lynn Barnwell
Hinkle Creek Pottery
Corinth, Mississippi
Bryan Hannis on sun 23 oct 05
How long are these thermocouples?????
Bryan Hannis
Clyde Tullis on mon 12 jul 10
I lent my ooolllldd test kiln to a friend who in fear of damaging the
thermocouple removed it and promptly lost it. It's about an 1/8" in
diameter. Does anyone know what type that is? All I know is it's not a =
=3D
K
William & Susan Schran User on mon 12 jul 10
On 7/12/10 11:05 AM, "Clyde Tullis" wrote:
> I lent my ooolllldd test kiln to a friend who in fear of damaging the
> thermocouple removed it and promptly lost it. It's about an 1/8" in
> diameter. Does anyone know what type that is? All I know is it's not a =
K
Probably a type "S" with ceramic sheath or a metal sheathed type "K".
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Clyde Tullis on tue 13 jul 10
now that I've looked further into this, it could be a K. I do believe tha=
=3D
t
it had a ceramic sheath.
Bill Merrill on wed 21 dec 11
Type K thermocouples need to have the wire made for them so the
temperature reads correctly.
There are thermocouples that will use a different wire but they are made
for specific thermocouples. Use the wrong wiring and the readings are
not accurate.
Type R use platinum and Rhodium in the thermocouple =3D20
Type K use nickel-chromium =3D20
I have used type K for over 40 years without any trouble. It is always
wise to have a spar thermocouple and wiring on hand. The any part that
operates any safety devices on your kiln. I always had fire eyes etc.
on hand should one malfunction during a firing.
Bill Merrill
Nils Lou on thu 22 dec 11
the K-type thermocouple has a couple advantages in cost
and the fact it will read out a digital temp. on inexpensive
meters. S and R types either need a very expensive meter for this
or just provide a mv that has to be interpreted. most electric
kilns come with K thermocouples, so to extend their life I coat
the tips with ITC 213, effectively doubling (at least) their life.
the coating does not affect the t/c in the least. I also use the
coated t/c for C10 gas firings. the current one has two years on it
--est. 40 firings or so. replacement cost for a K t/c is $12--for
S or R, $100.
the K t/c is not as accurate in the higher temps, but you can adjust
to the readings with cones. at C10, for example, I get a reading of
1280 C. plus or minus 10. It's just and indicator that I'd better check
the cones.
nils lou
prof. of art
linfield college
http://nilslou.blogspot.com
"Art of Play" now in e-book at Amazon
jonathan kaplan on sun 25 dec 11
A short note here on this subject....and Happy Holidays to all!!!
What has not been mentioned is "thermocouple drift", which is as a =3D
thermocouple ages and is subject to firing after firing, the accuracy of =
=3D
the read-out becomes less than accurate.
For me, wanting to be as precise as possible given the constraints and =3D
limitations of ceramics, I have type "S' thermocouples housed in =3D
protective tubes on all my kilns. Well worth the small additional =3D
up-charge. Type "S" is standard on my Nabertherm kilns, and available as =
=3D
a small up-charge on my Paragon.=3D20
There are also available sealed thermocouples, housed within a stainless =
=3D
steel shell. These are much better than an unprotected thermocouple.
Omega is an excellent source for all these products, and their print =3D
catalogs are certainly worthy of inclusion in any potter's bookshelf.=3D20
But regardless of whatever thermocouple one chooses, I cannot stress the =
=3D
importance of pyrometric cones as the de-facto indicator of heat-work. =3D
Any thermocouple with a digital readout is a great tool for watching =3D
rate of climb, and controllers are only as good as the person familiar =3D
with them.=3D20
I also cannot stress the importance of paying attention to your firing =3D
as you approach end points and watching those cones. they are the true =3D
indicator. Don't leave your kiln unattended. WIth all the hard work that =
=3D
you put into your work, the small amount of time put into watch ing =3D
those cones at the end seems to me to be very necessary.
Best to all
Jonathan
Jonathan Kaplan
curator
Plinth Gallery
3520 Brighton Blvd
Denver, CO 80216
www.plinthgallery.com
303 295-0717 =3D20
Steve Mills on mon 26 dec 11
An equally short addendum.=3D20
When the two dissimilar metals that form a T'couple element are joined, one=
w=3D
ill chemically "migrate" to the other, which over time causes the performan=
c=3D
e drift.=3D20
In Types R and S and N this becomes noticeable after five or so years, at w=
h=3D
ich point in Industry they are replaced.=3D20
Other types like K degrade much faster.=3D20
Steve M
Steve Mills
Bath
UK
Sent from my iPod
On 25 Dec 2011, at 16:15, jonathan kaplan wrot=
e=3D
:
> A short note here on this subject....and Happy Holidays to all!!!
>=3D20
> What has not been mentioned is "thermocouple drift", which is as a thermo=
c=3D
ouple ages and is subject to firing after firing, the accuracy of the read-=
o=3D
ut becomes less than accurate.
>=3D20
>=3D20
David Finkelnburg on mon 26 dec 11
Steve,
An alternative is to measure the thermocouple output at a known
temperature, usually 0 degrees C/32F, achieved with ice water, and again in
boiling water 100C/212F at sea level (lower temperatures at higher
elevations) and since TCs have a predictable temperature curve, use these
two points to predict the millivolt thermocouple output for the particular
thermocouple being calibrated at near peak firing temperature, say 1,200C
(2,192F) and adjust the readout accordingly. By calibrating the
thermocouple periodically one can continue to use it even as it
deteriorates over time. As long as the junction does not fail entirely one
can continue using the thermocouple. Even when it fails one can repair it
by rewelding the two thermocouple wires at the junction. Using this method
an expensive type S thermocouple should last indefinitely in pottery use.
As was mentioned by Jonathan Kaplan, a thermowell, or protective sheath
of metal, will protect the thermocouple from the effects of reduction
firing and extend its useful life.
Regards,
Dave Finkelnburg
-----------------------------
Date: Mon, 26 Dec 2011 00:31:10 +0000
From: Steve Mills
An equally short addendum.=3D20
When the two dissimilar metals that form a T'couple element are joined, one
w=3D
ill chemically "migrate" to the other, which over time causes the
performanc=3D
e drift.=3D20
In Types R and S and N this becomes noticeable after five or so years, at
wh=3D
ich point in Industry they are replaced.=3D20
Other types like K degrade much faster.=3D20
Steve M
Nils Lou on wed 18 apr 12
Robert Harris mentioned having to replace his t/c's
on his electric kiln because he fires to C9 plus. I've found
that coating them with ITC213 will extend the life considerably.
I haven't replaced one in ten years at Linfield College.
Admittedly, C6 is the highest we go on the electrics though.
nils lou
prof. of art
linfield college
http://nilslou.blogspot.com
"Art of Play" now in e-book at Amazon
Alice DeLisle on thu 19 apr 12
Nils, all,
Is it ok to coat TCs that have been used a few times with ITC213, or =3D
does it have to be put on when they are new?
Original msg:
"Robert Harris mentioned having to replace his t/c's
on his electric kiln because he fires to C9 plus. I've found
that coating them with ITC213 will extend the life considerably.
I haven't replaced one in ten years at Linfield College.
Admittedly, C6 is the highest we go on the electrics though.
nils lou"
Alice DeLisle
wanderland@att.net
http://www.etsy.com/shop/IslandTextures
http://www.flickr.com/photos/alice_delisle/
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