Arnold Howard on wed 6 jul 05
----- Original Message -----
From: "primalmommy"
I am still not sure whether it's kosher to keep the thermocouple inside the
> kiln for the whole firing, though. Opinions?
To get the longest life out of a Type-K thermocouple connected to a
pyrometer, leave the thermocouple in the firing chamber continuously below
2000 deg. F. Above that temperature, insert it only when you need to take a
reading.
The Type-K lasts indefinitely at low temperatures. They last many years in
glass kilns, which fire at around 1500 deg. F.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
Wayne Seidl on wed 6 jul 05
Arnold:
Would that include (K-type) thermocouples inside a ceramic
closed-end "protection" sleeve?
I leave mine in for the duration of the (electric ^10) firing,
haven't noticed any degradation yet. Maybe 20 firings is too early
to tell?
I love the ability to track temperature throughout the firing, but
I'm anal that way.
Wayne "Never was a clock watcher, but temp? You bet!" Seidl
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Arnold
Howard
Sent: Wednesday, July 06, 2005 11:34 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: A pyrometer's thermocouple
----- Original Message -----
From: "primalmommy"
I am still not sure whether it's kosher to keep the thermocouple
inside the
> kiln for the whole firing, though. Opinions?
To get the longest life out of a Type-K thermocouple connected to a
pyrometer, leave the thermocouple in the firing chamber continuously
below
2000 deg. F. Above that temperature, insert it only when you need to
take a
reading.
The Type-K lasts indefinitely at low temperatures. They last many
years in
glass kilns, which fire at around 1500 deg. F.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
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Arnold Howard on mon 11 jul 05
Wayne, the suggestion I offered last week about removing a Type-K
thermocouple from the firing chamber at high temperatures also includes
thermocouples in protection sleeves.
Ann brought up a good point about stressing the thermocouple tip by rapid
cooling/heating (see below). That may be a valid point. At Paragon, we
frequently remove a thermocouple from a test kiln. It is not to save on
thermocouple wear but to transfer the thermocouple to a different test kiln.
Rapid heating/cooling hasn't seemed to adversely affect the thermocouple
tip, though.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
----- Original Message -----
From: "Wayne Seidl"
Arnold:
Would that include (K-type) thermocouples inside a ceramic
closed-end "protection" sleeve?
I leave mine in for the duration of the (electric ^10) firing,
haven't noticed any degradation yet. Maybe 20 firings is too early
to tell?
I love the ability to track temperature throughout the firing, but
I'm anal that way.
Wayne "Never was a clock watcher, but temp? You bet!" Seidl
-----------------
I use both a digital and an analog pyrometer in the Skutt, and just leave
the thermocouples in position from one firing to the next. I've always
theorized that more stress would be placed on the connection between the two
metals at the tip by removal/reinsertion during firing- all that expanding
and shrinking quickly....
Ann Brink in Lompoc CA
-----Original Message-----
From: "primalmommy"
I am still not sure whether it's kosher to keep the thermocouple
inside the
> kiln for the whole firing, though. Opinions?
To get the longest life out of a Type-K thermocouple connected to a
pyrometer, leave the thermocouple in the firing chamber continuously
below
2000 deg. F. Above that temperature, insert it only when you need to
take a
reading.
The Type-K lasts indefinitely at low temperatures. They last many
years in
glass kilns, which fire at around 1500 deg. F.
Arnold Howard
Bruce Girrell on tue 12 jul 05
Arnold Howard wrote:
>...the suggestion I offered last week about removing a Type-K
>thermocouple from the firing chamber at high temperatures also includes
>thermocouples in protection sleeves.
>At Paragon, we frequently remove a thermocouple from a test kiln.
Glad to hear that Arnold. I have avoided doing so because I removed a
thermocouple at high temperature once* and the next time that I looked at
it, the protection sleeve was in two pieces, broken at about the position
where the end would have extended beyond the brick. From my one data point I
then concluded that removing a thermocouple at high temp induces too much
thermal stress on the sleeve, which then breaks.
Now I'll at least be willing to give it another go should I have occasion to
do so in the future.
Bruce "but it had better not break the next time or I'm calling my lawyer -
material losses, loss of income, mental anguish, pain and suffering..."
Girrell
* The wire connections at the terminal block had worked loose and I was
getting erratic readings on the pyrometer. I tried retightening the screws
in place but they just wouldn't set properly. So I got a spare pyrometer and
wired that up for the remainder of the firing. The protection tube was
pulled because I feared that I would push it into the kiln during the
reinsertion of the thermocouple.
Michael Wendt on tue 12 jul 05
Bruce,
The directions that came with one of my pyrometers said they can be removed
safely by gradual withdrawal. Pull the tube out an inch at a time over
several minutes with enough time for the new temperature to stabilize before
moving it. By the time it is down below red heat, the shock will be less
severe.
I also thought it might be possible to construct a Kaowool tube inside a
light metal jacket. Placing the protection tube immediately into the
insulated tube would also prevent thermal shock and loss of the tube during
the transfer to a new kiln..
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, Idaho 83501
USA
wendtpot@lewiston.com
www.wendtpottery.com
Bruce wrote in reply to Arnold:
>At Paragon, we frequently remove a thermocouple from a test kiln.
Glad to hear that Arnold. I have avoided doing so because I removed a
thermocouple at high temperature once* and the next time that I looked at
it, the protection sleeve was in two pieces, broken at about the position
where the end would have extended beyond the brick. From my one data point I
then concluded that removing a thermocouple at high temp induces too much
thermal stress on the sleeve, which then breaks.
Now I'll at least be willing to give it another go should I have occasion to
do so in the future.
Bruce "but it had better not break the next time or I'm calling my lawyer -
material losses, loss of income, mental anguish, pain and suffering..."
Girrell
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