Hendrix, Taylor J. on thu 22 apr 04
Howdy y'all:
I have been following my latest glaze firings using a pyrometer on loan
to me from a friend. I'm not sure of the accuracy of this pyrometer so
I want to buy a thermocouple and voltmeter. I will have my own
pyrometer that way. My last two firings did not get over 1900 degrees
according to the pyrometer.
See here: http://www3.baylor.edu/~Taylor_Hendrix/FiringCurves.htm
While I may not be getting past 1900, I want to have a second opinion
before I start worrying about having to replace one or more elements.
They seem to be heating fine, btw.
My question is what is the standard distance a thermocouple should
penetrate into the kiln? Another question for those that knows: where
can one get an N type thermocouple for the best price? Also, should I
get the porcelain block as well? I may drill a hole just for the
thermocouple if all works out, in which case I will buy the block for
mounting. Oh, will I have to buy a brick with spy hole spacing for the
elements if I do that? Grr.
Taylor, in Waco=20
Bruce Girrell on thu 22 apr 04
> While I may not be getting past 1900, I want to have a second opinion
> before I start worrying about having to replace one or more elements.
If your cones are going down then the problem is not with your elements.
> My question is what is the standard distance a thermocouple should
> penetrate into the kiln?
Now I think you're getting to the heart of the matter - what is the
thermocouple actually measuring? I have a nice, new Fluke 54-2. Beauty of a
pyrometer. Cone 10 is down when that puppy reads about 1175. Same results in
about five firings now. The discrepancy, I believe, is because my
thermocouples are too close to the kiln wall. The wall will, of course, be
cooler than the interior of the kiln.
I will be relocating the thermocouples soon and should have an answer. But
it really doesn't matter all that much. Repeatability will be more important
than accuracy. You need the pyrometer primarily to tell you whether you're
gaining or losing temperature and at what rate. The cones will tell you when
the cookies are done.
Bruce "chocolate chip, please" Girrell
BobWicks@AOL.COM on thu 22 apr 04
In a message dated 4/22/2004 6:07:35 PM Eastern Standard Time,
bigirrell@MICROLINETC.COM writes:
My question is what is the standard distance a thermocouple should
> penetrate into the kiln?
AMACO recommends a minimum of 2 inch penetration into the fire chamber.
Bob
Earl Krueger on thu 22 apr 04
On Wednesday, Apr 21, 2004, at 22:23 US/Pacific, Hendrix, Taylor J.
wrote:
> I may drill a hole just for the
> thermocouple if all works out, in which case I will buy the block for
> mounting. Oh, will I have to buy a brick with spy hole spacing for the
> elements if I do that?
Taylor,
My thermocouple is encased in ceramic tubes about 1/2" in diameter,
so I just drilled a hole, using a standard twist drill bit, through the
stainless skin and bricks. I was careful to make sure the drill came
through the bricks between elements. If you have never drilled a big
hole through thin metal there are some tricks you need to know.
I just slide the tc through the hole without any permanent mounting.
When I am loading I retract it so it's out of the way to insert shelves
and then push it in when I get to that level so I can load pots around
it making sure they don't touch.
However, the other day I did notice that on the other side of the kiln
there is a hole through the stainless skin that would be just the right
size. Would have been a lot easier to use that hole and just drill
through the bricks. Shoulda looked first!
Earl K...
Bothell, WA, USA
BobWicks@AOL.COM on fri 23 apr 04
I would be hesitate to drill through the kiln wall where you have elements as
they could well effect the temperature reading and also the danger of hitting
the element when drilling. See if there is a place such as the top where
there are no elements and drill there.
Bob
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