Optimum thermocouple location??

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gthomson
Posts: 23
Joined: Tue Jan 20, 2004 4:53 pm
Location: Ontario, Canada

Optimum thermocouple location??

Post by gthomson »

Hi All,

The new Euclid is installed, the floor (of the kiln!!!) is getting kiln washed, and I'm getting ready to characterise the heating and cooling rates this weekend. So: is there a consensus on the best location for the thermocouple (height, depth of insertion,...).

It's a 14" diameter, 9" high 120V toploader.

Thanks,

Glenn
Brock
Posts: 1519
Joined: Mon Mar 10, 2003 1:32 pm
Location: Vancouver, B.C.

Post by Brock »

Ideally, center of the killn, just above the height of the glass on the shelf. This won't happen however, so get it as central as you can, and learn what the temp reading means in your kiln. Brock
My memory is so good, I can't remember the last time I forgot something . . .
Phil Hoppes
Posts: 298
Joined: Wed Mar 12, 2003 2:20 pm
Location: Overgaard, AZ

Post by Phil Hoppes »

To Brock's point the center above the glass is ideal. For a top loader in particular this is difficult as it will be in the way of loading your glass. Putting in a shorter TC from the side that you can easily manuver around is what will probably be more practical. Run some tests with glass to check how it fuses/slumps etc. Or if you can get your hands on a portable thermo probe that can handle fusing temps you can get a more accurate actual number. I've characterized my kilns this way. The reading on my computer's TC vs what the temp is just above the glass varries by about 12-15 degrees with the computer reading a cooler number. I've learned what temps work for what glass however so the "actual" reading is somewhat more of just a novelty in knowing. In time you should learn how your kiln works too.

The actual readings are probably of most importance when you are trying to duplicate schedules on different kilns. Then you need to know the "error" of both kilns so you can compensate in your schedules accordingly. This is probably not an issue for you so I would not worry about it.

Phil
Tony Serviente
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Post by Tony Serviente »

If you are going to be doing any slumping or draping, just make sure you position it high enough to always be out of the "shade". If your probe gets glass between it and the elements it will cause you to say unpleasant things in the direction of your kiln. I use sheathed thermocouples, so if it's in the way, I just slide it back, load, then pull it forward.
gthomson
Posts: 23
Joined: Tue Jan 20, 2004 4:53 pm
Location: Ontario, Canada

Post by gthomson »

Thanks, guys.

I neglected to say that I'd planned to have a shelf and a couple of pounds of float in the kiln when I do the heating/cooling rate checks, just to model the actual use as much as possible. Sensible?

Glenn
Brock
Posts: 1519
Joined: Mon Mar 10, 2003 1:32 pm
Location: Vancouver, B.C.

Post by Brock »

rdguy wrote:Thanks, guys.

I neglected to say that I'd planned to have a shelf and a couple of pounds of float in the kiln when I do the heating/cooling rate checks, just to model the actual use as much as possible. Sensible?

Glenn
It probably doesn't make any difference, frankly.
The temp is being read at the tip of the thermocouple, and the glass is gonna be cooler going up, and hotter going down. You'll have to get used to, and compensate for, what X heat does to glass. Brock
My memory is so good, I can't remember the last time I forgot something . . .
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