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hershey8

How Deep Should Temperature Probe Be Inside Of Kiln?

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I have two older model thermocouples. Both are several inches long. Is it necessary to use the entire length of these devices inside of the kiln. A kiln sitter only protrudes a couple of inches and doesn't encroach too much, but a 6-8 inch thermocouple does seem to get in the way. Have thermocouples gotten shorter over the years? I'm talking about two thermocouples and two separate kilns, here. I plan to put a pyrometer on one and a controller on the other.

 

 

                                                                                     thanks,   john autry

 

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The probe tip only needs a inch or two so in the old fat ones.They come in many different lengths like 6 inch 8 inch and 12 inch. Most of thermocouple  just hangs out side.

I have mine all in a protection tube except for my electric bisque kiln.

Now the S thermocouples which are very thin  and usually white (no wire) protrude about 3 inches into the newer electrics.

Mark

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The probe tip only needs a inch or two so in the old fat ones.They come in many different lengths like 6 inch 8 inch and 12 inch. Most of thermocouple  just hangs out side.

I have mine all in a protection tube except for my electric bisque kiln.

Now the S thermocouples which are very thin  and usually white (no wire) protrude about 3 inches into the newer electrics.

Mark

Thanks Mark. Both of these are surrounded and covered pretty much by porcelain rings and collars.  I guess that keeps LOI stuff off, huh?  ja

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The 8 gauge thermocouples that most companies use now are usually covered by several ceramic collars which keeps the wires from touching each other and the bricks. The tip of the thermocouple, the important part, is exposed. The end of the thermocouple goes into a ceramic block where you can adjust how far into the kiln it goes. 1.5-2 inches is fine.

 

If you want your thermocouple to last as long as possible, get a ceramic protection tube. The tube will protrude into the kiln just a couple of inches, and thermocouple is pushed in so it touches the end of the tube. About half of the thermos I replace are due to being worn out, but half are due to getting bent and broken by kiln shelves banging into them. The protection tube will prevent breakage as well as keep ti from wearing out as quickly. The tube does insulate the thermo slightly, so you may have to adjust the calibration on the controller by 10 degrees or so.

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The 8 gauge thermocouples that most companies use now are usually covered by several ceramic collars which keeps the wires from touching each other and the bricks. The tip of the thermocouple, the important part, is exposed. The end of the thermocouple goes into a ceramic block where you can adjust how far into the kiln it goes. 1.5-2 inches is fine.

 

If you want your thermocouple to last as long as possible, get a ceramic protection tube. The tube will protrude into the kiln just a couple of inches, and thermocouple is pushed in so it touches the end of the tube. About half of the thermos I replace are due to being worn out, but half are due to getting bent and broken by kiln shelves banging into them. The protection tube will prevent breakage as well as keep ti from wearing out as quickly. The tube does insulate the thermo slightly, so you may have to adjust the calibration on the controller by 10 degrees or so.

Thanks Neil, I'll look around for a protection tube. Is this something I could make myself?

john

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John you can hand build a solid one from clay after seeing one-then make a two piece mold from it and slip cast one fired to cone 10.

Thats what I did so many years ago-I made a whole bunch of them.That whole process is way more work than buying one-heck they are on e-bay from Canada now for cheap.

Mark

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Bingo. Just buy one. I've got 900 firings on my smaller kiln and I've never replaced the tubes.

 

http://www.hotkilns.com/mullite-thermocouple-protection-tube-standard

 

Here's some info about the tests L&L ran on thermocouple life:

http://hotkilns.com/thermocouple-test

http://hotkilns.com/thermocouple-protection-tubes

 

It's amazing how much the metal thermocouples shed all over the inside of the kiln!

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