pyrometer

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chad2

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Sep 2, 2011
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i think my kiln might be off on temperature because two days ago it was reading 27 degrees F with the kiln open and there was a water bottle right next to it that was not frozen. i was just wondering where i can get a pyrometer or if someone is willing to let me barrow one just so i can adjust my paragon kiln.
 
The valid measurement range for your equipment may not include freezing temps.

put it in boiling water & check it against a chart for your altitude
 
Not to mention, how long had it been 27 degrees? Water can take quite a while to actually freeze, particularly if it's got some sunlight exposure. The water doesn't cool off as fast as the air around it, since the air is what's cooling the water. I'd think a water bottle could be out in 27 degree conditions for at least a few hours before any ice started to form.
 
All the above, plus:
Come on, a five degree variation at freezing, and you want to calibrate your oven? ( just kidding)

Seriously, I would not worry about a five degree variation. That is well withing the range of error of all but the best lab equipment.
 
Remyrw said:
Not to mention, how long had it been 27 degrees? Water can take quite a while to actually freeze, particularly if it's got some sunlight exposure. The water doesn't cool off as fast as the air around it, since the air is what's cooling the water. I'd think a water bottle could be out in 27 degree conditions for at least a few hours before any ice started to form.
Click to expand...

my kiln is in my garage and it had said 27 degrees all night i went out in the morning when it was wormer and it still said 27 degrees. but what i can say is that later on that day the temp finally changed on the kiln, but i never checked it with a thermometer i guess i should do that first.
 
bladsmth said:
All the above, plus:
Come on, a five degree variation at freezing, and you want to calibrate your oven? ( just kidding)

Seriously, I would not worry about a five degree variation. That is well withing the range of error of all but the best lab equipment.
Click to expand...


i have an oven thermometer i will check the the temp compared to that at 400 degrees :)
 
Oven thermometers or any other method used should be a calibrated/checked reading. Otherwise you might make an adjustment that makes it off even further.
Also, maybe Stevomiller could chime in, but since a Type K thermocouple doesn't put out a linear signal/voltage, calibrating at 212 degrees or 32 degrees might still leave you off 20-40 or more at 1475-1900 degrees.
I think that's why some use lead to calibrate.
Jason Magruder had an awesome explanation recently of how he calibrated his kiln with copper wire embedded In steel bars.
 
To calibrate a thermocouple, you have to read the millivolt output at the target temp. You need a digital voltage meter that is very accurate and is recently calibrated. It needs to read to .001mV. Look up the millivolt/temperature rating on the manufacturers chart for your thermocouple and the controller, and compare it to the reading you are getting. This will tell you the deviation for the TC.
On most cheaper controllers, you can't compensate for this, but if you know that 1450 reads 1470, then set the controller at 1430 ( when you want 1450).....and you will be fine. Most of the time the deviation isn't enough to worry about. Checking your PID against a calibrated pyrometer ( at something like 1500F) every now and then is a simpler way to determine the deviation.
 
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