Measuring brick temperature from 20°C to 800°C with thermocouple and microammeter

[cdm391]

How would I measure the temperature of the brick when it is between 20oC amd 800oC. Would I use a thermocouple/pyrometer?
If so, how would I put this in the circuit? Obviously, the resistance of the brick is high, so i will need a microammeter in series.

 

[Gokul43201]

Lately, it looks like bricks are in:
https://www.physicsforums.com/showthread.php?t=72062&highlight=brick
https://www.physicsforums.com/showthread.php?t=73481&highlight=brick
https://www.physicsforums.com/showthread.php?t=71022&highlight=brick

 

[Astronuc]

An optical pyrometer - that will measure the surface temperature.

If you use a thermocouple, it is customary to bore into the brick (masonary drill) - along one of the axes, and place the thermocouple junction in the center of the brick. The thermocouple leads are then connected to instrumentation outside the furnace.

Or you can use both the pyrometer and thermocouple.

 

[Gokul43201]

Or you can use both the pyrometer and thermocouple.

Most likely, you will have to calibrate the pyrometer against a thermocouple.

 

[Chirpy Chick]

I'm doing the same thing. What voltage are you using, and how have you connected the wires to the brick? I was thinking metal plates on either face of the brick, but I dunno. I'm using a thermocouple with probe and measuring device, but I'm not sure where to put it on the brick yet. And another thing, will the wires get too hot and melt?

 

[brewnog]

Oo, Chipy Chick is only up the road! Hello and welcome!

 

[Integral]

While the pyrometer would do great at 800C, it would not work for the low end of your range. I am not sure what the low end would be, but certainly well above 20C. Even a type K thermocouple, mounted per Astronuc, would give you good readings across the entire range.

 

[Astronuc]

For the low temperatures, an optical pyrometer would not work. Instead one needs an IR pyrometer.

I once worked as a maintenance person. One of my projects invovled working with an electrical engineer who roamed the local power grid to find 'hot spots' in the electrical system. He was using a liquid nitrogen cooled IR detector, and the brightness of the spot was a function of the local temperature. And he did find some poor connections.

Infrared pyrometers are ultra-fast - http://www.engineeringtalk.com/news/ipa/ipa104.html

http://www.wintron.com/Infrared/infrared.htm