colour vs temperature ?

try

The first one pretty well agrees with what I am seeing, the second is "off" IME. The system is melting Type B Pt/Pt-Rh thermocouples for fun, which I take to mean its WELL over 1900 C when they fail.

Thanks

Steve

So do we get to hear what you're doing?

Steve

Steve Taylor wrote:

One would think that all you'd see then is 'white'. Surely there are radiometric measurement systems that can look at the intensity and give you a reading, much like a bolometer only less meltable?

Tim, I have some sort of a "bolometer", military surplus, you sound like a person who may need one, I can give it to you for free (you would pay for shipping only).

Try searching for optical pyrometer. You can make one fairly easily. You just need a regulated power supply and a light bulb. You look thru the light bulb and adjust the current to the light bulb until the filament is invisible. Filament cooler than surface, then it shows up darker than the surface. Filament hotter than the surface, then it shows up as brighter.

Of course you need to calibrate your device. You can use kiln cones, but remember they are not quick to respond.

H> Does anyone know of a reasonable "colour" (oh alright, color) chart on

What sort? The only kind I ever met was for microwave power radiation measurement. Not to say there were not others. Just curious about what you have.

I think that that is what I have...

We are building instruments for measuring the viscosity of liquid glass and metals. The furnace is made of graphite, and is about the size of a soda can. We pump 7kW continuous into it, and it gets hot, fairly fast. There is a platinum thermocouple in the wall, and for some reason it reads wildly off - like 400 degrees COLDER than it should.

Following this thread, I have just ordered a 1000 dollar Raytex IR pyrometer, so I don't have to be anywhere near the furnace with anything very expensive that can melt.

Thanks for all the help and answers, which was rather OT for sci.welding.

Steve

how do you heat it? Sorry if you already answered your question. I would really like to have a little furnace, hence my question.

Graphite tube: end cut to make long path through the carbon, 200 Amps 40 V squirted up it. Easy (!)

My email is real. I'll send you a picture of our setup if you like.

Steve

email sent. I can easily get 200A, 40V, it is easy.

thanks!

Ok - let look at what you said - no hits - just hints.

You have a nice furnace. Sounds electric for nice inputs.

Putting a sensor inside a wall isolates it from the IR heat. It is also closer to the cooler outside.

If you need most of the inside for the object to be heated, see if a small shelf can be installed - and have the work put on the shelf while the thermo sensor either under or pinned over the work but inside the cavity.

Having a gun is a good idea - always have multiple sensors for verification.

Mart> Steve Smith wrote: