# Immersion type pyrometer



## autumnwillow (Jul 22, 2020)

Anybody knows where I could source these type of equipment? 
Its for measuring temperature of molten metal. I have the infrared type which does not work on reflective surfaces.

About +/- 5C would do.


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## goldandsilver123 (Jul 22, 2020)

What metal are you measuring?
There is ways to work around this issue. You can measure the crucible temperature, use a two-color IR pyrometer, use a jacketed thermocouple, etc..


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## autumnwillow (Jul 23, 2020)

Gold and silver.
Measuring the crucible temperature would not be accurate. I need about +/- 5c from the actual molten metal temp.
I've been browsing google, they don't post the price is this an expensive equipment?


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## goldandsilver123 (Jul 23, 2020)

If you do not trust the crucible temperature, I guess you are melting with a torch instead of a furnace (induction or gas).

For small amounts of metal, I think only the two-color pyrometer would be a choice, but control the temperature using a torch is something I do not think will give you good reproducibility.

If you have enough metal in crucible you can try a graphite jacket for the thermocouple.

You can see the thermocouple measuring the crucible temperature in this video, at 1:23
youtube.com/watch?v=MJlb4S1aEgw


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## snoman701 (Jul 23, 2020)

Yes they are expensive.

Further, what you are actually melting will determine how expensive they are, as well as sheath chemistry.


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## autumnwillow (Jul 24, 2020)

goldandsilver123 said:


> but control the temperature using a torch is something I do not think will give you good reproducibility.



I get it, since the torch would most like hit the thermocouple it would give an erroneous reading. I guess I'm off to find an induction melter w/ a pyrometer then.


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## FrugalRefiner (Jul 24, 2020)

If I may ask, why do you need such a close tolerance? I mainly go by when the metal melts and color as shown in Furnace Temperature Colors.

Dave


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## autumnwillow (Jul 27, 2020)

To figure out at what temp my torch is at which I think is impossible.

I find that melting silver at high temperature using a torch produces a white fume. While melting it at low temps produces none.


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## goldandsilver123 (Jul 27, 2020)

The torch BTU is more important than the tip temperature. An LPG/O2 torch exceeds 1900ºC (3600 F) at the tip, but with low flow of gas is impossible to melt silver that melts at 960 ºC.

The white fumes you see is evaporated silver. Depending on gas flow and tip distance, after melting you can sweep the bench and see lots of white particulate (silver dust). Don’t use the tip with bright blue color at the silver, use the darker blue plume.


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