infrared temperature sensor emissivity

[vscid]

I am looking for an Infrared sensor for measuring TIG welding temperature at every pass (interpass temperature). Should I go for a fixed or variable emissivity instrument?

What is the difference between the two realy?
I am welding Inconel pipe ID.

Thanks!

 

[itsmoked]

The emissivity takes into account the 'shinyness' of the targets. A shiny piece of metal will give badly offset readings from, say, a dull rough surface. Usually lower.

Are you talking about the temperature of a glowing weld or a just a large piece of clean metal? What kind of temps are you expecting?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[vscid]

well,it has to measure temperature right after welding, so it ll be glowing weld.
I am expecting about 275-325F.

 

[itsmoked]

Glowing => 6-800F

You might want to check with someplace like Omega.com to see what they suggest.

Or get a really handy unit like:

http://www.omega.com/ppt/pptsc.asp?ref=OSXL650&Nav=temj08

to experiment with, since it allows emissivity adjustments and is inexpensive.I use one like this weekly for something or other.

If this is for production monitoring then with shiny stuff you are often much better off with a rolling thermocouple.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com