Emissivity Setting Problems for Raytek 3i series IR Guns on Steel

[mcd853]

I work in the Forging industry and I am having an issue where Raytek 3i series Model 2ML3 IR guns are consistantly giving low temperature readings (such as 975 F when the actual temperature is 1200F) accross all grades and temperature ranges. [The actual temperature is measured by a surface welded thermocouple]

Case Example: Grade 1026

Welded thermcouple reads 1200F
Fluke Model 68 IR Gun read 1200F with an emissivity setting of .92
Raytek gun at the same emissivity setting gives a temperature of 975 F, to get an accurate readout of 1200F I had to input an emissivity setting of .65.
Both the Raytek and Fluke IR guns were used from the same distance at the same spot simultaniously.

Any thoughs on what the problem is here? Why is the Raytek IR gun reading so low?

 

[IRstuff]

HAve you asked Raytek?

TTFN

FAQ731-376

 

[mcd853]

Yep, Ive talked to several people over there and they have agreed with me that something is wrong, but no one has proposed any solution to the problem or reason yet after two weeks.

 

[mcgyvr]

The Raytek could simply be out of calibration.
When was calibration last done?

 

[mcd853]

Calibration to the Master was done 2 months ago, I have also conducted tests off the Master that was Calibrated by the Fluke Corperation in January with the same result.

 

[EdStainless]

What is the "L3" in the model number?
Does it matter how clean the surface is.
I had various guns once and one of them only liked more heavily oxidized surfaces. That is when I gave up and went to multi-band ratio devices.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[IRstuff]

You're either going to fix it, or not.

In either case, you already know that it needs to be fixed, presumably, by Raytek. The only unknown is whether you're going to do it or not. What more is there to know?

TTFN

FAQ731-376

 

[dbooker630]

Perhaps the focal area on the Raytek is larger than the Fluke device at a given distance; as a result the instrument may be averaging adjacent surfaces in addition to the noted hot workpiece. I had this problem once with a Land optical pyrometer, the Raytek may work on the same principle. Try using the Raytek at a closer distance to prove this out. You should not have to set the emissivity any lower than 0.9, generally where your Fluke is set for up to .95 works well for steel.