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Problem with readings - FLIR T440
09-29-2014, 12:34 PM
Post: #1
Problem with readings - FLIR T440
Hi all,
I am using a FLIR T440. Relatively new, just calibrated.
I'm applying a layer of black matte paint to the object I have to measure (otherwise the emissivity would be really low, it's polished SS).
At room temperature I calculated an emissivity of approx 0.95.

I am measuring temperatures of about 250C, but when I embed a thermocouple into the same material, very close to the measured surface, I have readings of 200C only.
The thermocouple is calibrated and reliable.

What could be going wrong here? I tried different settings and to get the same value I have to use 0.65 emissivity and a reflected temepratre of 300C - not realistic at all.

Any idea?

Thanks!
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10-03-2014, 10:37 AM
Post: #2
RE: Problem with readings - FLIR T440
Please upload an image so we can analyze it.

Thanks
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10-16-2014, 04:24 PM (This post was last modified: 10-16-2014 04:29 PM by Ziemianski.)
Post: #3
RE: Problem with readings - FLIR T440
(09-29-2014 12:34 PM)Gamella Wrote:  Hi all,
I am using a FLIR T440. Relatively new, just calibrated.
I'm applying a layer of black matte paint to the object I have to measure (otherwise the emissivity would be really low, it's polished SS).
At room temperature I calculated an emissivity of approx 0.95.

I am measuring temperatures of about 250C, but when I embed a thermocouple into the same material, very close to the measured surface, I have readings of 200C only.
The thermocouple is calibrated and reliable.

What could be going wrong here? I tried different settings and to get the same value I have to use 0.65 emissivity and a reflected temepratre of 300C - not realistic at all.

Any idea?

Thanks!

Gamella,
In my current position I work with many types of tubing, especially the different SS materials and like you I also use a T440 camera in my work. I specialize in testing of exhaust applications, thermal barriers, coatings and thermal blankets for the OTR / heavy truck industry.
I would like to ask a few questions to help me better understand your application.

The matte black paint you applied, what type, recommended temperature rating and how was the coating applied? How was the substrate prepped prior to applying the coating ?
How are you applying heat to the substrate ?
You mentioned a thermocouple being embedded into the material, what type and how was this attached ?
And last for now , what is the substrate your are working with, 304,409,439, ?
With the equipment in my lab, I am able to reach 3000*F if needed, but mostly stay below 2000*F as the extreme temps are not required in the current applications. Having tried high temp paints from several manufactures, most do not meet the claims and those few that do work, prep of the part is very important.
Dennis
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