Message Board Thread - "Temprature of molten iron."

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Temprature of molten iron. Justin 9/15/2004
We are trying to use our camera to determine the eth feasability of molten iron. The temprature of the iron is approxamitily 2650 deg. when we set the emissivity at .29 our camera will not read high enough. We have a flame filter which will read up to 2732 deg. None of our other measuring devices states that it is that high so i was just wondering if anybody has any suggestions.
 
Re:Temprature of molten iron. Manuel 9/15/2004
you mean something like this ??.

 
Re:Temprature of molten iron. Justin 9/16/2004
Thats a good image but can you get a correct temprature reading on it and if so what did you set your emissivity at. I'm looking at cast iron that is supposibly around 2650 deg. but when i set my emissivity at .29 which is what it supposibly is suppose to be my temp is way to high. I have to set my emissivity at .87 in order to get it to read close to the belived temp.
 
Re:Temprature of molten iron. Gary Orlove 9/16/2004
Are you actually looking at the molten metal or perhaps at the slag floating on top?

What is the wavelength sensitivity of your camera?

Gary Orlove
Infrared Training Center
 
Re:Temprature of molten iron. Justin 9/16/2004
Its actually a stream of irom coming out of a vessel. They are trying to get an accurate temprature reading to see how close there other instruments are. I can take five pictures in a row and on auto hot spot it will vary 500 degrees. The camera we are using is a pm280. Im wondering why we cannot get consistant readings.
 
Re:Temprature of molten iron. Manuel 9/16/2004
Iron Strip ??..

Justin, try using Long wave systems.

good luck.

thermoimagen.
 
Re:Temprature of molten iron. Gary Orlove 9/17/2004
I assume you are using the 3.9µm Flame suppression filter in your PM280 to look at this?

What temperature range are you set to?

Can you send me an image or two to analyze (original tifs)?

Email:mailto:gary.orlove@flir.com

Gary Orlove
Infrared Training Center
 
Re:Temprature of molten iron. Manuel 9/17/2004
hi gary ..

this images were take with no pm280 (240 x 240)

this images were gave to me by ron lucier at some itc course.

regards.
 
Re:Temprature of molten iron. Gary Orlove 9/20/2004
Manuel, I was not referring to your images but that of Justin, who started this thread.

Justin, can you provide camera info and send me some images per my previous post?

Gary
 
Re:Temprature of molten iron. Gary Orlove 9/22/2004
Ok Justin, thanks for sending the image. Here are the steps I used for analysis of this image.

1. I set the emissivity to 1.0

2. I noticed the reflected apparent temperature (background temperature) was set to 73 F. This is the default setting for the camera and I would be surprised if it were actually that low. To find a more reasonable value I used an area tool on the coolest parts of the image and came up with a minimum temperature of about 658 F. This is the value I used as the estimated reflected temperature.

3. Now looking at the molten iron stream itself I see areas that look cooler (mainly on the right side) interspersed with hot areas. My guess is that the hot areas are either bits of slag higher emissivity), oxidation products, and or ripples in the liquid pour that produce a cavity effect thus raising emissivity.

4. I will concentrate on the coldest looking areas and place an area tool there. I then adjusted the emissivity of the image to 0.29, your estimated value. Looking at the histogram output of this tool I can see that 85% of the area is at a temperature between 2320 F to 2520 F, which matches reasonably well with your estimated temperature of 2650 F.

The two big variables for this measurement are the reflected apparent temperature and the emissivity. Better knowledge about either would improve our accuracy and confidence in the measurement.

Gary Orlove
Infrared Training Center
 
Re:Temprature of molten iron. Justin 9/22/2004
Thanks Gary I think that will help.
 
Re:Temprature of molten iron. Carlos Medina 10/4/2004
Hi everyone,

I recently take some temperature measurements in a hot iron bars (1100°C), the problem consist in the emissivity value to use, because i try to make emissivity measurements whith tape 3M at diferents values of temperature (30°C, 80°C, 120°C), and i obtain diferents values of emiss.

I know that this low values of temperatures can distance the real values of emiss at high temperatures of the iron bar.

The question is: How can i estimate a "good" value of emiss at this high temperatures?

Finally and according whith the group in plant, I use 0.80 as the emiss value (prom of my obtained values an tables), due the resuls needed at this time. However i try to find a best criteria to use in a future case.

Excuse my short english, i put this case in a spanish forum too.

Thanks... and i hope you can bring me a little of your experience.

(y try to post an image of my case as soon i can)
 
Re:Temprature of molten iron. raffar 12/9/2004
In our experience, Gary Orlove on 9/22 is correct:"My guess is that the hot areas are either bits of slag higher emissivity), oxidation products, and or ripples in the liquid pour that produce a cavity effect thus raising emissivity." We have seen all these things, and each affects the emissivity. Emissivity of a pour stream is very different from emissivity of the native material, as the picture and graph show (lab emissivity is 0.5, varies from 0.75 - 0.95 in the graph). Turbulence is a huge factor (we've seen emissivity double thru electromagnetic stirring of vacuum melts).
We post emissivity as a function of wavelength and temperature for stuff we know on our website, www.pyrometry.com
 
Re:Temprature of molten iron. raffar 12/9/2004
Here's the pourstream data came from
 


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