Comments for Spectral Emissivity & Emittance

Comment on Emissivity Coefficients of Some Common Materials by Administrator

Administrator — Sun, 09 Oct 2011 15:48:02 +0000

Not quite certain what you mean as a transmitter of Infrared Radiation. Do you seek a specific portion of the Infrared, or the whole thing (It's relatively wide portion of the EM spectrum)? If you are seeking a window material that will meet your other conditions, the most complete technical resource on the web, one that I admire and think is perhaps the best so far, is on the website RefractiveIndex.INFO . While this is nominally a site with a physics slant, it includes a transmittance calculator to enable one to consider a very wide variety of materials available. You'll have to check the other properties separately. If you just want a selection of commercially available infrared windows, one can do a Google search and wade trough all the commercial offerings or, if that is not quite what you seek, check the available technical data from some of the optics makers around the world, like www.crystran.co.uk Personally, if you are considering something really inexpensive, look at some of the plastic materials available; most will fit your other specs.

Comment on Emissivity Coefficients of Some Common Materials by Lars Enström

Lars Enström — Mon, 03 Oct 2011 14:46:31 +0000

Hi
I am trying to find out what material to use as a transmitter of infrared radiation, with the limitations that the surface shall never be allowed to be hotter than 88 degrees Celsius, that the surface at such temperature shall not cause damage to humans if touched and that it will have a maximum thickness of 4 mm.
When I read all of what you write and refer to I understand that it is complex but do I understand fully, no I do not and can I answer my question, no
Can you help me?
Best Regards
Lars Enström

Comment on Fluke Calibrator Video by sansel

sansel — Thu, 22 Sep 2011 12:04:21 +0000

Calibrator is a the right instrumentation can sharpen your competitive edge by measuring and controlling your production down to the finest detail.

Comment on Water, Seawater, Ice, and Snow Sample Infrared Emissivities by Administrator

Administrator — Thu, 08 Sep 2011 15:43:48 +0000

Thanks -found it and erased forever – we hope!!!

Comment on Cool Roofing Samples (Emittance) by Aivars Erins

Aivars Erins — Thu, 25 Aug 2011 22:22:56 +0000

I am interested in heat cost allocators problems and the calculation algorithms that take into account the geometrical characteristics of housing and the wall, ceiling and floor surface properties.

Comment on Welcome by Administrator

Administrator — Sun, 21 Aug 2011 14:18:36 +0000

Vincent: Thanks for the very useful comment. A “Download in PDF” link has been added to every article on the site as a result.

Comment on Welcome by vincent

vincent — Fri, 05 Aug 2011 07:25:49 +0000

This site provides some useful knowledge of emissivity.
Some of the articles are worth keeping.
If export-to-pdf function can be provided, it’ll be great!

Comment on Table of Emissivities in Three Popular Spectral Regions by Administrator

Administrator — Thu, 28 Jul 2011 00:45:36 +0000

Thanks for the “Heads Up”. We had the same experience as you did. It looks like Lumasense Technologies has taken over the web name for Infrapoint. We didn’t find any distinct INFRAPOINT Messtechnik web presence. We were going to remove the link as a result, but found an archived version of it and have amended the page accordingly.

Comment on Table of Emissivities in Three Popular Spectral Regions by Frank Stake

Frank Stake — Thu, 14 Jul 2011 20:11:27 +0000

the above link ” Table of Emissivity on the INFRAPOINT Messtechnik GmbH website (Click here to visit) ”

does not seem to work, it goes to the hompage of lumasense technologies, not data tables

any help is appreciated

Comment on What The Heck is Emissivity? (Part 2) by Administrator

Administrator — Thu, 14 Jul 2011 19:46:44 +0000

This is a multi-faceted question. It depends not only on the temperature but also on the spectral response of the radiation thermometer.

One quick way of getting an estimate of the answer would be to look at the fine technical note that used to be published by Ircon, but it seems to be no longer available online.

Another would be to review the table of temperature errors induced by 1% emissivity changes in ASTM Standard E 1256. One can easily scale the change in temperature caused by either a 5% change in the emissivity correction or a change in emissivity of the object by 5%; they are nearly the same but can be in opposite directions.

Once one knows the temperature and the waveband center for an instrument, the approximate error, close enough for most industrial purposes or about 1% of temperature or less can be calculated from first principles. The formula for doing so is provided in the ASTM standard.

For instance, if one sites an accurate radiation thermometer into a blackbody running at 1000 Degrees C (assuming the entire field of view of the instrument is filled), and sets its emissivity correction to 0.95, the blackbody temperature will appear higher than 1000 Degrees. The size of the difference will depend on the waveband of the thermometer used.

A thermometer which has a waveband sensitivity on the long wavelength side of the Planck Curve for 1273 K, say centered on about 11 millimicrons, will show a very large difference, about 50 Degrees C.
A thermometer having a 1 millimicron waveband center, on the short wavelength side of the Planck Curve would exhibit a difference of only about 5 or 6 Degrees C. An instrument with a wavelength band centered at about 0.65 millimicrons would exhibit even less difference, closer to 4 Degrees C.