Emissivity affect on IR temperature devices
Emissivity affect on IR temperature devices
(OP)
Does the emissivity (hope spelled right) of a material affect the temperature reading of IR temperature measuring devices? Thanks
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Emissivity affect on IR temperature devices
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RE: Emissivity affect on IR temperature devices
RE: Emissivity affect on IR temperature devices
RE: Emissivity affect on IR temperature devices
Imagers with the capability of adjusting the E are typically set at 1 by the qualitative thermographer. Contact radiometry and spot radiometry may or may not be set at one. Typically these instruments are set at .96 or .97 because this most closely associates with the E of organics and allows for a little more accuracy. Check on the specs to ensure you are getting what you want. Be cautious about E tables as they serve to be close but each imager by model and even in some cases serial number will interpret E differently. Refer to the ASTM Standard E 1933-99 for details on deriving/compensating for E. Do not forget about the Reflectance and Transmittance errors when working towards your most accurate temperature.
Good Luck
RE: Emissivity affect on IR temperature devices
RE: Emissivity affect on IR temperature devices
RE: Emissivity affect on IR temperature devices
RE: Emissivity affect on IR temperature devices
So a 10% error is e equates to approx 2.5% error in T. If you're looking at something that is 100F actual that equatest to approx 14F.
ie if it had actual emissivity of 0.9 and you dialed in 1.0 your gun would telll you that it is 114F.
Another big source of error has to do with the "spot size" for guns and camera's. They will average all the temperatures over a certain spheradian field of view. If you move farther away from the target that area increase. If your spot size is 8 square inches and your target is 4 square inches, you will likely end up reading a temperature about half way between the target and the surrounding temperature.
RE: Emissivity affect on IR temperature devices
of .95. Stick a piece of it on whatever type of material you
want to measure , set the emissivity to .95 and take a reading. Measure just next to the tape and adjust your emissivity 'till the same temperature is indicated, you now
know the emissivity for future reference.
Dont forget about background (not ambient air) temperature,
the lower the emissivity the more influential the background
temperature is.