| Title | By | Posted On |
| determine reliable reflected temperature |
EnjoyEnergy |
2/9/2012 |
| Could anybody give me a good practical tip how to determine the wright (relaible) when there is a cold clear sky and temperatures are below zero. At present I determine it with a piece of alluminium. but I am not sure about this. Thanks in advance fro your help |
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| Re:determine reliable reflected temperature |
IRJay |
2/9/2012 |
If you are not sure then perhaps the training was not understood with the real intent of this measurement. There is an ASTM standard for this parameter. E1897.4369-1. The energy that is being measured and compensated for is the average energy of the background that can reflect off the target and be received in the camera. This energy can be significant if the emissivity is low (and correspondingly the reflection is high). It is also dependent on the angle that the target is being imaged. meaning, is the target partially reflecting the sky or the ground or the surroundings. So measuring the reflected energy is a view point consideration. In many cases if the emissivity is high (90s) then the reflected energy might not represent a significant consideration.
The foil being crinkled does the averaging for this measurement and then the camera must be set at an emissivity of 1.0 with the use of an averaging temperature tool to capture this value. Obviously we don't recommend foil in those areas where it may present a safety concern.
I advise my classes to trial many scenarios to get a feel for this value and its impact on measurements. |
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| Re:determine reliable reflected temperature |
Gary Orlove |
2/9/2012 |
See this link for more info:
http://irinformir.blogspot.com/2012/02/thermographic-measurement-techniques.html |
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