AIP Digital Archive
Electrical Engineering, Measurement and Control Technology
The Devices&Services Company model AE emissometer was evaluated by measurements at ambient temperature on materials with emittances, ε, from 0.03 to 0.95, including plates of copper and stainless steel, aluminum foil, adhesive tape, wood, paper, and oxide coatings on a metal pipe. A repeatability of ±0.008 units was observed for measurements of ε of working standards over a one-year period. The accuracy of the emissometer was established by measurements on specimens of known ε; an uncertainty of ±0.014 units was determined. These repeatability and accuracy values were confirmed by a round-robin investigation using two working standards whose ε's were measured by three independent laboratories using model AE emissometers and by four laboratories that used absolute methods. The instrument was shown to measure the total hemispherical ε, not the total normal ε. Experimental difficulties were encountered during measurements on a very anisotropic material and in determinations of ε's of materials with transparencies less than 0.1. Critical procedural steps are discussed.
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