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ASTM E408-13(2025)
Standard Test Methods for Total Normal Emittance of Surfaces Using Inspection-Meter Techniques
1.1 These test methods cover determination of the total normal emittance (Note 1) of surfaces by means of portable, as well as desktop, inspection-meter instruments.
Note 1: Total normal emittance ( N) is defined as the ratio of the normal radiance of a specimen to that of a blackbody radiator at the same temperature. The equation relating N to wavelength and spectral normal emittance [ N( )] is
| where: | ||
| L b( , T) | = | Planck's blackbody radiation function = c1 5(ec2/ T 1) 1, |
| c1 | = | 3.7415 × 10 16W·m 2, |
| c2 | = | 1.4388 × 10 2 m·K, |
| T | = | absolute temperature, K, |
| = | wavelength, m, | |
 | = | T4, and |
| = | Stefan-Boltzmann constant = 5.66961 × 10 8 W·m 2·K 4 | |
1.2 These test methods are intended for measurements on large surfaces, or small samples, or both, when rapid measurements must be made and where a nondestructive test is desired. They are particularly useful for production control tests.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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