Testing the total normal emittance of surfaces utilizing a portable reflectometer
This testing is intended for measurements on large surfaces or small samples, when rapid measurements must be made and where a nondestructive test is desired. They are particularly useful for production control tests.
What is ASTM E408?
ASTM E408-13 describes three test methods for determining the total normal emittance of surfaces using portable inspection-meter instruments. There are multiple commercially available instruments for performing this measurement, and ASTM E408 describes the methods used by these instruments and the limitations of the different methodologies.
Instrumentation
- ET100 Emissometer: Manufactured by Surface Optics Corporation, the ET100 measures directional reflectance at six bands in the thermal infrared spectral region at two incidence angles, 20° and 60°. Based on those values, directional and total hemispherical emissivity is calculated.