Scope:

To generate data that are accurate to within a few percent ASTM 307-72 needs expensive equipment. It is mostly suitable for research laboratories where the highest precision and accuracy is required. It cannot be recommended for usual production or acceptance testing. This method can be used as a preferred method for production and acceptance testing due to its high accuracy.

Test Procedure:

The Principle of the test method is a comparison of radial flux from a specimen at a given Temperature to the radial flux from a black body at the same temperature under the same environmental condition of atmosphere and pressure. The Conventional feature of this test method is the use of double beam ratio recording infrared spectrophotometer variable width which combines and compares the singles from the specimen and reference black body through monochrometer system that covers the wavelength range from 1 to 35 μm.

Figure 1: Appearance of Spectral Emissivity Measurement System

Test specimen: Test specimen can be anything in disk form, it must be electrically conductive or must have an electrically conducting substance.