ASTM E638-78(1992)

1.1 This test method covers employing the narrow beam of thermal energy emitted through the aperture of a blackbody to calibrate calorimetric devices. Although the calorimeter normally responds to incident heat which is predominantly convective, this method of calibration employs radiant energy. Use of radiant energy dictates that the absolute value of radiant flux at the surface of the calorimeter be determined to provide an accurate calibration. This method, applicable in place of the wide-angle source technique, is suited to relatively low values of irradiance (typically less than 10 W/m ).

1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibililty of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.