The thermal resistance of a composite is measured according to ASTM F 2731 Standard Test Method for Measuring the Transmitted and Stored Energy of Firefighter Protective Clothing Systems.
A test specimen is exposed to a low level radiant heat flux of 8.5 kW/m2 (0.2 cal/cm2-s) for a fixed period of time. A data collection sensor measures the heat energy transmitted through the test specimen during the time of radiant heat exposure. Following heat exposure, the specimen is moved away from the heating source and compressed against the data collection sensor for a fixed period of time. During the compression phase, the data collection sensor continues to measure the heat energy transferred from the test specimen. The total energy transmitted and stored by the test specimen is used in prediction of a second degree burn injury with time to a second degree burn injury reported.