Infrared Thermographic Diagnostics of Wood Fire Resistance under Combined Thermal Exposure of a Surface Fire Front and Burning and Smoldering Particles

The interaction of burning and smoldering particles with forest combustible materials, followed by their impact on certain types of combustible building materials and wood-based structures, has been experimentally investigated. Thermal flux values generated by smoldering particles were obtained, and the temperature field of the most thermally stressed areas of the tested structures was analyzed using noncontact IR diagnostic methods within narrow spectral ranges of infrared wavelengths. In the infrared range, the surface emission of the samples was recorded using a JADE J530SB thermal imager equipped with an optical filter for the 2.5–2.7 μm range; this enabled temperature measurements in the range of 310–1500 K. Calibration data provided by the manufacturer of the narrowband optical filter were used to interpret the recorded emissions from the tested samples.