Characterizing thermal protective fabrics of firefighters' clothing in hot surface contact

This study characterizes the thermal protective fabrics of firefighters' clothing under the exposure of hot surface contact. For this, thermal protective performance of different fabrics was evaluated using a laboratory-simulated hot surface contact test, and various factors affecting the performance were statistically identified. Additionally, heat transfer mechanisms during testing were analytically and mathematically modeled. It has been found that fabric's constructional features and properties are the key factors to affect its thermal protective performance. In this study, the presence of a thicker thermal liner in a layered fabric system resulted in higher performance; in contrast, a multi-layered fabric system incorporating a moisture barrier in its outer layer displayed the lowest performance. Furthermore, it was demonstrated that a fabric's air permeability has a minimal impact on performance, whereas weight, thickness, and thermal resistance have a significant positive impact on performance. Based on the analytical and mathematical models developed, it was apparent that conductive heat transfer mainly occurs through fabric during testing, and this conductive heat transfer depends upon the surface roughness and thermal properties (thermal conductivity, density, and specific heat) of the tested fabric. Here, thermal contact resistance between the hot surface and fabric also plays a crucial role in the heat transfer or thermal protective performance of fabric. Moreover, the heat transfer gradually decreases across fabric thickness, which can substantially affect thermal protective performance. This study can advance the theory of textile/materials science through better understanding of heat transfer in fabrics. This understanding can help in developing an integrated knowledge of fabric properties, heat transfer through fabrics, and thermal protective performance of fabrics. The findings from this study can also assist textile/material engineers with the development of a high performance thermal protective fabric for clothing to provide better occupational safety and health for firefighters.