Abstract: In the current evaluating thermal protective performance of firefighter protective clothing, the effect of moisture is ignored. Aiming to study the different impact of moisture in different fabric layers on thermal protective performance of fabric system, the different water contents were set in outer layer and comfort layer, experimental study with direct thermal exposure as well as with whole process of thermal exposure, heat storage and release were conducted under low-level radiant heat exposure condition. The results demonstrate that increasing moisture content of outer layer is beneficial for improving thermal protective performance of multi-layer fabric, in addition, with increasing moisture content, thermal protective performance is also the same, whether it is direct thermal exposure or considering the effect of heat storage and release. However, wetting comfort layer weakens thermal protective performance of fabric system, besides, the effective measures to improve thermal protective performance are to keep dry, increase moisture absorption and sweat releasing of comfort layer. When outer layer and comfort layer are simultaneously wetted, there is an interactive effect between the two, which can be deeply studied in the future.

Key words: moisture, multi-layer fabric, thermal protective performance, stored thermal energy, second degree burn