Evaluation of Heating Inserts in Active Protective Clothing for Mountain Rescuers—Preliminary Tests

Rescue operations in mountain areas, lasting many hours, pose a mental and physical burden on the rescuer’s body. In addition, they cause thermal discomfort associated with variable energy expenditures and the high variability of weather conditions. One of the solutions for improving the comfort of the work of mountain rescuers is clothing with an active heating function. This paper discusses the technology of manufacturing flexible heating inserts with steel thread as a heating element. In order to assess the durability and safety of the applied heating inserts, they were subjected to simulated conditions of use. Multiple washing (25 cycles) and bending (9000 cycles) as well as exposure to artificial acidic sweat did not cause a significant change in the electrical power and resistance of the heating inserts. In order to assess the effectiveness of the inserts, they were tested within a system of clothing fabrics on an “artificial skin model”. Supplying the heating insert with a voltage of 4 V increased the thermal resistance of the fabric system, incorporating the insert by approx. 40%. Due to their high flexibility, durability, and heating efficiency, the developed heating inserts are a major step towards the development of electrical heated clothing.