The fire field temperature for firefighters performing rescue operations is generally 600°C-1000°C, and the radiant heat is 115kW/(㎡·s)-200kW/(㎡·s), so firefighting clothing needs to have better heat insulation performance. Minimize the heat damage suffered by the wearer within a certain period of time. When the fire suit is between the heat source and the protected fire fighter, the heat will be transferred to the inside of the fire suit through the combined effects of heat conduction, convection and radiation. Due to the reflection effect of the fabric surface and the absorption effect of the fabric, it has a certain thermal insulation performance.
The thermal conductivity of fabric fibers is much greater than the thermal conductivity of air, so when the heat is transferred from the outside to the inside of the fire-fighting clothing, there is a certain lag behind the same distance and time when the heat is transferred directly in the air. The number of layers of fire-fighting clothing fabric, the nature of the fabric, the body shape and wearing state of firefighters, etc. all have an impact on the thickness of the air layer. A small thickness of the air layer under the clothes hinders the heat energy too little, and it is easy to cause secondary burns to the skin; but an excessive thickness of the air layer will produce a heat convection effect and promote heat transfer.
The thermal insulation performance of fire-fighting clothing has a great relationship with the thermal conductivity of fiber raw materials, the structural design of the fire-fighting clothing, the structure of the fabric and the lining. In the selection of fire-fighting clothing fibers, use textile fibers with poor thermal conductivity to make it difficult for the heat of the external heat source to be transmitted to the human skin, thereby improving the heat insulation of the fire-fighting clothing. In the design of the fire-fighting clothing structure, minimize openings and stitch leakage parts. The tightness of fire-fighting clothing fabrics reduces the direct passage of heat inward conduction in the environment, and achieves the purpose of optimizing the thermal insulation performance of fire-fighting clothing; the closer the air layer thickness is to a reasonable value, the greater the heat transmission resistance and the greater the thermal insulation performance. Great.