AbstractProtective clothing against head and flames should be evaluated not only for flame retardance but also for protection against various heat exposure from convection (flames), conduction (molten metal splashes) and radiation sources, depending on the end use, to ensure a realistic assessment of the potential protection offered and required. Evaluations of various flame‐retardant fabrics to different heat exposures showed that the fibre and the flame retardant finish should preferably form a well developed char on exposure to heat, without softening and melting. The flame retardant should act in the solid phase and the fibre should be of low thermal conductivity. For protection against convective heat (flames), a woven Zirpro wool fabric of high density over a bulky knitted Zirpro wool underwear fabric offered a significantly better protection than a single layer of a woven or knitted fabric or a double layer of a woven fabric of the same total weight. The optional multi‐layer fabric approach could also decrease overall garment weight and improve wearers' comfort without adverse effect on the protection offered. Of the FR fabrics evaluated, Zirpro wool fabric assemblies showed the longest time to reach pain (first degree burn) and blister (second degree burn) thresholds, as well as the longest pain alarm time–the time available to the wearer to withdraw from the flame heat source before serious injuries occur. Zirpro wool fabric assemblies had one of the lowest residual heat transfers after al limited flame exposure to the pain threshold while some other fibres, e.g. aramid and novoloid, transferred significant residual heat, possibly causing second degree burns. For protection against conduction, such as from molten aluminium splashes, the fabric should have a smooth surface, high density and thickness, besides the other previously mentioned, basic requirements. Zirpro wool fabrics offered a significantly better protection in this case than aramid, FR cotton, glass fibre, asbestos, and other FR fibres. Aluminized fabrics are essential for adequate protection against radiant heat and the aluminization technique affects heat transfer significantly. A low density base fabric made from a fibre of low thermal conductivity, such as Zirpro wool, reduces heat transfer in this
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