Protective Clothing—Evaluation of Wool and Other Fabrics

Abstract

Protective clothing against heat and flames should be evaluated not only for flame-rwistance but also for protection. against various heat exposures from convection, radiation, and conduction sources, depending on the end-use, to ensure a realistic assessment of the potential protection offered and required. Evaluations of various flame-resist-treated fabrics to different heat exposures showed that the fiber 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 fiber should be of low thermal conductivity. Properties of fabric construction such as density and thickness are also important. For protection against convective heat, a woven fabric of high density and integrity after exposure to flames, over a bulky knitted underwear fabric, appears to be the best approach. Aluminized fabrics are essential for protection against radiant heat, and the aluminization technique affects heat transfer significantly. A low-density base fabric reduces heat transfer in this case. For protection against conduction, such as from molten aluminum splashes, the fabric should have a smooth surface, high density and thickness, besides the other previously-mentioned basic require ments. Of the fabrics evaluated, Zirpro wool of adequate construction for the end-use required offered one of the best protections in the various heat-exposure tests.