This study explores the behavior of textile fabrics under thermal exposures. The performance of thermal protective textile fabric systems with different structural features was evaluated under laboratory simulated thermal exposures. The study demonstrated that the protective performance of textile fabric systems varies with different types of thermal exposure. To provide effective protection in flame and radiant-heat exposures, the most important fabric properties to address are emissivity, absorptivity and thermal resistance. In hot surface exposures, the compression property of the fabric systems is the primary feature to consider for protection. Hot water and steam exposures produce mass transfer through fabrics. In the presence of water or steam jet pressure, fabric compression is a primary factor in protecting the human body. The findings obtained in this study can be used to engineer fabric systems that provide better protection from various thermal exposures.

Wildland firefighters work in unfavourable environments involving both heat and moisture. Moisture in clothing systems worn by wildland firefighters may increase or decrease heat transfer, depending on its source and location in the clothing system, location on the body, timing of application and degree of sorption. In this experiment, 4 outerwear/underwear combinations were exposed to 1 of 5 different conditions varying on amount and location of moisture. The fabric systems were then exposed to either a high-heat-flux flame exposure (83 kW/m(2)) or a low-heat-flux radiant exposure (10 kW/m(2)). Under high-heat-flux flame exposures, external moisture tended to decrease heat transfer through the fabric systems, while internal moisture tended to increase heat transfer. Under low-heat-flux radiant exposures, internal moisture decreased heat transfer through the fabric systems. The nature and extent of such differences was fabric dependent. Implications for test protocol development are discussed.

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Flightsuit designs incorporating variation on four parameters of interest (one-piece vs two-piece, loose vs close fit, closure system, and seam type) were developed following a functional design process and using CAD procedures (Part I). Prototype garments were produced for each of three phases of instrumented mannequin testing of thermal protection. Fabrics used in the prototypes included a meta-aramid/carbon blend (phases 1 and 3), an FR viscose/meta-aramid blend (phases 2 and 3), and a meta-aramidlpbi blend (phase 3).Style, fit, and closure system each had small but significant effects on the thermal protection provided by flightsuits. Loose-fitting garments provided better protection than close-fitting ones if the fullness was controlled by appropriate closures. Close-fitting cuff closures on sleeves and pant legs were more effective than were zipper closures. A stand-up collar offered better protection for the neck than a convertible collar. Two-piece flightsuits provided somewhat greater protection than one-piece coveralls, mainly due to the effect of garment layering below the waist. These effects were detected when flightsuits were tested without underwear. The style effect was masked when the garments were worn over long thermal protective underwear, demonstrating the effectiveness of garment layering. Thus, for best assurance of thermal protection, flight personnel should wear long protective underwear under flightsuits at all times; in climates where this underwear might not be suitable, it is recommended that oneand two-piece flightsuits be made in a more loosely-fitting style and incorporate a stand-up collar and adjustable cuffs on sleeves and pant legs.

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