ENTORNO LOCAL

An inherent trade-off between personal protection and thermoregulatory stress exists for firefighters wearing multilayered protective clothing whilst working in hot, humid climates. Since the threat of injury during emergency response is not limited to situations where firefighting Turnout is being worn, firefighters must be assured that the additional protection provided by their Station Wear will prevent further grievous bodily harm.

A series of light-weight, heat and fire-resistant Station Wear fabrics, varying in fibre blend, yarn composition, and weave structure were designed, manufactured and tested to perform to, or exceed relevant Australian Standards. The Experimental Station Wear fabrics were developed with the objective of improving the protective performance, as well as functionality. Emphasis was also placed on the in-use durability of protective clothing materials containing UV-sensitive fibres, and the way in which these fibres behave over their service lifetime. The Experimentally-developed fabrics and the Commercially-available Master Control A (MCA) fabric will be evaluated to determine their performance properties.

In developing new Station Wear fabrics that cater for the operational needs of firefighters in the Australian climate, the methodology followed a basic research and product development cycle. Qualitative methods (e.g. feedback from textile manufacturers, firefighters and Australian Fire Services) were used in the initial phases of the study, followed by laboratory experiments and testing phases. To achieve the objective of this study, the following methodology (Figure 4.1) was implemented to address the research questions.

Commercial fabric selection

Experimental Fabric Production: weaving and finishing Establish method for Test result analysis and interpretation

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Figure 4.1 Methodology

Since the type of product must be appropriate to the activity, functional performance requirements for Station Wear materials should be evaluated in terms of the level of protection required, the firefighter's physiological response to internal and external heat, and the impact of environmental factors on thermo-physiological comfort. Durability should be addressed in terms of the thermal aging of protective clothing materials.

A review of the currently operating legislations and Standards governing firefighting Personal Protective Clothing (PPC) throughout Australia, was carried out to identify gaps in the minimum safety and performance requirements for secondary protective Station Wear materials. In the absence of an Australian firefighting PPC Standard specifically applicable to Station Wear, the most appropriate test methods from existing Structural (AS/NZS 4967:2009) and Wildland (AS/NZS 4824:2006) PPC Standards, and work wear Standards (AS 2919-1987) were selected to evaluate the Commercial and the Experimental fabrics' protective, mechanical and comfort performance properties.

The Commercial fabric was selected based on market availability and end-use suitability, in terms of fabric weight and blend ratio for middle-layer firefighting Station Wear applications.

Existing looms on-campus were unsuitable to produce the proposed light-weight protective fabrics, therefore the Experimental fabrics were woven by Bruck Textiles Pty Ltd. To avoid the cost of a dedicated warp and gear changes, an existing loom setup consisting of a common warp yarn was used to weave small lengths (4-5 m) of the Experimental fabrics. This allowed the Experimental fabrics to be woven quickly, without being especially planned into Bruck's production timeline.

Stage One Testing: Commercial and Experimental samples

Initial UV experiment: Commercial sample

Stage Two Testing: best-candidate fabrics (CHR, MMT and UV experiment)

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The Experimental Station Wear fabrics were produced as single-layers, following the weaving specification that had been developed to produce samples with specific blend ratios, in similar target weights and cover factors. Two weave designs (i.e. plain and 2/1 twill) were selected to evaluate whether a particular fibre blend performed better or worse in another weave structure. The Experimental fabrics were deliberately undyed, but fully finished by scouring and drying to remove dirt, oil or other contaminants such as size.

Preliminary testing was carried out to verify the physical and structural properties (e.g. mass per unit area and cover factor) of woven, single-layer Experimental Station Wear fabrics according to their weave design specifications. An additional experiment which involved dyeing samples of the Experimental fabrics, and testing them against undyed samples for dimensional stability to washing, was performed to ensure that shrink percentages remained within Standard guidelines.

Stage One Testing involved comprehensive fabric testing on the Commercial MCA and Experimentally-developed sample fabrics, to establish their quality and protective performance (i.e. Limited Flame Spread), mechanical performance (i.e. Tear Resistance and Tensile Strength), and comfort performance (i.e. Sweating Guarded-Hotplate Test) properties, according to functionality criteria and relevant Standards.

Due to the limited lengths of the Experimental fabrics, a sample of the Commercial MCA fabric was initially exposed to UV radiation using an artificial light (MBTF) source, and tested for strength loss. Previous RMIT experience gained from UV exposures of different aramid-based materials had indicated that significant strength loss could be expected. Thus, further investigation of UV effects may be warranted but only on the best-candidate fabrics in Stage Two Testing to evaluate if fabrics would also experience a compromise in flame performance.

Samples of the un-irradiated, best-candidate fabrics were also evaluated in Stage Two Testing for thermal shrinkage resistance (Convective Heat Resistance (CHR)), and liquid moisture transfer properties (Moisture Management Tester (MMT)). As an accepted Turnout fabric, but not meant for Station Wear applications, Melba Fortress® was used as a comparative fabric but for the MMT tests only. This was done to evaluate the two extremes of protection on a fabric's liquid moisture transfer properties.

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The results from Stage One and Stage Two Testing were analysed to establish which fabrics would be most suitable for use in Station Wear protective clothing, and whether the performance properties of the Commercial MCA fabric outperformed the Experimental Station Wear fabric samples.