Beyond a Single Use: Understanding the Longevity and Reusability of Fire Proximity Suits

Firefighters frequently wear fire proximity clothing to shield themselves from high heat fluxes, especially radiant heat. The outer layer in these proximity suits is a laminate of aluminised polyethylene terephthalate (PET) film with a flame resistant fabric, usually belonging to the class of glass or aramids. The role of the outer layer is to reflect the radiant component of the heat flux. A common concern revolves around whether the performance of these suits degrade over time or with repeated use, exposure to flames or other factors. This study investigated the effect of these parameters like abrasion and folding operations, natural weathering, repeated radiant and convective exposures as well as contamination, on the thermal and radiant protective capabilities of these proximity firefighting suits. Our studies clearly indicate that abrasion as well as chemical etching lead to significant reduction in the protection level, from a time to second degree burn (t_2nd) of 41 ± 1 s for unabraded to as low as 14 ± 0.5 s after 500 abrasion cycles and 6 ± 0.5 s after chemical etching. Although repeated short duration 30 s radiant exposures does not have any adverse effect on the protective performance of the suit, however, flame exposure led to significant damages in the aluminised layer and t_2nd reduced to 5 ± 0.5 s. In addition, operations like folding and contamination with soot significantly contributed to deterioration of the suits' performance. Radiant Protective Performance of soot contaminated samples and folded samples reduced to 7 ± 0.5 s and 18 ± 0.5 s respectively. Our findings address longstanding enquiries regarding the post usage utility of aluminised suits. Our study reinforces the importance of proper care and the maintenance of these suits in order to improve their service life.