The Heat reducing Effects of Reflective Clothing in Firefighting : A study on the efficiency of reflective textiles in personal protective equipment

Abstract: Modern firefighter protective equipment is excellent at protecting firefighters from surrounding heat, but how effective is at deflecting incoming radiant heat, and would the use of more reflective textiles, be able to further increase the equipment’s protective properties? This study aims to understand the different properties that reflective materials, compared to standard firefighter outer layers, have against radiative heat flux. The textiles of firefighter turnout gear and the reflective textiles used in the smelting industry have been examined when exposed to varying levels of radiant heat in a cone calorimeter. The materials were examined before and after a layer of soot was applied to them, to understand their capabilities if used in a soot-rich environment. The change in material emissivity, when soot was applied, could then be calculated for each material. The heat reducing properties of the sooted and non sooted materials emissivities were tested, using computer simulations of a firefighter’s full turnout gear. First the radiative and convective heat fluxes were compared within a computational fluid dynamics software called FDS, second the skin level temperature was calculated using VGP, a finite element software that accounts for heat flow further into the skin and body.  During the experiment it was found that the emissivity of the reflective material even after soot application, performed better than that of the standard firefighter gear. In the simulations, the sooted reflective material emissivity would reduce the total heat flux to the firefighter with an average of 19% compared to the sooted standard turnout gear. Using the temperature of 44 °C as the limit for human skin damage, the use of a reflective emissivity would allow a 19% longer exposure to the same incident heat before possible skin damage would occur. Reducing the emissivity of current turnout gear would prove valuable as a method of reducing heat accumulation in a firefighter, especially at key areas more susceptible to the radiative heat flux from smoke-layers and radiative flames. This would in turn provide safer work environments for structural firefighting by reducing heat stress during active operations.