A Review of Test Methods for Determining Protective Capabilities of Fire Fighter Protective Clothing from Steam
Shonali Nazare, Christopher W. Meyer, Daniel M. Madrzykowski
Firefighters working inside a burning structure often experience burns related to hot water vapor inside firefighter protective clothing (FFPC). For these burns to occur, the water vapor is heated by the high temperatures outside the FFPC and it diffuses across the FFPC fabric layers. Condensation of this vapor on the firefighters cooler skin releases the waters latent heat of vaporization, rapidly raising the temperature of the skin. Burns from this moisture-driven heat transfer are often called steam burns. The water vapor can come from humidity in the burning-structure environment that penetrates through the outer shell of the FFPC. The humidity arises from firefighter water sprays and from combustion (which produces water vapor as a byproduct). The water vapor can also come from firefighter perspiration. The moisture, through a wicking process, spreads to the outer layers of the FFPC, where it is vaporized from a flashover exposure. In this technical note, we review existing test methods for quantifying steam burns and evaluating moisture-driven heat transfer in protective clothing are reviewed, with an emphasis on the instrumentation, methodology, merits, and limitations of each method. We discuss bench-scale test methods using pre-wetted samples (simulating perspiration-sourced water vapor) as well as those using external steam exposures (simulating water vapor from humid environments). Gaps in test methodology are identified and suggestions for improvements in bench scale testing are made. From this review, we note that research on moisture-driven heat transfer through FFPC has primarily focused on perspiration-sourced water vapor. Better bench scale test methods are needed for quantifying the moisture-driven heat transfer through FFPC resulting from the humidity in environments such as those encountered during interior firefighting.