Radiative properties of firefighter helmets: Effect of color and soot deposition on thermal performance

Abstract

This study investigates the thermal radiative properties of firefighter helmets, focusing on the influence of helmet color and soot deposition on their performance. Firefighters’ helmets, often chrome plated for reflectivity or colored for functional visibility, play a critical role in protecting against radiant heat during operations. Through infrared spectrum measurements, this work analyzes the directional-hemispherical reflectivity and absorptivity of various helmets, assessing factors such as helmet color and surface conditions. Results indicate that chrome plated helmets reflect most of the radiative heat (average reflectivity of 83% at 1000 K) providing superior thermal protection. In contrast, colored helmets show reduced reflectivity, ranging from 3% to 14%, resulting in increased radiative absorption. Helmets, covered by soot and combustion products), demonstrate a reflectivity drop to approximately 36% for a chrome plated helmet, highlighting the importance of regular cleaning to maintain thermal protection. These findings advance the understanding of thermal performance differences among helmet types, contributing to improved firefighter safety and offering insights into future helmet design considerations. All experimental data collected in this study are available in an open-access database for further uses.