Effects of Outer Shell Fabric Color, Smoke Contamination, and Washing on Heat Loss through Turnout Suit Systems

Textile Research Journal · 2022 · 11 citations

• Materials science
• Composite material
• Environmental science

Firefighters frequently have to work in direct solar radiant heat. To reduce firefighter heat stress, the influence of turnout garment properties on heat gain from solar radiation must be understood. This research studied the effects of color, texture, washing, and contamination of outer shell fabrics on heat loss through firefighter turnout fabric materials in simulated solar exposures. It showed that solar radiation could be a major factor in heat loss through turnout suits. Solar radiation equivalent to a sunny day completely reversed heat exchange through the turnout fabric systems, converting a heat loss of about 240 W/m 2 to a heat gain exceeding 100 W/m 2 . Solar radiation caused turnout fabric systems to dry out and this decreased the performance of turnout systems that incorporated bi-component moisture barriers. Most significantly, the color of the outer shell had a major influence on lowering turnout heat loss in solar exposures. Composites with a black-dyed outer shell absorbed more solar energy than composites with lighter colored shell materials. Soot and fire-ground contaminants present on turnout outer shell fabrics also reduced heat loss under solar exposure. The findings of this study answered long-standing questions about the importance of turnout fabric color on heat exchange with the environment. The results provide additional motivation for efficient turnout cleaning practices, not only to reduce potentially toxic exposure to smoke contaminants, but to reduce turnout-gear-related heat strain on firefighters.

Identifying factors that contribute to structural firefighter heat strain in North America

International Journal of Occupational Safety and Ergonomics · 2021 · 12 citations

• Political Science
• Forensic engineering
• Environmental science

This article describes results from a survey of firefighters designed to identify conditions that contribute to heat strain in structural firefighting. Based on responses from about 3000 firefighters across the USA and Canada, the article provides invaluable information about how firefighters associate environmental conditions, work tasks and other factors with heat strain. One-half of firefighters surveyed have experienced heat stress during their service. They can wear fully deployed turnout gear for 2 h or more at the fire scene, reinforcing the importance of turnout suit breathability as a factor in heat strain. Survey results are useful in weighing the comparative value of total heat loss (THL) and evaporative heat resistance (Ref) for predicting turnout-related heat strain. Survey findings support the inclusion of a performance criterion in the National Fire Protection Association 1971 standard for firefighter personal protective equipment based on limiting Ref of turnout materials along with current THL requirement.

Effects of environmental temperature and humidity on evaporative heat loss through firefighter suit materials made with semi-permeable and microporous moisture barriers

Textile Research Journal · 2021 · 24 citations

• Materials science
• Composite material
• Environmental science

The goal of this research was to understand how firefighter protective suits perform in different operational environments. This study used a sweating guarded hotplate to examine the effect of environmental temperature (20–45°C) and relative humidity (25–85% RH) on evaporative heat loss through firefighter turnout materials. Four firefighter turnout composites containing three different bi-component (semi-permeable) and one microporous moisture barriers were selected. The results showed that the evaporative resistance of microporous moisture barrier systems was independent of environmental testing conditions. However, absorbed moisture strongly affected evaporative heat loss through semi-permeable moisture barriers coated with a layer of nonporous hydrophilic polymer. Moisture absorption in mild environment (20–25°C) tests, or when testing at high humidity (>85% RH), significantly increased water vapor transmission in semi-permeable turnout systems. It was also found that environmental conditions used in the total heat loss (THL) test (25°C and 65% RH) produced moisture condensation in bi-component barrier systems, making them appear more breathable than could be expected when worn in hotter environments. Regression models successfully qualified the relationships between moisture uptake levels in semi-permeable barrier systems and evaporative resistance and THL. These findings reveal the limitations in relying on THL, the heat strain index currently called for by the NFPA 1971 Standard for Structural Firefighter personal protective equipment, and supports the need to measure turnout evaporative resistance at 35°C (Ret), in addition to THL at 25°C.