Contents
Preface vii
Woodhead Publishing Series in Textiles ix
1 Introduction 1
1.1 A brief background on thermal protective clothing for firefighters 2
2 Fires and thermal environments 5
2.1 Uncontrolled fires 5
2.2 Thermal environments faced by firefighters 7
3 Skin burn injuries and heat stress/fatalities 17
3.1 Burn injuries 17
3.2 Heat stress/fatalities 23
3.3 Present scenario on firefighter injuries and fatalities in the United States 25
4 Development of high performance thermal protective clothing 27
4.1 Development of fire-retardant/resistant fibers 27
4.2 Development of high performance fabrics 51
4.3 Development of thermal protective clothing 55
5 Performance evaluation of thermal protective clothing 57
5.1 Softening/melting temperature and flammability evaluation 57
5.2 Thermal protective performance evaluation 60
5.3 Clothing comfort (physiological) evaluation 97
6 Modeling and its implications on performance of thermal protective clothing 145
6.1 Heat and/or mass transfer models 145
6.2 Metabolic heat and/or sweat-vapor transfer models 157
6.3 Further research directions 161
7 Effects of various factors on performance of thermal protective clothing 163
7.1 Fiber properties 164
7.2 Yarn Properties 167
7.3 Fabric properties 168
7.4 Clothing features 178
8 Key issues related to thermal protective clothing 183
8.1 Thermal protective performance evaluation 183
8.2 Design of thermal protective clothing 186
References 189
Index 219
Preface
Firefighters, as first responders to unwanted fires and rescue victims, require highperformance protection to ensure their safety and health. Clothing is one of the most important potential protective barriers for people working in hazardous environments. Ineffective clothing protection can cause injury and fatality among victims and firefighting personnel, as well as potentially increasing property damage and loss. Every year, throughout the world, thousands of firefighters receive burn injuries, many of them resulting in fatalities. The best approach for firefighters to mitigate burn injuries and reduce risk of death from unpredictable hazards is to wear high performance thermal protective clothing.
Firefighters face complex environments and conditions and must be able to perform their duties within a wide range of possible hazards (thermal, chemical, biological, radiation, and physical). Thermal exposure, which may result from conduction, convection, hot liquid, steam, and/or hot solids, is the primary hazard exposure for firefighters. These hazards present specific characteristics in terms of protection and injury. Heat convection, radiation, and heat conduction are the main heat hazards aside from open flame. During combustion of structural materials, firefighters can encounter heat hazards including collapsing objects, hot liquid, and molten material. In a fire, cool water from a hose can quickly become hot water, and then steam. Steam and wet air cause more serious burns because more heat energy can be stored in water vapor than in dry air. However, these hazards and the challenges posed are not fully considered in current protective clothing engineering.
In order to provide protection from heat and flame, current firefighter protective ensembles typically consist of multiple layers. However, this multilayer system increases clothing weight and reduces vapor permeability, which in turn limits the rate of evaporative heat exchange with the environment, increasing physiological strain. The combined effects of strenuous exercise, protective clothing, and high ambient temperatures may lead to high levels of cardiovascular and thermoregulatory strain. Such physiological pressures are frequently associated with reduced work capacity, and, more seriously, heat-induced exhaustion, which is the paramount cause of skin burn injuries and fatalities. Garments must provide protection against hazards while maintaining an acceptable level of thermal comfort to the wearer. These requirements pose a tremendous challenge to textile material and clothing engineers.
The other key issue associated with protective clothing performance is thermal stored energy and its effect on clothing performance. Firefighters’ multilayer fabric systems and the air spaces between these layers provide resistance to heat transfer from environments hazardous to human skin. However, depending on the thermal intensity and structure of the fabric systems, a large amount of thermal energy stored during exposure can be discharged to the skin after exposure and can contribute significantly to burn injuries. This discharge process can be natural or forced by compression, and the resulting burn injury often occurs to firefighters’ arms and legs, to knees while crawling on hot surfaces, to elbows due to repetitive limb movement, to shoulders where SCBA (self-contained breathing apparatus) straps have squeezed the surrounding fabric against the skin, and to areas that contact a hot garment compressed against a wall or other fixed surface. Thermal energy stored in protective clothing during exposure to heat has been recognized as a major contributor to skin burn injuries; thus, the amount of thermal energy stored in clothing systems and its subsequent discharge to skin from clothing have been investigated.
This book covers eight chapters. Chapter 1 outlines a general introduction about protective clothing, with a focus on thermal protective clothing for firefighters. In Chapter 2, the characteristics of uncontrolled fires (wildfires, structural building fires, and vehicle fires) are discussed in detail, and the thermal environments (intensity and exposures) faced by firefighters in these fire hazards are also examined. Chapter 3 analyzes the different types of potential burn injuries (first-degree, second-degree, third-degree, and fourth-degree) and heat stress to firefighters’ bodies when exposed to such thermal environments. In Chapter 4, the development of various high performance fibers and fabrics (chemically modified fire-retardant, inherently fire-resistant) for thermal protective clothing is discussed. The test methods (bench-scale, full-scale manikins, and/or human trials) and existing standards to evaluate the thermal protective and physiological comfort performances of the fabrics and clothing are critically reviewed in Chapter 5. Throughout this review, the gaps and limitations in the existing test methods and standards are identified and approaches are discussed for further development of new test methods. The modeling and its implications on firefighters’ protective clothing is discussed in Chapter 6 and various factors (fiber, yarn, fabric, and clothing) affecting the performance of firefighters’ protective clothing is established in Chapter 7. In Chapter 8, various key issues related to thermal protective clothing are addressed to direct the future research in the field of thermal protective clothing for firefighters.
This book presents a comprehensive review on thermal hazards, textile materials, garment engineering and design, as well as evaluation methods, standards, and challenges relating to protective clothing used by firefighters. It is our hope that this book provides fundamental knowledge and a review for further development of new textile materials, methods, and approaches. We also introduce the theoretical study of modeling and its implications for firefighters’ protective clothing. Finally, various key issues related to thermal protective clothing are addressed to direct the future research in the field of thermal protective clothing for firefighters. This book will help materials/ textile engineers to develop high performance thermal protective clothing that can enhance the protection, safety, and comfort of firefighters.
Guowen Song
March, 2016 in Ames, Iowa