Fire Dynamics

Improve readers’ understanding of fire dynamics with real-world insight and research
Written to the FESHE baccalaureate curriculum for the Fire Dynamics course, Fire Dynamics offers a comprehensive approach to fire dynamics that integrates the latest research and real experiments from the field. The Second Edition’s all-new design makes locating information even easier for the reader. With twelve chapters and FESHE and NFPA references and guidelines throughout, this book is a useful resource for all fire service professionals–from the student to the fire investigator.

Greg Gorbett is an Associate Professor in the Fire Protection and Safety Engineering Technology Program at Eastern Kentucky University in Richmond, Kentucky. He currently serves as a director for the National Association of Fire Investigators, as a co-chair for the Fire and Arson Investigator journal of the International Association of Arson Investigators, and as the executive secretary of the Crime Scene/Death Investigation Scientific Area Committee’s (SAC’s) Fire and Explosion Investigation Subcommittee within the Organization of Scientific Area Committees (OSAC) through the National Institute of Standards and Technology (NIST). For the past fourteen years, he has worked as a fire and explosion expert with John A. Kennedy and Associates, Madison County Fire Investigation Task Force, and runs his own consulting firm. Professor Gorbett holds two BS degrees, one in Fire Science, and the other in Forensic Science. He also holds two MS degrees, one in Executive Fire Service Leadership, and the other in Fire Protection Engineering. He also holds a PhD in Fire Protection Engineering. Additionally, he is a certified fire and explosion investigator (CFEI), a certified fire investigator (IAAI-CFI), a certified fire protection specialist (CFPS), a certified vehicle fire investigator (CVFI), and a certified fire investigation instructor (CFII).

James L. Pharr is currently assistant professor in fire and safety engineering technology at Eastern Kentucky University (EKU). Professor Pharr specializes in fire dynamics, building and life safety, supervision, emergency scene operations, and hazardous materials response. Pharr received an AS in fire science technology from Rowan Technical Institute and a BS in fire and safety engineering technology from the School of Applied Science at the University of Cincinnati. Pharr holds an MS in executive fire service leadership from Grand Canyon University. Professor Pharr has also completed the Executive Fire Officer Program at the National Fire Academy in Emmitsburg, Maryland, where he is an adjunct instructor. Prior to joining EKU, Pharr was the emergency management director and fire marshal in Gaston County, North Carolina. Pharr is a member of the International Association of Arson Investigators and the International Association of Fire Chiefs. Pharr has published a number of journal articles and research papers.

Scott R. Rockwell is an assistant professor at Eastern Kentucky University, where he teaches classes on fire behavior and combustion and fire dynamics along with conducting research and supervising graduate student thesis projects. He has earned a BS degree in Aerospace Engineering along with a MS and PhD in Fire Protection Engineering. Additionally, he is a certified fire and explosion investigator (CFEI) and a certified fire investigation instructor (CFII) through the National Association of Fire Investigators (NAFI). His current research includes active learning teaching techniques that minimize the student’s cognitive load, use of digital media in fire science education, alternative flame extinguishing techniques, radiation from dust flash fires, and investigations into the scaling of fire whirls. Among others, he has served on the Society of Fire Protection Engineering (SFPE) Educational Committee and the Association for Fire Safety Science (IAFSS) Education Subcommittee. He also operates a website to provide freely available fire science educational material called www.firesciencetools.com.

 

Preface xv New to This Edition xvii Acknowledgments xix About the Authors xxiii Chapter 1 Introduction 1 1.1 Introduction to Fire 1 1.2 Changes That Affect Fire Dangers 4 1.3 Fire Dynamics: The Link to Collaborative Fire Protection 7 1.3.1 Fire Suppression Personnel 8 1.3.2 Fire Protection Engineering and Code Enforcement Personnel 8 1.3.3 Fire and Explosion Investigator Personnel 9 1.4 Outline of the Text 9 Summary 12 Case Studies 12 Review Questions 13 Reference 14 Chapter 2 Fire Basics 15 2.1 Definition of Fire 16 2.2 The Fire Triangle and Fire Tetrahedron 16 2.3 Classification of Fuels in Fire 18 2.3.1 Class A 18 2.3.2 Class B 18 2.3.3 Class C 18 2.3.4 Class D 18 2.3.5 Class K 19 2.4 Fire Hazards Related to the U.S. Department of Transportation Hazard Classification System 19 2.4.1 Class 1–Explosives 20 2.4.2 Class 2–Compressed Gas 20 2.4.3 Class 3–Flammable and Combustible Liquids 20 2.4.4 Class 4–Flammable Solids 20 2.4.5 Class 5–Oxidizing Agents 20 2.4.6 Class 6–Poisons 21 2.4.7 Class 7–Radioactive Materials 21 2.4.8 Class 8–Corrosives 21 2.4.9 Class 9–Miscellaneous Hazardous Materials 21 2.5 Flames 21 2.6 Fire Plume 24 2.7 Flame Spread 25 2.8 Heat and Temperature 26 2.9 Energy, Work, and Thermodynamics 27 2.10 Heat of Combustion 29 2.11 Combustion Efficiency 30 Summary 31 Review Questions 31 References 32 Chapter 3 Math Review for Basic Fire Science Applications 33 3.1 Algebra 34 3.1.1 Algebraic Expressions 34 3.1.2 Order of Operations 35 3.1.3 Rate 36 3.1.4 Flux 37 3.1.5 Significant Integers 37 3.1.6 Coordinate System 37 3.2 Units of Measure 38 3.2.1 Length 38 3.2.2 Area 40 3.2.3 Volume 42 3.2.4 Temperature 43 3.2.5 Energy 45 3.2.6 Mass 45 3.2.7 Pressure 45 3.2.8 Time 45 3.3 Conversion Between Units 45 3.4 Scaling Images 47 Summary 48 Review Questions 48 References 49 Chapter 4 Fires from Gas Phase Fuels 50 4.1 Matter 51 4.1.1 Vapor Density 52 4.2 General Physical Properties of the Gaseous State 54 4.2.1 Boyle’s Law 54 4.2.2 Charles’s Law 54 4.2.3 Combined Gas Law 55 4.3 Pressure and Its Measurement 57 4.4 General Chemistry Concepts 58 4.4.1 Chemical Reactions and Equations 59 4.4.2 Polymers 63 4.4.3 Balancing Chemical Equations 64 4.5 Oxidation Reactions 65 4.5.1 Combustion of Methane 66 4.6 Smoke 67 4.6.1 Toxicity of Smoke 67 4.6.2 Visibility Effects of Smoke 69 4.7 Gaseous Combustion 71 4.8 Dependence of Flammability Limits on Temperature, Pressure, and Oxygen Concentration 73 4.9 Ignition Energy 74 4.10 Flame Propagation 74 4.11 Warning About Flammable Gases 75 Summary 76 Review Questions 76 References 78 Chapter 5 Fires from Liquid Phase Fuels 79 5.1 Liquid Matter 79 5.2 General Physical Properties of the Liquid State 80 5.2.1 Specific Gravity 81 5.2.2 Miscibility and Solubility 82 5.2.3 Vapor Pressure 82 5.3 Altering Phase Change Temperatures 83 5.3.1 Solutions and Compounds 83 5.3.2 Pressure Change 84 5.3.3 Specific Heat 84 5.4 Change in States of Matter 85 5.4.1 Volume Expansion 89 5.4.2 Expansion of Matter (Solids and Liquids) 89 5.5 Liquid Ignitability 91 5.5.1 Flash Point and Fire Point 91 5.5.2 Classification of Ignitable Liquids 92 5.5.3 Ignition Concepts 94 5.6 Combustible Liquids 94 5.6.1 Mixtures 94 5.6.2 Aerosols 94 5.6.3 Thin Film 95 5.6.4 Wicking 95 5.7 Pool Fires 95 5.7.1 Burning Duration 96 5.7.2 Application of Knowledge 97 5.7.3 Frothing, Slopover, and Boilover 97 Summary 98 Review Questions 98 References 99 Chapter 6 Fires from Solid Phase Fuels 100 6.1 Solid Matter 100 6.2 Pyrolysis 102 6.3 CHAR 103 6.4 Smoldering Combustion 103 6.5 Melting 103 6.6 Dehydration 104 6.7 Characteristics of Cellulosic Fuels 104 6.8 Characteristics of Upholstered Furniture 106 6.9 Characteristics of Polymer Fuels 106 6.10 Characteristics of Combustible Metals 107 6.11 Flame Spread 109 6.12 Variables Affecting Solid Combustion 109 6.12.1 Surface Area—to—Mass Relationship 109 6.12.2 Orientation 110 6.12.3 Thermal Inertia 111 6.13 Fire Retardants 112 6.13.1 Potential Toxicity of Fire Retardants 113 Summary 114 Review Questions 114 References 115 Chapter 7 Heat Release Rate 117 7.1 Importance of Heat Release Rate 117 7.2 General Introduction 118 7.3 Methods for Determining Heat Release Rate 119 7.3.1 Heat of Combustion 120 7.3.2 Combustion Efficiency 121 7.3.3 Mass Burning Flux (Mass Flux) 122 7.3.4 Area 124 7.4 Heat Release Rate Curves 125 7.5 Heat Release Rate of Some Objects 128 7.6 Methods of Applying Heat Release Rate Curves 130 7.6.1 Simplified Shapes for Fire Growth Curves 130 7.6.2 t2 Fire Growth Curves 131 7.6.3 Combining Multiple Fuel Packages into a Single Fire Growth Curve 134 7.7 Some Practical Applications 137 7.7.1 Pool Fires 137 7.7.2 Solid Fuels: Upholstered Furniture 140 7.8 Flame Height 140 7.8.1 Method of Thomas 140 7.8.2 Method of Heskestad 141 7.9 Relationship of Heat Release Rate and the Plume 142 7.10 Measuring Heat Release Rate and Its Effects 142 7.10.1 Measurement of Heat Release Rate Using Oxygen Consumption Calorimetry 143 7.11 Basic Fire Testing Instrumentation 146 7.11.1 Thermocouple 147 7.11.2 Heat Flux Gauge 148 7.11.3 Bi-Directional Probe (BDP) 148 Summary 149 Review Questions 149 References 150 Chapter 8 Ignition 151 8.1 Fire Triangle/Fire Tetrahedron Revisited 152 8.2 Fire Ignition Statistics 152 8.3 Ignition Energy 153 8.3.1 Minimum Ignition Energy 153 8.3.2 Piloted Ignition 153 8.3.3 Autoignition (Autogenous Ignition) 154 8.3.4 Differences and Similarities between Ignition Concepts 155 8.4 Energy of the Ignition Source 155 8.5 Heat Transfer 157 8.6 Historical Background on Heat 157 8.7 Conduction 158 8.8 Convection 162 8.9 Radiation 165 8.9.1 Empirical Approach to Heat Flux 166 8.9.2 Point Source Model for Heat Flux 167 8.9.3 View Factor Model for Heat Flux 168 8.9.4 Emissive Power 169 8.10 Relationship to the Flame 172 8.11 Material Properties 173 8.11.1 Surface Area—to—Mass Ratio 174 8.11.2 Geometry 175 8.11.3 Density 175 8.11.4 Orientation 176 8.12 Time to Ignition Calculations for Solid Fuels 178 8.12.1 Ignition of Thermally Thin Solids 178 8.12.2 Ignition of Thermally Thick Solids 180 8.13 Spontaneous Ignition 181 8.14 Ignitability and Flammability Testing 183 Summary 184 Review Questions 184 References 185 Chapter 9 Enclosure Fire Dynamic Basics 186 9.1 Introduction 186 9.2 Ignition 187 9.3 Growth 188 9.3.1 Plume Formation 189 9.3.2 Ceiling Jet 189 9.3.3 Upper Layer Development 190 9.3.4 Sprinkler and Heat Detector Activation 194 9.3.5 Ventilation Openings 194 9.4 Progression of a Fuel-Controlled Enclosure Fire 197 9.4.1 Curve Number 1 197 9.4.2 Curve Number 2 197 9.4.3 Components That Control Flashover 201 9.4.4 Indicators of Flashover 201 9.4.5 Flashover Calculations 202 9.4.6 Curve Number 3 205 9.5 Progression of a Ventilation-Controlled Enclosure Fire 205 9.5.1 Curve Number 4 206 9.5.2 Curve Number 5 206 9.6 Impact of Changing Ventilation Conditions 209 9.6.1 Curve Number 6 209 9.7 Misconceptions Regarding Backdraft 213 9.7.1 Misconception: “Backdraft Is Fueled by Carbon Monoxide” 213 9.8 Full-Room Involvement 214 9.9 Combustion Products for Occupant Safety 214 9.9.1 Fire Environment Exposure (Toxicity) 215 9.9.2 Smoke, Irritants, and Visibility 215 9.9.3 Asphyxiant Gases 215 9.10 Calculations 217 9.11 Decay 217 9.12 Effects of Smoke in Compartments 217 9.12.1 Stack Effect (Buoyancy Effects on Smoke Movement) 217 9.12.2 Smoke Control Methods 217 9.11.3 Amount of Smoke Produced by a Fire 218 9.11.4 Smoke Fill Rate in a Compartment 219 9.13 Reaching the LFL within a Compartment 220 Summary 221 Case Study 221 Review Questions 221 References 223 Chapter 10 Extinguishment 225 10.1 Extinguishment of Fire 225 10.2 Removal of Fuel 226 10.2.1 Turn Off Fuel Supply 226 10.2.2 Separation of Fuel 226 10.2.3 Fire Consumes Fuel 227 10.3 Removal of Heat 227 10.3.1 Air Movement 227 10.3.2 Water 228 10.3.3 Volume Expansion 232 10.3.4 Fog Fire Streams 232 10.4 Water Volume Calculations 232 10.5 Fire Suppression Calculations 233 10.6 Sprinkler Systems 234 10.7 Water Summary 236 10.8 Foam Extinguishing Agents 236 10.8.1 Environmental Concern for Foam Use 237 10.9 Removal of Oxygen 238 10.10 Oxygen Displacement 239 10.11 Cooling Effect of Inert Gas 240 10.12 Class D Fires 240 10.13 Interrupting a Chemical Chain Reaction 240 Summary 241 Review Questions 241 References 242 Chapter 11 Explosions 243 11.1 Introduction to Explosions 243 11.2 Gas Explosions 246 11.2.1 Common Fuel Gases 247 11.3 Boiling Liquid Expanding Vapor Explosions (BLEVE) 248 11.4 Unconfined Vapor Cloud Explosion (UVCE) 249 11.5 Fire and Explosion Dangers in Concentrated Dust Environments 249 11.6 Blast Effects and Overpressure Effects 25011.6.1 Blast Damage to Buildings 250 11.6.2 Blast Injuries 251 11.7 TNT Equivalency 252 11.7.1 Relationship of TNT Equivalence to Overpressure 253 11.7.2 Relationship of Overpressure to Damage 255 Review Questions 256 References 256 Chapter 12 Introduction to Fire Modeling 258 12.1 History and Basics of Fire Testing and Modeling 258 12.2 Computer Fire Modeling Applications 260 12.2.1 Fire Protection Engineering 260 12.2.2 Fire Investigation 261 12.3 Types of Models 263 12.3.1 Hand Calculations 263 12.3.2 Spreadsheet Models 264 12.3.3 Zone Models 265 12.3.4 Computational Fluid Dynamics Models (Field Models) 271 12.4 Input Data Needed for Computer Fire Modeling 272 12.5 Testing of an Origin Hypothesis with Computer Fire Models 273 12.6 Modeling Fire Suppression Activities 277 12.7 Verification and Validation of Computer Models 277 Summary 278 Review Questions 278 References 279 Appendix A Digital Resources 280 Appendix B 281 Appendix C Reference Tables 282 Glossary 297 Index 301