Table of contents
Detailed Contents are given at the start of the individual chapters.
Foreword, by Morgan J. Hurley...... iii
Preface...... iv
Acknowledgements ...... v
Chapter 1. Introduction ...... 1
Chapter 2. Terminology ...... 13
Chapter 3. Fundamentals of combustion ...... 24
Chapter 4. Ignition of gases and vapors ...... 41
Chapter 5. Ignition of dust clouds ...... 141
Chapter 6. Ignition of liquids ...... 182
Chapter 7. Ignition of common solids ...... 234
Chapter 8. Ignition of elements ...... 352
Chapter 9. Self-heating ...... 367
Chapter 10. Explosives, pyrotechnics and reactive substances ...... 444
Chapter 11. Characteristics of external ignition sources...... 497
Chapter 12. Preventive measures ...... 591
Chapter 13. Special topics ...... 609
Color Plates...... 637
Chapter 14. Information on specific materials and devices...... 675
Chapter 15. Tables ...... 1022
Index...... 1081
Chapter 1. Introduction
Background ...... 1 Fire ignition statistics...... 2 The fire triangle and taxonomy of ignitions...... 6 Some complications of definition...... 8 Types of combustion and combustion-like reactions ...... 8 Apparatus-dependent nature of ignition...... 9 The probabilistic nature of ignition and negative proof...... 9 Comments to the fire investigator ...... 10 Computer methods ...... 11 References ...... 12
Chapter 2. Terminology
Terms used in this book ...... 13 Definitions ...... 13 Abbreviations and acronyms...... 20 References ...... 22
Chapter 3. Fundamentals of combustion
Introduction...... 24 Thermochemistry ...... 24 Heat of combustion...... 25 Constant-volume heat of combustion...... 27 Effective heat of combustion; heats of explosion and detonation ...... 28 Relations between fuel and air...... 28 Adiabatic flame temperature ...... 30 Reaction kinetics ...... 32 Branching chain reactions...... 33 Autocatalytic reactions...... 34 Flame speed...... 35 Types of explosions ...... 36 Pressure piling ...... 37 Deflagration to detonation transition...... 38 Catalytic combustion...... 38 Tests for fundamental combustion properties ...... 39 Further readings ...... 39 References...... 39
Chapter 4. Ignition of gases and vapors
Highlights and summary of practical guidance ...... 43 Exothermic reactions in gases...... 44 Slow oxidation...... 44 Cool flames...... 45 Multiple ignition temperatures...... 45 Autoignition of premixed gases...... 46 Theory ...... 46 Ignition of specific fuels...... 53 Experimental determination of the AIT...... 54 Variables affecting the AIT ...... 55 Molecular structure...... 55 Fuel concentration...... 56 Pressure...... 57 Oxygen concentration...... 57 Vessel size and operating conditions...... 58 Wall material...... 59 Flow velocity and turbulence ...... 59 Other relations ...... 60 AIT of mixtures...... 60 Ignition time ...... 60 Effect of fuel type and mixture composition ...... 61 Effect of pressure ...... 63 Effect of flow rate ...... 63 Sub-ignition, two-stage, and multi-stage ignitions ...... 63 Ignition due to compression or shock...... 64 Piloted ignition of premixed gases...... 65 Ignition with the presence of excited species...... 65 Spark ignition phenomema...... 65 Theories for spark ignition, MIE, and quenching distance...... 66 Ignition from breaking wires or moving contacts ...... 70 Pilot flame ignition...... 73 Ignition by burning particles ...... 74 Variables affecting ignition of gases when piloted with the presence of excited species ...... 74 Chemical nature of the fuel...... 74 Oxygen concentration...... 75 Diluents...... 75 Fuel concentration...... 76 Temperature...... 77 Pressure...... 78 Gravity ...... 78 Test geometry...... 79 Mixture velocity and turbulence ...... 79 Wall materials ...... 79 Circuit topology ...... 79 Spark duration ...... 80 Electrode arrangement...... 81 Electrode materials ...... 83 Ignition in the absence of excited species and hot-wire ignitions of all types...... 83 Hot surface ignition and catalytic effects ...... 83 Fused wire ignition...... 94 Ignition by hot, non-flaming gases and MESG...... 96 Ignition by laser energy...... 101 Direct thermal heating of gas...... 101 Photochemical excitation of gas...... 101 Laser-induced breakdown of gas ...... 101 Radiative heating of small particles in the atmosphere...... 102 Laser-induced breakdown of gas aided by presence of small particles...... 104 Flammability limits ...... 104 Theory ...... 107 Flammability limits in mass units ...... 108 Estimation of flammability limits...... 109 Flammability limits for mixtures ...... 111 Variables affecting flammability limits...... 112 Oxygen concentration ...... 112 Pressure...... 112 Temperature ...... 114 Velocity ...... 116 Gravity ...... 116 Turbulence and sloshing...... 116 Measuring apparatus ...... 116 Ignition source...... 118 Additives...... 118 Minimum oxygen concentration for flammability...... 118 Unified theories of gas ignition...... 120 Ignition of non-premixed gases...... 120 Initiation of gaseous detonations...... 121 Minimum energy for detonation...... 123 Detonation limits ...... 123 Tests for ignition properties of gases ...... 123 Autoignition temperature ...... 123 Early methods ...... 123 Heated tube tests...... 124 Tests primarily for liquids...... 124 Other test methods ...... 124 Heated-surface ignition...... 124 Flammability limits...... 124 Bureau of Mines flammability tube...... 124 ASTM E 681 ...... 125 Proposed EN method...... 126 ASTM E 918 ...... 126 ASTM E 2079 ...... 126 UL tests ...... 126 Research tests ...... 126 Minimum ignition energy ...... 127 ASTM E 582 test...... 127 Quenching distance ...... 127 MESG ...... 128 IEC/PTB and HSE 20 mL spheres...... 128 Westerberg apparatus (UL)...... 128 Further readings ...... 128 References ...... 128
Chapter 5. Ignition of dust clouds
Highlights and summary of practical guidance ...... 142 General principles ...... 143 Chemistry of combustion ...... 144 Flammability limits ...... 145 Lower flammability limits...... 145 Upper flammability limit ...... 148 AIT, quenching distance and MESG...... 148 Theory of ignition of dust clouds ...... 149 Hybrid gas/dust-cloud ignitions ...... 151 Ignition sources for dust clouds...... 152 Mechanical sparks...... 153 Electric sparks...... 153 Hot surfaces ...... 153 Glowing nests ...... 153 Others ...... 154 Clouds of powdered fibers (flock)...... 154 Analysis and application of data...... 154 Variables affecting the AIT ...... 154 Dust concentration ...... 154 Volatile content...... 154 Particle diameter...... 155 Moisture...... 156 Oxygen concentration...... 156 Residence time ...... 156 Turbulence...... 156 Test apparatus volume ...... 157 Variables affecting the flammability limits ...... 157 Probability level used for the definition of the LFL...... 157 Particle diameter...... 157 Temperature...... 158 Pressure...... 158 Moisture...... 158 Oxygen concentration...... 159 Igniter energy supplied ...... 159 Variables affecting the MIE...... 161 Dust concentration ...... 161 Particle diameter...... 161 Temperature...... 162 Pressure...... 162 Moisture...... 162 Oxygen concentration...... 162 Turbulence...... 163 Charge on particles...... 163 Spark electrodes: material and gap size ...... 163 Spark circuit parameters...... 163 Air velocity and turbulence...... 166 Test vessel size ...... 166 Risk management based on the MIE ...... 167 Diluting with inert gases ...... 167 Diluting with inert dusts...... 169 Tests for ignition properties of dust clouds ...... 170 ASTM E 1491 ...... 170 ASTM E 2019 ...... 170 Godbert-Greenwald furnace ...... 171 Bureau of Mines 1.2 L furnace...... 171 BAM oven ...... 171 Hartmann apparatus...... 172 Bureau of Mines 6.8 L chamber ...... 173 Spheres and other 20 L chambers ...... 173 Nordtest 15 L apparatus...... 175 1 m3 spheres...... 175 ASTM E 1232 ...... 175 IEC 61241-2-3/Mike 3 ...... 175 CMI mechanical impact test...... 176 Further readings ...... 176 References...... 177
Chapter 6. Ignition of liquids
Highlights and summary of practical guidance ...... 183 Accidental ignitions of liquids...... 184 Properties of liquids ...... 184 Autoignition of liquids ...... 186 Ignition of single drops...... 187 Liquid aerosols or sprays ...... 190 Flash point and fire point ...... 192 Flash point...... 192 Upper flash point...... 193 The fire point ...... 193 The pre-flash ‘halo’ ...... 194 The distribution of fuel vapors above the surface ...... 194 Estimations of flash point...... 196 Flash points of mixtures...... 198 Ideal mixtures...... 199 Non-ideal mixtures...... 199 Mixtures with halogenated components...... 200 Flash points of petroleum distillates...... 202 Relation between flash point and MIE ...... 202 Piloted ignition of liquids ...... 202 Spark ignition of liquid aerosols or sprays ...... 202 Minimum ignition energy ...... 203 High flash-point liquids...... 205 Limits of flammability for liquid aerosols...... 206 MESG of liquid aerosols...... 207 Hot surface ignition of droplets, sprays or spills...... 207 Single droplets of a pure fuel ...... 207 Hot engine surfaces and related problems...... 209 Pools ...... 213 Pools at or above their flash point...... 213 Pools below their flash point...... 215 Ignition of fuel in closed vessels...... 215 Effect of vapor/liquid volume ratio...... 216 Effect of slosh...... 217 Radiant ignition of liquids...... 217 Thick layers ...... 217 Thin layers...... 218 Ignition of liquids by other means ...... 219 Tests for ignition properties of liquids...... 219 Autoignition temperature ...... 219 Early test methods ...... 219 ASTM D 286...... 221 ASTM D 2155 ...... 222 ASTM E 659...... 222 Other Bureau of Mines tests...... 223 Flash point ...... 223 ASTM D 56 ...... 224 ASTM D 92 ...... 225 ASTM D 93 ...... 225 ASTM D 1310 ...... 225 ASTM D 3278 ...... 225 ASTM D 3828 ...... 226 ASTM D 3934 ...... 226 ASTM D 3941 ...... 226 Abel flash point test ...... 226 Tests for other properties...... 226 ASTM D 4206 test for sustained burning ...... 226 Hydraulic fluid sprays...... 226 Further readings ...... 227 References ...... 227
Chapter 7. Ignition of common solids
Highlights and summary of practical guidance ...... 237 Types of ignition ...... 238 General principles of flaming ignition...... 238 Qualitative features...... 238 The ignition problem for solids...... 239 Research into ignition of solids...... 241 Ignition temperature as ignition criterion...... 243 Mass loss rate as ignition criterion ...... 246 HRR as an ignition criterion...... 248 Other criteria for ignition...... 249 Ignition from radiant heating ...... 250 Gas phase events...... 250 Cool flames ...... 250 Comprehensive theories...... 251 Atreya’s model ...... 254 Engineering treatments for thermally thick solids ...... 256 Development of approximate solutions ...... 257 Janssens’ procedure ...... 260 Quintiere’s procedure ...... 262 Tewarson’s procedure ...... 264 Other data treatment procedures...... 264 Relation between minimum and critical fluxes ...... 265 Engineering treatments for thermally thin solids ...... 265 Condition 1—back face insulated...... 266 Condition 2—back face cooled ...... 267 Condition 3—back face also heated ...... 268 Other issues for thin slabs...... 268 Illustrative data...... 268 Composite materials ...... 269 Criteria for distinguishing thermally thick versus thin materials ...... 271 General and intermediate-thickness materials ...... 272 Energy needed for ignition...... 274 Laser ignition ...... 275 Ignition from convective heating or immersion in a hot environment...... 277 Ignition theories for convective heating ...... 280 Lumped-capacitance model...... 280 Thermally-thick solid—constant heat flux ...... 280 Thermally-thick solid—constant convective transfer coefficient...... 280 Thermally-thick solid—boundary layer solution...... 281 Ignition theories for submersion in hot environments ...... 281 Theoretical solutions for other problem conditions...... 281 Thermally-thick inert solid with fixed net heat flux...... 282 Thermally-thick inert solid with fixed heat flux and convective cooling...... 282 Thermally-thick reactive solid with fixed heat flux ...... 282 Finite-thickness inert plate with fixed heat flux...... 283 Finite-thickness reactive plate...... 283 Finite-thickness polymer undergoing charring...... 283 Thermally-thick reactive solid held at a fixed face temperature indefinitely...... 284 Thermally-thick reactive solid held at a fixed face temperature for a finite time...... 284 Thermally-thick reactive solid receiving fixed radiant heat flux only...... 284 Solid receiving a brief, high-intensity pulse of radiation ...... 285 Porous solids ...... 285 Diathermanous solids ...... 285 Miscellaneous geometries...... 285 Depletion of reactants not ignored...... 285 Ignition from localized sources...... 286 Small flames...... 286 Small-diameter, high-intensity heat sources...... 287 Hot bodies ...... 287 Ignition from large flames ...... 289 Duration of ignited burning ...... 290 Flashing vs. sustained flaming ...... 290 Sustained flaming after initial ignition ...... 290 Variables affecting ignition of solids...... 292 Type of pilot (or lack thereof)...... 292 Orientation ...... 294 Exposed area size...... 295 Air flow rate...... 297 Oxygen concentration...... 299 Piloted ignition ...... 299 Autoignition ...... 300 Chemical composition of diluents ...... 300 Total pressure...... 301 Moisture and relative humidity...... 302 Initial temperature of specimen...... 304 Acceleration of gravity...... 304 Surface absorptivity, material transparency, surface coatings, and spectral characteristics of the radiant source...... 305 Polymer structure ...... 308 Porosity...... 308 Fire retardants ...... 308 Movement of the surface ...... 309 Surface roughness ...... 310 Ignitability of aged, degraded, or charred materials...... 310 Wetting by water ...... 310 Type of apparatus ...... 311 Mass of sample...... 311 Long-term radiant exposures ...... 312 Arcing across a carbonized path...... 312 Glowing ignition...... 315 Smoldering ignition ...... 315 Theory ...... 318 Effect of layer thickness...... 318 Effect of packing density or porosity ...... 318 Smolder promoters and smolder inhibitors ...... 318 Transition from smoldering to flaming ignition ...... 319 Indicators of smoldering...... 320 Tests for ignition properties of solids ...... 320 Flame ignition tests...... 320 ASTM D 2859 methenamine pill test...... 321 CS 191-53 (16 CFR 1610) flammable fabrics test...... 321 FF-3-71 (16 CFR 1615) and FF-5-74 (16 CFR 1616) children’s sleepwear tests ...... 322 CPSC 16 CFR 1500.44 flammable solids test ...... 322 NFPA 701 and NFPA 705 methods...... 322 ASTM D 1692 ...... 322 UL 94 test series ...... 323 UL end-product tests ...... 326 Small-flame tests for wire and cable...... 327 MVSS 302 ...... 328 FAR Bunsen burner test ...... 328 ISO 11925-2 small flame test ...... 329 Large-flame tests ...... 329 Radiant ignition tests...... 330 The Cone Calorimeter ...... 330 ISO 5657...... 331 ASTM E 1321 (LIFT)...... 331 FM Fire Propagation Apparatus—ASTM E 2058...... 332 ASTM E 1623 (ICAL)...... 333 Arc tracking and arc ignition tests ...... 333 ASTM D 495 ...... 333 ASTM D 2303 ...... 333 ASTM D 3032 ...... 334 ASTM D 3638 ...... 334 MIL-STD-2223...... 334 UL tests...... 334 Electric spark or arc ignition...... 334 Bureau of mines electric spark method...... 334 Nordtest NT Fire 016 method...... 335 NIST electric arc method...... 335 Smoldering ...... 335 Cellulose insulation ...... 335 Mattress tests ...... 335 Burning brand ignition...... 335 ASTM E 108 roof test ...... 335 Other types of tests...... 336 Convective heating tests ...... 336 Hot wire or bar ignition tests ...... 336 Hot rivet or nut tests ...... 336 Setchkin furnace, ASTM D 1929 ...... 336 Limiting oxygen index (LOI), ASTM D 2863...... 338 Thermal analysis tests...... 338 Further readings ...... 338 References...... 339
Chapter 8. Ignition of elements
Highlights and summary of practical guidance ...... 352 Ignition of metals...... 353 General principles ...... 353 Theories ...... 356 Theories for a single, isolated mass...... 356 Theories for metal dust layers...... 358 Effect of oxygen concentration ...... 359 Effect of pressure ...... 359 Effect of flow velocity...... 359 Effect of moisture...... 359 Ignition of carbon...... 359 Graphite and other relatively pure forms of carbon...... 359 Coal, coke, and other relatively impure forms of carbon...... 360 Single particles ...... 360 Dust clouds ...... 363 Test methods ...... 364 References...... 364
Chapter 9. Self-heating
Highlights and summary of practical guidance ...... 369 Introduction ...... 371 Basic phenomena ...... 373 Theory of self-heating...... 374 Steady-state theory for symmetrically cooled bodies...... 377 Peak temperatures under subcritical conditions ...... 379 Bodies of other shapes...... 380 Steady state theory for unsymmetrically cooled bodies...... 382 Infinite slab...... 382 Hollow infinite cylinder ...... 383 Steady-state theory including oxygen diffusion...... 383 Steady-state theory including fuel depletion...... 384 Correction for low activation energy...... 385 More complex reactions ...... 386 Hot work, cold work, and hot spots...... 387 Hot work...... 387 Cold work...... 389 Inert hot spots...... 390 Reactive hot spots...... 390 Applied heat flux...... 391 Transient theory...... 391 Estimating time to criticality ...... 391 Linearly increasing surface temperature...... 394 More advanced models...... 394 Applications...... 395 Ignition from self-heating ...... 395 Effects of different variables on self-heating...... 395 Chemical and physical nature of the substance ...... 395 Pile size and shape, and porosity of the substance ...... 395 Particle size ...... 396 Temperature ...... 396 Time of storage...... 396 Access of air...... 396 Oxygen concentration...... 397 Insulation...... 398 Multiple packing ...... 398 Moisture and rain ...... 398 Density ...... 400 Antioxidants ...... 400 Contaminants...... 400 Multiple-component substances ...... 401 Ignition of dust layers...... 401 Electrical heating problems ...... 402 Hot spots ...... 402 Self-heating in liquids ...... 403 Liquid-soaked porous solids ...... 403 Detonation or deflagration upon self-heating...... 404 Preventive measures...... 404 Tests for self-heating or reactivity ...... 405 Real-scale tests ...... 406 UN Test H1—The US SADT test ...... 406 Geometric-scaling tests ...... 406 Scaling according to Frank-Kamenetskii theory...... 406 Oven-basket tests: FRS method...... 406 Oven-basket tests: crossing point methods ...... 414 Oven-basket tests: Nordtest method...... 417 Oven-basket tests: IMO test...... 417 Oven-basket tests: UN Test N4 ...... 418 Hotplate tests...... 418 Scaling according to Semenov theory ...... 420 General Dewar flask testing ...... 420 UN Test H2—Adiabatic storage test ...... 421 UN Test H4—Heat accumulation storage test...... 422 Calorimeter tests ...... 422 Adiabatic calorimeters...... 423 Isothermal calorimeters ...... 425 ARC and APTAC tests...... 425 Other industrial reaction calorimeters...... 428 Thermal analysis methods...... 428 DTA, DSC, and related techniques...... 429 Simple screening test based on DSC ...... 430 Quantitative ASTM procedures...... 431 ASTM E 698 ...... 431 ASTM E 793 ...... 431 ASTM E 1641 ...... 431 ASTM E 1231 ...... 432 Qualitative ASTM procedures...... 432 UN Test H3—Isothermal storage test...... 432 Empirical or qualitative tests ...... 433 Mackey test and related tests ...... 433 Ordway test ...... 433 Mackey test ...... 433 ASTM E 771 test ...... 434 ASTM E 476...... 434 UN Test O1 for oxidizing solids...... 434 UN Test O2 for oxidizing liquids ...... 435 UN Test S1—Trough test for fertilizers containing nitrates...... 435 Bureau of Mines dust layer ignition temperature test ...... 435 Oxygen consumption calorimetry...... 435 Further readings ...... 436 References...... 436
Chapter 10. Explosives, pyrotechnics and reactive substances
Highlights and summary of practical guidance ...... 445 Unstable substances...... 446 Heat of formation ...... 447 Heat of decomposition ...... 447 Self-heating of liquids...... 448 Theory ...... 449 Experimental studies...... 451 Self-heating of solids...... 451 Runaway exothermic reactions...... 451 Reactive substances ...... 452 Explosives ...... 452 Types of explosives ...... 454 Chemistry of explosives...... 455 Oxygen balance ...... 456 Initiation and ignition...... 457 Self-heating, stability in storage, and exposure to heat...... 457 Impact and shock...... 459 Flames ...... 464 Radiant heating...... 465 Hot bodies in contact ...... 465 Friction ...... 466 Compression...... 466 Electricity ...... 466 Light energy and ionizing radiation...... 468 Crystal growth ...... 469 RF initiation...... 469 Modeling detonation ...... 469 Ignition of air/fuel-gas atmospheres by condensed-phase explosives...... 470 Variables affecting the behavior of explosives...... 470 Practical applications ...... 472 Initiating devices ...... 472 Permissible explosives...... 473 Blasting agents...... 474 Insensitive munitions...... 474 Safe distances for storage ...... 474 Propellants...... 475 Ignition theory and experimental data ...... 476 Pyrotechnics ...... 479 Chemistry of pyrotechnic reactions...... 480 Practical applications ...... 481 Test methods ...... 482 UN tests ...... 482 Drop-hammer tests ...... 483 Koenen/BAM friction sensitivity test...... 483 Card-gap test...... 484 Readily combustible solids...... 484 Pyrophoric solids...... 484 Pyrophoric liquids ...... 485 Water-reactive solids or liquids...... 485 Oxidizing solids...... 485 Oxidizing liquids...... 485 US military standard tests...... 485 Vacuum stability and chemical decomposition tests...... 485 Laboratory scale impact test...... 486 Electrostatic sensitivity test...... 486 Adiabatic sensitivity test ...... 487 Cookoff tests ...... 487 Shock initiation sensitivity test...... 487 Henkin test for explosion temperature ...... 487 Sensitivity to initiation ...... 488 Permissible explosives...... 488 Other tests...... 488 Pendulum friction test for glancing blows...... 488 NOL thermal sensitivity test...... 488 Bureau of Mines test for oxidizing solids...... 489 LLNL Steven test ...... 489 Further readings ...... 489 References ...... 490
Chapter 11. Characteristics of external ignition sources
Highlights and summary of practical guidance ...... 498 Introduction ...... 499 High ambient temperatures ...... 499 Hot solids or liquids...... 499 Large hot surfaces in contact—Theory ...... 500 Small hot objects—Theory ...... 500 Airborne burning objects (flying brands) ...... 500 Ignition of buildings...... 501 Ignition of wildland fires...... 503 Prediction of spotting distances ...... 503 Exhaust particles...... 505 Welding spatter...... 506 Brands ejected from fireplace...... 507 Friction and mechanical sparks...... 507 General principles ...... 507 Ignition of flammable gas atmospheres ...... 509 Ignition of dust clouds and layers of porous materials...... 515 Shock, impact, pressure, vibration ...... 517 Shock and impact ...... 517 Dropped objects...... 517 High-velocity impacting particles (unheated)...... 517 Pressure (compression ignition) ...... 517 Vibration ...... 518 Flames or remote objects ...... 518 Small burner flames and small burning objects...... 518 Larger flaming sources and burners ...... 519 Kitchen sources...... 519 Large laboratory burners...... 519 Jets and high velocity burners...... 519 Solid-fuel ignition sources ...... 520 Burning fabrics ...... 520 Burning furniture...... 520 Large burning objects...... 521 Liquid pools , wood cribs...... 521 Fireballs and jet flames ...... 524 Burning buildings...... 527 Burning forests and vegetation...... 531 Burning vehicles ...... 532 Heat fluxes in pre-flashover room fires ...... 532 Heat fluxes on burning walls...... 532 Heat fluxes in post-flashover room fires...... 532 Attenuation of radiation by window glass and window screens...... 533 Electric phenomena...... 534 Electric discharges...... 534 The electric spark...... 537 The electric arc...... 540 Electric current ...... 548 Overheating wires ...... 549 Overheating electrical connections...... 549 Ejection of hot particles...... 553 Dendrites...... 553 Adventitious batteries...... 553 Static electricity...... 553 General principles...... 553 Discharge types...... 554 Measuring of discharges...... 557 Electrostatic charging and discharging of solids...... 557 Electrostatic charging and discharging of persons and apparel ...... 559 Electrostatic charging and discharging of granular materials...... 561 Electrostatic charging and discharging of liquids...... 562 Safety measures...... 567 Lightning...... 567 Ordinary lightning...... 567 St. Elmo’s fire...... 569 Ball lightning ...... 570 Exploding wires...... 571 Electromagnetic waves and particulate radiation ...... 571 Eddy currents...... 571 Radio transmitters ...... 572 Nuclear weapons ...... 574 Light energy, lenses and mirrors...... 575 Aerodynamic heating ...... 576 Further readings ...... 576 References...... 577
Chapter 12. Preventive measures
General precautions ...... 591 Measures against static electricity ...... 591 Lightning protection...... 592 Arresters—flame and spark ...... 594 Flame arresters...... 594 Spark arresters ...... 596 Design of electrical equipment for flammable atmospheres ...... 596 NEC requirements ...... 596 Article 500 (traditional classification)...... 597 Article 505 (IEC classification)...... 599 Design of equipment for hazardous locations ...... 599 Explosionproof equipment ...... 600 Dust-ignition-proof equipment...... 601 Intrinsically safe equipment ...... 601 Increased safety protection...... 603 Pressurized enclosures...... 603 Sealed, encapsulated, oil-immersed, and powder-filled devices ...... 603 Miscellaneous protection strategies...... 604 Design of equipment for mining ...... 604 Arc fault and cord fault interrupters ...... 604 Further readings ...... 604 References ...... 605
Chapter 13. Special topics
Explosions in buildings...... 609 Diffusion of flammable vapors from spills ...... 612 Ignition of gas jets from broken pipes...... 614 Damages and ignitions from gas explosions ...... 614 Ignition in room fires...... 615 Upper layer ignition in room fires ...... 616 Backdrafts and smoke explosions...... 617 Rekindle ignitions ...... 618 Unconfined vapor cloud explosions (UVCEs)...... 619 BLEVEs (boiling liquid, expanding vapor explosions)...... 619 Oxygen-enriched atmospheres...... 625 Test methods ...... 628 ASTM G 72 autoignition test ...... 628 ASTM G 124 piloted ignition test for metals ...... 628 ASTM G 74 gas stream impact test...... 628 ASTM D 2512 and ASTM G 86 mechanical impact tests ...... 628 ASTM G 125 oxygen-index test for oxygen-enriched atmospheres ...... 629 Wildland-urban interface...... 629 Determining ignition properties in fire investigations ...... 631 Further readings ...... 631 References ...... 632
Chapter 14. Information on specific materials and devices
Introduction ...... 683 Accelerants in incendiary fires...... 683 Acetylene and related compounds...... 683 Aerosol cans ...... 687 Agricultural products...... 687 Self-heating ...... 687 Electrostatic properties...... 688 Air compressors and compressed air systems ...... 688 Aircraft cabin wall panels ...... 691 Airplanes ...... 691 Alcoholic beverages...... 691 Aldehydes...... 691 Ammonia ...... 692 Ammonium nitrate and ANFO ...... 692 Ammonium perchlorate...... 694 Antifreeze...... 696 Arsenic compounds ...... 696 Ashes ...... 696 Asphalt...... 696 Automatic transmission fluid...... 696 Aviation fuels ...... 696 Azides...... 700 Bagasse and bagasse products ...... 700 Boranes...... 701 Boron ...... 702 Brake fluid...... 702 Calcium resinate...... 703 Camping fuel ...... 703 Candles ...... 703 Tea candles...... 704 Gel candles ...... 705 Carbon disulfide ...... 705 Carbon monoxide...... 705 Cellulose...... 705 Cellulose insulation ...... 706 Cellulose nitrate, Celluloid, pyroxylin ...... 708 Charcoal, coke, and related products ...... 711 Charcoal ...... 711 Charcoal briquettes ...... 712 Coke...... 713 Activated charcoal...... 713 Activated carbon ...... 715 Chimneys and flues ...... 715 5-Chloro-1,2,3-thiadiazole...... 716 Christmas trees, artificial...... 716 Cigarettes and cigars...... 717 Clothes irons ...... 720 CO2 extinguishers...... 720 Coal ...... 720 Properties of coal ...... 720 Porosity and sorption of water...... 720 External ignition ...... 721 Self-heating...... 721 Coal dust ...... 725 Coal pulverizers...... 725 Coffeemakers and teapots ...... 726 Composite materials ...... 726 Fiber-reinforced plastic...... 726 High-pressure laminates, low-pressure laminates, and related products...... 727 Compost, manure, garbage, sewage, and landfills...... 727 Computer and information technology equipment...... 727 Conveyor belts...... 728 Cooking appliances ...... 728 Grills ...... 730 Cork ...... 730 Cotton ...... 730 Crankcase explosions ...... 731 Crude oil ...... 732 Curling irons and hair dryers...... 732 Curtains...... 732 Diapers, disposable...... 733 Diesel fuel...... 733 Dinitrosopentamethylenetetramine ...... 733 Dishwashers...... 733 Dryers and washers (for clothes)...... 733 Dryers (process dryers)...... 735 Dung, fecal matter...... 736 Dusts...... 736 Ignition of layers ...... 736 Explosions ...... 737 Earthquakes...... 738 Electric (general statistics) ...... 738 Electric appliances and electronic equipment ...... 741 High-limit switches...... 742 Electric batteries ...... 743 Electric blankets and mattress pads...... 744 Electric circuit interruption devices...... 745 Electric fences...... 748 Electric lamps and lighting fixtures...... 748 Ordinary incandescent lamps ...... 748 Halogen lamps...... 750 Arc discharge lamps...... 752 Fluorescent lamps ...... 753 Lighting fixtures: Incandescent ...... 753 Christmas tree lights...... 754 Lighting fixtures: Fluorescent...... 755 Electric motors ...... 756 Electric outlets, plugs and connections...... 756 Failures at plugs...... 757 Failures at outlets...... 760 Miscellaneous connection failures ...... 763 The aluminum wiring problem ...... 764 Incendiarism ...... 767 Electric switches ...... 767 Electric transmission and distribution systems ...... 767 Transformers...... 767 Busbars, switchboards, and panelboards...... 770 Insulated distribution cables...... 773 Service drops and high current capacity conduits ...... 774 High voltage insulators...... 774 Electric wires and cables...... 775 Modes of ignition of wiring...... 775 Arcing...... 775 Excessive ohmic heating ...... 781 Ignition from external heating...... 786 Contributory factors...... 788 Mechanical injury...... 788 Poor splices or terminations ...... 792 Degradation and aging of insulation...... 792 Partial discharges...... 794 Chemical damage ...... 794 Alloying during melting ...... 794 Appliance cords and extension cords ...... 795 Impaired cooling...... 795 Wires in steel conduits...... 796 Electric wiring: Cause or victim? ...... 796 Arc beads and fire-melted wires...... 796 Proposed methods of distinguishing ‘cause’ from ‘victim’ beads...... 798 Viability of proposed schemes ...... 804 Electric wiring and equipment in motor vehicles...... 805 Electric wiring in aircraft...... 805 Electronic components ...... 807 Engines, diesel...... 807 Ethers...... 807 Ethylene ...... 808 Ethylene glycol ...... 808 Ethylene oxide ...... 809 Explosives...... 812 Fabrics ...... 817 Ignition temperature...... 819 Flame ignition...... 820 Radiant ignition...... 823 Convective heating ...... 825 Other forms of heating ...... 826 Elevated oxygen conditions...... 827 Effects of treatments...... 827 Farm machinery...... 828 Feedstuffs...... 828 Felt...... 828 Fertilizers ...... 828 Fibers ...... 829 Fibers covered with oil...... 829 Fire hoses ...... 831 Fishmeal...... 831 Floor buffers...... 831 Floor coverings...... 831 Foodstuffs...... 835 Forest materials, vegetation, and hay ...... 835 Ignition by hot gases and hot surfaces...... 837 Ignition by matches and small flames ...... 839 Ignition by cigarettes...... 841 Ignition by lightning...... 842 Ignition from contact with power lines ...... 842 Radiant ignition ...... 843 Ignition by brands or small hot particles...... 844 Spotting fires ...... 846 Self-heating...... 847 Fuel oil...... 849 Furnaces and boilers...... 849 Gas-fired...... 850 Oil-fired...... 850 Furniture ...... 851 Gas meters, regulators, and piping ...... 851 Gasoline ...... 851 Gasoline substitutes ...... 853 Filling of portable gasoline containers...... 853 Fueling vehicles at filling stations...... 854 Filling station tanks ...... 855 Ground fault circuit interrupters...... 855 Gypsum wallboard ...... 855 Hair ...... 856 Hairdresser chemicals ...... 856 Heat guns...... 856 Heat tapes and heat cables...... 856 Heat transfer liquids...... 858 Heaters, catalytic...... 858 Heaters, electric...... 858 Built-in heaters...... 858 Portable heaters ...... 860 House furnaces ...... 860 Heating equipment (general statistics) ...... 860 High-temperature accelerants...... 860 Hops ...... 861 Humans...... 861 Human skin ...... 863 HVAC equipment...... 864 Hydraulic fluids ...... 864 Hydrazine...... 864 Hydrocarbon gases ...... 865 Hydrogen...... 865 Explosions due to adventitious hydrogen presence...... 866 Hydroxylamine...... 866 Incendiary timing, delay, and actuation devices...... 866 Insecticides, pesticides, fungicides...... 866 Iron sulfides...... 866 Jute...... 867 Kerosene ...... 867 Kerosene heaters ...... 867 Lambswool pads, imitation...... 868 Lawn mowers...... 868 Lime...... 868 LNG and LPG ...... 868 Marijuana and hemp...... 869 Matches and lighters ...... 869 Properties of matches ...... 869 Ignition potential of blown-out matches ...... 871 Lighters ...... 871 Metal alkyls...... 871 Metal alloys...... 872 Metal carbonyls...... 872 Metal hydrides...... 872 Metal oxides...... 872 Metals...... 872 Aluminum...... 872 Bulk material...... 872 Single particles ...... 873 Dust clouds and layers...... 873 Aluminum in physical mixtures ...... 874 Antimony...... 874 Barium ...... 874 Beryllium ...... 874 Bismuth...... 874 Brass...... 874 Cadmium...... 874 Calcium...... 874 Cerium, pyrophor, and cigarette-lighter ‘flints’...... 874 Cesium ...... 875 Chromium...... 875 Cobalt...... 875 Copper...... 875 Hafnium ...... 875 Iron and steel...... 875 Lead ...... 876 Lithium...... 876 Magnesium...... 876 Manganese ...... 877 Molybdenum ...... 877 Nickel ...... 877 Plutonium ...... 878 Potassium...... 878 Rare earth elements ...... 878 Rubidium...... 878 Sodium ...... 878 Strontium...... 878 Tantalum...... 878 Thorium...... 879 Tin...... 879 Titanium ...... 879 Tungsten ...... 880 Uranium...... 880 Zinc ...... 880 Zirconium ...... 880 Methane and natural gas...... 881 Methyl bromide...... 882 Methylene chloride...... 882 Microwave ovens...... 882 Mineral wool...... 882 Motor vehicles ...... 883 Flammability of interior combustibles...... 885 Automobile exhaust systems ...... 885 Automotive air bags ...... 886 Flammable refrigerants ...... 887 Neon lighting...... 887 Nitrates...... 887 Nitric acid and nitrogen oxides ...... 887 Nitrides ...... 888 Nitrogen, liquid...... 888 Oils...... 888 Vegetable and animal oils...... 888 The iodine number test...... 890 Mineral and synthetic oils...... 892 Oil-water emulsions ...... 892 Organometallic compounds ...... 892 Otto fuel II...... 892 Oxidizing chemicals ...... 892 Halogen fluorides ...... 893 Gaseous fluorine...... 893 Liquid chlorine ...... 893 Water purifying and bleaching chemicals ...... 893 Carbon tetrachloride...... 896 Aircraft oxygen generation canisters...... 896 Compressed gaseous oxygen ...... 897 Liquid oxygen...... 897 Oxygen pumps...... 898 Oxygen regulators...... 898 Paints, dyes, and related substances...... 898 Paper products...... 900 Paper ...... 900 Cardboard...... 901 Paper vapor barrier ...... 902 Peat and organic soils...... 902 Perchloric acid ...... 903 Perfluorocarbons...... 904 Peroxides...... 904 Inorganic peroxides...... 904 Organic peroxides ...... 904 Pharmaceuticals...... 905 Phosphines...... 905 Phosphorus...... 905 Pillows...... 905 Pipe insulation...... 906 Plastics...... 907 Self-heating of solid plastics...... 911 Elastomers and foams...... 911 Potassium chlorate...... 914 Powdered milk ...... 915 Power steering fluid ...... 915 Propane ...... 915 Propylene oxide...... 915 Pyrotechnics...... 915 Radio and audio equipment ...... 920 Railroads...... 920 Rayon...... 920 Refrigerators ...... 920 Rice husks ...... 921 Roofing materials...... 921 Sanding machines...... 921 Saunas ...... 922 Shredded materials...... 922 Siding, plastic ...... 922 Silane and chlorosilanes...... 922 Silicon ...... 923 Silicone fluids and polymers...... 923 Skins and leathers...... 923 Soaps ...... 923 Sodium chlorate and sodium chlorite...... 923 Sodium dithionite...... 924 Solder and soldering irons...... 924 Soots, lampblack, other ‘blacks’...... 924 Soybeans...... 924 Spas...... 924 Stearic acid...... 924 Steel turnings...... 924 Styrene...... 924 Sugar...... 925 Sulfur...... 925 Surge suppressor MOV devices ...... 925 Surgical tubing ...... 925 Tanks ...... 925 Asphalt storage tanks ...... 926 Tar (wood)...... 926 Telephones, cellular...... 926 Television sets and computer monitors ...... 926 Tents ...... 928 Textile wall coverings...... 928 Thatch...... 928 Thermostats...... 928 Tinder ...... 928 Tires and wheels...... 928 Toasters ...... 930 Town gas...... 930 Turpentine...... 930 Unsymmetrical dimethylhydrazine...... 930 Upholstered furniture and mattresses...... 930 Smoldering and ignition from cigarettes...... 930 The possibility of safer cigarettes ...... 932 Ignition from small flames ...... 933 Ignitability from radiant heat...... 934 Ignition from burning brands ...... 936 Ignitability mode comparisons ...... 936 Effect of wear and soiling ...... 937 UFAC and BIFMA requirements for ignitability ...... 937 California TB 117 standard for ignitability ...... 938 Flaming-source ignition experiments and proposed test by CPSC...... 938 UK furniture regulations ...... 939 Mattresses ...... 939 Vacuum cleaners ...... 940 Wastes...... 941 Water heaters...... 941 Electric water heaters ...... 941 Gas-fired water heaters...... 941 Welding...... 943 Wood and related products ...... 944 Whole wood ...... 944 Properties of wood and its degradation and combustion ...... 944 Ignition temperature of wood ...... 947 Ignition from radiant heat flux...... 948 Ignition from flames ...... 952 Glowing or smoldering ignition and ignition by firebrands ...... 952 Ignition from other external heating sources...... 954 Effects of various factors on external ignition of wood ...... 954 Self-heating, ‘pyrophoric carbon,’ and ignitions from hot pipes...... 957 Ignition by arc tracking ...... 962 Wood components ...... 963 Painted wood...... 964 Hardboard ...... 964 Fiberboard ...... 964 Plywood...... 966 Particleboard and oriented strand board...... 967 Wood sawdust, chips, and wastes ...... 967 Oiled sawdust ...... 968 Wood pulp...... 969 Shingles and shakes...... 969 Wood-burning appliances...... 969 Wool ...... 969 Further readings ...... 970 References ...... 971
Chapter 15. Tables
Introduction...... 1022 Pure chemical substances ...... 1024 Mixtures and commercial products...... 1056 Aviation hydraulic fluids and lubricating oils...... 1059 Refrigerants...... 1060 NEC Groups according to chemical families ...... 1061 Dusts...... 1062 Ignition temperatures of solids ...... 1066 Radiant ignition of plastics and elastomers...... 1070 Miscellaneous thermophysical properties of solids...... 1072 Further readings ...... 1077 References...... 1077