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Fire Behavior Understanding the Basics

Fire Behavior Understanding the Basics. Pat Hultman FF/MICT/LEO-AAS Training Officer. Learning Outcomes. List different types of Extreme Fire Behavior Differentiate between Fuel and Air controlled fires Understand the importance of reading smoke and fire

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Fire Behavior Understanding the Basics

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  1. Fire Behavior Understanding the Basics Pat Hultman FF/MICT/LEO-AAS Training Officer

  2. Learning Outcomes • List different types of Extreme Fire Behavior • Differentiate between Fuel and Air controlled fires • Understand the importance of reading smoke and fire • Appreciate the dangers assosciated in regards to extreme fire behavior

  3. Why this matters • In 2007, 20 LODD due to Extreme Fire Behavior. Plus numerous close calls. Video 4.5 min. !!!1:41!!!

  4. Fire Tetrahedron • Fire Triangle • H2O?? • Combustion

  5. Flame Types

  6. Fuel State • What Burns? • So how does a solid burn? • Pyrolisis

  7. Common Fire Gases CO HCN Hydro Carbons Methane Propane Pyrolisis Decomposition by heat ↑ build up of combustible gases Where does the heat come from? Fire Gases and Pyrolisis

  8. Heat Transfer • Conduction • Direct transfer through contact • Convection • Transfer through a medium such as air, H2O, etc • Radiation • Transfer in the form of light energy

  9. Is radiant heat visible? At 900° F visible Heat Release Rate Cigarette 5w Wastebasket 50-150 KW Pool of Gasoline (2 QTS) 1MW Sofa 1-3 MW Direct Summer Sun 1kw/m² 100° F Surface No Pain Near Proximity to Fireplace 10kw/m² 200-300° F Surface 2° Burns ≤ 10Sec Scorching of and Melting of Adjacent to flames 50 kw/m² 800° F Surface Autoignition of nearly all materials in ≤ 5 sec Understanding Radiant Heat The avg residential fire will double in size every 15-30 secs

  10. Limits of Flamability • LFL/UFL • What are some materials you can think of? • Propane 2.1-9.5% Ideal 4% • Gasoline 1-6% • Acetylene 2.5-80% • CO 12.5-74% What is this in PPM (move decimal right add 3 zeros) • Think about the CGI • We know we are immersed in flammable gases when going into a fire

  11. Smoke is Fuel Smoke Video

  12. Smoke is Fuel

  13. The Neutral Plane • Two Separate Layers • Hot Buoyant Combustible gas • Major source of radiant heat • Cooler, cleaner • Commonly discussed as thermal layering (Discussed More Later)

  14. Stages of Fire Phase 1 Incipient and Growth Stage What is happening? What is the next phase? Phase 2 Flashover What happened? Auto-ignition temp What is the significance? Transition From Room and Contents Phase 3 Fully Developed Phase 4 Decay Stage What is a significant threat at this stage? Fire Progression

  15. Smoke Explosion Flame Over Flash Fire Fire Gas Ignitions Flashover Back Draft Extreme Fire Behavior These are not some strange uncontrolled phenomenen. There are key things to watch for both inside on the knob and outside as IC. The Firefighter must remain ever vigilant of the conditions around them

  16. Flashover • Sudden and Sustained transition from a developing fire to a fully developed fire. • 2/3rds of the heat is radiated down from the neutral plane Video 1:01

  17. Signs and Symptoms of Flashover • Ventilated Fire • Painful Radiant Heat (forces you down) • Hot Surfaces (Conduction) • Lowering Neutral Plane • Fingers of flame – Dancing angels • Increased Pyrolisis • Increased turbulence of smoke and flame

  18. Back Draft • The spontaneous ignition of combustible fire gases. • What are some cause? Why? • Gases at auto ignition temperature • Lack of Oxygen • Pyrolisis will continue to occur until sufficient cooling Video 0:44

  19. Signs and Symptoms of Back Draft • No or limited ventilation • Lack of visible or blue flame • Thick rolling black, yellow, or white smoke • Smoke Pulsating/Whistling

  20. Point of No return • 5 feet (Chief Dunn) • Burns • 1° @ 118° F • 2° @ 131° F • 3° @ 152° F • Heat Output • Trash Can Fire

  21. Methods of Extinguishment • Direct vs. Indirect • Smooth Bore vs. Fog • Gas Cooling • Can disrupt neutral plane • Use small fine droplets in short bursts to minimize • How much water in GPM for a 19x16 MBR • 300 ft² approx • Round Up to 375 ft² or 3000 ft³ for chart • NFA- 125 GPM • Iowa – 30 GPM • 3D- 75 GPM

  22. Case Study • April 16 2007 • 24 Y/O Kyle Robert Wilson 2 yrs exp. • 0604 AM • Weather- 25 MPH sustained

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