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  • 1. Chapter 7 Reading Smoke
  • 2. Objectives
    • Define “smoke”
    • List common hostile fire events and their associated warning signs
    • List the four attributes of smoke
    • Describe what each of the four smoke attributes contributes to the understanding of fire behavior in a building
  • 3. Objectives (con’t.)
    • Define “black fire” and its relevance to firefighting efforts
    • Explain how influencing factors can affect smoke attributes
    • List the three steps in the reading smoke process
  • 4. Introduction
    • History of reading smoke
      • Older practices of reading smoke based on experience and intuitiveness
      • Low-mass synthetics and the consumer “glut” in the 1990s led to a more volatile smoke and fire environment
      • Current trends of reading smoke triggered by ISO Academies in 1990s
        • Developed by David Ross and David Dodson
  • 5. “ Smoke” Defined
    • Smoke
      • Product of incomplete combustion
      • Aggregate of solids, aerosols, and fire gases
      • Toxic, flammable, and volatile
    • Four key attributes of smoke
      • Volume
      • Velocity (pressure)
      • Density
      • Color
  • 6. Table 7-1 Properties of gases typically found in smoke.
  • 7. “ Smoke” Defined (con’t.)
    • “ Open flaming” is desirable
      • Products of combustion are minimized
      • Smoke displaces air in underventilated fires
    • Two triggers cause accumulated smoke to ignite
      • Right temperature
      • Right mixture
    • Watch smoke instead of focusing on flaming
  • 8. Hostile Fire Events
    • Events that can catch firefighters off guard and endanger them
      • Flashover
      • Backdraft
      • Smoke explosions
      • Rapid fire spread
    • ISOs must know and watch for proactive warning signs of hostile fire events
  • 9. Table 7-2 Hostile fire events.
  • 10. Volume, Velocity, Density, and Color Figure 7-2 Comparing smoke volume, velocity, density, and color can help the ISO understand fire behavior. (Photo by Keith Muratori.)
  • 11. Volume, Velocity, Density, and Color (con’t.)
    • Volume
      • May indicate the amount of fuel that is off-gassing in a given amount of space
      • High volume of smoke can occur with:
        • Hot, fast moving fire in an underventilated building
        • Dampened material
        • Low mass contents
      • High volume of smoke can create the impression of a fire
  • 12. Volume, Velocity, Density, and Color (con’t.)
    • Velocity
      • Speed at which smoke leaves a building
      • Indicator of pressure within building
      • Turbulent smoke flow
        • Ready to ignite
        • Flashover is likely to occur
      • Laminar smoke flow
        • Stable and smooth smoke flow
        • Heat of smoke is being absorbed
  • 13. Volume, Velocity, Density, and Color (con’t.)
    • Density
      • Refers to the thickness of smoke
      • Indicates how much fuel is laden in the smoke
      • Thick smoke spreads a fire event farther than less dense smoke
      • Thick black smoke in a compartment reduces the chance of life sustainability
  • 14. Volume, Velocity, Density, and Color (con’t.)
    • Color
      • Indicates the stage of heating
      • Points to the location of the fire in a building
      • The more black the smoke, the hotter the smoke
        • High velocity, low density black smoke is flame-pushed
        • Interpreted, thin black smoke indicates nearby open flaming
  • 15. Volume, Velocity, Density, and Color (con’t.)
    • Color (con’t.)
      • Can indicate distance from fire
        • Fast moving white smoke has traveled
      • Brown smoke from structural spaces
        • Indicates transition from a contents to a structural fire
    • Watch for the fastest/darkest smoke from the most resistive crack (Dave Dodson)
  • 16. Figure 7-5 Smoke that appears the same color and velocity from multiple openings indicates a deep-seated fire. (Photo by Keith Muratori.)
  • 17. Volume, Velocity, Density, and Color (con’t.)
    • Black fire
      • Slang term to describe high-volume, turbulent, ultradense, and deep-black smoke
      • Sure sign of impending autoignition and flashover
      • Can reach temperatures of over 1,000 degrees Fahrenheit
      • Solution: vent and cool!
  • 18. Other Factors That Influence Smoke
    • Weather
      • Temperature, humidity, and wind change the look of smoke
      • Cold air cools smoke faster, causes it to stall/fall, and turns it white
      • Humidity increases air resistance to smoke
      • Wind-fed fires can cause firefighters to be overrun
  • 19. Other Factors That Influence Smoke (con’t.)
    • Thermal balance
      • Notion that heated smoke rises and creates a draft of cool air into the flame source
      • Not maintained in most fires within buildings
      • Indicated by air being sucked into a building
        • Intense fire struggling for airflow
        • Sudden inflow of air can trap firefighters
  • 20. Other Factors That Influence Smoke (con’t.)
    • Container size
      • All smoke observations must be analyzed in proportion to the building
      • Size of the building is an important indicator of the significance of the smoke leaving it
        • Example: light, thin smoke showing from more than one opening of a very large building may indicate a large, dangerous fire
  • 21. Other Factors That Influence Smoke (con’t.)
    • Firefighting efforts
      • Four attributes of smoke should change in a positive manner if fire stream and ventilation efforts are appropriate
        • Volume should rise
        • Velocity should gradually slow and change to laminar flow
        • Density should thin
        • Color should eventually turn white
  • 22. Other Factors That Influence Smoke (con’t.)
    • Firefighting efforts (con’t.)
      • Forced-ventilation tactics should cause an increase in smoke velocity
      • PPV tactics are contraindicated if:
        • Smoke is turbulent
        • Location of fire seat is unknown
        • Fire is in a vented, combustible void space
        • Smoke become thicker and darker during PPV use
  • 23. Reading Smoke: The Three-Step Process
    • Step 1
      • View the volume, velocity, density, and color of smoke
      • Compare the difference in the attributes from each opening from which smoke is emitting
  • 24. Reading Smoke: The Three-Step Process (con’t.)
    • Step 2
      • Analyze contributing factors (size, weather, firefighting efforts) to determine if they are affecting volume, velocity, density, and color
    • Step 3
      • Determine the rate of change of each attribute
        • If deterioration can be measured in seconds, firefighters are at risk
  • 25. Table 7-3 Reading smoke shortcuts.
  • 26. Summary
    • Predicting fire behavior is based on understanding:
      • Physical and chemical properties of smoke
        • Volume, velocity, density, and color
      • Proactive warning signs of hostile fire events
      • Factors that influence smoke
        • Weather, container size, thermal balance, and firefighting efforts
      • Rate of change in smoke attributes