Chapter 07


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Chapter 07

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