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Behavior of Fire.pptx

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Behavior of Fire.pptx

  1. 1. Chapter 3 Presented by: Ahmed Rashdee Indal Al-Rashid Biting Mohammad Alih S. Hashim (BSCRIM 3A)
  2. 2. It used to describe the magnitude, direction, and intensity of fire spread.
  3. 3.  Conduction - it describes the transfer of heat within a solid material from hotter to cooler parts.  Convection - it describe a mass movement in a fluid i.e., a liquid or a gas where fluid at one temperature and density moves under the influence of gravity through surrounding fluid at a different temperature and density.  Radiation - it describe the transfer of heat through a gas or vacuum in a similar way to light.
  4. 4. 1. Incipient - the product in this phase may be so minuscule as to be detected only by an ionization detector. 2. Emergent Smoldering - in this phase, the product of combustion become increasingly more pronounced. There is no meaningful change in the oxygen content of the air. 3. Free-Burning - during this phase of the fire, the rate and intensity of open burning increases geometrically. Flashover is the best example for this phase. › Flashover - is defined as a stage in the development of contained fire in which all exposed surfaces reach ignition temperature, more or less simultaneously, and fire spreads rapidly. 4. Oxygen - regulated smoldering - if the room or area of the fire's origin is adequately airtight, thereby limiting the amount of oxygen-rich air being drawn into that area, then the open burning that occurs in free-burning phase will deplete the available oxygen. › Back draft - sudden and rapid (violent) burning of heated gasses in a confined area that occurs in the form of explosion
  5. 5. 1. Fuel – It is the name given to the suite of variable used o describe the vegetation the fire is spreading through. 2. Slope – Assuming all other condition are equal, the rate of spread of a fire increases as slope increases. 3. Aspect – in general, south-facing slope receive more direct sunlight throughout the day in comparison to north-facing slopes. 4. Weather – components of weather which influence fire spread are wind speed, wind direction, and moisture present in the fuel.
  6. 6. Different kind of fires burn at different rates, one fire may slowly smolder, while another may quickly use up its fuel. The rate of at which a fire burns depends on the composition of the fuel, the surface area of the fuel, and the amount of oxygen that is available. Most plastics burn at twice the rate of cellulose fuels, such as wood and leaves because of the different chemical reactions involved. Kindling use of small twigs and pieces of woods to start a camp fire.
  7. 7. 1. The total surface of material available for combustion, more substantial materials, such as most timbers will only burn at the outer surface. 2. The quantity of heat energy locked in the chemical composition which can be release by burning; which can vary considerably for different material 3. The length of flames produced; flames radiate heat and the size of the flames affects the intensity 4. The Adequacy of the supply of oxygen to the fire, the total surface area of the material available for combustion, and he length of flames produced.
  8. 8. 1. Structural Fire Spread Fire spread involves the extension of fire from one point to another. The transfer of heat and wind facrors plays a large role in this extension. 2. Direction and rate of Spread heat from the fire in the open rises as a column of hot gas called plume. In doing so, it pre-heats any fuel or combustible materials located above the point of origin and when heated sufficiently, this ignites greatly increasing the volume and upper progression of Flame. The resulting air flow draws cool air into the base of the fire from all direction. This in-flow air into the plume is called Entrainment. 3. Chimney effect since there is natural tendency for flame and heated gases to rise, any structural element that enhances this upward movement serve as a natural chimney effect. Such enhancement is called the chimney effect
  9. 9. 1. V Pattern - Fire, if unobstructed, will shoot upward and fan out, often registering as a "V" or cone pattern left after the fire is put out.
  10. 10. 2. Pour Patterns - The kind of burn pattern that results from pouring an accelerant on the floor of the room is particularly important.
  11. 11. 3. Alligatoring – Anyone who has observed the partially burned residue of a campfire is familiar with how the blisters on the logs resemble the skin of an alligator.
  12. 12. 4. Charring - The charring of wood inevitably is observed in structural fires and can be an indicator of fire travel and point of origin.
  13. 13. The upward movement of flame can be affected and altered by many factors. Among the most common are the following: 1. A draft or crosswind from an open window, door or skylight. 2. An available secondary fuel source in close proximity to the original point of ignition. 3. A highly combustible fuel at the point of origin, e,g., A large pool of liquid accelerant, when ignited, causes the apex of "V" to be at least as wide as the pool. 4. Environmental consideration, such as class and type of construction, and other conditions that might impede or block the upward progression of the products of combustion.
  14. 14.  The density and color of the smoke and flame associated with a particular fire can show the type of material or fuel that is burning.  The color of the flames can also indicate the approximate temperature of the flame.  Fire suppression efforts will also affect the color of the smoke. The application of water can produce large volume of condensing vapor that appears white or gray when mixed with black smoke from the fire.
  15. 15.  White smoke – indicates light fuels burning or from pre combustion/Dehydration of fuels  Tan and Brown smoke – woody materials burning and poor air quality  Grey smoke – indicates that a fire is slowing down or running out of combustible material to burn.  Black smoke – heavy and or oily/resinous fuels and man-made material burning
  16. 16. The way that a fire develops is affected by many factors. As fire continue to grow, Environmental factors become increasingly important in influencing its extent.  Amount of oxygen  Fuel supply and composition  Fire suppression
  17. 17.  The energy released by combustion causes rise in temperature of the product of combustion. The temperature attained depends on the rate of release of the energy and the quantity of combustion products.  Most combustible processes release energy, or heat, for the production of power, for use in industrial processes, and for domestic heating and lighting
  18. 18. 1 en and of 2 3
  19. 19. MOST COMMON CAUSES OF HOUSE FIRE 47% 32% 10% 3% 7% Electrical Gas Leaks Open Flames (e.g. candles, fireplaces) Children Playing Fires Spreading of fires from house to house
  20. 20. END OF THE PRESENTATION

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