IFSTA Chapter 3 - Fire Behavior

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jessjohnson0617
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233036
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IFSTA Chapter 3 - Fire Behavior
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2013-09-05 15:54:25
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Fire Behavior
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Fire Behavior
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  1. Define Matter.
    anything that occupies space and has mass
  2. What is an exothermic heat reaction?
    • chemical reaction between two or more materials that changes the material and produces heat, flames, and toxic smoke
    • (heat is released)
  3. What is an endothermic heat reaction?
    chemical reaction in which a substance absorbs heat energy
  4. What is potential energy?
    • energy that is stored but not is use
    • energy that may be released in the future
  5. Define combustion
    • an exothermic chemical reaction that is a self-sustaining process of rapid oxidation of fuel
    • produces heat and light
  6. What are the 3 parts of the fire triangle?
    • heat
    • fuel
    • oxygen
  7. What are the 4 parts of the fire tetrahedron?
    • fuel
    • heat
    • oxygen
    • self-sustaining chemical reaction
  8. Define kinetic energy.
    the energy possessed by a moving object
  9. What are Btus?
    • unit of measurement for heat
    • the amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit
  10. Define pyrolysis.
    the chemical decomposition of a substance through the action of heat
  11. What is piloted ignition?
    occurs when a mixture of fuel and oxygen encounter an external heat course with sufficient heat energy to start the combustion reaction
  12. What is autoignition?
    • occurs without any external flame or spark to ignite the fuel or gases or vapors
    • fuel surface is chemically heated to the point at which combustion occurs
  13. True or false: The autoignition temperature of a substance is always higher that it's piloted ignition temperature.
    True
  14. Define autoignition temperature
    the temp to which the surface of a substance must be heated for ignition and self-sustaining combustion to occur
  15. True or False: Chemical heat energy is the most common source of heat in combustion reactions
    True
  16. Define self-heating.
    a form of chemical heat energy that occurs when a material increases in temperature without the addition of external heat
  17. What are the ways electrical heating can occur?
    • resistance heating
    • overcurrent or overload
    • arcing
    • sparking
  18. Define mechanical heat energy.
    heat energy generated by friction of compression
  19. What is heat of friction?
    heat created by the movement of two surfaces against each other
  20. What are the ways heat can be transferred from one body to another?
    • conduction
    • convection
    • radiation
  21. Define conduction.
    physical flow or transfer of heat energy from one body to another through direct contact or an intervening medium from the point where heat is produced
  22. Define convection
    the transfer of heat by the movement of heated fluids or gases, usually in an upward direction
  23. Define radiation.
    the transmission of heat energy as an electromagnetic wave, such as light waves, radio waves, or x-rays, without an intervening medium
  24. What are passive agents?
    • materials that absorb heat but do not participate actively in the combustion reaction
    • ex: fuel moisture - a well watered shrub will be slower to ignite than a dehydrated one
  25. What are inorganic fuels?
    • fuels that do not contain carbon
    • ex: hydrogen, magnesium
  26. What are organic fuels?
    fuels containing carbon
  27. What are examples of hydrocarbon fuels?
    • gasoline
    • fuel oil
    • plastics
  28. What are examples of cellulose-based materials?
    • wood
    • paper
  29. What are gaseous fuels?
    • fuels that are already in the sate required for ignition
    • ex: methane, hydrogen, acetylene
  30. Define vapor density.
    the density of gases in relation to air
  31. Define specific gravity.
    the weight of a substance compared to the weight of an equal volume of water at a given temp
  32. Define vaporization
    the process that charges a liquid into a gaseous state
  33. Define flash point
    minimum temperature at which a liquid gives off enough vapors to ignite, but not sustain combustion
  34. Define fire point
    the temperature at which sufficient vapors are being generated to sustain the combustion reaction
  35. What is solubility?
    the extent at which a substance will mix with water
  36. What is miscible?
    materials that are capable of being mixed
  37. Define heat release rate.
    • the energy released per unit of time as a given fuel burns
    • usually expressed in kilowatts
  38. What are common products of combustion?
    • Carbon monoxide (CO)
    • Hydrogen cyanide (HCH)
    • Carbon dioxide (CO2)
  39. What is a Class A fire?
    • involve ordinary combustible materials such as wood, cloth, paper, rubber, grass, and many plastics
    • water is most commonly used on Class A fires
  40. What is a Class B fire?
    • fires involving flammable and combustible liquids and gases such as gasoline, oil, lacquer, paint, mineral spirits, and alcohol
    • extinguished by cutting off gas supply, applying appropriate foam or dry chemical agents
  41. What are Class C fires?
    • involve energized electrical equipment such as household appliances, computers, transformers, electric motors
    • actual fuel burning is usually the insulation on wiring or lubricants
    • always cut the power if possible
  42. What are Class D fires?
    • involve combustible metals such as aluminum, magnesium, potassium, sodium, titanium
    • in the right concentrations, airborne metal dusts can cause powerful explosions when given an ignition
  43. What are Class K fires?
    involve oil and grease normally found in commercial kitchens
  44. Define saponification.
    • a endothermic way to put out class k fires
    • occurs when mixtures of alkaline-based chemicals and certain cooking oils come into contact and form a soapy film that absorbs heat
  45. What are the stages of fire development (in order)?
    • incipient
    • growth
    • fully developed
    • decay
  46. Define the incipient stage.
    • first stage of the burning process
    • the substance being oxidized is producing some heat but has not spread to other substances nearby
  47. Define the growth stage
    • early stage of fire development during which fuel and O2 are virtually unlimited
    • characterized by a rapid increase of heat
  48. Define thermal layering.
    the outcome of combustion in a confined space in which gases tend to form into layers, according to temp (hottest gases at the top/ceiling, coolest gases as the bottom/floor)
  49. What is the neutral plane?
    the interface of the hot and cooler gas layers (where they meet)
  50. What is a rollover?
    condition where the unburned fire gases accumulated at the top of a compartment ignite and flames propagate through the hot gas later or across the ceiling
  51. What is a flashover?
    stage of a fire at which all surfaces and objects within a space have been heated to their ignition temp and flame breaks out almost at once over the surface of all objects in the space
  52. What is the fully developed stage?
    stage of burning process where energy release in at maximum rate and is limited only by availability of fuel and O2
  53. What is the decay stage?
    • state of fire development when fuel is consumed, energy release diminishes, and temp decreases
    • fire goes from ventilation controlled to fuel controlled
  54. Define backdraft.
    instantaneous explosion or rapid burning of superheated gases that occurs when O2 introduced into an O2-depleted confined space
  55. What are the factors that affect fire development?
    • fuel type
    • availability and location of fuel in relation to the fire location
    • compartment geometry (volume/ceiling height)
    • ventilation and changes in ventilation
    • thermal properties of the enclosure
    • ambient conditions (wind, temp, humidity)
  56. When water is converted into steam at 212 degrees F, it expands approximately ____ times.
    1,700
  57. What is the most common method of fire control and extinguishment?
    cooling with water

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