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Questions and Answers
What is the normal human oral/body temperature in Celsius?
At what temperature does human skin receive a second degree burn injury?
What is the characteristic of a fully developed fire in the traditional fire development curve?
In a ventilation limited fire, what is the characteristic of the early fire growth stage?
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At what temperature does water boil and produce steam?
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What is the characteristic of temperatures above 300°C in relation to modern protective clothing fabrics?
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What occurs when a vent is opened during a fire, such as when the fire department enters a door?
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What is a characteristic of modern building materials and furniture that promotes rapid Heat Release Rates?
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What is the transition phase in the development of a contained fire, in which surfaces exposed to thermal radiation reach ignition temperature and fire spreads rapidly?
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What occurs when a fire takes place in a confined area and burns undetected until most of the oxygen within is consumed?
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What happens when a supply of oxygen is introduced to a confined area where a fire has been burning undetected?
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What is the term for a condition in which unburned fuel from the originating fire has accumulated in the ceiling layer to a sufficient concentration that it ignites and burns?
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Study Notes
Temperature and Firefighters
- Normal human body temperature is 37°C (98.6°F)
- At 44°C (111°F), human skin begins to feel pain
- At 48°C (118°F), human skin receives a first-degree burn injury
- At 55°C (131°F), human skin receives a second-degree burn injury
- At 62°C (140°F), a phase where burned human tissue becomes numb
- At 72°C (162°F), human skin is instantly destroyed
- At 100°C (212°F), water boils and produces steam
- At 140°C (284°F), glass transition temperature of polycarbonate
- At 230°C (446°F), the melting temperature of polycarbonate
- At 250°C (482°F), charring of natural cotton begins
- Above 300°C (572°F), charring of modern protective clothing fabrics begins
- Above 600°C (1112°F), temperatures inside a post-flashover room fire
Fire Development
- Traditional Fire Development curve shows the time history of a fuel-limited fire
- Fire growth is not limited by a lack of oxygen
- Energy level continues to increase until all fuel is burning (fully developed)
- As fuel is burned away, energy level begins to decay
- Oxygen is available to mix with heated gases (fuel) to enable the completion of the fire triangle and the generation of energy
Fire Behavior in a Structure
- Fire starts in a structure with closed doors and windows
- Early in the fire growth stage, there is adequate oxygen for flaming combustion
- As oxygen level within the structure is depleted, fire decays, heat release decreases, and temperature decreases
- When a vent is opened, oxygen is introduced, and energy level begins to increase, potentially leading to a flashover
Extreme Fire Events
- Modern construction materials and furnishings can rapidly reach temperatures contributing to Extreme Fire Events
- Extreme Fire Events can be classified as Flashover, Backdraft, Smoke Explosion, or Flame Over (Roll Over)
- Firefighters should be aware that rapid Heat Release Rates contribute to earlier Extreme Fire Events
- Flashover: transition phase where surfaces exposed to thermal radiation reach ignition temperature, and fire spreads rapidly
- Backdraft: phenomenon that occurs when a fire takes place in a confined area, burning undetected until most oxygen is consumed
- Flameover (Rollover): condition where unburned fuel accumulates in the ceiling layer, ignites, and burns
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