Chapter 2-Fire Behavior Flashcards
Transfer of heat energy by movement of heated liquids or air
Convection
Point-to-point transmission of heat energy
Conduction
Direct flame contact is actually a form of _________ heat transfer.
Convective
He transfer in a straight line
Radiation
_________ heat is one of the major sources of fire spread to structures
Radiated
Approved SI unit for all forms of energy including heat is ________.
Joule
The temperature of a substance when vapor pressure exceeds atmospheric pressure. At this temperature, the rate of evaporation exceeds the rate of condensation. At this point, more liquid is turning into gas than gas is turning back into a liquid.
Boiling point
Boiling point of water
212 degrees F
The amount of heat needed to raise the temperature of 1 pound of water 1°F.
British thermal units (BTU)
Amount of heat needed to raise temperature of 1 g of water 1°C
Calorie
The minimum temperature at which a liquid fuel gives off sufficient vapors to form an ignitable mixture with the air near the surface. At this temperature, ignited vapors will flash but will not continue to burn.
Flashpoint
The temperature at which a liquid fuel will produce vapor sufficient to support continuous combustion once ignited. The _______ is usually a few degrees above the flashpoint.
Firepoint
The minimum temperature to which a fuel in air must be heated to start self sustained combustion without a separate ignition source.
Ignition temperature
The percentage of a substance (vapor) in air that will burn once it is ignited. Most substances have an upper (too rich) and a lower (too lean) flammable limit.
Flammable or explosive limits
The material or substance being oxidized or burned in the combustion process.
Fuels
Flammable or explosive limits of:
Fuel Oil:
Methane:
Carbon Monoxide:
Propane
Fuel oil: 0.7-5
M: 5-15
CO: 12.5-74
P: 2.1-9.5
Flammable or explosive limits(range)
Ethyl Alcohol:
Gasoline:
Hydrogen:
Acetylene:
EA: 3.3-19
G: 1.4-7.6
H: 4-75
A: 2.5-100
______ fuels can be the most dangerous of all fuel types because they are already in the natural state of ignition. No ______ or ______ is needed to ready the fuel and less energy is required for admission.
Gaseous
Pyrolysis or vaporization
______ is the decomposition of matter through the action of heat. Fuel gases are evolved from solid fuels by _________ chemical heat energy is the most common source of heat in combustion reactions.
Pyrolysis for both
A form of chemical heat energy that occurs when the material increases in temperature without an outside heat source.
Self heating or spontaneous heating
Examples of high spontaneous heaters are:
Linseed oil rags
Charcoal
Anything with “fish”
The rate at which most chemical reactions occur doubles with each _______ temperature increase in reacting materials.
18°F
The tendency of gases to form into layers according to the temperature
Thermal layering of gases
Thermal layering of gases is also known as:
Heat stratification and
thermal balance
_______ is the energy component of the fire tetrahedron
Heat
The fire tetrahedron consists of:
> Heat
Fuel
Oxygen
Chemical chain rxn or self sustaining chemical rxn
The five stages of fire development are:
Ignition Growth Flashover Fully developed Decay
Stage of fire that is total room involvement and precedes fully developed
Flashover
No exact temperature is associated with flashover, a range from approximately _________ is widely used
900°F to 1200°F
The flashover temperature range correlates with the ignition temperature of _________ of ______, one of the most common gas is given off from pyrolysis.
Carbon monoxide of 1128°F
The heat released from a fully developed room at flashover can be on the order of ________.
10,000 kW or more
__________ describes a condition where flames move through or across the unburnt gases during a fire’s progression.
Flame over or rollover
Flame over is distinguished from flashover by it’s involvement of __________ and not the surfaces of other fuel packages within a compartment.
Only the fire gases
_______ occurs in the decay stage (smoldering stage – i.e. no oxygen)
Backdraft
__________ is the key upon recognizing any of the signs of Backdraft
Vertical ventilation
The following characteristics may indicate potential for a Backdraft to occur:
> Pressurized smoke exiting small openings
Black smoke becoming dense gray yellow
confinement & excessive heat
Little or no visible flame
smoke leaving the building in puffs or at intervals (breathing)
smoke stained windows
sudden rapid movement of air inward when opening is made
_______ is a self-sustaining chemical reaction yielding energy or products of combustion that cause further reactions of the same kind.
Combustion
_____ is a rapid, self-sustaining oxidation process accompanied by the evolution of heat and light of varying intensities.
Fire