fire
a rapid chemical process that usually produces heat and light.
fuel
form of energy
types of energy
chemical, electrical, and nuclear
chemical energy
source of thermal energy most common source of heat in combustion reactions
endothermic reaction
absorbs heat
exothermic reaction
produces heat
electrical energy
energy that produces heat while traveling through a wire or another conductive material
nuclear energy
energy produced by splitting the nucleous of an atom into two smaller nuclei or by combining two smaller nuclei into one large nucleous
3 factors of fire
heat, fuel, oxygen
oxidation
combining oxygen with another substance to create a new compound
combustion
combining a substance with oxygen to produce heat and light
pyrolysis
process that can generate sufficient quantities of burnable vapors to ignite in the presence of a sufficient oxidizer
smoke
a toxic by product
direct contact
contact that can spread fire quickly
conduction
method of heat transfer occurs when a material is heated as the result of direct contact with a heat source
convection
heat transfer method usually occurs through movement of hot smoke and fire gases
radiation
the transfer of heat through the emission of energy in the form of invisible waves
thermal radiation
when fire is spreading in all directions
methods of extinguishment
cool burning material, exclude oxygen, remove fuel, break chemical reaction
class A fire
fire that involves ordinary solid combustibles
Class B fire
fire that involves flammable or combustible liquids
Class C fire
fire that involves energized electrical equiptement
Class D fire
fire that involves combustible metals
Class K fire
fires that involves combustible cooking fats and oils
ignition phase
phase where heat ignites a combustible and heat from the combustible sets up a small convection current and flame produced small amount of radiated energy
growth phase
kindling starts to burn increasing convection of hot gases upward, energy generated by the growing fire starts to radiate in all directions
fully developed
produces the maximum release of energy, all fuel in area has been ignited and heat is being produced
decay phase
the period when the fire is running out of fuel, rate of burning slows down because less fuel is available
thermal layering
when gases rise and form layers
flame over(rollover)
spontaneous ignition of hot gases layered in developing room of compartment fire
backdraft
introduction of oxygen in an enclosure where super heated gases and contents are hot enough but do not have oxygen to burn
BLEVE
occurs when a vessel storing liquid fuel under pressure is heated excessively
kinetic energy
moves from high-temperature to low-temperature substances
Dark materials emit and absorb heat more effectively than light materials.
What BEST describes the influence of exposed surfaces on radiant heat
Inorganic
fuel that does not contain carbon
Heat of combustion
total amount of energy released when a specific amount of fuel is burned
Gaseous
type of fuel can be the most dangerous of all the types
Liquids with a specific gravity of less than 1
float on the surface
Flash point
minimum temperature at which a liquid gives off sufficient vapors to ignite, but still not sustain combustion
Solubility
extent to which a substance will mix with water
Chemical energy
most common source of heat in combustion reactions
Organic
Contains carbon
Incipient stage
First stage of the burning process in a compartment in which the substance being oxidized is producing some heat, but the heat has not spread to other substances nearby. During this phase, the oxygen content of the air has not been significantly reduced a
sink below the surface
Liquids with a specific gravity of greater than 1
Materials burn more intensely
What BEST describes the impact of higher oxygen concentration on combustion
Vaporization
minimum concentration of fuel vapor and air that supports combustion
It interferes with the chemical reaction
What BEST describes the impact of an extinguishing agent when trying to extinguish flaming combustion