Essentials of Firefighting - Objective 5: Fire Behavior Pt. 5

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