fire dynamics

fire in fuel packages can only entrain air from

2 sides

fire in fuel packages near walls entrain air from

3 sides

the quantity of heat required to change the temperature of 1 gram of water by 1 degree celsius is

4.2 joules

Combustion

A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light in the form of either a glow or flame.

chemical flame inhibition

Extinguishment of a fire by interruption of the chemical chain reaction.

asphyxiation

Fatal condition caused by severe oxygen deficiency and an excess of carbon monoxide and/or other gases in the blood.

autoignition

Initiation of combustion by heat but without a spark or flame.

backdraft

Instantaneous explosion or rapid burning of superheated gases that occurs when oxygen is introduced into an oxygen-depleted confined space. The stalled combustion resumes with explosive force; may occur because of inadequate or improper ventilation procedures.

Autoignition Temperature (AIT)

The lowest temperature at which a combustible material ignites in air without a spark or flame.

concentrations above the ---- are said to be too rich to burn

UEL

any open space with no complete fire barriers dividing it is considered

a compartment

all fires involve

a heat producing chemical reaction

all fuel is

a reducing agent

in the case of heat, work means increasing - ------ --------

a substance's temperature

what is a feature of older structures built prior to approximately 1990?

air pockets in empty wall cavities

fire in fuel packages in the middle of the room entrains air from

all sides

the energy release in fire is directly proportional to the

amount of oxygen available for combustion

Combustion zone

area surrounding a heat source in which there is sufficient air available to feed a fire

the best indicators of the structural integrity of a burning building are gathered

at the scene

in which kind of structure is bowstring truss most likely to be found

bowling alley

gaseous combustion products rise and move away from the fire due to

buoyancy

production of complete combustion of organic materials; creates an oxygen deficient atmosphere

carbon dioxide

toxic and flammable product of the incomplete combustion of organic materials

carbon monoxide

in terms of fire behavior, which potential energy of a fuel converts into heat and light during combustion

chemical

the rate at which fuel releases energy over time depends on

chemical composition arrangement density of the fuel availability of oxygen for combustion

what occurs when an extinguishing agent interferes with this chemical reaction, forms a stable product, and terminates the combustion reaction

chemical flame inhibition

carbon monoxide

colorless, odorless, dangerous gas. toxic and flammable. formed by incomplete combustion of carbon. binds with hemoglobin 200 times faster than oxygen and decreases blood ability to carry oxygen

carbon dioxide

colorless, odorless, heavier than air gas that neither supports combustion nor burns. used in portable fire extinguishers, puts out class b or c fires

the transfer of heat through and between solids

conduction

wood shakes, when treated with fire retardant, can significantly ________ to fire spread

contribute

transfer of thermal energy by circulation or movement of a fluid

convection

consumes the available fuel or oxygen and the heat release rate begins to decline

decay stage

reactions that absorb energy as they occur are

endothermic reactions

kinetic energy is

energy that moving object has

potential energy

energy that will release at some point

reactions that emit energy as they occur are known as

exothermic

temperature is an accurate measurement of heat transfer

false

two modes of combustion

flaming and nonflaming

When sufficient oxygen is available for flaming combustion, the fire is said to be ------ ------

fuel limited

carbon based fuels

fuels where the energy of combustion derives from carbon ex: wood, cotton, coal, or petroleum

when all combustible materials in the compartment are burning at their peak heat release rate based on the available oxygen

fully developed stage

more of the initial fuel package becomes involved and the production of heat and smoke increases

growth stage

flaming combustion requires liquid or solid fuels to be converted to the gas phase through the addition of

heat

potential energy available for release in the combustion process is

heat of combustion

gases move from areas of _____ pressure to areas of ______ pressure

higher, lower

ceiling jet

horizontal movement of a layer of hot gases and combustion byprods from the center point of the plume when a horizontal surface redirects vertical development of the rising plume

significant byproduct of the combustion of polyurethane foam used in many household furnishings

hydrogen cyanide

starts with ignition when the three elements of the fire triangle come together and the combustion process begins

incipient stage

smoke is the product of

incomplete combustion

the thermal properties of the building that can contribute to rapid fire development are ------, ----- ----, and -----

insulation, heat reflectivity, retention

when a fire cannot grow without the introduction of fuel source or a new oxygen source

it has left the growth stage and become fully developed

hypoxia

lack of oxygen

what type of combustion occurs more slowly and at a lower temperature, producing a smoldering glow in the material's surface

nonflaming

the ------ of the fuels as well as their ---- --- -- ----- will also influence the rate and intensity of fire spread

orientation, surface-to-mass-ratio

the oldest and simplest model, the fire triangle, shows three elements necessary for combustion to occur: ----, ----, and ----

oxygen, fuel, heat

energy is the capacity to

perform work

most common form of ignition

piloted

the amount of energy delivered over a given period of time is the definition of

power

what is an indicator for backdraft

pulsing smoke

common cause of exposure fires

radiation

transmission of energy as electromagnetic waves, such as light waves, radio waves, or x rays, without an intervening medium

radiation

which of the following is a significant indicator of flashover

rollover

example of oxidation

rust

Gases with a vapor density greater than 1 will:

sink

which of the following can occur when a mixture of unburned fuel gases and oxygen comes in contact with an ignition source

smoke explosion

ignition without the addition of external heat in known as

spontaneous

buoyant

tendency or capacity of a liquid or gas to remain afloat or rise

the tendency of gases to form into layers according to temperature, gas density, and pressure

thermal layering

four flashover indicators

transition from growth to fully developed rapidity enclosed space fire gases ignite

liquids that are less dense than water are difficult to extinguish using water as the sole extinguishing agent

true

oxidizers are combustible

true

oxidizers are not combustible but will support or enhance combustion

true

piloted ignition occurs without any external flame or spark to ignite the fuel gases or vapors

true

when firefighters ventilate windows or make entry into a building, they establish new flow paths between the fire compartment and exterior vents of the building

true

while the heat from a fire is a danger to anyone directly exposed to it, exposure to toxic gases found in smoke and/or lack of oxygen causes most fire deaths

true

------- ------ occurs when when a structural member fails and introduces a new source of oxygen to the fire

unplanned ventilation

most residential fires that develop beyond the incipient stage become ---------------

ventilation limited

there are two main types of fully developed fires: fuel-limited and ----- -----

ventilation limited

heat transfers from ______ objects to _______ objects.

warmer, cooler

heat is a form of

work