Chapter 3 Flashcards
Which of the following occurs when a substance remains chemically the same but changes in size, shape, or appearance?
Physical change
When a substance changes from one type of matter to another?
Chemical change.
A chemical reaction involving the combination of oxygen (or similar types of substances) with other materials?
Oxidation
Reactions that give off energy as they occur?
Exothermic reaction
Refers to reactions that absorb energy as they occur
Endothermic reactions
Modes of combustion are different based on:
Where the reaction is occuring
Which mode of combustion requires liquid or solid fuels to be converted to the gas phase or vaporized?
Flaming combustion
Which mode of combustion occurs when solid fuels undergo oxidation at the surface of the fuel.
Nonflaming or smoldering combustion
What are the three components of the fire triangle?
Oxygen, Fuel, and Heat.
Flaming combustion is accurately best explained by what?
The fire tetrahedron
What are the elements of the fire tetrahedron?
Oxygen, Fuel, Heat, and a self-sustained chemical reaction.
Energy possessed by a moving object.
Kinetic energy
Temperature is a messurment of:
Kinetic energy
In the customary system, the unit of measure for heat is:
British thermal units (BTU)
Applying large amounts of heat to solid fuels such as wood causes.
Pyrolysis
What is the temperature to which the surface of a substance must be heated for ignition and self-sustained combustion to occur?
Autoignition temperature
What is the most common source of heat in combustion reactions?
Chemical heat energy
What occurs when any combustible is in contact with oxygen?
Oxidation
What mode of electrical heat energy occurs when electric current flows through a conductor at a normal design limit?
Resistance Heating
What type of heat energy is generated by friction or compression?
Mechanical heat energy
The rate at which heat is transfered is related to the temperature differentialof the bodies and
Thermal conductivity of the material involved
What refers to the transfer of heat within a body or to another body by direct contact
Conduction
What refers to the transfer of heat energy from a fluid (liquid or gas) to a solid surface?
Convection
What refers to transmission of energy as an electromagnetic wave without an intervening medium?
Radiation
What is the dominant mode of heat transfer when a fire grows in size?
Radiant heat
What refers to materials that absorb heat but do not participate actively in the combustion reaction?
Passive agents
Fuel in combustion is known as the
Reducing agent
For flaming combustion to occur, fuels must be in the:
Gaseous state
In order to burn, liquids must be:
Vaporized
What refers to the temperature at which a liquid gives off sufficient vaporsto ignite, but not sustain, combustion?
Flash point
What is the primary consideration in whether solids are easy or difficult to ignite.
Surface to mass ratio
What are the factors that heat release is dependant on?
Type of fuel, Quanity of fuel, Orientation of fuel.
What is the primary oxidizing agent in most fires?
Oxygen
What should you be cautious of in oxygen enriched atmospheres?
Materials that wont burn at normal oxygen levels, may burn readily.
What refers to the minimum concentration of fuel vapor and air that supports combustion?
Lower Flammable Limit
What involves many types of intermediate combustion products, many of which are flammable and toxic?
Self-sustained chemical reaction.
What cannot be extinguished by chemical flame inhibition?
Surface combustion
In flamming combustion, the fire will continue to burn until the fuel or oxygen is exhausted or:
An extinguishing agent is applied in sufficient quanity to interfere with the ongoing reaction.
What causes most fire deaths?
Toxic smoke
What product of combustion is frequently identified as the cause of death for civillian fire fatalities and acts as a chemical asphyxiant by binding with hemoglobin in the blood
Carbon Monoxide
What product of combustion is produced in the combustion of materials containing nitrogen and is a significant byproduct of the combustion of polyuerethane foam?
Hydrogen Cyanide
What product of combustion is a product of complete combustion of organic materials and also acts as a respiratory stimulant?
Carbon Dioxide
Which class of fires involves ordinary combustible materials such as wood, cloth, paper, rubber, grass, and many plastics?
Class A fires
What class of fires involve energized electrical equipment?
Class C fires
What class of fire involve flammable and combustible liquids and gasses such as gasoline, oil, laquuer, paint, mineral spirits, and alcohol?
Class B fires
What class of fire involve combustible metals such as aluminum, magnesium, potassium, sodium, titanium, and zirconium?
Class D fires
What class of fires involve oils and greases normally found in commercial kitchens and food preparation facilities using deep fryers?
Class K fires
When fire development is limited by air supply, it is said to be:
Ventilation controlled
Which stage of fire development is the fire small, confined to the materialfirst ignited, and may self extinguish?
Incipient stage
During which stage of fire development has the fire not yet influenced the environment to a significant extent?
Incipient stage
Which stage of fire development does the fire begin to influence the environment within the compartment?
Growth stage
In thermal layering, the hottest gasses tend to be:
In the top layer.
What refers to pockets of flames that may be observed moving through the hot gas layer above the neutral plane?
Isolated flames
A condition where unburned fire gases accumulated at the top of a compartment ignite and propagate through the hot gas layeror across the ceiling?
Rollover
What refers to the transition when conditions in the compartment change very rapidly from partial to full involvement of the compartment
Flashover
What happens just before flashover?
Temperatures rapidly increase, additional fuel becomes involved, and fuel in the compartment gives off combustible gases.
During which stage of fire development are all combustible materials in the compartment burning?
Fully developed stage
During which stage of fire development does the fuel become consumed or the oxygen concentration fall to the point where flaming combustion can no longer be supported?
Decay stage
An increase in ventilation in a fire that is in the decay stage can result in a deflagration called a:
Backdraft
What are the most fundamental fuel characteristics influencing fire development in a compartment fire?
Mass and surface area
What factors influance the availability and location of additional fuels?
Contents (nonstructural fire load), construction (structural fire load), configuration of the building.
All other things being equal, a fire in a large compartment will:
Develop more slowly than one in a small compartment.
What are examples of pre-existing ventilation.
Structural openings, construction type, building ventilation systems.
Examples of some thermal properties of an enclosure.
Insulation, retention, and conductivity.
What ambient condition can be extreamly significant in structural fire development?
Strong winds
What method of controlling and extinguishing a fire depends on reducing the temperature of a fuel to a point where it does not produce sufficient vapor to burn?
Temperature reduction
which method of controlling and extinguishing a fire effectively extinguishes any fire?
Fuel removal
Which method of controlling and extinguishing fire reduces a fires growth and may totally extinguish it over time, but is not generally used for extinguishment in structure fires?
oxygen exclusion
which method of controlling and extinguishing a fire interupts the cobustion reaction and stopd flame production?
Chemical flame inhibition
Which method of controlling and extinguishing a fire uses water for the extinguishment of smoldering fires?
Temperature reduction
