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 a flame.
Fire
A rapid oxidation process, which is a chemical reaction resulting in the evolution of light and heat in varying intensities.
Heat
A form of energy characterized by vibration of molecules and capable of initiating and supporting chemical changes and changes of state.
Temperature
Measure of a material's ability to transfer heat energy to other objects; the greater the energy, the higher the temperature. Measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees designated o
Fuel
A material that will maintain combustion under specified environmental conditions.
oxidizer
Any matieral that readily yields oxygen or other oxidizing gas, or that readily reacts to promote or initiate combustion of combustible materials.
Matter
anything that occupies space and has mass
Physical change occurs when...
a substance remains chemically the same but changes in size, shape, or appearance.
Chemical change occurs when...
a substance changes from one type of matter into another, such as two or more substances combining to form compounds.
Energy
the capacity to perform work
Work
occurs when a force is applied to an object over a distance or when a substance undergoes a chemical, biological, or physical change.
Oxidation
chemical process that occurs when a substance combines with an oxidizer such as oxygen in the air; a common example is the formation of rust on metal
Potential energy
stored energy possessed by an object that can be released in the future to perform work once released.
Kinetic energy
the energy possessed by a body because of its motion
Potential chemical energy of a fuel is converted to...
thermal energy and released as heat
Types of energy
chemical, thermal, mechanical, electrical, light, nuclear, and sound
Joules
The measure for energy in the International System of Units (SI). 4.2 joules required to raise the temperature of one gram of water one degree Celius
Methods used to control and extinguish fire
temp reduction, fuel removal, oxygen exclusion, chemical flame inhibition
Stages of fire development
incipient, growth, fully developed, decay
Modes of combustion are differentiated based on:
where the reaction is occurring
What mode of combustion requires liquid or solid fuels to be converted to the gas phase or vaporized?
Flaming combustion
What mode of combustion occurs when solid fuels undergo oxidation at the surface of the fuel?
Non-flaming or smoldering combustion.
The 3 components of the fire triangle
oxygen, fuel and heat
Flaming combustion is accurately explained best by what?
The fire tetrahedron
Components of fire tetrahedron
Chemical chain reaction between the reducing agent (fuel) oxidizing agent and heat
Temperature is a measurement of what energy?
Kinetic
The unit of measure for heat is:
joules
Applying large amounts of heat to solid fuels such as wood causes?
pyrolysis
The temperature to which the surface of a substance must be heated for ignition and self-sustained combustion to occur is called what?
Autoignition
Most common source of heat in combustion reactions is what?
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?
arcing
What type of heat energy is generated by friction or compression?
Mechanical heat energy
The rate at which heat is transferred is related to the temperature differential of the bodies and what?
the thermal conductivity of the material involved.
The term that refers to the transfer of heat within a body or to another body by direct contact.
conduction
The term that refers to the transfer of heat energy from a fluid (liquid or gas) to a solid surface.
convection
The term that refers to transmission of energy as an electromagnetic wave without an intervening medium.
Radiation
Radiant heat becomes the dominant mode of heat transfer when the fire grows in size.
True
What term refers to materials that absorb heat but do not participate actively in the combustion reaction?
Passive agents
Fuel in a combustion reaction is known as the?
reducing agent
For flaming combustion to occur, fuels must be in what state?
Gaseous state
In order to burn, liquids must be _________
vaporized
The term referring to the temperature at which a liquid gives off sufficient vapors to 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 rate is dependent upon?
type of fuel, quantity of fuel and orientation of fuel. NOT ignition source.
What is the primary oxidizing agent in most fires?
oxygen
What is true about materials that do not burn at normal oxygen levels?
These materials may burn readily in oxygen-enriched atmospheres.
The term that refers to the minimum concentration of fuel vapor and air that supports combustion.
lower flammable limit
Self-sustained chemical reactions involves...
many types of intermediate combustion products, many of which are flammable and toxic.
How can surface combustion be extinguished
by chemical flame inhibition
In flaming combustion, the fire will continue to burn until the fuel or oxygen is exhausted or:
an extinguishing agent is applied in sufficient quantity 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 civilian 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 or polyurethane 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
What classification of fire involves ordinary combustible materials such as wood, cloth, paper, rubber, grass, and may plastics
Class A
Classification of fire that involves energized electrical equipment
Class C
Classifications of fire that involves flammable and combustible liquids and gases such as gasoline, oil, lacquer, paint, mineral spirits, and alcohol.
Class B
Classification of fires that involves combustible metals such as aluminum, magnesium, potassium, sodium, titanium, and zirconium.
Class D
Classification of fires that involves oils and greases normally found in commercial kitchens and food preparation facilities using deep fryers.
Class K
Fire development limited by the air supply is called:
ventilation controlled
What stage of fire development is the fire small, confined to the material first ignited and may self-extinguish?
Incipient stage
What stage of fire development has the fire not yet influenced the environment to a significant extent?
Incipient stage
What stage of fire development does the fire begin to influence the environment within the compartment?
Growth stage
In thermal layering, the hottest gases tend to be:
in the top layer
The term that refers to pockets of flames that may be observed moving through the hot gas layer above the neutral plane.
Isolated flames
Condition where the unburned fire gases accumulated at the top of a compartment ignite and flames propagate through the hot gas layer or across the ceiling.
rollover
The transition when conditions in the compartment change very rapidly from partial to full involvement of the compartment.
Flashover
An increase in ventilation in a fire that is in the decay stage can result in a deflagration called?
backdraft
What are the most fundamental fuel characteristics influencing fire development in a compartment fire?
mass and surface area
What is not a determination of pre-existing ventilation?
occupant load
What method of controlling and extinguishing a fire effectively extinguishes any fire?
fuel removal
What method of controlling and extinguishing a fire reduces a fire's growth and may totally extinguish it over time, but is not generally used for extinguishment in structure fires?
oxygen exclusion
what method of controlling and extinguishing a fire interrupts the combustion reaction and stops flame production?
chemical flame inhibition
what method of controlling and extinguishing a fire uses water for the extinguishment of smoldering fires?
temperature reduction
Gaseous fuels
methane, hydrogen and acetylene. can be the most dangerous of all fuel types because they are already in the physical state required for ignition.
Hydrocarbon fuels
Gasoline, diesel and fuel oil are lighter than water and do not mix with water.
Polar solvents
alcohols (i.e. methanol, ethanol) will mix readily with water