CHAPTER 5 - FIRE BEHAVIOR Flashcards
A rapid oxidation process, which is a chemical reaction resulting in the evolution of the light and heat in varying intensities.
Fire.
A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light in the form of either glow or flame.
Oxidation.
A form of energy characterized by a vibration of molecules and capable of initiating and supporting chemical changes and changes of state.
Heat.
Measure of a materials ability to transfer heat energy to other objects; the greater the energy, the higher the temperature.
Temperature.
A material that will maintain combustion under specific environmental conditions.
Fuel.
Any material that readily yields oxygen or other oxidizing gas, or that readily reacts to promote or initiate combustion of combustible materials.
Oxidizer.
Anything that occupies space and mass.
Matter.
Capacity to perform work; occurs when a force is applied to an object over a distance, or when a chemical, biological, or physical transformation is made in a substance.
Energy.
Chemical process that occurs when a substance combines with an oxidizer such as oxygen in the air.
Oxidation.
Stored energy possessed by an object that can be released in the future to perform work once released.
Potential energy.
The energy possessed by a body because of its motion.
Kinetic energy.
Defined in terms of mechanical energy. It is equal to the energy expended in applying a force of 1 N through a distance of matter. Energy required to increase temperature 4.2 J raises raises 1 g of water 1°.
Joules.
Chemical reaction that releases thermal energy or heat.
Exothermic reaction.
Chemical reaction that absorbs thermal energy or heat.
Endothermic reaction.
Chemical decomposition of a solid material by heating. Often precedes combustion.
Pyrolysis.
Physical process that changes a liquid into a gaseous state; the rate of vaporization depends on the substance involved, heat, pressure, and exposed surface area.
Vaporization.
The process of initiating self sustained combustion.
Ignition.
Moment when a mixture of fuel and oxygen and counters an external heat source with sufficient heat or thermal energy to start the combustion reaction.
Piloted ignition.
Initiation of combustion by heat but without a flame or spark.
Auto ignition.
The lowest temperature at which a combustible material ignites in the air without a spark or flame.
Autoignition temperature.
Visible, luminous body of burning gas emitting radiant energy including the light or various color given off by burning gases or vapors during the combustion process.
Flame.
A model used to explain the elements/conditions necessary for combustion. The sides of the triangle represent heat, oxygen, and fuel.
Fire triangle.
Model of four elements/conditions required to have a fire. The four sides represent fuel, heat, oxygen, and self-sustaining chemical chain reaction.
Fire tetrahedron.
Materials that absorb heat but do not participate actively in the combustion process.
Passive agent.
Materials produced and released during burning.
Products of combustion.
Colorless, odorless us, dangerous gas formed by the incomplete combustion of carbon. It combines with hemoglobin more than 200 times faster than oxygen, the decreases the blood’s ability to carry oxygen.
Carbon monoxide
Colorless, toxic, flammable liquid until it reaches 79°F. Above that temperature, it becomes a gas with a faint odor similar to better almonds produced by the combustion of nitrogen bearing substances.
Hydrogen cyanide.
Colorless, odorless, heavier than air gas that neither supports combustion nor Burns; used in portable fire extinguishers as an extinguishing agent to extinguish class B or C fires by smothering or displacing oxygen.
Carbon dioxide.
The kinetic energy associated with the random motions of the molecules of a material or object. Often used interchangeably with the terms heat and heat energy. Measured in joules or BTU.
Thermal energy.
The result of exothermic reactions, occurring spontaneously in some materials under certain conditions, whereby heat is generated at a rate sufficient to raise the temperature of the material.
Self-heating.
Initiation of combustion of a material by an internal chemical or biological reaction that has produced sufficient heat to ignite the material.
Spontaneous ignition
The measure of the rate of transfer to a surface.
Heat flux.
Transfer of heat through or between solids that are in direct contact.
Conduction.
Heat transfer by circulation within a medium such as a gas or a liquid.
Convection.
Heat transfer by way of electromagnetic energy.
Radiation.
The tendency or capacity to remain a float in a liquid or rise in air or gas.
Buoyant.
Composed of at least one inlet opening, one exhaust opening, and the connecting volume between openings. The direction of the flow is determined by difference in pressure. Heat and smoke and high-pressure area will flow to low-pressure area.
Flow path.
Buoyant layer of hot gases and smoke produced by a fire in a compartment.
Upper layer.
The fuel that is being oxidized or burned during combustion.
Reducing agent.
Total amount of thermal energy that could be generated by the combustion reaction if a fuel were completely burnt. Measured in BTU per pound or megajoules per kilo gram.
Heat of combustion.
Total amount of heat released per-unit time. Measured in kilowatts and megawatts of output.
Heat release rate (HHR).
A unit of measure of power or rate of work equal to one joule per second.
Watt.
Weight of a given volume of pure vapor or gas compared to the weight of an equal volume of dry air at the same temperature and pressure.
Vapor density.
Mass of a substance compared to the mass of an equal volume of water at a given temperature.
Specific gravity.
Any liquid having a flashpoint below 100° and a vapor pressure not exceeding 40 psi absolute.
Flammable liquid.
Measure the tendency of a substance to a evaporate. The pressure at which the vapor is in equilibrium with its liquid phase for a given temperature. Liquids that have a greater tendency to evaporate have higher vapor pressure for a given temperature.
Vapor pressure
Minimum temperature at which a liquid gives off enough vapors to form and ignitable mixture with air near the liquid surface.
Flashpoint