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65 Cards in this Set
- Front
- Back
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Chapter 3
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Fire Behavior
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matter
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Anything that occupies space and has mass
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Physical Change
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Liquid to solid; liquid to gas
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Chemical reaction
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substance changes from on type of matter into another
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Oxidation
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Chemical reaction involving the combination of oxygen with other materials
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Exothermic Heat reaction
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Chemical reaction between two or more materials that changes the materials and produces heat, flames and toxic smoke
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Endothermic Heat reaction
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chemical reaction in which a substances absorbs heat energy
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Combustion
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exothermic chemical reaction that is a self sustaining process of rapid oxidation of a fuel, produces heat and light
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Fire Triangle
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Oxygen, Fuel, heat
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Fire Tetrahedron
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Fuel, Oxidizing agent, Chemical chain reaction, heat
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Potential energy
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Stored energy possessed by an object that can be released in the future to perform work
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Kinetic energy
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The energy possessed by a moving object
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Joules
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Measure of heat energy – metric system
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Joules
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1 joule = 1 newton over 1m distance
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British Thermal Unit
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amount of heat required to raise the Temp. of 1 pound of water 1 degree
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Heat
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Form of energy
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Pyrolysis
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Chemical decomposition of a substance through the action of heat
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Piloted Ignition
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When a mixture of fuel and oxygen encounter an external heat source with sufficient heat energy to start the combustion reaction
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Auto Ignition
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Ignited fuel gases or vapors without any external flame or spark
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Autoignition Temperature
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Temperature to which the surface of a substance must be heated for ignition and self sustained combustion to occur
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Self heating
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Form of chemical heat energy that occurs when a material increases in temp without additional external heat
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Resistance heating
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Electrical current flowing through a conductor
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overcurrnet (overload)
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current flowing through a conductor exceeds its design limits
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Arcing
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High temperature luminous electric discharge across a gap
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Sparking
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Glowing particles that spatter away from point of arcing
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Mechanical heat
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Generated by friction or compression
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Heat of Friction
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movement of two surfaces against each other
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Heat Compression
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Generated when a gas is compressed
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Conduction
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Transfer of heat within a body or to another body by direct contact
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Convection
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transfer of heat energy from a fluid to a solid surface
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Radiation
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Transmission of energy as a electromagnetic wave without a intervening medium
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Passive Agents
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materials that absorb heat but do not participate actively in the combustion reaction
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Fuel Moisture
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Water content of a combustible material; passive agent that slows the absorption of heat energy and retards the process of ignition of combustion\
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Fuel (reducing agent)
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material or substance being oxidized or burned in the combustion process
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Inorganic fuels
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hydrogen or magnesium – does not containing carbon
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organic Fuels
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Fuels that contain carbon
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Gaseous fuels
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methane (ng) hydrogen, acetylene, mass but no shape or volume
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Vapor density
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density of gases in relation of air; air = Vapor density of 1; <1 floats >1 sinks
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Liquid fuels
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has mass volume, but no shape, except for when on flat surfaces
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Specific Gravity
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ratio of mass of given volume of liquid compared to mass of an equal volume of water @ same temp. water – 1 <1 – floats (gas, flammable liquids) >1 sinks
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Vapor pressure
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Pressure produced or exerted by vapors released by a liquid
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Flash point
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Temp at which a liquid gives off sufficient vapors to ignite but not sustain combustion
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Fire point
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Temperature at which sufficient vaporware being generated to sustain the combustion reaction
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Solubility
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Ability to mix with water
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Polar solvents
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Lighter then water and does mix with water
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Miscible
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materials that will mix with water in any proportion
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solid fuels
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have definite size and shape
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Surface to mass ratio
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surface area of fuel in proportion to mass
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Heat of combustion
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Total amount of energy released when a specific amount of fuel is oxidized
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Heat release rate
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energy released per unit of time as a given fuel burns and is usually expressed in kilowatts
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14% 02 concentration
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temp at which materials can ignite and burn
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Flammable range
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range of concentrations of fuel vapor and air
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Lower flammable limit
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minimum concentration of fuel vapor and air that supports combustion
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Upper flammable limit
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concentration above which combustion cannot take place “Too rich to burn”
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Chemical flame inhibition
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Halon – replacement extinguishing agent interferes with chemical reaction
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Carbon monoxide
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colorless orderless dangerous gas
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Carbon dioxide(Co2)
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colorless odorless, neither supports combustion nor burns
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Flame
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visible luminous body of a burning gas
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Class A fires
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wood, cloth, paper, rubber, grass, plastics
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Class B fires
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Flammable and combustible liquids and gases
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Class C fires
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energized electrical equipment
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Class D fires
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Combustible metals (aluminum, magnesium, potassium, sodium, titanium, zirconium)
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Class K fires
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Oils and gases
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Saponification
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agents that turn fatty oils into soapy foam
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stages of fire
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1) Incipient (ignition); 2) growth; 3) fully developed; 4) decay
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