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56 Cards in this Set
- Front
- Back
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Matter
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anything that occupies space and has mass
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3 states of matter
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liquid, gas, solid
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physical change
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substance stays the same chemically but changes in size, shape, or appearance
ie water freezing |
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chemical changes
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substance changes from one type of matter to another, often involves two or more substances that form other compunds
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exothermic reaction
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gives off energy (combustion)
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endothermic reaction
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absorbs energy
liquid to a gas (water to steam) |
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combustion
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a rapid self sustaining chemical process that yields heat and sometimes light
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Fire Triangle
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heat, oxygen, fuel
describes smoldering combustion |
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fire tetrahedron
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flaming combustion
fuel, heat, oxygen, self sustaining chemical reaction |
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what is heat?
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-form of energy
-2 states (kinetic and potential) in case of heat work means increasing temperature |
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potential energy
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energy possessed by an object that be released in the future
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kinetic energy
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energy possessed by a moving object
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Law of Conservation of Mass Energy
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Mass and energy may be converted from one to another but there is never any net loss of total mass energy
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temperature
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measure of kinetic energy
heat energy will move from those of higher temps to those of lower temps |
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What is energy
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capacity to perform work
cant measure directly( measure the work that energy performs) |
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sources of heat energy
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common-mechanical, electrical, chemical
other-nuclear, light, sound |
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chemical heat energy
2 types |
most common
any combustible in contact with oxygen heat of combustion self heating/spontaneous heating |
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spontaneous combustion
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heat cannot dissipate
must reach autoignition temperature poor ventilation |
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things that can spontaneous combust
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charcoal, hay, manure, linseed oil rags
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electrical heat energy
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think ROAS
resistance overload arcing sparking |
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Mechanical Heat energy
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heat of compression (filling scba and diesel engine)
heat of friction-belt rubbing |
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measuring heat enrgy
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BTU and calorie
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BTU
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British thermal unit
amount of heat it takes to heat 1 lb of water by 1 degree Fahrenheit customary |
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calorie
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amount of heat it takes to heat 1 gram of water by 1 degree celcius
si system |
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measuring work in Joules
what is a joule |
-1 newton over a distance of 1 meter
4200 joules to heat 1 kilogram of water by 1 degree celcius |
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Fahrenheit v Celsius
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f-water freezes at 32 and boils at 212
c- water freezes at 0 and boils at 100 |
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3 methods of heat transfer
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conduction, convection, and radiation
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conduction
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direct contact-closer the molecules of a substance the better it conducts electricity
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convection
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movement through air or liquid
usually through smoke and fire gases hot up |
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radiation
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heat and light waves
major cause of spread of fire most dominant mode |
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Fuel (reducing agent) in solids broken down into?
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inorganic-w/out carbon hydrogen or magnesium
organic- with carbon hydrocarbons(gasoline, oil, plastics) cellulose (wood and paper) |
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for flaming combustion to occur fuels must be in what state?
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gaseous
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pyrolysis
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decomposition of a solid fuel by heat
begins at 400 ignition vapors range from 1000 to 1300 |
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heat release rate (HRR)
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energy released per unit of time as a given fuel burns
-expressed in kilowatts |
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reducing agent gas
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(hydrogen methane, etc)
most dangerous form, ready to burn |
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vapor density
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density of gases in relation to air
air is 1 less than 1 will rise heavier than 1 sink |
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solubility of a liquid
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hyrdorcarbon fuels- wont mix with water
polar solvent- will mix with water, methanol and ethanol |
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vaporization
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transformation of a liquid to a vapor
must overcome atmospheric pressure 14.7 psi |
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flash point
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temp at which a liquid gives of sufficient vapors to ignite but not sustain combustion
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fire point
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temp at which sufficient vapors are being generated to sustain the combustion process
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specific gravity
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ratio of the mass of a given liquid compared to the weight of of an equal amount of volume of water
water equals 1 -more than 1 sink -lighter than 1 will float (gas and flamm liquids) |
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air is
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21 percent oxygen
-19.5 percent considered oxygen deficient -23.5 percent oxygen rich |
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oxidizing agent
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supports combustion
lfl -to lean ufl-too rich |
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products of combustion
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light
flame heat smoke |
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smoke is what in regards to killer
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number 1 in civilian and ff deaths
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carbon monoxide
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incomplete combustion
odorless, tasteless, colorless combines 200 time quicker with hemoglobin than oxygen |
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carbon dioxide
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complete combustion
displacing oxygen |
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hydrogen cyanide
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chemical asphyxiate
-comes from polyurethane foam and other things |
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class d fires (some metals)
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potassium, zinc, magnesium, sodium, titanium
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class d does what with water
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reacts violently because high temp
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class k
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saponification- alkaline based chemicals combines with cooking oils to form a soapy film
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flashover
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all objects have reached ignition temp 900- 1200 degrees f
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fully developed
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maximum hrr
limited by fuel and oxygen vent controlled |
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decay
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4th and final stage
backdraft energy release rat and temps drop goes back to fuel contolled |
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backdraft indicators
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yellow grayish smoke
pressurized smoke exiting small openings inwardly drawn smoke smoke puffing soot stained cracking windows little or no visible flame |
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factors that affect fir development
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-fuel types
-availability and location of other fuel volume and ceiling height of compartment -ventilation and changes in ventilation -thermal properties to enclosure -ambient conditions |
