Flashcards in IFSTA(5th)-Chapter 3 Deck (113):
anything that occupies space and has mass
substance changes size, shape, or state
substance changes from one type of matter to another
heat is produced
heat is absorbed
rapid, self-sustaining chemical reaction that produces heat and light
form of combustion. can be smoldering or flaming
fuel, oxygen, heat
best describes smoldering combustion
Fuel, oxygen, heat, self-sustaining chemical chain reaction. best describes flaming combustion
kinetic energy associated with the movement of the atoms and molecules in matter. measured in Joules (Newtons/meters)
measurement of KE due to heat
energy of a moving object
energy within an object at rest that can be released in the future
from hot objects to cold ones
capacity to perform work
force applied over distance
(mass x acceleration)/distance
mass x acceleration
British thermal unit
amount of heat required to raise Temp of 1# of water 1 degree F.
F=(C x 1.8) + 32
C = (F-32)/1.8
auto ignition temp.(AIT)
point at which a material ignites without an external ignition source
chemical decomposition of a substance due to heat
ignition due to external source
6 energy forms that can create heat
occurs when a combustible comes into contact with oxygen. when an oxygen electron is added to something. almost always produces heat.
Increase in 10 degrees C
results in most chemical reaction rates doubling
electrical heating occurs 4 ways
electric current flowing through a conductor
when electric current exceeds conductor capacity
high temp. luminous electric discharge across a gap or through a medium. e.g., when a conductor is separated, lightning, static electricity, or due to excessive voltage
the glowing particles that spatter away from the point of arcing
Mechanical heat energy
due to friction or compression
Rate of heat transfer
is greater between 2 objects with a greater Temp. difference.
transfer of heat from one solid object to another solid object by direct contact.
measure of an object's capacity to transfer heat via conduction. the greater the conductivity, the faster the heat transfer!
made of fine particles or fibers with lots of air filled voids.
because molecules are far apart in gases, air doesn't conduct heat very well.
transfer of heat from a liquid or a gas to a solid
transmission of heat energy as an electromagnetic wave through space.
examples: infrared, radio, x-rays
360 degree spread at the speed of light
As Temp. increases the radiant energy...
increases by a factor to the 4th power. for example: if T is doubled, then 2 to the 4th is 16. so T is doubled and the radiant energy is 16x greater
substance such as water that is inside a substance or within a gas and absorbs heat but does not participate actively in combustion. relative humidity and fuel moisture are examples.
the fuel that is being oxidized. it is being reduced 2 ways: reduction of fuel and the addition of electrons(negative charge)
2 types of organic fuels
flaming combustion only occurs in which state?
if > 1 the gas will sink
if < 1 the gas will rise
liquid petroleum gas
also known as propane
if SG < 1, floats on water
if SG > 1, sinks in water
transformation of a liquid to a gas
Rate of Vaporization depends on...
vapor pressure of substance
amount of heat energy applied
Minimum Temp. when a liquid gives off enough vapors to form an ignitable mixture with air.
Temp. at which a liquid fuel produces enough vapors to support combustion once the fuel is ignited. normally a few degrees higher than the flash point.
As surface area of a liquid increases, vapor production...
degree of a substance to dissolve in a solvent (usually water)
Polar sovents ____ with water
do not mix
0.72, floats on water
material that can mix with water in any proportion
is > 1, sinks
= 0.78, floats
= 0.79, floats
for solids, as surface-to-mass ratios increase, ignitability...
4 stages(Temp. Ranges) of Pyrolysis
< 392 degrees F, moisture is being releases
392 - 536 degrees F, charring begins
536 - 932 degrees F, rapid pyrolysis occurs, charcoal is produced, ignition can occur
> 932 degrees F, free burning as wood is converted to flammable gases
Do solids burn more rapidly due to position?
yes, due to convection solids that are vertical burn more rapidly
Heat of Combustion
total amount of energy released when a fuel is burned(oxidized).
heat release rate
energy released over time for a given fuel
atmosphere with less than 19.5% oxygen
atmosphere with > 23.5% O2
Common Oxidizers(other than O2)
calcium hypochlorite-chlorination of water in pools
chlorine gas-water purification
hydrogen peroxide-antiseptic, industrial bleaching
methyl ethyl ketone peroxide-plastics
O2 concentration that Nomex ignites and readily burns
range of concentrations of fuel vapor and air that allow for combustion. LFL-UFL lower flammable limit to the upper flammable limit
fuel vapor concentration in air is < LFL
fuel vapor concentration in air is > UFL
Common Flammable Ranges
Methane is also known as _____
electrically charged, highly reactive parts of molecules that combine with other components of a fuel to create new substances
Chemical flame inhibition
extinguishing agent interrupts the self-sustaining chemical reaction and terminates combustion. halon is an example...or a halon replacement. this cannot be done on smoldering combustion
mixture of gases, vapor, and solid particulates
formed by the incomplete combustion of carbon
combines to hemoglobin 200x quicker than O2
colorless, odorless, heavier than air.
neither burns or supports combustion.
used as an extinguishing agent by displacing O2 or smothering fires
produced in the combustion of materials containing nitrogen. produced when polyurethane foams burn (furniture/bedding)
prevents the body from using O2 at the cellular level.
visible, luminous body of a burning gas
Class A Fire
wood, cloth, paper, plastics, rubber, grass, etc.
primary extinguishment via cooling with water
Class B Fires
flammable liquids and gases
use class B foams to blanket or dry chemicals.
Class C Fires
energized electrical fire
de-energize before extinguishment.
Class D Fire
Class K Fire
when extinguishing agents turn fats and oils into a soapy foam that extinguish the fire
fuel controlled fire
when O2 is sufficiently available
Ventilation controlled fire
when fire is limited by air supply
4 stages of fire
mostly confined to the material burning
2-in/2-out is now required
rapidly increasing heat
other materials are now burning
gases form into layers according to temperature. hottest are at the ceiling and coolest are at the floor.
also known as stratification and thermal balance.
where high pressure gases level off thru an opening with inward moving cooler air.
when fire gases ignite at the ceiling level and flames propagate through the hot gas layer across the ceiling
rapid transition from growth to fully developed fire stage that is when all contents within a structure reach their ignition Temp. and flames erupt all at once.
lower hot gas layers
strong bidirectional air/smoke movement
rapid increase in heat
isolated flames in a hot gas layer
flashover Temp. Range
900-1200 degrees F
btw, CO auto ignites at 1128 F
Fully Developed Fire
when all combustible materials in a compartment are burning
when most fuel has been consumed or the O2 has diminished enough where flaming combustion is no longer supported
Is decay fuel or ventilation controlled?
Fully developed fire is _____ controlled
instantaneous explosion or rapid burning of superheated gases that occurs when O2 is introduced into a confined space
explosively rapid combustion
T or F. the more confined the deflagration, the more violent it will be.
little or no visible flame
inward sucking smoke
pressurized smoke exiting small openings
dense gray/yellow smoke
smoke stained/cracked windows
confined excessive heat
6 factors that affect fire development
location/availability of another fuel
thermal properties of structure
heating ventilation and AC
4 thermal properties that affect fire