Brannigans Building Construction CH.5 Fire Behavior & Building Construction Flashcards
a rapid oxidation (chemical) reaction that produces heat and visible light
fire
4 essential elements to have a fire
fuel
oxidizing agent
heat
uninhibited chemical chain reaction
a material that will sustain combustion (a.k.a. reducing agent)
fuel
normally atmospheric oxygen, but may also be chemical compounds known as oxidizers that will release oxygen as they react
oxidizing agent
form of energy that is the source of ignition
heat
sustained oxidation reaction that produces sufficient excess heat to continue heating unburned fuel, making it available for combustion
uninhibited chemical chain reaction
dictates how a fire spreads
heat transfer
3 methods of heat transfer
conduction
convection
radiation
transfer of heat w/in an object or b/w objects through direct contact
conduction
transfer of heat through circulation w/in medium such as gas or liquid
convection
transfer of heat through electromagnetic waves
radiation
a bare steel beam above fire, immersed in hot gases from fire below, receives heat energy through
convection
as a beam begins to heat up, heat is transferred w/in beam as well as down length of beam igniting a combustible material (i.e. cardboard box) through
conduction
a large, fully involved wood frame multiple dwelling in a row of similar structures may ignite adjacent exposures through
thermal radiation
large quantities of radiation applied to a combustible material can cause
autoignition
phenomenon in which a combustible material ignites spontaneously w/o application of flame or spark
autoignition
ignition of heated combustible material when a flame or spark is applied
piloted ignition
vertical spread of fire on exterior of multistory building, from one floor to floor(s) above
autoexposure
in autoexposure of fire coming out of window into upper floor, heat is transferred through a combination of
radiation and convection
2 way relationship b/w building construction & fire behavior
fire influences by building
building reacts to effects of fire
enclosure around a fire; area commonly called a room
compartment
4 stages of a fire
incipient
free burning
flashover
smoldering/ decay
initial stage of fire after ignition, usually involving single or small # of combustibles
incipient
secondary stage of fire in which it spreads to adjacent combustible materials
free burning
transition stage in which exposed surfaces w/in compartment ignite simultaneously and fire spreads throughout compartment; results in full room involvement
flashover
stage in which glowing combustion takes place. w/o flame
smoldering/ decay
fire may be forced into smoldering stage when key components of what are in short supply
fire tetrahedron are in short supply (i.e. limited oxygen)
elements of a compartment fire
fire plume
smoke
ceiling layer
neutral plane
bi-directional flow
columns of flames
fire plume
heated gases rising above burning object
smoke
consists of hot, buoyant gases that collect at very top of room
ceiling layer
interface b/w hot ceiling layer and the cooler air flowing into compartment
neutral plane
movement of cooler air (oxygen) into room and hot gases leaving room from the ceiling layer
bi-directional flow
in compartment fire, fresh air drawn into fire from doorway and is drawn into fire itself
entrainment
observed in ceiling layer; hot unburned fuel gases, having gathered in sufficient quantities at ceiling layer, suddenly ignited
flameover (a.k.a. flashover)
in compartment fire, overwhelming radiant heat from ceiling layer drives the room toward
flashover
dictates how the fire burns and grows
location and quantity of oxygen to feed fire
if what is cut off or greatly reduced, flaming combustion will likely cease and the fire will begin smoldering
oxygen supply
sustained winds accelerate fire and speeds up its spread
wind driven fire
in wind driven fire, if winds exceed what mph, their role in driving the fire w/in a building must be considered from a tactical standpoint
winds exceeding 10-20 mph
aside from door & window opening supplying o2, other construction factors influencing fire behavior
combustible interior finishes or walls
vertical openings
height of fire room
proximity of walls
HVAC
as wood burns and is consumed is loses strength which is important for what members ?
load bearing wood member
(no way to determine exactly when a charred wood member under load will fail)
aluminum will melt at around what temp
1200F
(649C)
occurs when heated gaseous products of combustion burn when oxygen is introduced into an environment in which oxygen supply has been depleted due to fire; usually occurs w/ explosive force due to increased airtightness of building
backdraft
describe the movement of hot fire gases/ smoke from areas of high pressure to low pressure; created when windows or doors are opened by FF’s or fail as a result of fire itself
flow path
providing what, allows flow of oxygen into fire compartment and products of combustion to exit compartment, allowing fire to grow in size
flow path
flame spread =
fire growth
combustible tile ceilings are often suspended below the floor above, creating a void in which what can be generated and stored ?
explosive carbon monoxide (CO)
when this gas ignites, it can cause an extremely violent explosion
CO (carbon monoxide)
building problem w/ regard to fire growth can be differentiated on its location:
hidden
exposed
contents problems w/ regard to fire growth can result from which elements:
furnishings
interior finish, including decorations
mercantile stock
flame spread or rapid fire growth can be a problem caused by
both building itself and by its contents
in addition to fire growth, what may contribute heavily to fire load and to generation of smoke and toxic by products?
high flame spread materials
what is non combustible and combustible in glass fiber reinforced polyester resin plastic?
glass fibers = non combustible
plastic = combustible
paper vapor seal on batt-type glass fire insulation leads to a phenomenal rate of what?
rate of flame spread
laid in ceilings; must be kept away from light fixtures b/c heat from fixture can ignite paper
batt insulation w/ paper facing
older motels are often built w/ back to back rooms; for privacy batt type fiberglass is sometimes installed b/w studs, leaving paper vapor seal on insulation exposed which can be easily ignited by
plumbers torch (can spread through corridor and pipe channels)
commonly used as insulating sheathing on wood frame buildings; also used as soundproofing; can support a fire hidden in walls
combustible fiberboard
used as sheathing, concealed in cavity walls, or glued to interior surface of masonry wall panels
foamed plastic insulation
when foamed plastic insulation is installed, it should be protected from exposure to flame by what?
half inch gypsum board covering
in a well developed fire, you can expect a gypsum board to fail causing what to be involved suddenly and explosively as gypsum falls away?
foamed plastic
manufactured so that its flame spread is reduced, but can still melt; also lacks dimensional stability
foamed plastic
air duct insulation that was commonly installed years ago was usually made of what?
hair felt w/ high flame spread
today, air duct insulation used that present little flame spread problem
aluminum faced foil (not aluminum faced paper), glass fiber insulation
electrical insulation may be
self extinguishing
when electrical wiring is operated at or above its rated capacity, the heat can break down insulation and what can be emitted?
flammable gases
large groups of electrical wires can support what?
self sustaining ignition
was almost universal finish for ceilings, although some ceilings were also made of embossed steel (tin ceilings) and wooden boards called match boarding
lime plaster
does not contribute to fire; absorbs heat slowing progress of fire
lime plaster
3 ways in which interior finishes may increase fire hazard
-increase fire extension by surface flame spread
-generate smoke & toxic gases
-add fuel to fire, contributing to flashover
commonly sued interior finishes include materials such as=
wallboard
wallpaper
lay-in ceiling tile
vinyl wall covering
interior finish items (i.e. carpeting)
in the 1930’s, low-density fiberboard made of what came into use; called bagasse?
made of wood fibers or sugar cane residue
when low density fiberboard is sued for sheathing and soundproofing, it is concealed in walls and is commonly ignited by what?
plumbers torch
when punched with holes, fiberboard acquires desirable acoustical properties and becomes what?
combustible acoustical tile
it has become common practice to install what below acoustical tiles?
dropped ceiling below
flame spread characteristics of interior finishes are regulated in what?
building codes
used in variety of applications in building construction, including to secure roof surfaces, onsite assembly of prefabricated modular units, and to connect plastic pipes
adhesives
manufactured to very high density; selected for radiation shielding; regarded fire safe
high density fiberboard
when punched w/ holes, high density fiberboard is called what?
pegboard
one manufacturer (Masonite Corp) produces such hardboard (pegboard) w/ very low what?
very low flame spread rating
used to protect finished lumbar; has a high flame spread rating
reinforced bituminous-impregnated paper
the unexposed side of plywood or any wood paneling can burn unobserved & protected from fire dept streams, that is why it is not sufficient to correct exposed surfaces by applying what?
applying a flame retardant surface treatment
although standard for installation of sprinklers allows for omission of sprinklers in concealed void spaces w/ such combustible surfaces, in “fully” sprinklered buildings, what treatment are no substitute for exposed plywood surfaces in rooms and other open areas?
flame retardant surface treatment
used as interior finish in may house
rigid foamed polyurethane
Robertson protected metal =
asphalt coated steel
loss of 6 FF’s in Worcester Cold Storage warehouse in Massach. in 1999 was due to rapid fire spread across what?
interior surfaces of building
carpeting installed on wall must be tested for what?
tested for flame spread and compliance w/ building and fire codes
when carpeting has been installed on walls, it must be removed if carpeting has not achieved what?
appropriate interior finish rating
form void spaces in which fire can burn undetected until fire bursts out furiously
suspended ceilings of combustible tile
beware: tip of fire iceberg =
light smoke showing
codes require installation of new ceilings that meet what?
flame spread requirements
codes do not require what when installing new ceilings?
do not require removal of old ceiling
when new fire rated ceiling is installed in remodeled building, what is most likely left above ceiling?
old ceiling, dangerous and combustible
fire can spread quickly above what type of ceiling?
tin ceiling
effective August 1990, new aircrafts have to meet stricter what from Federal Aviation Administration (FAA)?
standards for fire and heat resistance
in open plan officers, restrictions on flame spread in codes are typically strictest and less strict for what?
strictest for corridors
less strict for rooms off corridors
if there is no wall, there is no room=
all corridor
strict interpretation of what includes the provision that they be enclosed, w/ rated walls and doors
corridors
from a fire prevention perspective, what are 2 things difficult to control
decorations (usually hanging) & contents (like furniture)
a light bulb of how many watts can ignite cotton?
100 watt bulb
foamed polyurethane samples have ignited after how much time of application of flame from a butane lighter
1 sec
have replaced much wood, cotton, wool, and other material that use to make up furniture and contents
solid and foamed plastics
formerly known as National Bureau of Standards (NBS)
Fire Research Division of NIST
test no.14 consisted of a room 10x15 and furniture consisted of sofa, upholstered love seat, 1 ottoman (foam rubber) , 2 end tables, coffee table 2 bookcases, ceiling tiles (wood fiber w/ flame spread rate of 200), plywood walls resulted with what type of fire after 4 & 6 minutes of ignition
4 minutes: fire pouring out of doorway
6 minutes: average gas temp was reported at 1300F (700C)
several possible approaches to control problem of fast fire growth
- eliminate high flame spread surfaces
- separate materials from source of combustion
- cut off extension of fire
- coat materials
U.S. mercantile ships took path of eliminating what
eliminating high flame spread surfaces
U.S. merchant ships severely limit what
limit combustibility of construction materials and surface finishes
ships that contain combustible trim and veneer rely on what
fire suppression from automatic sprinklers
defective ballast in fluorescent fixtures can reach temperatures of
1500F (816C)
some codes require a what to separate more flammable carpeting from less flammable carpeting (i.e. motel carpet on floor separate in corridors)
metal door sill
materials can be painted w/ what (does not make it “flameproof”)
fire retardant coating
effective only if applied as specified
fire retardant surface coating
often used where a wood surface is desired and flame spread requirements must be met
pressure treated fire retardant wood
wooden materials can also be formulated to be
flame resistant
plastics can be manufactured to be more
flame resistant
more significant than thermal exposure in deaths from fire
smoke and toxic gases
provides first warning of most fires
smoke
can do more damage to property than fire or water, may reduce visibility, irritating particles can cause retching and immobility
smoke
generic term used to describe airborne solid and liquid particulates and gases produced by a fire
smoke
solid particulate, that give smoke its opaqueness is typically what
carbon
liquid particulates typically in smoke
acrolein and halogen acids
gases typically in smoke
CO, hydrogen cyanide (HCN) and carbon dioxide
can paralyze or slow ability of human function or escape; more prevalent toxic fire gas
CO
for most toxic materials, the toxic effect is a product of what
concentration and exposure time
Habers rules states that any exposure in which concentration (in PPM) x minutes exposed equals what is likely to be dangerous
33,000
NFPA Fire Protection Handbook, a 10 minute exposure of what would be hazardous, possible incapacitating
to 3500 ppm of CO
concentration of how many PPM of CO would be fatal after only a few breaths
12,500 ppm
other fire gases such as nitric acid and hydrochloric acid can be
toxic, and in sufficient dosage lethal
deadly nitrous oxide gas usually emitted from fire found in film storage (x-ray) of clinic or from test tubes for blood test
nitrocellulose
was used for commercial motion pictures; fire codes still regulate it
nitrocellulose based film
an effective electrical insulator that has become indispensable as a contemporary material; when it burns it emits toxic gases
polyvinyl chloride (PVC)
flammable gas; when ignited in confined area wide range of overpressures can result
CO
a gas that ignites when sufficient oxygen is available; can be caused by gas trapped in a void or pocket and simply “lights up”
CO
gases from polyurethane can
explode
research at NIST has pointed out that generation of CO can be up to how many times greater in enclosed voids as in the open
50 times greater
does not prevent CO explosion; gas-air mixture can still pocket in a fully or partially enclosed location
ventilation of building
filter mask were dangerous b/c they removed solid particles but allowed what through?
odorless CO
this odorless, colorless, and tasteless gas can stratify well above the fire, on floors where there is little or no smoke, heat or air movement
CO
smoke particles can plug up screens, which can be a problem in which location (used on windows to prevent contraband)
prison
often considered the most expensive by product of fire suppression
water damage
cost of cleanup can be astronomical if smoke is contaminated with this health hazard
radioactive material or polychlorinated biphenyl (PCB)
easiest control of health hazard of contamination
keep people away
b/c loss of use of property can be very costly and cleanup can be prohibitive, it is sometimes less expensive to what a property that has been contaminated?
abandon the property
PCB’s were used as nonflammable coolants in
transformers
delicate equipment as well as brickwork and concrete can be damaged or destroyed by corrosive products of
combustion
plastics containing halogens such as chlorine, fluorine, bromine, or iodine form corrosive acids when combined w/ what
hydrogen or oxygen or moisture in air
most common extinguishing agent
water
absorbs heat and cools fuel below its ignition temperature so it is not giving off fumes
water
what type of large fire can take a long time to burn itself out
magnesium fire
in a fire, hose streams must be applied where on exposure to remove heat
directly on exposure
simply placing a stream b/w buildings will not stop what and it will go straight through
stop radiant heat
ceilings layer gases must be vented or cooled or they will
ignite
3 issues of “thermal balance”
- you have good visibility below neutral plane
- soon as nozzle open up into ceiling, thermal layer is stirred and visibility is lost
- you create steam
modern bunker gear can withstand temperatures above
220F (104C)
protecting the neutral plane is a plus if you can ventilate but if you cannot or ventilation is going to be delayed you must do what to ceiling gases?
must cool ceiling fire gases below their ignition temperatures with water
maybe your last warning sign before flashover
flameover (rollover)
fire is always looking for path of
least resistance
trailer mounted what are becoming more popular for ventilating big box stores
mobile ventilation units (MVU)
depending on wind speed and cubic feet per min (cfm) capacity of the MVU, you might be able to overpower and reverse what?
overpower wind currents and reverse effects of wind driven fire
if using MVU is not possible in helping stop a wind driven fire, then the wind driven fire will not stop until it meets a
fire rated barrier
when attacking a a wind driven fire from floor above, using this appliance that is 2.5 in and can throw 260-290 gpm can be inserted through a hole cut in floor
Bresnan distributor nozzle
in a wind driven fire, what can be lashed to an attic ladder and inserted from floor below if there are no concrete floors
Bresnan nozzle
in a wind driven fire and cant be controlled, protect doors to stairwells, write off fire floor and concentrate firefighting efforts to
floor above fire
in a wind driven fire if concentrating on floor above fire you should
-“flow the floor” keep everything wet
-remove all fire load away from windows and exterior walls
-watch for smoke and fire extension through HVAC, shafts, or other poke-through holes
in a wind driven fire when flowing the floor of floor above fire there should be standing water especially if it has
carpet
aluminum will melt at approximately what temp
1200F (649C)
(good # to know since most ground ladders and aerials are of aluminum)
aluminum anneals (starts to lose its rated strength) when exposed to prolonged heat of
350F (177C) or higher
fire will take path of least resistance, using what will help located hidden fire by pressurizing space and accelerate the burn by introducing forced oxygen rich air
PPV
when overcrowded patrons are trying to escape, it is best to do what to doors versus using wedges (b/c they can be kicked out easily)
tie door off or make existing exits larger by removing doors
space SCBA bottle, face piece, and regulator that is carried in a special bag that is specifically designed for rapid intervention emergencies when a firefighter is trapped
Rescue Air Kit (RAK)
what can be considered when facing insulation fire in floors, walls and ceilings; insulation fires tend to smolder for hours
piercing nozzle
when entering a below grade, confined space for rescue check the oxygen percentage before entering the space by
lowering gas detector on tag line to check for CO and oxygen deficient atmospheres
in an overhead void space, what levels must be determined b/c they can explode under right conditions
CO levels
in an overhead void space, if we had smokE conditions we know what was generated
CO
an activated sprinkler head is an indirect
offensive attack
if you look at sprinkler system in any hotel room, it resembles a what; plumbing is inserted through wall
piercing nozzle
ARFF stands for
Aircraft Rescue and Fire Fighting
ARFF does not take a defensive approach if
passengers aboard
Snozzle and fuselage w/ piercing nozzle introduces sprinkler system into a cabin used by
ARFF
when flowing the floor you should keep exposed fuel
wet
a crew going up to investigate a fire alarm should always have a
2.5 gal pressurized water extinguisher
CO levels in a building need to be checked from
top floor down to bottom floor
only method by which FF’s can expel CO from building
ventilation
aside from removing smoke from a building PPV can also help with
-introduction of fresh air
-create more survivable atmosphere
-cools environment
-dilutes products of combustion
-helps spread water vapor created from hose streams
-changes direction of smoke & fire (tactical perspective)
effective what can make the fire behavior
ventilation
most important factor is often oxygen supply; location and quantity of oxygen needed to feed fire will dictate how
fire burns and grows
