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fire science chapter 17 fire control
Terms in this set (68)
rescue and/or fire extinguishment may be the objective for an offensive strategy. in some fire incidents, rescue and extinguishment will occur simultaneously. engine crews will attack the seat of the fire while other personnel search for the victims. in some cases where the victim is known to be trapped, rescue will become the primary activity and fire attack will be performed only to protect rescuers and the victim.
typically selected given one or more of the following factors:
-no threat to occupant life exists
-occupants are not savable
-the property is not salvageable
-sufficient resources are not available for offensive strategy
-there is no danger of structural collapse
-an offensive strategy would endanger FFs.
the defensive strategy is intended to isolate or stabilize an incident and keep it from expanding. in the case of a structure fire, a defensive strategy may mean sacrificing a building that is on fire to save adjacent buildings that are not burning. a defensive strategy is generally an exterior operation that is chosen because an interior attack is unsafe or resources are insufficient.
defensive strategies are employed when there is:
-excessive volume of fire
-risk outweighs benefit
-unfavorable wind conditions
the more common and less dangerous transition is from defensive to offensive. a transition from offensive to defensive occurs when conditions in the structure deteriorate rapidly and unexpectedly.
defensive to offensive - in some situations, the first-arriving unit may need to deploy hoselines and begin with a defensive strategy until additional resources arrive or the amount of fire has been reduced or extinguished to safe levels
offensive to defensive - when a situation rapidly changes, the IC must make the decision to transition, communicate the change to all personnel and then order a personal accountability report (PAR) from all personnel to ensure that they have been advised and have withdrawn from offensive positions. all personnel must be made aware of the transition.
during an orderly, tactical withdrawal, hoselines should not be abandoned unless absolutely necessary.
rapid intervention crew or team (RIC/RIT) personnel must be ready to assist any units during the transition.
fire control will be successful only if the amount of water applied is sufficient to cool the burning fuels. selecting the correct size of hoseline is critical for efficiency and safety. for example, using a small-diameter hoseline (SDH) may allow water to be applied sooner than deploying a larger attack line. however, the size of the hoseline may not provide a sufficient volume of water for the size of the fire, which may, in turn, delay extinguishment. for an interior fire, a hoseline no smaller than 1.5in should be used to provide a sufficient volume of water to cool the fire and protect the FFs.
besides the primary attack hoseline, a backup hoseline must be placed in service at the same time. the backup hoseline performs three critical functions by:
-protecting the attack hoseline team from extreme fire behavior
-protecting the means of egress for the attack hoseline team
-providing additional fire suppression capability in the event that the fire increases in volume
the backup hoseline should be at least the same size and provide the same fire flow as the attack hoseline. a fog nozzle is also preferred.
small diameter hose (SDH)
hose of 3/4in to 2in in diameter; used for fire fighting purposes
for an interior fire attack, a fog nozzle is generally the most useful. a wide fog pattern can be used to protect FFs from radiant heat as well as cool the hot fire gases. when it becomes necessary to penetrate the hot gas layer and cool the compartment linings (ceiling or wall) or reach the burning fuel, the nozzle can be adjusted to a straight stream
if an attack is going to be made from the structure's exterior, a solid stream nozzle may be the best choice. the solid stream will deliver the greatest amount of water over the farthest distance.
the water pressure and quantity available will also determine the type of nozzle selected. generally, an automatic fog-stream nozzle will adjust to the volume and pressure of the water supplied by the pumper.
nozzle reaction will also dictate the number of personnel required to advance the hoseline and operate the nozzle within the confines of the structure.
the IC or supervisor will decide where and from what direction to make entry for an interior fire attack. before entering a burning building, every member of the crew should perform a quick size-up and maintain a high level of situational awareness.
interior fire attack crews advancing hoselines must carry tools and equipment needed to open interior doors, check concealed spaces for fire extension, or to make an emergency exit. before entering the building, the FF assigned to the nozzle should open the nozzle fully to ensure adequate flow, check the pattern setting, and bleed air from the hoseline. *do not open the door until you have a charged hoseline and are ready to control the conditions encountered.
when an interior attack is going to be made on a structure fire, FFs should wait in a safe area near the building entrance. from this location extinguish visible fires around entry or exit points. when the attack crew moves to the building entrance, they should stay low and out of the doorway while the door is forced open. check the door for heat before opening with the back of a gloved hand, a TI, or applying a small amount of water spray to the surface of the door.
if the fire is ventilation controlled, cooling the hot gases overhead can reduce the risk of ignition potentially leading to flashover and provide a safer operating environment.
you must observe the smoke movement and air flow when the door is opened: fast air movement in at the bottom and smoke moving out at the top indicates an active fire. with the attack hoseline in place, open the door slightly, apply water to the hot gas layer, and wait 5-10 seconds to observe any reactions before entering the structure.
FFs must maintain control of the door as it is opened. place a rope hose or utility strap over the doorknob so that it can be quickly pulled closed if necessary. once the door is open and entry is made, chock the door to prevent it from closing on the hoseline.
because wind can cause unpredictable changes to the fire, you should attack with the wind at your back.
fire attack - direct attack
a direct attack on the fire using a solid or straight stream uses water most efficiently on free-burning fires. the water is applied directly onto the burning fuels until the fire is extinguished. water should not be applied long enough to upset the thermal layering in the compartment; the steam produced will begin to condense, causing the smoke and heat to drop rapidly to the floor
fire attack - indirect attack
when FFs are unable to enter a burning building or compartment because of the intense heat inside, an indirect attack can be made from outside the structure or involved area. the attack is made through a window or other opening, directing the stream toward the ceiling to cool the room. this method of attack produces large quantities of steam and must be coordinated with ventilation. while an indirect attack cools the fire environment, it results in a fairly uniform temperature from floor to ceiling and fills the compartment with a combined mixture of smoke and steam.
to make an indirect attack on a fire, a fog stream is introduced through an opening and directed at the ceiling where the temperature is highest. the heat converts the water spray to steam, which fills the compartment and absorbs the majority of the heat. once the majority of the fire has been reduced in quantity and the space has been ventilated, hoselines can be advanced inside and FFs can make a direct attack on the body of the fire.
fire attack - combination attack
extinguishing a fire by using both a direct and an indirect attack. this method combines the steam-generating technique of a ceiling level attack with an attack on the burning materials near floor level.
gas cooling is not a fire extinguishment method but is a way of reducing heat release from the hot gas layer. this technique is effective when faced with a shielded fire; that is, a fire that is located in a remote part of the structure hidden from view.
the hot gas layer in the upper levels of the compartment presents problems as it is a fuel and it radiates heat to furniture and other combustibles in the compartment. cooling the gas layer slows the transfer of heat to other combustibles and reduces the chances of the overhead gases igniting.
to cool the hot gas layer, direct short bursts or pulses of water fog into it. your intent is to cool the gases, not to cool the ceiling, as this will produce a large volume of steam. if water droplets fall out of the overhead smoke layer, it means that the gases have been cooled and you can stop spraying water into the smoke.
fires in the upper levels of structures
multistory structures may or may not have standpipe systems; a standpipe may be required on buildings three stories or higher. in structures that lack standpipes, fire attack proceeds through the main entrance and up the closest stairway to the fire location. always check for fire extension below the fire floor before before advancing up the stairs.
most modern structures have the standpipes located in protected stairways. if standpipe connections are locate in unprotected locations, the attack hoseline is connected on the floor below the fire floor and advanced up the nearest stairwell.
if the standpipe connection is in a protected stairway, hoselines may be connected on the fire floor.
fires in upper levels of structures can require large numbers of personnel to conduct large-scale evacuations, carry tools and equipment to upper levels, and maintain a sustained fire attack. elevators must not be used to transport crews to the fire floor.
to minimize the danger from falling objects or debris, cordon off safe paths of entry into the building.
belowground structure fires
residential basements may be totally unfinished, partially unfinished, or completely finished. in an unfinished basement, the floor joists are exposed to the fire and will fail sooner than a ceiling protected with drywall.
factors that contribute to basement fires include:
-fuel loading, especially on the floor above the basement
-age of exposed joists
-hidden paths for fire in walls and ducts that could be exposed in basements
-use of lightweight construction materials that are susceptible to rapid collapse.
basement fires weaken the main floor of a structure creating a constant danger of structural collapse. during initial fire fighting operations, sounding the floor and using a thermal imager have been used to determine if the floor is safe to walk on. when the fire is extinguished, a visual inspection of the floor joists should be made before personnel are permitted to work on the first floor.
accessing the basement is also very dangerous. interior and exterior enclosed stairwells act as a flow path for smoke, flames and heat red gases, much like a chimney. attempting to advance an attack hoseline down an enclosed stairwell may be the only avenue available but it exposed FFs to tremendous hazards. if the first floor is determined to be unsafe, an exterior attack can be made through basement windows. if any openings into the basement exist, use it to apply water to the area before ventilating or entering the first floor. a penetrating or cellar nozzle can also be used if it can be installed without placing personnel on the weakened floor.
in an interior stairwell attack, it is critical that you have enough hoseline to reach the base of the stairs and an additional 6 to 8ft at the bottom to get through the door and out of the narrow area created by the doorway and stairwell.
basement fires are hot and opening a vent point to allow oxygen to enter is going to create more problems
commercial basements and subfloors
basements and subfloors in commercial structures may have similar construction as those in residential structures, though they may be more robust if the fuel load on the main floor is significant. in older type III construction, the first floor joists may be exposed wood joists or even heavy timbers. in more modern structures, the floors may be exposed or unexposed concrete panels or metal C-joists.
exposure to fire may weaken metal floor supports. unprotected steel girders and other supports elongate when exposed to temperatures of 1000F or more.
unaffected areas are referred to as exposures and may exist inside or outside of a structure. interior exposure protection generally involves closing door or other openings between the fire area and the unaffected area and the proper use of tactical ventilation to ensure that smoke movement is limited.
to protect exterior exposures either remove the endangered persons, property or items or apply a protective spray of water or foam extinguishing agent between the fire and the exposure. this spray keeps the exposed surface cool, limiting the effect of radiated heat on the exposure.
controlling building utilities - electricity
*fire department personnel are not responsible for turning utilities back on and should not attempt to do so.
the sources of electricity are usually a commercial power company or an alternative power source in the form of solar panels, wind generators, or fuel-powered generators. in any case, electric service must be disconnected when there is a fire in the structure.
-commercial power supply: electric lines that may be aboveground or buried connect structures to the main power grid. if the lines are aboveground, they will run from the power company pole to a weather head and service mast which will extend down the side of the house to the electric meter box and shutoff. when shutting off the power, pull the handle on the side of the meter box down. in a residential structure, you can shut off the main circuit breakers and cut power to the structure; however, the meter box is the only location that will shut off power to the entire structure. *never touch a steel service mast
electrical power to the entire building should not be shut off until ordered because electrical power is necessary to operate elevators, air-handling equipment, and other essential systems in all types of occupancies.
both high voltage and low voltage systems may be found in many buildings. if power is shut off to the entire building or any device in it, the main power switch should be locked out and tagged out to prevent it from being turned back on before it is safe to do so.
when alternative sources of energy are present, such as solar power or turbines, removing the meter or turning off the master switch may not turn off the power entirely. solar panels generate current whenever there is a light source and are always energized. for wind turbines, even if the power is turned off at the meter box, the power line from the turbine to the meter will remain energized.
high voltage vs low voltage
high voltage is any voltage in excess of 600 volts
low voltage is any voltage that is less than 600v and safe enough for domestic use, typically 120v or less.
controlling building utilities - gas utilities
many houses, manufactured homes, businesses, and industrial properties use natural gas or LPG for cooking, heating, or industrial processes.
natural gas: in its pure form, natural gas is methane, a colorless odorless gas; however, mercaptan is added to give it the smell of rotten eggs. natural gas is lighter than air and so it tends to rise and diffuse in the open. while it is nontoxic, it is classified as an asphyxiant because it may displace normal breathing air in a confined space.
when ordered, the natural gas supply to a structure must be shut off at the meter. the shutoff is an inline valve located on the owner supply side of the meter; that is, between the distribution system and the meter. it is the responsibility of the utility company, not the FD, to turn gas utilities back on.
caution: natural gas that leaks underground in wet soil can lose its odorant and become difficult to detect without instruments
liquified petroleum gas (LPG): refers to fuel gases stored in a liquid state under pressure. butane and propane are the two main gases in this category, although propane is the most popular. like methane, propane is colorless and odorless but mercaptan is added. also, it is nontoxic but is classified as an asphyxiant.
LPG is heavier than air and so will sink to the lowest point possible. the gas is explosive in concentrations of 1.5-10%. it is stored in cylinders and tanks near its point of use. the tank or cylinder is then connected by steel piping and copper tubing to the appliances the gas serves. an LPG leak will produce a visible cloud of vapor that hugs the ground. a fog stream of at least 100gpm can be used to dissipate this cloud of unburned gas.
controlling building utilities - water
it will be necessary to shut off the water supply to prevent water damage from broken pipes. water shutoff valves are located underground with the water meter. commercial structures and industrial facilities have large supply lines that require a special water shutoff key that the FD may assign to certain units or the water dpt may have to provide
supporting fire protection systems at protected structures
protected structures feature some sort of fire protection system such as an automatic sprinkler system and/or standpipe system.
one of the first priorities at a fire in a protected structure is to connect the FD pumper to the FDC. FDCs allow a pumper to supplement the water supply and pressure in a structure's sprinkler or standpipe system.
one means of stopping the water flow from activated sprinkler heads to is close the system's control valve. the control valve is located between the sprinkler system and the main water and is used to shut down water supply to the entire system. shutting the sprinkler system's control valve should only be done once the fire has been brought under control and the IC has given the order to do so.
once the fire has been brought under control, FFs should stop the flow from any activated sprinklers in order to minimize the amount of water damage to the structure and its contents. wooden wedges, sprinkler tongs, and other devices can be used to stop the flow of water
fire suppression system control valves
-outside stem and yolk valve: has a yolk on the outside with a threaded stem that opens and closes the gate inside the valve housing. the threaded portion of the stem is visible beyond the yolk when the valve is open and not visible when the valve is closed
-post indicator valve (PIV): hollow metal post that houses the valve stem. attached to the valve stem is a movable plate with the words OPEN or SHUT
-wall post indicator valve (WPIV): similar to a PIV except that it extends horizontally through the wall with the target and valve operating nut on the outside of the building.
-post indicator valve assembly (PIVA): uses a circular disk inside of a flat plate on top of the valve housing. the PIVA is operated with a built in crank
deploying master stream devices
placement of the device is critical because any movement of the device requires that it be shut down.
FFs should aim the stream so that it enters the structure at an upward angle causing it to deflect off the ceiling or other overhead objects. this angle makes the stream diffuse into smaller droplets that rain down on the fire, providing maximum extinguishing effectiveness.
place the master stream in a location that allows the stream to cover the most surface area of the building.
master stream devices can be very effective at providing exposure protection to other structures. there are two approaches for this. the first, and most effective, is to direct the stream at the surface of the structure that faces the fire. the stream should strike the surface and run down it. the second approach is to create a water curtain between the fire and the exposure.
supplying master streams
master stream devices flow a minimum of 350gpm which can mean high friction loss in supply hose. therefore, it is not practical to supply master stream appliances with anything less than two 2.5in hoselines. when greater quantities of water are needed, a third 2.5in or large-diameter supply line will be required.
*added weight from master stream operations increases the potential for structural collapse.
staffing master stream devices
deploying a master stream device and the necessary hoselines will usually require a minimum of two FFs. once a portable master stream device is in place, one FF can operate it. if the situation is too dangerous to have a FF stationed at the device, it can be securely anchored in position.
suppressing class C fires
class C fires involved energized electrical equipment. when the electrical equipment is de-energized, these fires may self-extinguish or may become either a class A of class B fire. *before initiating fire suppression activities, stop the flow of electricity to the device involved.
when handling fires in delicate electronic or computer equipment, clean extinguishing agents such as Halotron should be used to prevent further damage to the equipment. using water on energized equipment is inappropriate because of the inherent shock hazard and resulting damage to the electrical equipment. if water must be used, apply it from a distance in the form of fog or spray stream.
suppressing class C fires - transmission lines and equipment
to reduce the risk of shock from electric current in the ground, a circle with a radius equal to the distance between the power poles should be cordoned off around the point where the power line contacts the earth. if a ground cover fire does start, FFs should wait for the fire to burn away from the point of contact before attempting to extinguish it. for maximum safety, only utility personnel should cut electrical power lines.
*assume that all power lines are energized until the power company informs you otherwise
fires in older electrical transformers can present a serious health and environmental hazard because of coolant liquids that contain polychlorinated biphenyls (PCBs). these liquids are both flammable and carcinogenic. FFs should assume transformers contain PCBs until proven otherwise.
use a dry chemical or CO2 extinguisher to extinguish fires in transformers at ground level. allow pole-top transformer fires to burn until utility personnel can extinguish the fire
underground transmission lines
explosions caused when a fuse opens or a short circuit ignites accumulated gases are the most serious hazards underground transmission systems present. FFs and the public should stay at least 300ft away from the site and make sure that the apparatus is not positioned over a utility access cover.
only personnel who are properly trained and equipped for confined space entry should enter a utility vault.
commercial high-voltage installations
many commercial and industrial complexes have electrical equipment that requires current in excess of 600v, including transformers and large electric motors. water should not be used in these situations because of the damage it may cause to the electrical equipment.
smoke from these fires may contain toxic chemicals and so SCBA must be worn. a rapid intervention crew/team (RIC/RIT) is required in these situations. entrants should search with a clenched fist or the back of the hand to prevent the reflex action of grabbing energized equipment if it is touched accidentally.
the consequences of electrical shock can include:
-involuntary muscle contractions
-surface or internal burns
-damage to joints
-ultraviolet arc burns to the eyes
factors affecting the seriousness of electric shock:
-path of electricity through the body
-degree of skin resistance - wet (low) or dry (high)
-length of exposure
-available current - amperage flow
-available voltage - electromotive force
-frequency - alternating current (AC) or DC
guidelines for electrical emergencies
-establish an exclusion zone equal to the distance between power poles in all directions from downed power lines
-be aware that a short circuit may have weakened other wires
-only use approved tools with insulated handles
-do not use solid or straight streams on fires in energized electrical equipment
-use of streams with at least 100psi nozzle pressure on energized electrical equipment
-remain inside a vehicle or apparatus that is in contact with power lines. if you must leave the apparatus, jump clear of it and land with both feet together
ground gradient is an electrical behavior that produces electrical pulses in the ground starting at the point where the power line contacts the earth and expanding out in concentric circles, similar to the ripples when you throw a stone into a pond. each ripple is a pulse of electrical current alternating from high to low voltage. stepping from one ripple to another creates an electrical differential that will result in shock.
if you find yourself in a gradient field or feel a tingling in your legs, put your feet close together and hop or shuffle until you are out of the danger area (can be upwards of 150ft)
suppressing class D fires
class D combustible metal fires present the dual problem of burning at extremely high temperatures and being reactive to water. directing hose streams at burning metal can result in the violent decomposition of the metal and subsequent release of hydrogen gas. in these cases, water is only effective at keeping nearby exposures below their ignition temperatures.
class D extinguishing agents can be used to cover the burning metal or if these are not available, exposures can be protected and the fire allowed to burn itself out.
combustible metal fires emit a characteristic brilliant white light. do not assume that these fires are extinguished just because flames are not visible.
combustible metal fires are very hot - greater than 2000F - even after they appear to be extinguished.
suppressing vehicle fires
first size up the scene of the accident and then determine the type of fuel and select the appropriate extinguishing agent. when approaching the vehicle, avoid components that are under constant pressure such as bumpers and sometimes hoods and trunk lids.
-position a hoseline between the burning vehicle and any exposures
-attack the fire from a 45-degree angle to avoid the potential for injuries from exploding hydraulic or pneumatic struts
-extinguish any fire near the vehicle occupants first
-issue an "all clear" when all occupants are out of the vehicle
deploy an attack hoseline that will provide a minimum 95gpm flow rate, such as 1.5 or 1.75in attack hose. a backup hoseline should be deployed ASAP. portable fire extinguishers can extinguish some fires in the vehicle's engine compartment or electrical system and some alternative fuel types.
if combustible metal components become involved, apply large amounts of water to protect adjacent combustibles while applying class D extinguishing agent to the burning metal.
overhaul considerations include disconnecting the battery, securing air bags and cooling fuel tanks and any intact, sealed components
engine or trunk compartment fires
cool the front and rear bumper struts to prevent accidental activation from heat exposure. use forcible entry techniques if necessary and then direct the hose stream into the space until the fire is extinguished.
in many engine compartment fires, the fire must be controlled before the hood can be opened using one of the following methods:
-direct a hose stream through the grill or air scoop
-drive a piercing nozzle through the hood
-make or cut an opening large enough for a hose stream
three methods can be used:
-if there is a hazard in getting close to the vehicle, use a straight stream from a distance to reach under the vehicle
-if the vehicle is on a hard surface, direct the stream downward and allow the water to deflect up toward the underside of the vehicle
-open the hood and direct the stream through the engine compartment
alternative fuel sources tactics
-park apparatus a minimum of 100ft from the incident
-approach from upwind and uphill
-approach from a 45-degree angle
-use non sparking extrication tools
-deploy a backup hoseline
alternative fuel sources - natural gas (CNG and LNG)
natural gas has a high ignition temperature, is colorless and odorless (mercaptan is added), is lighter than air, and is stored under pressure.
currently, government agencies and taxi cab, utility, refuse and mass transit bus companies are most likely to have CNG or LNG. fuel tanks are usually located in the trunk area, under side panels, or in the open bed of pickup trucks.
tactics for fires or leaks in CNG vehicles include:
if no fire is visible:
-use a gas detector to locate leaks, shutoff valves, and eliminate any ignition sources
-stay clear of any detected vapor clouds
if fire is visible:
-allow fuel to burn itself out
-use water or foam to extinguish if necessary
-use fog stream to disperse vapor clouds
LNG is stored in a liquid state by cooling to -260F in double-walled, vacuum-insulated pressure tanks. frost on the fuel tank exterior indicates tank failure.
-avoid any contact with LNG
-stay clear of vapor clouds identified
-shut off the ignition to stop the fuel flow to a leak or fire
-use purple K dry-chemical agent or high-expansion foam on the surface of LNG fire
-use sand or dirt to prevent LNG from entering storm drains
alternative fuel sources - liquified petroleum gas
also known as propane, it is clean burning, safer than gasoline, colorless and odorless (mercaptan is added), and is stored under pressure. LPG expands rapidly when heated, creating the conditions for Boiling Liquid Expanding Vapor Explosion (BLEVE) when an LPG tank is exposed to heat.
tactics to be used with LPG vehicles:
-use gas detectors
-allow the fire to self extinguish
-use foam or water when necessary
-direct streams at the top of the tank to provide adequate cooling
-stay clear of vapor clouds
alternative fuel sources - electric or hybrid electric
batteries may be located in the engine compartment, trunk area, or under the vehicle.
if no fire is visible, secure the vehicle, chock the wheels, turn off the ignition and remove the key. if smoke is visible, PPE/SCBA must be worn. do not approach the vehicle if it is on fire or there is arcing under the hood.
use inertia switches and pilot circuits to shut off a high-voltage system. it will take ~5min for the energy in the system to dissipate. do not cut orange, blue, or yellow color-coded electrical cables or components in electric or hybrid electric vehicles
alternative fuel sources - ethanol/methanol
these are gasoline blends. they are water-soluble, electrically-conductive, clear liquids that have a slight gasoline odor. ethanol and methanol fires burn bright blue and may be hard to see during the day; a TI will need to be used to see the flames.
if a fuel leak is suspected, use caution and approach in full PPE/SCBA, with hoselines deployed and charged. if the vehicle is on fire, establish a control zone and use only alcohol resistant (AR) class B foam, such as AR-AFFF, to extinguish the fire. in both fire and leak situations, request a HAZMAT team response
alternative fuel sources - biodiesel
a blend of liquids made from natural plants and diesel. it is a yellow liquid with the odor of cooking oil.
if there is a fuel leak, control the leak per local SOPs and request a HAZMAT team. if the vehicle is on fire, use dry chemical, CO2, water fog spray, or foam to extinguish
alternative fuel sources - hydrogen
hydrogen is colorless, odorless, non-toxic, and energy efficient. because the flame is invisible during the day, a TI should be used to see the flame.
do not extinguish the fire. instead, protect the exposures and allow the fuel to burn off. if extrication is required, do not cut C-posts which contain the vents
suppressing fires in other class A materials
-stacked and piled materials: the possibility than any portion can be salvaged once a fire starts is small. the greatest danger is to the exposures, primarily nearby structures and ground cover. fire streams should be directed at the extreme edge of the fire, controlling the spread. use a straight stream from a distance and then switch to a fog pattern as you move the nozzle closer.
class A foam, applied with an eductor or through a compressed air foam system (CAFS), is very effective for these types of fires
-small, unattached structures: should be attacked from the exterior. class A foam and fog streams can be very effective for exposure protection, advancing close to the fire and extinguishment.
you should assume that chemicals, flammable/combustible liquids, explosives or illegal materials may be inside the building. if there is any question of the hazard, water should be applied through a straight stream, the exposures protected, and the structure allowed to self-extinguish
-trash container fires: toxic products of combustion will be present so PPE/SCBA must be worn. it may be advantageous to attack the fire using class A foam
combatting ground cover fires
the three main influences on ground cover fire behavior are fuel, weather and topography.
typically, two of the elements of the fire triangle - oxygen and fuel - are always present where ground cover fire is found. it is the addition of an ignition source, either naturally or by human action, that will result in ground cover fire.
types of ground cover fires
-ground fire: burn in the dead layer of organic matter (called humus) that generally covers the soil in forested areas. they are slow-moving, smoldering fires that can go undetected for months before they enter a flaming stage
-surface fire: also known as a crawling fire, it is the most common type of ground cover fire, burning on the soil surface consuming low-lying grass, shrubs and other vegetation
-crown or canopy fire: wind-driven, high-intensity fires that move through the tree tops of heavily forested areas. the typical causes of crown fires are lighting strikes or extensions from ground surface fires. these extensions are called ladder fires.
ground cover fire behavior - fuel
ground cover fuels are typically categorized based upon the location of the fuels as follows:
-subsurface fuels: roots, peat and other partially decomposed organic matter that lie under the surface of the ground
-surface fuels: needles, duff, twigs, grass, field crops, brush up to 6ft in height, downed limbs, logging slash, and small tress on or immediately adjacent to the surface of the ground
-aerial fuels: suspended and upright fuels (brush over 6ft) physically separated from the ground's surface to the extent that air can circulate freely between them and the ground
the following factors affect the burning characteristics of ground cover fires:
fuel size, compactness, continuity, volume, fuel moisture content
ground cover fire behavior - weather
weather factors that influence ground cover fire behavior:
-wind: fans the flames into greater intensity and supplies fresh air that speeds combustion; very large-sized fires create their own winds
-temperature: primarily affects the fuels as a result of long-term drying
-relative humidity: significantly affects dead fuels that only gain moisture from the surrounding air rather than their root system
-precipitation: determines the moisture content of live fuels
ground cover fire behavior - topography
topography refers to the features of the earth's surface.
fires will usually spread faster uphill than downhill, and the steeper the slope, the faster the fire spreads.
-aspect: determines the affects of solar heating. in NA, full southern exposures receive more of the sun's direct rays and therefore receive more heat. ground cover fires typically burn faster on southern exposures.
-local terrain features: features such as canyons, ridges, ravines, and even large rock outcroppings may alter air flow and cause turbulence or eddies, resulting in erratic fire behavior.
-drainages: these steep ravines are terrain features that create turbulent updrafts causing a chimney effect. wind movement can be critical in chutes (narrow V-shaped ravines) and saddles (depression between two adjacent hilltops).
parts of a ground cover fire
-origin: area where the fire started and the point from which it spreads
-head: the part of the ground cover fire that spreads most rapidly. usually found on the opposite side of the fire from the area of origin and in the direction toward which the wind is blowing.
-finger: fingers are long, narrow strips of fire extending from the main fire. when not controlled, they can form new heads
-perimeter: the outer boundary, or the distance around the outside edge, of the burning or burned area.
-heel: the opposite side of the head. because it usually burns downhill or against the wind, it burns slowly and isn easier to control than the head
-flanks: the sides of a ground cover fire, roughly parallel to the main direction of fire spread. a shift in wind direction can change the flank into a head
-spot fire: caused by sparks or embers landing outside the main fire.
-islands: patches of unburned fuel inside the perimeter
-green: area of unburned fuels next to the involved area
-black: the opposite of the green, the black is the area in which the fire has consumed the fuels
wildland PPE and equipment
when fighting a ground cover fire, FFs should wear PPE that meets the requirements of NFPA 1977, standard on protective clothing and equipment for wild land firefighting. NFPA 1500, standard on fire dpt occupational safety and health program, specifies the minimum PPE for FFs to participate in ground cover firefighting. this standard requires FFs to be equipped with the following:
-helmet with eye protection and neck shroud
-flame retardant shirt and pants
-protective footwear (sturdy boots w/o steel toes)
attacking the fire
the methods used to attack ground cover fires revolve around perimeter control. the objective is to establish a control line that completely encircles the fire with all the fuels inside rendered harmless.
direct attack: operation where action is taken directly on burning fuels by applying an extinguishing agent to the edge of the fire or close to it
indirect attack: a method of controlling a ground cover fire in which a control line is constructed or located some distance from the edge of the main fire, and the fuel between the two points is burned. generally used against firs that are too hot, too fast, or too big for a direct attack.
safety principles and practices
Lookouts, Communications, Escape routes, and Safety zones (LCES)
-lookouts: know where the fire is and where its going. lookouts are placed at locations that can observe the fire without being in front of it.
-communications: know who is operating above, below and adjacent to you
-escape routes: know more than one way out of the area you are working in. an escape route is a marked path that leads to a safety zone and is short enough to allow personnel to safely travel to it
-safe zones: know how to quickly get to an area of refuge.
take the following precautions to protect yourself from lightning hazards:
-do not stand under tall, isolated trees
-if you are in a flat field and feel your hair stand on end, it is an indication that lightning is about to strike: drop to your knees and bend forward putting your hands on your knees
Ten standard fir fighting orders
1. keep informed on weather conditions and forecasts
2. know what the fire is doing at all times
3. base all actions on current and expected behavior of the fire
4. identify escape routes and safety zones and make them known
5. post lookouts when there is possible danger
6. be alert, keep calm, think clearly, and act decisively
7. maintain prompt communications with your forces, your supervisor and adjoining forces
8. give clear instructions and ensure that they are understood
9. maintain control of your forces at all times
10. fight fire aggressively, providing for safety first.
coordinating fire ground operations
the incident priorities for any emergency are life safety, incident stabilization and property conservation. to accomplish these priorities, fire officers and FFs apply tactics traditionally known by the acronym RECEO-VS:
R - rescue
E - exposures
C - confinement
E - extinguishment
O - overhaul
V - ventilation
S - salvage
fireground roles and responsibilities - first-arriving engine company
your department SOPs will define the actions that the first-arriving person or unit is expected to take, but typically these include:
-making the initial size-up
-deploying additional resources
-communicating the situation to the communication center and other responding units
if smoke or fire is visible, some SOPs require that the unit stop and lay a supply line from the closest fire hydrant to the scene. other SOPs allow the first arriving truck to initiate a quick attack using the water supply on the apparatus.
if there are too few resources assigned to the incident to meet incident objectives established during size-up, then additional resources must be requested. departments must adhere to the two-in, two-out regulation which requires that when two FFs enter a structure fire that has developed beyond the incipient stage, there must be two fully equipped FFs outside to rescue the attack team in an emergency.
once the size-up is compete and the location of the fire is known, the first engine company will deploy the initial attack hoseline to accomplish the following priorities:
-intervene between trapped occupants and the fire
-protect primary means of egress
-protect interior exposures
-protect exterior exposures
-operate master streams
fireground roles and responsibilities - second arriving engine company
unless otherwise assigned, the second engine company must first make sure that adequate water supply is established to the fire ground. the second-arriving engine company may be required to complete tasks that the first engine company began such as:
-finishing a hose lay
-deploying an additional hoseline
-connecting to a hydrant to support hoselines that are already deployed.
once the water supply has been established, the personnel from the second company will perform tasks that the IC assigns including:
-assist in advancing first attack hoseline
-back up the initial attack line
-protect secondary means of egress
-prevent fire extension
-protect the most threatened exposure
-assist in extinguishment
-assist with foreground support company operations
-form the rapid intervention crew/team (RIC/RIT)
fireground roles and responsibilities - fireground support company
if a support company (aerial apparatus or rescue unit) has been dispatched to the fire, the situation will dictate the tasks the support company will perform including any of the following:
-search and rescue
-ground or aerial ladder placement
-checking for fire extension
-operating elevated fire streams
depending on the situation, teams may first search areas closest to the fire if doing so will not put them at risk of severe injury or death.
in addition to search and ventilation operations, some SOPs allow support company personnel to assist engine companies in making the fire attack.
in other situations, a master stream can be used to attack the fire in what is called a blitz attack. a blitz attack is to aggressively attack a fire from the exterior with a large-diameter (2.5in or larger) fire stream.
fireground roles and responsibilities - rapid intervention crew/team (RIC/RIT)
RIC/RIT are tasked with locating and assisting FFs who have become trapped, lost, or incapacitated during interior structural fire fighting. RIC/RIT may be any engine, ladder or rescue company that is equipped and assigned the task once they arrive on scene.
each RIC/RIT consists of two or more members wearing complete PPE and respiratory protection. the team should be equipped with a radio, any special rescue tools needed, a spare SCBA or air cylinder, and equipment necessary to perform a rescue of other emergency personnel.
fireground roles and responsibilities - chief officer/ incident commander
upon arrival at the scene, a chief officer may choose to assume command from the original IC and take responsibility for all on-scene operations. alternatively, if the original IC has the incident well organized and reasonable progress toward incident stabilization is being made, the chief officer may choose to assume another role in the IC structure.
the first arriving fire officer or FF must establish command. generally, there are three initial command options that should be relayed when command is taken.
1. nothing showing - when the problem is not obvious, the officer or FF should assume command of the incident and broadcast on the radio that "nothing is showing". that person should direct the other responding units to assume predetermined positions at the scene to allow for a maximum of deployment flexibility. the officer/FF then accompanies unit personnel on an investigation of the situation and maintains command using a portable radio
2. fast-attack - when the officer of FFs direct involvement is necessary for the unit to take immediate action to save a life or stabilize the situation, they should take command and announce that the unit is initiating a fast attack. personnel will continue the fast attack, which usually only lasts a short time, until one of the following situations occurs:
-incident is stabilized
-incident is not stabilized, but the officer/FF must withdraw to establish a formal incident command post (ICP)
-command is transferred
3. name the incident and establish the ICP - officer or FF should assume command by naming the incident and designating an ICP, giving an initial report on the conditions and requesting the additional resources needed.
-combat command: office/FF performs multiple tasks such as serving as IC, developing incident action plan (IAP), and performing active tasks such as advancing hoseline
-formal command: involves the company officer remaining at the mobile radio in the apparatus, assigning tasks to unit personnel, communicating with other responding units, and expanding the NIMS-ICS as needed by the complexity of the incident. in addition, the officer/FF must decide how to deploy the remainder of the unit.
the fire officer assuming command must communicate either face-to-face or over the radio with the officer/FF being relieved. command should never be transferred to anyone who is not at the scene. the officer/FF being relieved should brief the relieving officer on the following items:
-name of incident
-goals and objectives listed in the incident action plan (IAP)
-progress toward completion of tactical objectives
-deployment of assigned resources
-assessment of the need for additional resources
fires in underground spaces
electrical equipment such as flashlights, portable fans, portable lights, and radios should be intrinsically safe for use in flammable atmospheres. the atmospheric and physical hazards that may be expected include the following:
-flammable gases and vapors
-limited means of entry and egress
-cave-ins or unstable support members
-standing water or other liquids
because of the hazards that may exist in these spaces, the command post and staging area must be established outside the hot zone. an accountability officer or incident safety officer must be stationed at the confined space entrance to track personnel and equipment entering and leaving the space.
an effective air-management system should be part of the IAP to prevent FFs from advancing into confined spaces farther than their air supply will safely allow
suppressing class B fires
class B fires involve flammable and combustible liquids an gases. flammable liquids have flash points of less than 100F; examples are gasoline and acetone. flammable liquids can be ignited without being preheated. combustible liquids have flash points higher than 100F; examples are kerosene and vegetable oil. combustible liquids must be heated above their flash point before they can be ignited. flammable and combustible liquids can further be divided into hydrocarbons (that do not mix with water) and polar solvents (that do mix with water).
because wind currents can spread the vapors or gases, your first action should be to determine the wind direction. after determining wind direction, take the following actions:
-locate the apparatus upwind and uphill of the incident
-establish a perimeter
-report current conditions to all responding units and the communications center
-evacuate any civilians in the affected area
-request a HAZMAT response team and remain outside the hot zone
-establish a water supply and deploy attack hoselines as required.
safety precautions at flammable/combustible liquid fire incidents
the first precaution is to avoid standing in pools of fuel or runoff water contaminated with fuel on top.
flammable/combustible liquid fires burning around relief valves or piping must not be extinguished until the leak is controlled. unburned vapors are usually heavier than air and form pools or pockets of gas in low areas where they may ignite.
if a closed container, such as a pressure vessel containing liquids or liquified gases (LPG) is heated, the liquid inside begins expanding. when the liquid reaches its boiling point, it begins to return to its gaseous state and the internal pressure on the vessel increases. when too much pressure builds up, the vessel loses its structural integrity and ruptures, releasing massive amounts of pressure and the flammable contents of the vessel. the release and subsequent vaporization of these flammable liquids can result in a BLEVE. for a BLEVE to occur, the liquid or liquified gas must be above its boiling point when the container failure occurs.
tank failure may occur as a result of mechanical damage to the tank or from direct flame impingement on the vapor space in the tank. the most common cause of BLEVE is when flames contact the tank shell above the liquid level and when insufficient water is applied to keep a tank shell cool. when attacking these fires, apply water to the upper portions of the tank, preferably from unattended master stream devices.
applying foam is the method most often used to control flammable liquid fires
-automatic sprinkler system
-standpipe system: permit FFs to deploy attack hoselines on upper stories of structures and in large area structures and industrial sites.
-foam systems: installed in locations where large quantities of class B flammable/combustible liquids are stored or used. in some locations such as aircraft hangars and transformer vaults, a total flooding system will be installed. in these sites the entire compartment or structure is filled with foam.
often found in industrial occupancies such as coal-fired power plants.
nonwater-based systems include CO2, clean agent, and wet and dry chemical systems. the extinguishing agents should not be disturbed or removed and attack hoselines should be deployed and in position in the event that fires in adjacent class A materials need to be extinguished. SCBA must be worn in areas where these agents have been used
using water to control class B fires
even though water alone is an ineffective extinguishing agent for class B fires, it can be used in various ways to safely control them. remember that hydrocarbons (gasoline, kerosene, and other petroleum products) do not mix with water, and polar solvents (alcohols, lacquers) do mix with water.
-cooling agent: water can be used as a cooling agent to control class B fires and to protect exposures. water without foam additives is not particularly effective on lighter petroleum distillates (such as gasoline or kerosene) or alcohols. however, water applied as droplets in sufficient quantities can absorb the heat from fires in heavier oils such as raw crude and extinguish the fires.
-mechanical tool: water from hoselines can be used to move class B fuels to areas where they can safely burn or where ignition sources are more easily controlled. class B fuels must never be flushed down storm drains or into sewers. use appropriate fog patterns for protection from radiant heat and to prevent "plunging" the stream into the liquid. plunging a stream into burning flammable liquids causes increased production of flammable vapors and greatly increases fire intensity. slowly move the stream from side to side and "sweep" the fuel or fire to the desired location.
-crew protection: fog stream patterns can be used as crew protection when advancing to shut off liquid or gas control valves. although one hoseline can be used for crew protection, two lines with a backup line are preferred for fire control and safety.
when pressure vessels containing flammable/combustible liquids or compressed gases are exposed to flame impingement, apply solid streams from their maximum effective reach until relief valves close. a minimum of 500gpm must be applied at each point of flame impingement
bulk transport vehicle fires
at least one lane of traffic in addition to the accident lane should be closed during the initial emergency operations.
during fire control procedures, the fire dpt is obligated to protect the environment as well. to prevent runoff of contaminated water and spilled liquids, storm water drains should be blocked.
flammable gas incidents
the distribution system for natural gas consists of a vast network of surface and subsurface pipes. gas pressure in these pipes range from 1000psi in the distribution network to .25psi at the point of use. however, the pressure is usually below 50psi in local distribution piping.
excavation equipment breaking through underground pipes is generally the cause of most natural and liquified petroleum gas incidents. apparatus should approach from and stage on the upwind side.
if gas is burning, the flame should not be extinguished. provide protection for exposures. the utility company should be contacted and an attempt to shut off the pressurized gas supply should be made.
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