IFSTA CH 14 Fire Suppression Flashcards
4 types of fire suppression
temperature reduction
fuel removal
oxygen exclusion
chemical flame inhibition
Temperature Reduction
To extinguish a fire by reducing its temperature, enough water must be applied to absorb the heat being generated and stop the gas phase chemical reaction
The use of water for cooling is the most effective method available for the extinguishment of smoldering fires
cooling burning gases
Limits or stops flaming combustion in the upper layer
Slows the pyrolysis process of combustible materials
Reduces radiant heat flux from the upper layer
Reduces the potential for flashover
Removing fuel is a more common tactic at:
o Ground cover fires
o Exterior stacked material fires
o Vehicle fires
o Flammable liquid/gas fires
Fuel Removal
Allowing a fire to burn until all available fuel is consumed while firefighters protect exposures is another example of fuel removal
A fuel source may be removed as follows:
Stopping the flow of a liquid fuel
Closing valves to stop emission of gaseous fuels
Moving solid fuels out of the path of the fire
Oxygen Exclusion
In its simplest form, this method is used to extinguish stove-top fires when a cover is placed on a pan of burning grease
Chemical Flame Inhibition
Extinguishing agents such as some dry chemicals, halogenated agents (halons) and Halon-replacement “clean” agents, inhibit or interrupt the combustion reaction and stop flame production
The following are also pre-entry considerations critical to firefighting safety and effectiveness:
Reading fire behavior indicators
Understanding the crews tactical assignment
Identifying potential emergency escape routes
Evaluating forcible entry requirements
Identifying hazards
Verifying that radios are receiving and transmitting on the correct channel
Ensuring that SCBA is on, cylinder is full and operating properly
Ensuring that all PASS devices are on and operating properly
Doing a buddy check to ensure other team members are prepared to enter the structure
Fire attack crews advancing hose lines must carry tools and equipment needed to open interior doors
o Portable radios
o Hand light
o Pike pole
o Thermal imager
o Forcible entry tools
Before entering the building or the fire area, the firefighter assigned to the nozzle should:
Open the nozzle fully to ensure adequate water flow
Check the pattern setting
Ensure hose is kink free
Bleed the air from the hose line
Gas Cooling - This technique is effective when faced with a shielded fire*
That is, a fire you cannot see from the doorway because it is located in a remote part of the structure or objects are shielding the fire
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 duels until the fire is extinguished
Indirect Attack
An indirect attack can be made from inside or outside the structure
The attack is made by directing the stream toward the ceiling to cool the room or by banking the stream off of the walls
An effective technique is to direct the stream onto the ceiling and walls, which can slow or stop the pyrolysis process on these hot surfaces
Combination Attack
A combination attack combines cooling the hot gas layer at the ceiling level using an indirect attack with a direct attack on the fuels burning near the floor level
To combine both attacks, move the nozzle from the area overhead to the floor in a Z, T or rotational manner
Transitional Attack
Uses an exterior fire attack through a ventilation opening to help a fire transition from ventilation-limited conditions to fuel-limited conditions
Reduces the potential for flashover and creates a more survivable interior environment
Short applications (30 seconds) of a solid or straight stream applied in a side-to-side motion into the super-heated products of combustion overhead can inhibit flashover conditions
Fires in Upper Levels of Structures
Multistory structures may contain standpipe systems (three stories or higher)
In structures equipped with standpipe systems, the location of the standpipe connections determines the fire attack method
location of standpipe systems
If standpipe connections are located in unprotected locations, the attack hose line is connected on the floor below the fire floor and advanced up the nearest stairwell
If the standpipe connection is in a protected stairway, hose lines may be connected on the fire floor
Residential Basements
In unfinished basements, the first floor joists are exposed to the fire and will fail sooner than a ceiling protected with drywall
Collapse hazards during basement fires include:
Fuel loading, especially the fuel load 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
Exposure Protection
Preventing a fire from spreading to unaffected areas is a critical tactic
Unaffected areas are referred to as exposures and may exist inside or outside of a structure
Can take a number of forms depending on the location and type of exposure and the resources available to the fire department
Interior exposure
Protection generally involves closing doors or other openings between the fire area and the unaffected area and the proper use of tactical ventilation to ensure limited smoke movement
Exterior exposures
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
Connecting to a Fire Department Connection (FDC)
One of the first priorities at a fire in a protected structure is to connect the pumping apparatus to the fire department connections
FDCs allow a pumper to supplement the water supply and pressure in a structures sprinkler or standpipe system
Ones means to stop the water flow from activated sprinkler heads is to close the systems control valve
The control valve is located between the sprinkler system and the main water supply and is used to shut down water supply to the entire system
Should only be done once the fire is under control and the IC has given the order to do so
Several types of control valves are installed on the fire suppression system
o Outside screw and yoke valve
o Post indicator valve
o Wall post indicator valve
o Post indicator valve assembly
BUILDING UTILITIES
Controlling building utilities helps control the fire and limits damage
You must know the location of the control switches and valves and how to shut them off
turning utilities back on
Fire department personnel are not responsible for turning utilities back on and should not attempt to do so
Turning the electricity or natural gas back on could reignite the fire due to damage wiring, pipes or appliances
Electricity
Electricity usually comes from a commercial power company or an alternative source such as solar panels, wind generators or fuel-powered generators
Commercial power supply
The electric meter is the primary location for shutting off power
The only safe way to cut all the power to a structure is at the main breaker or meter shutoff
Lockout/tagout devices
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
Alternative Energy Sources
Firefighters should be alert for installations with alternative emergency power capabilities such as solar panel arrays, wind turbines and liquid/gas fueled generators
Where these sources are present, removing the meter or turning off the master switch may not turn off the power
Natural Gas
In its pure form is methane, which has a flammability range of 5 percent to 15 percent but it is nontoxic
Natural gas is lighter than air, so it tends to rise and diffuse in the open
While it is nontoxic, it is classified as an asphyxiant because it may displace air in a confined space and lead to suffocation
Liquefied Petroleum Gas (LPG)
Refers to fuel gases stored in a liquid state under pressure
There are two main gases in this category – butane and propane – propane is the most widely used
LPG is about 1.5 times as heavy as air, so it will sink to the lowest point possible
The gas is explosive in concentrations between 2 percent and 9.5 percent
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
Vehicle Scene Safety
Before attacking the fire or commencing with extrication, isolate the vehicle from any ignition sources or eliminate the ignition source
Next, stabilize the vehicle, control any downed power lines and address any additional hazards
Avoiding common injuries at vehicle scenes
When approaching the vehicle, avoid components that are under constant pressure such as bumpers and sometimes hoods and trunk lids
These components incorporate hydraulic or pneumatic struts intended to absorb the shock of minor collisions
Controlling fuel leaks can be accomplished in various ways:
broken fuel line may be Crimped with pliers or Plugged with rubber, plastic or wooden plugs
Broken or punctured fuel tanks may be:
Plugged with rubber, plastic or wooden plugs or Sealed with a fuel resistant sealing compound
Selecting hose streams for vehicle fires
In most passenger vehicle fires, one or two 1.5 or 1 ¾ - inch handlines can extinguish an automobile fire
inch to mm
1 inch = 25.4mm
The basic procedures for attacking a fire in a vehicle are as follows:
Position a hose line between the burning vehicle and any exposures
Position for attack uphill of the fire to avoid standing in the path of leaking fuels running downhill
Attack the fire at a 45-degree angle from the side of the vehicle 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 get out of the vehicle
Extinguish any ground fire around or under the vehicle
Extinguish any fire remaining in or around the vehicle
vehicle fire attack -Extraordinary hazards include the following:
Large-capacity saddle fuel tanks
Alternative fuel tanks
Pressurized natural gas tanks
Hazardous materials
Natural Gas Vehicle Fuel (CNG and LNG)
Natural gas is used in vehicles in the form of compressed natural gas (CNG) or liquefied natural gas (LNG)
Government agencies, taxis, utility, refuse and mass transit bus companies are most likely to use CNG or LNG
Natural Gas Vehicle Fuel (CNG and LNG) - If no fire is visible:
Use a gas detector to locate leaks, locate shutoff valves and eliminate ignition sources
Stay clear of any detected vapor clouds
Natural Gas Vehicle Fuel (CNG and LNG) - If fire is visible:
Allow fuel to burn itself out
Use water or foam to extinguish if necessary
Cool the container from a safe distance
Use fog stream to disperse vapor clouds
Avoid contact with high velocity jet of escaping gas
LPG (liquefied petroleum gas) Vehicle Fuel
Also know as propane, is the third most common vehicle fuel type after gasoline and diesel and is safer than gasoline
Tactics that should be used at incidents involving LPG (propane) vehicles:
Use gas detectors to determine leaks and isolate leaks from ignition sources
Allow the fire to self-extinguish
Use foam or water when necessary for extinguishment
Direct hose streams at the top of the LPG tank to provide adequate cooling or high-expansion foam on the surface of the fuel
Stay clear of any identified vapor clouds
Ethanol/Methanol
Are gasoline blends
They are water soluble, electrically-conductive, clear liquids that have a slight gasoline odor
If the vehicle is leaking or on fire, establish a control zone and request a hazardous materials response team
EXTERIOR CLASS A FIRES
Exterior fires may occur in stacked and piled materials, small unattached structures and trash containers
The following conditions specific to Class A exteriors fires should be observed and communicated:
Changes to the configuration of the materials
Changes to firefighter position to the fire based upon changes to fire spread or other factors
Indicators of imminent collapse
Spread of fire to exposure
Wind direction and speed
Effectiveness of fire attack
Stacked and Piled Materials
The greatest danger is to exposures, primarily nearby structures and ground cover
Stacked and Piled Materials nozzle tips
As the fire is reduced, move the nozzle closer to the stacked material using the fog pattern to protect yourself
Other personnel can use pike poles and hay hooks to break up or pill apart the stacked or piled material so that the stream can reach all the burning material
Stacked and Piled Materials and class A foam
applied with an eductor or through a compressed-air foam system, is very effective for these types of fires
The foam will soak into the materials and coat the ground cover and exposures, preventing fire spread
Small Unattached Structures
Fire that should be attacked from the exterior
The primary mission is to prevent fire spread to exposures and then extinguish the fire
Class A foam and fog streams can be very effective for exposure protection, advancing close to the fire and extinguishment
Trash Container Fires
Toxic products of combustion will be present in trash container fires of all types, so full PPE and SCBA should be worn when attacking any trash container fire
Three main influences on ground cover fire behavior are
fuel, weather and topography
Weather is the most significant
Ground cover Fires - Fuel characteristics
Fuel type such as grass, trees or underbrush
Fuel moisture content (wet or dry)
Arrangement of fuels and location of exposures
Ground cover Fires - topography
Location of the fire
Upward slope or downward slope
Terrain features (canyons, chutes)
Ground cover Fires - weather
Visibility
Wind speed and direction
Relative humidity
Thunderstorm development or other weather events
Ground cover Fires - fire behaviour
Location of fire
Changes to spread, and growth
Ground cover Fires - location of resources
Water supply
Personnel
Apparatus/equipment
Types of Ground Cover Fires
ground fire
surface fire
crown fire
ground fire
Burn in the layer of dead organic matter that generally covers the soil in forested areas
These are slow-moving, smoldering fires that can go undetected for months before they enter a flaming stage
Due to composition of the fuel, these fires are generally limited to forests and are very difficult to extinguish
surface fire
Or crawling fire is the most common type of ground cover fire
Burning on the soil surface consuming low-lying grass, shrubs and other vegetation
Can occur anywhere and can be natural or human caused
crown fire
Or canopy fires are wind-driven, high-intensity fires that move through the tree tops of heavily forested areas
Ground cover fuels
Subsurface or ground fuels
Surface fuels
Aerial fuels
Fuel size (small or light burn faster)
Compactness (tightly compacted burn slower)
Continuity
Volume
Fuel moisture content
Weather
Wind
Temperature
Temperature differences (high to low pressure)
Relative humidity
Precipitation
Topography
Refers to the earth surface features
The steepness of a slope affects the rate and direction of a ground cover fire spread
Ground Cover - Types of fire attack
direct attack
indirect attack
flank attack
parallel attack
Ground Cover - direct attack
action taken directly against the flames at its edge or closely parallel to it
Ground Cover - indirect attack
used at varying distances from the advancing fire
Ground Cover - flank attack
are normally used for moderately intense fires and can be either direct or indirect
The attack begins at a secure anchor point* (road, highway, body or water or previous burn) on one or both of the fires flanks and works toward the head
Ground Cover - parallel attack
is a form of indirect attack
Involves creating a control line quickly using bulldozers or other heavy equipment
Ground cover fires - Fire lines
Are parts of control lines along which fuel and sometimes earth are removed to create a fire stop
To make a line as effective as possible, the following must be done:
Remove all vegetation and debris from the line
Clear the line down to mineral soil
Widen the line as directed in order to provide sufficient fire breaks depending upon height of the vegetation
Throw all burned/charred material into the black
Scatter all cut and unburned fuels into the green
Remove all branches that hang over the line
Ground Cover Fire Safety Principles and Practices
LACES
LOOKOUT
ANCHOR POINTS
COMMUNICATION
ESCAPE ROUTES
SAFETY ZONES
lookouts
monitor fire development and spread
communication
is an essential part of any ground cover operation
Rapid communication can prevent personnel form being trapped by changes in fire behavior and/or wind speed and direction
escape routes
is a marked path that leads to a safety zone and is short enough to allow personnel to safely travel to it
safety zones
may be in the burned area if it is sufficiently cooled and accessible
