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
