Chpt 14 Flashcards
The national institute of standards and technology has determined that foam is ______ more effective than plain water in extinguishing fires, which can justify its use and added expense at an incident site
Three to five times
Is a device that mixes the foam concentrate into the fire stream in the proper percentage
Foam proportioner
The expansion of foam solution depends on good mechanical agitation and effective ______, the process of introducing air into the foam solution
Aeration
Foam tetrahedron includes four components
Water
Foam concentrate
Air
Mechanical agitation
Are produced when water and foam concentrate are mixed in the appropriate amounts
Mechanical foams
Hydrocarbon fuels, such as gasoline, jet fuel, and kerosene, have a lower _______ than water
Surface tension
Comprises the time required for a foam blanket to spread out across a fuel surface
Knockdown and speed flow
Are used on ordinary combustible materials such as wood, textiles, and paper; they are also effective on organic materials such as straw and hay.
Class A
Class A foams sometimes referred to as ______, are very effective because they improve the penetrating effect of water and allow for great heat absorption
Wetting agents
According to foam manufacturers, these wetting agents can extinguish fie involving class A materials as much as _____ faster than water
20 times
Is particularly useful for protecting buildings in rural areas during forest and brush fires when the water supply is limited
Class A foam
Many fire departments use ____ while performing initial attack and overhaul of fires
Class A foam
Class A foam increases the effectiveness of the water as an extinguishing agent by reducing the _____ of the water
Surface tension
Are used on hydrocarbon, combustible fuels, or polar solvent fires
Class B foams
A _____ reduces the surface tension of water and enhances penetration into fuel that is burning
Wetting agent
A ____ creates a stable mass of small, air filled bubbles with lower density than oil, gas, or water and will float on top of burning fuel, creating a blanket that separates the fuel from air, lowering the Temperature and suppressing the vapors
Foam
Are used to extinguish class B fires involving hydrocarbons
Protein foams
Contain naturally occurring proteins that is, animal by product as the foaming agent.
Protein foams
They produce highly stabilized mechanical foam with good expansion properties, excellent heat, and ______ and good drainage characteristics
Burn back resistance
Consists of hydrolyzed protein, stabilizers, preservatives, and synthetic fluorocarbon surfactants
Fluoroprotein foam
This type of foam is used for hydrocarbon vapor suppression and extinguishment of fuel in depth fires
Fluoroprotein foam
Have slower knockdown characteristics than other concentrates, but they provide a long lasting foam blanket after the fire is extinguished
Regular protein foams
Because they must be properly aspirated, these foams should not be used with non aspirating structural fog nozzles
Fluoroprotein foams
Is able to form a vapor sealing film on non polar solvents
Film forming fluoroprotein foam
Knockdown performance is improved because the foam releases an aqueous film on the surface of the hydrocarbon fuel
Film forming fluoroprotein foams
Can be used on both hydrocarbon and water soluble fuels
Alcohol resistant film forming fluoroprotein foam
AR-FFFP is basically FFFP with a _______ additive
Polysaccharide polymer additive
Is based on combination of flurochemical surfactants, hydrocarbon surfactants, mad solvents
AFFF aqueous film forming foam
Because of the versatility of ____; it is used by the majority of municipal and airport fire departments in North America
AFFF
It’s ability to flow quickly allows _____ to achieve a very fast knockdown of hydrocarbon fuels
AFFF
Aspirating foam nozzles Should be used to apply _____ to ensure maximum performance
AFFF
Comprises a combination of synthetic detergents, flurochemicals, and high molecular weight polymers
Alcohol resistant aqueous film forming foams
AR-AFFF
Is one of the most versatile type of foam.
AR -AFFF
Are highly effective in confined space firefighting operations and in areas where access is limited or entry is dangerous to fire fighters, such as basements, ship board compartments, warehouses, aircraft hangars, and mine shafts
High expansion foams
High expansion foams can be used on either ____ fires
Class a or class b fires
The foam concentrates are normally proportioned in rations between 1 to 3 percent for these uses
High expansion foams
Are designed to be mixed with water at specific ratios
Foam concentrates
Foam concentrate ratios vary from _____ for class a foams
0.1 to 1 percent
Foam concentrate ratio for class b
1 to 6 percent
Alcohol resistant foams can be used effectively on both hydrocarbon and polar solvent fuels. ______ is the most commonly used concentrate for this purpose; it is available in a variety of percentages
AR-AFFF
The _____ is the ratio of finished foam to foam solution after the concentrate is mixed with water, agitated, and aspirated through a foam making appliance
Foam expansion rate
Low expansion foam Has a foam expansion ratio of up to
20:1
This type of foam is primarily designed for use on flammable and combustible liquids
Low expansion foam
Low expansion foam is effective in controlling and extinguishing most
Class B fires
Medium expansion foam has a foam expansion ratio in the range of _______
20:1 to 200:1
This kind of foam is used primarily to suppress vapors from hazardous chemicals
Medium expansion foam
Foams with expansion ratios between ______ have been found to produce the optimal foam blanket for vapor mitigation of highly reactive chemicals and low boiling points
30:1 and 55:1 medium expansion foam
High expansion foams has a foam expansion ratio in the range of
200:1 to 1000:1
This type of foam is designed for confined space firefighting
High expansion foams
The foam concentrate consists of a synthetic, detergent type foam used in confined spaces such as basements, mines, ship board, and aircraft hangars
High expansion foams
The ____ is a device that mixes the foam concentrate into the fire steam in the proper percentage
Foam proportioner
Is the process of pouring foam concentrate directly into the fire apparatus water tank, thereby mixing a large amount of foam at one time
Batch mixing
Class a foams concentrates that are batch mixed must be used within ____ if they are to be effective
24 hours
Premixing of foam solutions is a technique that is usually reserved for
Portable fire extinguishers
Involves the use of an eductor to introduce the appropriate amount of foam concentrate into a stream of water flowing from a discharge
Induction
An ____ is an appliance that uses the Venturi principle to introduce foam concentrate into the water stream
Eductor
A ___ is usually designed to work at a predetermined pressure and flow rate; it’s metering valve can be adjusted to set the percentage of foam concentrate that is educted into the stream
Foam eductor
In line eductors should only be used for the application of
Foam
Those mounted to permanently to the fire pump are dedicated to one foam discharge; such as ____ are in line devices dedicated to producing foam only
Pump mounted eductors
Are permanently mounted appliances that can be used for water or foam application, depending on what is required at the incident scene
By pass eductors
Eductors use the ____ to mix a specific amount of foam concentrate into the water stream
Venturi principle
Foam concentrate is introduced into the eductor using a ____ which allows the driver operator to adjust the percentage of foam concentrate being added to the water system
Metering valve
An eductor inlet pressure of _____ is necessary to overcome friction loss through the eductor as well as the friction loss between the eductor and the nozzle
200 psi
The ____ controls the flow of concentrate into the eductor
Metering device
The amount of foam concentrate introduced into the water stream is controlled by adjusting the _____
Metering valve
Metering valves have adjustable settings that range from
0 closed position to 6 percent
The percentage set on the metering valve will be achieved only if the inlet pressure at the eductor matches the manufacturers recommend
Inlet pressure
An ______ is attached to the hoseline no more than 150 ft from the nozzle and no more than 6ft above the surface of the foam concentrate— a placement that makes it easy to set up and take down
In line eductor
This system uses a diaphragm type pressure control valve to sense and balance the pressures in the foam concentrate and water lines to the proportioner
Balanced pressure systems
Is a device required for each foam outlet to proportion the correct amount of foam concentrate into water stream over a wide range of flows and with minimal pressure loss
Ratio controller
A _____ at the pump panel allows the driver operator to monitor the foam concentrate and water pressures
Duplex gauge
A ____ located at the pump panel enables the driver operator to override the automatic system by increasing or decreasing foam concentrate pressure, in case a problem occurs within the system
Manual throttling control
The ____ uses water as its cooling source and prevents the foam concentrate from overheating
Heat exchanger
Use an electrically operated, variable speed foam concentrate pump that directly injects foam concentrate into the discharge side of the pump manifold
Injection systems
Are the most common type of system in use today and are designed for use in class A foam concentrates and with many class B concentrates, depending on the viscosity of the concentrate
Injection systems
With____ the driver operator can adjust the foam concentrate percentage while the system is in operation
Injection systems
Concentrate injection rates can be set anywhere in the range of 0.1 to 10 percent. These percentages, can be changed in ______, are selected using a button on the control unit.
0.1 percent increments
Combines compressed air and a foam solution to create the finished foam
CAFS combined air foam systems
This type of system is generally used to generate class A foam specifically, to create a high quality finished foam that clings to vertical surfaces
CAFS combined air foam systems
CAFS hoselines are typically filled with approximately____ compressed air
30 percent
Because the hose is filled with air, ______ is insignificant
Friction loss
CAFS
Produce medium and high expansion foams
Foam generators
A _____ aspirating type of generator uses a water motor driven fan to produce the required air flow
Water powered aspirating generator
Mechanical generators operate similarly to a water aspirating generator. The difference is that the mechanical generator is______, which forces air flow through the unit
Electrically powered by a fan
A ____draws the foam into the master stream nozzle, this tube is placed into the foam concentrate supply and operated as an eductor system
Pick up tube
Are designed to mix air with the foam solution as it is discharged
Air aspirating foam nozzle
Are the nozzle of choice when using CAFS
Smooth bore nozzles
Not aeration is the major concern when a smooth bore nozzle is used with CAFS
Application
Foam concentrate is stored in containers that range in size from
5 gal pails to 55 gallon drums
Totes and trailers of foam concentrate are available in different sizes as well ranging from _____ of foam concentrate
100 to 1000 gallons
Typical protein concentrate has a shelf life in the range of
7 to 10 years
Synthetic concentrates and high expansion concentrates have a shelf life of
20 to 25 years
Should be used only on a pool of flammable product that is located on open ground
Sweep roll method
Is employed at fires where the fire fighter can use an object to deflect the foam stream and let it flow down the burning surface
Bankshot bank down method
Can be used when there is no vertical object to use for a bank shot and it would be to dangerously get close and use a roll on method of foam application.
Rain down method
This foam application technique consists of lofting the foam stream into the air above the material and letting it fall down onto the surface
Rain down method
The maximum inlet pressure to the water pump cannot be more than
10 psi
The _____ used for firefighting purposes is a stable mass of small, air filled bubbles.
Foam
Foam Is created through the application of four components:
Water, foam concentrate, mechanical agitation, and air
Foams come into two basic types
Chemical and mechanical foams
Fuel resistance is foams ability to minimize ______, which is the absorption of the burning fuel into the foam itself.
Fuel pick up
Firefighting foams are classified as either
Class A or class B
Many fire departments use _____ while performing initial attack and overhaul of fires.
Class A
A _____ is a chemical compound that contains the elements carbon and hydrogen
Hydrocarbon
Class b foams are divided into the following categories
Protein foams
Fluroprotien foams
Alcohol resistant film forming fluoroprotien foam
AR-FFFP
Protein foams also include stabilizers and inhibitors, which prevent corrosion and control _____.
Viscosity
These foams must be properly aspirated, however; thus they should not be used with non aspirating structural fog nozzles
Protein foams
Notably, _____ is effective for subsurface application to hydrocarbon fuel storage
FP fluoroprotien foam
With these foams, the fluorochemical surfactants are generally present in higher concentrations than in standard FP
Film forming fluoroprotien foam FFFP
On hydrocarbon fires, the film forming ability of this foam allows for a rapid fire knockdown and excellent burn back resistance.
Alcohol resistant film forming fluoroprotien foam ARFFFP
It extinguishes fire by forming an aqueous film on the fuel surface
AFFF
When applied to polar solvents, however, ______ forms a ploymeric membrane on the fuel surface
AR-AFFF
Foams based on combinations of hydrocarbon surfactants and solvents
High expansion foams
They are useful of fuels such as liquified natural gas for vapor dispersion and control.
High expansion foams
In certain concentrations, these foams are effective extinguishing agents for flammable liquid spill fires of most types
High expansion foams
Have a tremendous smothering and steam generation effect because the water contained in them is divided into such fine particles, which enhances the heat absorption quality of water.
High expansion foams
When using class A foam for initial fire attack on a vehicle fire, you might use a ______ percent ratio of foam concentrate to water
0.3 to 0.5
If you were supplying a hoseline that was spraying foam on a house to protect it during a brush fire, you might increase the ratio to ______, thereby creating a thicker foam that would last longer and protect the house for extended period
3 percent
If the water tank on the fire apparatus holds 500 gallons of water and you want to use class A foam at 1 percent, you would add ______ of foam concentrate with an in line eductor
5 gallons of foam
As the water travels through the in line eductor, it draws foam concentrate into the water at a desired percentage using the
Venturi principle
Two types of eductors in use today
In line eductors and bypass eductors
Most eductors are calibrated to flow the rated capacity at _____ inlet pressure
200 psi
This kind of system uses a fire pump, foam concentrate injection system, and an air compressor to produce high quality finished foam streams inside the fire apparatus piping
CAFS
Some water powered high expansion generators are designed to achieve expansion rates of as much as _______ gal of finished foam for every 1 gal of foam solution
1000 gallons
High expansion foam systems are designed for use in total flooding applications and are effective at the following locations
Mines Machinery spaces
Warehouses. Hazardous waste facilities
Aircraft hangars Wildland fire breaks
Basements
Storage buildings
Paper warehouses
