58 Questions
What is a foam proportioner?
A device that injects the correct amount of foam concentrate into the water stream
What is required for mechanical foams to be ready for use?
Proportioning and aeration
What is foam concentrate?
Raw foam liquid in its storage container before being combined with water and air
What is foam solution?
Mixture of foam concentrate and water before the introduction of air
When is foam considered as completed product?
After air is introduced into the foam solution
How do class B foams suppress fires involving hydrocarbon fuels?
They float on the surface of the fuel
What is the specific gravity of hydrocarbon fuels like crude oil and gasoline?
Less than one
What are polar solvent fuels known as?
Miscible liquids
What is the typical water concentration for firefighting foam concentrates?
94 to 99.9 percent water
What method of proportioning foam uses an external pump to force foam concentrate into the fire stream?
Injection method
What is the purpose of the premixing method of proportioning foam?
Mixing premeasured portions of water and foam concentrate in a container
How does foam extinguish and/or suppress vapors?
Separating, cooling, suppressing, or smothering
What is the induction method of proportioning foam?
Using the pressure of a water stream to induct foam concentrate into the fire stream
What method is used when foam is poured directly into the tank?
Batch mixing
What is the range of foam concentrate tank size for fire apparatus equipped with onboard foam proportioning systems?
20 - 200 gallons
How much foam may foam tenders carry for storage?
8,000 gallons or more
How much foam is in a pail?
5 gallons
How much foam is stored in barrels?
55 gallons
How much foam is stored in totes?
275 gallons
What is the shelf life of properly stored foam solution?
20 years
At what percentage may class A foam concentrates be mixed for fire attack and overhaul with standard fog nozzles?
0.2 to 0.5%
What is the application rate in relation to the amount of foam solution applied to a fire?
Per minute, per square foot of fire
What type of foam is suitable for areas requiring maximum penetration?
Wet foam
What is the appropriate percentage range for proportioning class A foam for any application with air aspirating foam nozzles?
0.3 to 0.7%
What is the recommended percentage range for proportioning class A foam for any application with CAFS?
0.2 to 0.5%
What is the recommended shelf life for properly stored synthetic foam concentrate?
20 - 25 years
What is the typical concentration range for Class B foams when used with polar solvents?
3 - 6%
What factors can affect foam expansion?
Type of foam concentrate used, accurate proportioning, and method of aeration
What is the ratio range for medium expansion foam?
20:1 to 200:1
How is the application rate available from a specific nozzle calculated?
Divide the flow rate by the area of fire
What is the key feature of regular protein foam?
Good heat stability and burnback resistance
What is the defining characteristic of fluoroprotein foam concentrate?
Contains protein concentrate with added fluorochemical surfactants
Which type of foam concentrate is the most commonly used?
AFFF
What is the purpose of fluorochemical surfactants in foam solutions?
To reduce the surface tension of water and spread a thin aqueous film across fuel
What occurs when AFFF or FFFP is applied to hydrocarbon fuel fires?
An air/vapor excluding film is released ahead of the foam blanket
At what concentration is Alcohol Resistant AFFF concentrate generally used?
3 or 6%
What is the basic principle of foam proportioning devices?
A venturi effect created by the pressure of a water stream flowing through a restricted orifice inducts foam concentrate into the water stream.
What is the primary application of high expansion foam?
Concealed space fires
What is the purpose of an in-line foam eductor?
To be attached directly to the pump panel discharge or connected at some point in the hose lay
What is the maximum pressure allowed at the discharge side of the eductor?
70% of eductor inlet pressure
What happens if the inlet pressure at the eductor is too high?
Creates a foam solution that is too rich
The nozzle and eductor must have what to operate successfully?
Same gpm rating
What is the recommended inlet pressure range at the eductor for accurate blending of foam solution?
150 - 200 psi
What height above the foam concentrate should a foam eductor not exceed?
6 ft
What is the purpose of letting the eductor educt water for at least one minute?
To clean thoroughly
What is a disadvantage of an around the pump proportioner?
Inability to flow foam and plain water simultaneously
Which type of foam proportioner is known for its accuracy in foam proportioning and ability to flow plain water and foam simultaneously?
Bypass-type balanced pressure proportioner
What is a limiting factor of using CAFS (Compressed Air Foam System)?
Increases the purchase and maintenance costs
What tactical advantage does CAFS offer in comparison to low energy systems?
Stream reach is longer than low energy systems
What is the typical airflow rate of foam solution used in most structural and wildland operations with CAFS?
0.5 to 1 cubic feet per minute
How are smooth bore nozzles utilized in relation to foam usage?
Limited to class A foam from a CAFS system
What is the primary function of air aspirating foam nozzles?
Induct air into the foam solution by a venturi effect
Which method is used for class B application when a vertical surface is near or within a pool of ignitable liquid?
Bank-down method
How is the biodegradability of foam determined?
By the rate at which natural bacteria can degrade the foam
What did studies by U.S. Forest Service reveal about class A foam in bodies of water?
It can be lethal to fish
What is the standard application ratio when using durable agents as an extinguishing agent?
1:100
What is the chemical composition of durable agents compared to class A foam?
Water absorbent polymers vs. hydrocarbon based surfactants
For structure protection, what is the recommended application ratio for durable agents?
2 to 3%
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