Firefighting Foam Flashcards
What types of fires are foaming agents effective in controlling and extinguishing?
Class A and B fires
Class A fires involve ordinary combustibles, while Class B fires involve flammable liquids.
What are the main components of foaming agents?
Biodegradable fluorocarbon and hydrocarbon surfactants
These components are diluted with water to create the foam.
Why is foam particularly effective on Class B fires?
It can float on the surface of liquids
This property allows it to effectively smother the fire.
What factors affect the effectiveness of foam?
Rate of application, expansion ratio, and stability of the foam
These factors determine how well the foam can control a fire.
How is low- and medium-expansion foam usually produced?
By injecting concentrate into a fire stream via an eductor
This foam is discharged through a fog nozzle or specialty foam tube.
What is a Compressed Air Foam System (CAFS)?
A system used to produce low- and medium-expansion foam
It utilizes compressed air to enhance foam generation.
How is high-expansion foam generated?
Mechanically using a powered foam generator
This can be powered by an engine or water.
What are the primary functions of foam in firefighting?
- Creates a barrier between the fire and the fuel
- Cools the temperature of the fuel and adjacent surfaces
- Smothers the fire by preventing air from reaching the fuel
- Lowers the surface tension of water for better penetration of Class A materials
What is the Roll-on Method of applying foam?
Foam stream is directed at the front edge of a burning liquid
The foam rolls across the surface until the entire area is covered.
When is the Rain-down Method used?
When the fire or spill area is too large or there is no object to bank the foam
The foam is directed into the air to fall gently onto the surface.
Describe the Bank-down Method of applying foam.
Foam stream is directed at an elevated object near a Class B fire
The foam runs down the surface onto the liquid’s surface.
What is the expansion ratio of low-expansion foam or aqueous film-forming foams (AFFF)?
10:1
What types of fires is AFFF best used on?
Two-dimensional fires, Class B fires such as fuel spills
What is the effectiveness of AFFF on three-dimensional Class A fires?
Limited effectiveness
What principle do in-line hose or nozzle eductors use to introduce foam concentrate?
Venturi principle
How does water under pressure affect the eductor in an in-line hose or nozzle eductor?
Creates low pressure within the eductor
What type of foam hardware can AFFF be used with?
Both aspirating and non-aspirating mechanical foam hardware
What is the purpose of aspirating nozzles in foam application?
To entrain air into the diluted foam-water solution
What is the primary design purpose of non-aspirating type foam hardware?
Application of water in either spray or straight stream patterns
What types of fires are foaming agents or aqueous film-forming foams effective in controlling?
Class A and B fires
Fill in the blank: AFFF is also known as _______.
Aqueous film-forming foam
True or False: AFFF is recommended for use when there is considerable risk to firefighters.
False
What are compressed air foam systems used for?
Deploying a foam solution when water supply is limited or large quantities of water are not advisable
Examples include the Rapid Response Unit (RRU) Foam Tote Series
What is the water tank capacity in a compressed air foam system?
Up to 120 gallons (455 liters)
What components make up a compressed air foam system?
- Water tank
- Compressed air/gas cylinder
- Foam reservoir
- Water-powered proportioner
- Dispensing hose
What is the foam reservoir capacity in a compressed air foam system?
Up to five gallons (19 liters)
How does the compressed air foam system create foam?
Air/gas is released from the cylinder, mixing with water and foam concentrate in the water tank
What is the factory setting foam-water ratio for the system?
About 20:1
How far can foam be projected from the system?
About 12 to 15 metres (40 to 50 ft)
What technique should be used to deploy foam on a fire?
Shoot foam at its base and work up
What is the recommended depth for broadcasting foam to protect a fuel spill?
No more than two inches in depth
What should be done if the system is not used for three or more minutes?
Shut off at the master valve to prevent pressure buildup
True or False: The compressed air foam system can be operated on a truck, trailer, or skid.
True
What is the expansion ratio range of high expansion foams classified as Class A?
100:1 to 1,000:1
In what types of environments are high expansion foams best suited for use?
Flooding in three-dimensional fires in confined spaces, inaccessible spaces, and mine environments
What is one primary function of high expansion foam?
Transporting wet foam to inaccessible places
How does high expansion foam help in fire situations?
Displacing vapour, heat, smoke, and air
What protective benefit does a mass of in-depth foam provide?
Insulation barrier for exposed materials not on fire
What generates the foam in high expansion foams?
A foam generator
What is passed through a porous medium to create high expansion foam?
Air or other gases
What solution is used to wet the porous medium in foam generation?
Aqueous solution of surface-active foaming agents
True or False: Foam becomes non-toxic upon contact with the gases of combustion.
False
What safety equipment should be used when entering a space filled with foam?
Self-contained breathing apparatus
What hazard does foam mass present when entering it?
Obscures vision
What must be used when entering a foam-filled space to maintain orientation?
Link lines
