Podcast
Questions and Answers
Which statements regarding Class A and Class B foam are true? (Select all that apply)
Which statements regarding Class A and Class B foam are true? (Select all that apply)
- Class B foam is effective on hydrocarbon fuels. (correct)
- Class A foam reduces the surface tension of water. (correct)
- Class A foam is used on flammable liquids.
- Class B foam is used on Class A materials.
Hydrocarbon fuels are lighter than water.
Hydrocarbon fuels are lighter than water.
True (A)
Which foam extinguishment method intervenes between the fuel and the fire?
Which foam extinguishment method intervenes between the fuel and the fire?
Separating
Polar solvent is another name for a hydrocarbon fuel.
Polar solvent is another name for a hydrocarbon fuel.
Which are foam extinguishment methods for Class B firefighting foam? (Select all that apply)
Which are foam extinguishment methods for Class B firefighting foam? (Select all that apply)
Which statements about Class B firefighting foam are TRUE? (Select all that apply)
Which statements about Class B firefighting foam are TRUE? (Select all that apply)
In general, there are three types of foams used in firefighting.
In general, there are three types of foams used in firefighting.
Which are essential ingredients for producing firefighting foam? (Select all that apply)
Which are essential ingredients for producing firefighting foam? (Select all that apply)
What is the device called that injects the correct amount of foam concentrate into the water stream?
What is the device called that injects the correct amount of foam concentrate into the water stream?
What is the correct term for 'a mixture of foam concentrate and water before the introduction of air'?
What is the correct term for 'a mixture of foam concentrate and water before the introduction of air'?
High-quality fire-fighting foam can be produced by mixing all of the required elements in any ratio.
High-quality fire-fighting foam can be produced by mixing all of the required elements in any ratio.
After the foam solution reaches the nozzle and air is mixed in, what is the product called?
After the foam solution reaches the nozzle and air is mixed in, what is the product called?
What is raw liquid in its storage container called?
What is raw liquid in its storage container called?
Eductors use the pressure of air flowing through a restriction to create suction of the foam concentrate.
Eductors use the pressure of air flowing through a restriction to create suction of the foam concentrate.
Which is the most common type of portable proportioner used in the fire service?
Which is the most common type of portable proportioner used in the fire service?
Apparatus equipped with balanced-pressure proportioners MUST have the foam concentrate supplied from an off-the-truck source.
Apparatus equipped with balanced-pressure proportioners MUST have the foam concentrate supplied from an off-the-truck source.
Which statements about the proportioning rates for foam concentrates are TRUE? (Select all that apply)
Which statements about the proportioning rates for foam concentrates are TRUE? (Select all that apply)
To produce a foam that sticks to vertical surfaces for exposure protection, you should use?
To produce a foam that sticks to vertical surfaces for exposure protection, you should use?
Which are usually built directly into the apparatus fire pump? (Select all that apply)
Which are usually built directly into the apparatus fire pump? (Select all that apply)
What type of portable educator would you use if you wanted to switch from foam to water and back quickly?
What type of portable educator would you use if you wanted to switch from foam to water and back quickly?
Which are types of foam proportioners? (Select all that apply)
Which are types of foam proportioners? (Select all that apply)
What type of educator is part of the nozzle?
What type of educator is part of the nozzle?
Uniformly sized bubbles result in a longer-lasting foam blanket.
Uniformly sized bubbles result in a longer-lasting foam blanket.
The ______ foam nozzle produces a higher quality finished foam, but the energy required...
The ______ foam nozzle produces a higher quality finished foam, but the energy required...
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Study Notes
Foam Types and Properties
- Class A foam is designed for fires involving ordinary combustibles, reducing water's surface tension for better penetration.
- Class B foam is effective for flammable liquids, especially hydrocarbon fuels and polar solvents.
Hydrocarbon Fuels
- Hydrocarbon fuels are lighter than water and will float on the surface.
Foam Extinguishment Methods
- Key methods include smothering, cooling, and separating to effectively extinguish Class B fires.
Characteristics of Class B Foam
- Creates a cohesive blanket that floats on fuel surfaces.
- Effective on hydrocarbon fuels; special formulas needed for polar solvents.
Foam Production Essentials
- Four essential ingredients for fire-fighting foam: mechanical aeration, foam concentrate, air, and water.
Foam Equipment
- Foam proportioner injects foam concentrate into water to create foam solution.
- Foam solution refers to the mixture before air is added.
Foam Quality and Production
- High-quality foam requires precise mixing ratios; not just any ratio will suffice.
- Finished foam is produced after air is mixed with the foam solution at the nozzle.
Eductors and Proportioners
- Eductors create suction for foam concentrate using water pressure, not air pressure.
- In-line eductor is the most common portable proportioner in fire services.
- Balanced-pressure proportioners utilize foam concentrate lines from the apparatus or an external source.
Proportioning Rates
- Typical rates are 3% to 6% for polar-solvent foams and 1% to 6% for hydrocarbon foams, marked on foam containers.
- Class A foams can have adjustable proportioning rates to fit specific objectives.
Vertical Surface Application
- A higher percentage of Class A foam solution is required to stick to vertical surfaces.
Types of Proportioners
- Types include eductors, around-the-pump proportioners, and balanced-pressure proportioners.
- Self-educting nozzles have built-in educators.
Foam Durability
- Uniformly sized bubbles contribute to a longer-lasting foam blanket.
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