Chapter 15 Foam Equipment and Systems Flashcards
What are the 3 reasons that the use of foam and durable agents in fire fighting has increased?
- Magnitude and frequency of hazardous materials incidents
- New advances in foam concentrate technology
- New advances in proportioning equipment and system
Mechanical foams must be _____ and _____ before they are used.
proportioned (mixed with water)
aerated (mixed with air)
Class B fuels are divided into what 2 categories?
- hydrocarbons
2. polar solvents
What are polar solvents?
flammable liquids that mix with water
alcohol, acetone, lacquer thinner
How does foam extinguish and/ or prevents fire?
- Separating
- Cooling
- suppressing
Can foam concentrates be mixed with salt water?
yes
What are the 4 basic methods by which foam is proportioned?
- Induction
- Injection
- Batch mixing
- Premixing
What method of proportioning is achieved by passing the stream of water through a venturi device?
Induction
What is the venturi device called used for induction foam proportioning?
eductor
What type of foam proportioning systems are commonly employed in apparatus-mounted or fixed fire protection system applications?
Injection
What type of foam should only be BATCH MIXED as a last resort?
Class B foam
What are the 4 common foam concentrate storage methods?
- pails
- barrels
- 275 gallon tote tanks
- apparatus tanks
What is Class A foam?
formulation of hydrocarbon surfactants that reduce the surface tension of the water in the foam solution
What is the shelf life of Class A foam?
Up to 20 years
What proportions are Class A foams mixed (%)
0.1%-1.0%
The application rate for Class A foam is the same as what?
the minimum critical flow rate of water
Breakdown of the blanket is greatly affected by what?
Heat of fire
height of flame front (wildfires)
and to lesser extent–
the ambient air temp
wind
What is Class B foam used to extinguish?
Fires involving flammable and combustible liquids
Class B foam may be proportioned into the fire stream how?
apparatus-mounted or portable foam proportioning equipment
What type of nozzles are used to apply Class B foam?
Standard fog nozzles (AFFF and FFFP)
air-aspirating foam nozzles (all types)
Class B foam concentrates are manufactured from what two products?
Synthetic (fluoro-surfactants) Protein base (animal base)
Protein foams have a normal shelf life of how long?
10 years
Synthetic-based foams have a shelf life of how long?
20-25 years
Class B foams are mixed in proportions from __% to __%.
1% to 6%
What does foam expansion refer to?
the increase in volume of a foam solution when it is aerated
Foam can be described by what 3 types?
- Low-expansion (up to 20:1)
- Medium-expansion (20:1 – 200:1)
- High-expansion (200:1 –1000:1)
How do you determine the application flow rate available from a nozzle?
Divide the nozzle flow rate by the area of the fire
When should foam concentrate supplies be on the fire ground?
before application is started