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
How long does ALCOHOL-RESISTANT FLUOROPROTEIN FOAM maintain its alcohol-resistive properties?
15 minutes
What type of foam is useful for attacking fires involving densely packed materials?
Class A
What are Class A fuels?
Class A - Wood, paper, cloth, trash, plastics
Solid combustible materials that are not metals.
What is a Class B fuel?
Class B - Flammable liquids: gasoline, oil, grease, acetone
Any non-metal in a liquid state, on fire.
What type of foam is used to extinguish fires involving flammable and combustible liquids?
Class B foam
What are two ways that Class B foam can be proportioned into the fire stream?
Apparatus-mounted
or
Portable foam proportioning equipment
FFFP (film forming fluoroprotein ) concentrates incorporate what two characteristics ?
- AFFF’s fast fire knockdown
2. Fluoroprotein foam’s long lasting heat resistance
What is the most commonly used foam today?
AFFF
Is AFFF protein based or synthetic?
fully synthetic
What 3 things occur when AFFF is applied to a fire?
- Air-vapor excluding film released ahead of foam blanket
- Foam blanket moves across surface and around objects
- Foam blanket drains water and more film is released (gives ability for AFFF to “heal”)
At what concentrate are alcohol-resistant AFFFs used on polar solvents?
3%-6%
At what concentrate are alcohol-resistant AFFFs used on hydrocarbon fires?
1%-3%
How should alcohol-resistant AFFF be applied? Why?
Gently, to allow the membrane to form first
What are the 3 basic applications of high-expansion foams?
- Concealed spaces
- Fixed-extiguishing systems
- Class A fires
Foam proportioning devices operate by what two basic principles?
- Venturi action
2. Pressurized proportioning
How does a low-energy foam system impart pressure on the foam solution?
by the use of the fire pump
How do high-energy foam systems work?
By introducing compressed air into the foam solution before it it discharged
What are the simplest and most common foam proportioning devices in use today?
Portable foam proportioners
What are the 3 types of portable foam proportioners?
- in-line foam eductors
- foam nozzle eductors
- self-eructing master stream nozzles
What is the most basic type of portable foam proportioner in the fire service?
in-line foam eductor
The pressure at the outlet of the eductor (back-pressure) must not exceed ___ % of the educator inlet pressure.
65%-70%
Foam solution concentration is only correct at the rated inlet pressure of the eductor, which is usually what?
150 psi – 200 psi
The foam concentrate inlet to the eductor should not be more than how far above the liquid surface of the foam concentrate?
6 feet
What is a JET RATIO CONTROLLER?
A type of in-line eductor that allows the foam concentrate supply to be as far away as 3,000 feet from the self-educting MASTER STREAM NOZZLE.
Why are INSTALLED IN-LINE EDUCTORS not effective for proportioning Class A foams?
because Class A foams are normally used at very low concentrations (0.1%-1.0%)
What type of proportioner is one of the most common built-in proportioner installed in fire apparatus today?
Around-the-Pump proportioners
What are the 2 disadvantages of AROUND-THE-PUMP proportioners?
- older versions could not take advantage of incoming pressures
- When lines are shut down, water can still circulate through the eductor and continue adding concentrate—the bypass valve must be closed
What “apparatus-mounted foam proportioner” is one of the most accurate methods of foam proportioning?
Bypass-type balanced pressure proportioner
BTBPP=Accuracy
Batch-mixing is only used with what 2 types of concentrates?
- REGULAR AFFF–not alcohol resistant
2. Class A concentrates
What are the tactical advantages of CAFS over low-energy foam?
- longer reach of fire stream
- production of durable, uniform air bubbles
- adheres to fuel and resists heat longer
- hoselines weigh less
- safer fire suppression action–greater distance
What are some limitations of CAFS?
- expensive
2. hose reaction can be erratic
IFSTA defines a “handline nozzle” as what?
any nozzle that 1 to 3 firefighters can safely handle and flow less than 350 gpm.
With respect to foam application, the use of SMOOTHBORE nozzles are limited to what application?
Class A CAFS applications
The reach of the CAFS fire stream can be how much greater than the reach of low-energy fire streams?
greater than twice the reach
FOG NOZZLES are utilized best when used with what 2 types of foams?
- regular AFFF
- Class A foams
(same as batch-mixing)
FOG NOZZLES can not be used with what types of foams? why?
Protein and fluoroprotein–because of the insufficient aspiration
What is the only type of nozzle that can be used with protein and fluoroprotein concentrates?
Air-Aspirating Foam nozzles
What are the 4 techniques for applying foam to a liquid fuel fire or spill?
- direct-application
- roll-on method
- bank-down method
- rain-down method
Class A foams can be lethal to what? and should not be discharged where?
fish —- any body of water
Chemically, what are durable agents?
water-absorbing polymer
What is the difference between durable agents and Class A foam?
durable agents consist primarily of water while Class A foams consist primarily of air
What ratio are durable agents applied when used for:
a. fire extinguishment
b. line construction
c. structure protection
A. 1%
B. 1 ½%-2%
C. 2%-3%
