IFSTA - Chapter 14 Flashcards
Mechanical Foams
Foam produced by a physical agitation of a mixture of foam, concentrate, water, and air
Most common foams in use
PG 480
Proportioned
Mixing of water with an appropriate amount of foam concentrate in order to form a foam solution
Mixed with water
PG 480
Aerated
Introduction of air into a foam solution to create bubbles that result in finished foam
Mixed with air
PG 480
Eduction
- Process used to mix foam concentrate with water in a nozzle or proportioner
- Concentrate is drawn into the water stream by the Venturi method
PG 480
Foam Concentrate
1) Raw chemical compound solution that is mixed with water and air to produce finished foam
- May be protein, synthetic, aqueous film forming, high expansion, or alcohol types
2) Raw foam liquid as it rests in its storage container before the introduction of water and air
PG 480
Foam Proportioner
Device that injects the correct amount of foam concentrate into the water stream to make the foam solution
PG 480
Foam Solution
1) The result of mixing the appropriate amount of foam concentrate with water
- Foam solution exists between the proportioner and the nozzle or aerating device that adds air to create finished foam
2) The mixture of foam concentrate and water before the introduction of air
PG 480
Foam
- Completed product after air is introduced into the foam solution
- AKA Finished Foam
- For use on Class A and Class B fires
- May be protein, fluoroprotein, film forming fluoroprotein, synthetic, aqueous film forming, high expansion, alcohol type, or alcohol-resistant type
PG 480
Class B Fuels (2 Categories)
1) Hydrocarbons
- A petroleum-based organic compound that contains only hydrogen and carbon
EX. Fuels (crude oil, fuel oil, gasoline, benzene, kerosine)
- Specific gravity less than 1 = will float on water
2) Polar Solvents
- Liquid having a molecule where the positive and negative charges are permanently separated, resulting in their ability to ionize in solution and create electrical conductivity
EX. Water, alcohol, sulfuric acid
PG 480
Class B Foam
- Used to extinguish and suppress vapors of Class B fires by floating on the surface of the hydrocarbon fuels
PG 480
Miscible
- Materials that are capable of being mixed in all proportions
- Polar solvent fuels (such as alcohol, acetone, ketones, and esters) are MISCIBLE, because they mix with water
PG 481
How Foam Works
1) Separating = creates a barrier between the fuel and the fire
2) Cooling = lowers the temperature of the fuel and adjacent surfaces
3) Suppressing/Smothering = prevents the release of flammable vapors, reducing the possibility of ignition or reignition
PG 481
Foam Proportioning
- Mixing foam concentrate with water to make foam solution
- Most FF foams are formulated to mix with 94-99.9% water
EX. When a 3% foam is used, the finished foam solution consists of 97 pats water mixed with 3 parts foam concentrate = 100 parts foam solution
PG 482
Foam Proportioning Methods (4)
- Induction
- Injection
- Batch Mixing
- Premixing
PG 482-483
Induction
- Uses the pressure of a water stream to induct (draft) foam concentrate into the fire stream
- Achieved by passing the stream of water through a Venturi device called an EDUCTOR
- A PICKUP TUBE connected to the eductor is inserted into the foam concentrate container
- The pressure differential created by the water passing through the Venturi causes a reduction in pressure in the device that allows atmospheric pressure to force foam concentrate into the water stream
PG 483
Eductor
1) Portable proportioning device that injects a liquid, such as foam concentrate, into the water flowing through a hoseline or pipe
2) Venturi device that uses water pressure to draw foam concentrate into a water stream for mixing
- Also enables a pump to draw water from an auxiliary source
PG 483
Injection
1) Method of proportioning foam that uses an external pump or head pressure to force foam concentrate into the fire stream at the correct ratio for the flow desired
2) Process of taking in materials through a puncture or break in the skin
Most commonly employed in apparatus mounted or fixed fire protection systems
PG 483
Batch Mixing
Production of foam solution by adding an appropriate amount of foam concentrate to a water tank before application
- The resulting solution must be used or discarded following the incident
Commonly used with Class A foams
Not effective during large incidents, as foam lines must be shut down when the tank is emptied
PG 484
Premixing
Mixing premeasured portions of water and foam concentrate in a container
- Typically the premix method is used with portable extinguishers, wheeled extinguishers, skid-mounted tank systems
PG 484
How Foam is Stored
- Pails
- Barrels
- Totes
- Apparatus Tanks
PG 484
Pails
- 5 gallon, plastic
- Not affected by corrosive nature of foam concentrates
PG 485
Barrels
- 55-gallons, plastic or plastic-lined barrels
- Most commonly used for bulk storage, but more commonly used in industrial applications
PG 485
Totes
- 275-gallons
PG 485
Apparatus Tanks
- Onboard foam proportioning systems have foam concentrate tanks pumped directly into the delivery system
- Generally range from 20-200 gallons
- Foam tenders can carry up to 8,000 gallons
PG 485
Class A Foam
- Foam specifically designed for use on Class A combustibles (ordinary combustibles)
- Hydrocarbon-based surfactants that are essentially wetting agents that reduce the surface tension of water and allow it to soak into combustible materials more easily than plain water
- May be mixed in percentages as low as 0.1-1.0%
PG 486
Surfactant
Chemical that lowers the surface tension of a liquid –> allows water to spread more rapidly over the surface of Class A fuels and penetrate organic fuels
PG 487
Class A Foam - Common Proportion %’S
- 0.2-0.5 = fire attack and overhaul, standard fog nozzle
- 0.5-1.0 = exposure protection, standard fog nozzle
- 0.3-0.7 = any application with air aspirating foam nozzles
- 0.2-0.5 = any application with compressed air foam systems (CAFS)
PG 488
Application Rate
Minimum amount of foam solution that must be applied to an unignited fire, spill, or spill fire to either control vapor emission or extinguish the fire
- Measured per minute per square foot (or square meter) of area to be covered
PG 488
Class A Foam - Application Scenarios
- Areas that require maximum penetration
- Vertical surfaces
- Surface of a fuel
PG 488
Class B Foam
- Applied to suppress fires involving flammable and combustible liquids
- Used to suppress vapors from unignited spills involving these liquids
- Concentrates consist of a synthetic or protein base
PG 488-489
Military Specifications (Mil-Spec)
Specifications developed by the US Department of Defense (DoD) for the purchase of materials and equipment
PG 489
Class B Foam - Common Proportion %’S
- 1.0-6.0%
- Concentration for hydrocarbon fuels = 1.0-3.0%
- Concentration for polar solvents = 3.0-6.0%
PG 490
Foam Expansion
- Result of adding air to foam solution consisting of water and foam concentrate
- Expansion creates the foam bubbles that result in finished foam or foam blanket
- Rate at which expansion occurs is based on:
1) Type of concentrate
2) Whether or not fuel is on fire
3) Type of fuel involved (hydrocarbon vs polar solvent)
4) Whether fuel is contained or uncontained
PG 490
NFPA 11
- Standard outlines the variables involved and application rate requirements of foam solution application for many possible scenarios
PG 490
Foam Application Rate Calculation
- To calculate the application rate available from a specific nozzle
- Divide flow rate by the area of the fire
EX. 250gpm nozzle on a 1000sq ft fire = rate of 0.25gpm/sq ft
PG 491
Types of Specific Foam Concentrates
1) Regular protein foams
2) Fluoroprotein foam
3) Film Forming Fluoroprotein foam (FFFP)
4) Aqueous Film Forming Foam (AFFF)
PG 492
Regular Protein Foams
- Derived from animal protein sources such as hooves, horns, or feather meal
- Generally have good heat stability and burnback resistance
- Degrades more quickly in storage than synthetic foam
PG 492
Hydrolyze
To cause or undergo a chemical process of decomposition involving the splitting of a bond and the addition of the element of water
PG 492
Burnback Resistance
Ability of a foam blanket to resist direct flame impingement such as would be evident in a partially extinguished petroleum fire
PG 492
Fluoroprotein Foam
- Combination of protein-based foam and synthetic foam
- Ability to flow more readily than ordinary protein foam
- Provides longer lasting vapor suppression
PG 492
Film Forming Fluoroprotein Foam
- Foam concentrate that combines the qualities of fluoroprotein foam with those of aqueous film forming foam
- Long lasting heat resistance and capabilities of AFFF for quick knockdown
PG 492
Aqueous Film Forming Foam (AFFF)
- Synthetic foam concentrate that, when combined with water, can form a complete vapor barrier over fuel spills and fires and is a highly effective extinguishing and blanketing agent on hydrocarbon fuels
- Most common used synthetic foam concentrate
- How it works:
1) An air/vapor excluding film is released ahead of the foam blanket
2) a fast moving foam blanket spreads across the surface of the fuel surrounding objects and providing insulation
3) As the aerated foam blanket drains its water, more film is released giving the foam an ability to recover, or “heal: areas where the foam blanket is disturbed
PG 493
Alcohol Resistant AFFF Concentrate
- AFFF that is designed for use with polar solvent fuels
- Used at 3 or 6%
PG 493
High Expansion Foams
- Contains a detergent base and low water content
- Low water content provides less run off and minimizes water damage
- Common applications:
1) Concealed space fire - cellars, coal mines, tunnels, sewers
2) Fixed extinguishing systems for specific industrial hazards
3) Class A fire applications
PG 494
Low Energy Foam Proportioning Systems
- Impart pressure on the foam solution with the use of the main fire pump
- Introduces are into the foam solution when it reaches the nozzle or is discharged through the nozzle
PG 494
Portable Foam Proportioners
1) In-Line Foam Eductor
2) Foam Nozzle Eductor
3) Self Educting Master Stream Nozzle
PG 494
In-Line Foam Eductor
- Attached directly to the pump panel discharge or connected at some point in the hose lay
- Uses the Venturi principle to draft foam concentrate into the water stream
PG 495
Foam Nozzle Eductor
- Operates under same principle as an In-Line Foam Eductor
- Built into the self-educting nozzle, rather than being attached to the hoseline
PG 496
Self-Educting Master Stream Foam Nozzle
- Large-capacity nozzle with built-in foam eductor
- Uses modified Venturi design to draw concentrate into its water stream
- Pickup tube is located in the center bore of the nozzle
- Deployed when flows in excess of 350GPM are required
- Capable of delivering up to 14,000 GPM
- Major advantage = pressure drop is much lower (10% or less) than most standard foam nozzle eductors
PG 496
Jet Ratio Controller (JRC)
- Type of in-line eductor that may be used to supply foam concentrate to a self-educting master stream nozzle
- Allows the foam concentrate to be located as far as 3000 feet away from a self-educting master stream nozzle
PG 497
Apparatus Mounted Foam Proportioning Systems
- Installed In-Line Eductor Systems
- Around the Pump Proportioners
- Bypass-Type Balanced Pressure Proportioners
- Variable-Flow Variable-Rate Direct Injection Systems
- Variable-Flow Demand-Type Balanced Pressure Proportioners
- Batch Mixing
PG 497-501
Installed In-Line Eductor Systems
- Operates under same principles as portable in-line eductors
- Only difference between the systems is the fixed-position mounting of the apparatus
- Most commonly used to proportion Class B foam; not as effective for proportioning the very low concentrations used in Class A foam
PG 497
Around the Pump Proportioners
- One of the most common types of installed proportioners used in modern fire apparatus
- A small quantity of water is diverted from the apparatus pump through an inline proportioner –> there, it picks up the foam concentrate and carries it to the intake side of the pump
PG 498
Bypass-Type Balanced Pressure Proportioners
- Foam concentrate proportioner that operates in tandem with a fire water pump to ensure a proper foam concentrate to water mixture
- Used on large mobile apparatus installations (ARFF)
- One of the most accurate methods of foam proportioning
- Can discharge foam from some outlets and plain water from others, at same time
- Requires a foam pump with a PTO or other means of power supply
PG 499-500
Variable-Flow Variable-Rate Direct Injection Systems
- Injects the correct amount of foam into the pump piping, thereby supplying all discharges with foam
- Automatically monitors the operation of the hoselines and maintains a consistent quality of foam solution
- Generally operate off power supplied by the apparatus electrical system
- Can be used with ALL Class A foams, SOME Class B foams, and NO alcohol resistant foam concentrates
PG 500
Variable-Flow Demand-Type Balanced Pressure Proportioners
- AKA Pumped/Demand System
- Foam proportioning system that is used in both fixed and mobile applications
- A variable speed mechanism drives the foam pump and automatically monitors the flow of foam to produce an effective foam solution
PG 500
Batch Mixing
- AKA Dump in Method
- Simplest method of proportioning foam
- Approximate amount of concentrate required for a given amount of water is poured into the tank using the top fill opening in the tank at the time when the foam is needed
- Generally only used with Class A foams and AFFF
PG 501
High Energy Foam Generating Systems/CAFS
- Differ from other methods in that they introduce compressed are into the foam solution PRIOR to discharge into a hoseline
- The turbulence created by the foam solution and air flowing through the piping and/or hoseline creates finished foam
- Generally is designed to only flow foam through preselected discharges while other discharges are provided to flow plain water
PG 503
Foam Application - Handline Nozzles
- Most common used for foam application are smooth bore, fog, and air-aspirating foam nozzles
1) Smooth Bore: - Limited to application of Class A foam
- Provide effective stream with excellent reach capabilities
2) Fog Nozzles: - Break the foam solution into droplets while using the agitation of water droplets moving through air to achieve the foaming action
- Expansion ratios are 2:1-4:1
- Most efficient for Class A and AFFF foam
3) Air-Aspirating Foam Nozzle: - Induct air into the foam solution by Venturi action
- Class A foam in wildland fires
- Provide maximum expansion of the agent, but does not reach as far as standard fog nozzle
PG 503-504
Medium and High Expansion Foam Generating Devices
- Produce foam containing high air content (Medium = ranges from 20:1-200:1; High = 200:1-1000:1)
1) Water Aspirating: - Similar to other foam producing nozzles, except they are larger and longer
2) Mechanical Blower: - Look similar to ordinary smoke ejector
- Air is forced through the foam solution by the fan instead of being pulled by water movement
- Well suited for incidents requiring total flooding
PG 505
Foam Application Techniques
1) Direct Application
- Applying finished foam directly on burning material
- Class A foam
2) Roll On
- Directing a foam fire stream on the ground near front edge of burning liquid spill, allowing foam to roll across the surface of the fuel
- Class B foam
- Effective on pools of liquid fuel on the open ground
3) Bank Down
- Directing foam onto the vertical surface and allowed to run down and spread across the pooled fuel product
- Class B foam
4) Rain Down
- Most common method of application for aboveground storage tank fires
- Direct foam into air above fire and let it gently rain down on surface of fuel
- Class B foam
PG 506
NFPA 1150
Standard on Foam Chemicals for Fire in Class A Fuels
What is an attribute of Film Forming Fluoroprotein Foam (FFFP)?
Quick fire knockdown
PG 492
Typical Class A foam proportioning range for exposure protection using standard fog nozzle is ________ ?
0.5-0.1%
PG 488
What is an advantage of the use of a jet ratio controller?
The foam concentrate supply can be located a remote distance from the nozzle
PG 497
Foam concentrate (definition)
The raw liquid foam in its storage container
PG 480
Foam application method used for pool of liquid fuel on open ground?
Roll-on Method
PG 506
Foam that works best when used with standard fog nozzle?
AFFF
PG 504
Foam application method used for above ground storage containers?
Rain-down method
PG 506, 508
Correct in-line foam educator inlet pressure is typically ______ to ______ psi?
150-200 psi
PG 495
A water aspirating nozzle is designed for use with _______ (type of foam)?
High-expansion foam
PG 505
Typical Class A foam proportioning range for fire attack using standard fog nozzle is ________ ?
0.2-0.5%
PG 488
Which form of proportioning is commonly used with Class A foams?
Batch mixing
PG 483
In a high energy CAFS system, compressed air is injected into the ________ ?
Foam Solution
PG 502
Adding foam concentrate to a fire apparatus water tank is called ________ ?
Batch Mixing
PG 483
According to NFPA, high expansion foam creates up to ______ parts finished foam for every part of foam solution?
1000
PG 490
What type of foam is most commonly used?
Mechanical
PG 480
Which type of foam equipment works best with solid bore nozzles?
Compressed air foam systems (CAFS)
PG 504
According to NFPA, low expansion foam creates up to ______ parts finished foam for every part of foam solution?
20
PG 490
When using an in-line foam eductor, which item will result in foam solution concentration that is too rich?
Inlet pressure is high
PG 495
Which statement about a foam nozzle eductor is correct?
The device design may compromise firefighter safety
PG 496
TRUE/FALSE: Alcohol is a polar solvent?
True
PG 480-481
Which method of proportioning uses a pump to force foam concentrate into the water stream?
Injection
PG 483
According to NFPA, medium-expansion foam creates up to ______ parts finished foam for every part of foam solution?
200
PG 490
Which form of apparatus-mounted foam proportioning system is most commonly used in aircraft rescue and firefighting (ARFF) applications?
Bypass-type balanced pressure proportioner
PG 499
Which water additive forms tiny polymer bubbles filled with water?
Durable Agent
PG 509
Which statement about regular protein foam is correct?
It is not commonly used
PG 492
A jet ratio controller is used with a(n) ________ ?
Self-educting master stream foam nozzle
PG 497
Which statement about fluoroprotein foam is correct?
It provides long-lasting vapor suppression
PG 492
Which statement about installed in-line foam eductors is correct?
They are generally not effective with Class A foams
PG 497
An in-line foam eductor body should be positioned no higher than ______ feet above the surface of the foam concentrate?
6 feet
PG 495-496
What type of nozzle should be used with fluoroprotein foams?
Air-aspirating foam nozzle
PG 504
Which statement about an in-line foam eductor is correct?
It uses the Venturi principle to draft foam concentrate
PG 494-495
What is the proportioning range for Class B foams?
1%-6%
PG 490
What is the advantage of durable agents over Class A foams?
They have no environmental impact
PG 509
