Title: Aircraft Rescue and Fire Fighting,
1- Aircraft Rescue and Fire Fighting,
- 5th Edition
Chapter 6 Extinguishing Agents
2Chapter 6 Lesson Goal
- After completing this lesson, the student shall
be able to describe types of extinguishing agents
and systems used in aircraft rescue and fire
fighting operations.
3Objectives
- 1. Explain the use of water as an extinguishing
agent in aircraft rescue and fire fighting
operations. - 2. Explain the use of foam as an extinguishing
agent in aircraft rescue and fire fighting
operations. - 3. Identify types of foam concentrates.
(Continued)
4Objectives
- 4. Describe foam proportioning systems.
- 5. Discuss portable foam application devices.
- 6. Explain foam application.
-
(Continued)
5Objectives
- 7. Describe dry chemicals and their
applications. - 8. Describe clean agents and their applications.
-
6Water Use in ARFF
- Water most commonly used extinguishing agent in
the fire service - Alone not generally suitable for large aircraft
fuel fires - Foaming agents added
- May push burning fuel away
- May increase size of Class B fires
(Continued)
7Water Use in ARFF
- Uses in ARFF operations
- Cool aircraft fuselage
- Controlling spot fires/eliminating reignition
sources - Provide heat shield
- Preferred agent for Class A interior fires
8Structural Apparatus and Water
- Guidelines when used for spilled fuel fire
- 1 ½-inch (38 mm) or larger lines
- Fog pattern
- Avoid straight streams
(Continued)
9Structural Apparatus and Water
- Structural apparatus water supply
- Does not carry as much water
- Supply may last long enough for personnel to
effect rescue
10Hazards of Water
- Excellent conductor of electricity
- Steam can obscure vision, scald individuals
11Water and Aircraft Interior Fires
- Straight stream may be best in well-involved,
unventilated interior fires - Straight stream advantages
- Will not upset thermal layering
- Will generate less steam
- Will have better reach
12Foam Use in Fire Fighting
- Used to combat fires in hydrocarbon fuels
- Lower specific gravity than hydrocarbon fuels
- Floats on surface
(Continued)
13Foam Use in Fire Fighting
- Works by forming blanket
- Excludes oxygen
- Stops burning process
- Water in foam
- Slowly released
- Provides cooling effect
14Foam Extinguishing Methods
- Separating
- Smothering
- Cooling
- Suppressing
(Continued)
15Foam Extinguishing Methods
16Applying Foam
- Applying foam
- Cools the fuel
- Prevents flammable vapors from mixing with air to
form a flammable mixture - Foam blanket
- Should be homogeneous mass
- Minimally disrupted by factors
(Continued)
17Applying Foam
- As foam is applied
- Breaks down
- Water content drains out or vaporizes
- Foam must be applied
- In sufficient volume
- At an adequate rate
- Reapplied as necessary
18Critical Area
- Density and rate of application are crucial
- Critical area
- Around aircraft fuselage
- Feasible to extinguish or control a fire for
rescue - NFPA 403 contains information
19Foam Proportioning
- Foams must be proportioned and aerated
- Requires specific factors
- Foam concentrate, water, air, and mechanical
aeration - Removing an element
- No foam
- Poor-quality foam
(Continued)
20Foam Proportioning
21Terms
- Foam concentrate
- Foam proportioner
- Foam solution
- Finished foam
-
22Using Foam Concentrates
- Aeration produce an adequate amount of bubbles
to form an effective blanket - Better aerated, longer blanket will last
- Air-aspirating foam nozzle/attachment
(Continued)
23Using Foam Concentrates
- Must match fuel to which applied
- Class A foams not designed to extinguish Class B
fires - Class B fuels
- Hydrocarbons
- Polar solvents
(Continued)
24Using Foam Concentrates
- Hydrocarbon fuels
- Petroleum-based
- Hydrophobic
- Standard fire fighting foam
- Effective agent and vapor suppressant
- Float on surface of hydrocarbon fuels
(Continued)
25Using Foam Concentrates
- Polar solvents
- Flammable
- Hydrophilic
26Class A Foam
- Effective in incidents involving deep-seated
Class A fuels - May be used to attack interior aircraft cabin
fires/structural-related fires - Essentially wetting agents
27Class B Foam
- Uses
- Extinguish fires involving flammable and
combustible liquids - Suppress vapors from unignited spills
- Proportioned into the fire stream via
apparatus-mounted or portable foam proportioning
equipment
(Continued)
28Class B Foam
- Do not mix different manufacturers foam
concentrates - Military specifications AFFF is exception
- Causes no adverse effects for military
specification AFFF
(Continued)
29Class B Foam
- Chemical properties and environmental impact vary
- Generally not good for environment
- Use minimum needed
- Contain and recover aircraft fuel and foam runoff
30Class B Foam Proportioning
- Mixed in proportions from 1 to 6
- Some multipurpose foams used on both hydrocarbon
and polar solvent fuels
31Class B Foam Foam Expansion
- Increase in volume of a foam solution when it is
aerated - Expansion depends on factors
- Type and quality of foam concentrate
- Accurate proportioning
- Methods of aspiration
(Continued)
32Class B Foam Foam Expansion
- Depending on its purpose foam is
- Low-expansion
- Medium-expansion
- High-expansion
33Class B Foam Rates of Application
- Depend on several variables
- Type of foam concentrate used
- Whether or not the fuel is on fire
- Type of fuel
- Whether fuel is spilled or in a tank
(Continued)
34Class B Foam Rates of Application
- NFPA 403 states application rates
- Unignited spills do not require same
application rates as ignited spills
35Specific Foam Concentrates
- Foams are selected based on
- Properties
- Performance
- Consult the UL listing
36Aqueous Film Forming Foam (AFFF)
- Recommended extinguishing agent for hydrocarbon
fuel fires - Characteristics make it good for ARFF operations
- Applied to a hydrocarbon fire causes specific
actions
(Continued)
37Aqueous Film Forming Foam (AFFF)
- Available in 1, 3, or 6
- Mixed with water
- Resists breakdown by dry chemicals
(Continued)
38Aqueous Film Forming Foam (AFFF)
- How fast fire is extinguished depends on
- Manner applied
- Application rate
- Density
- Applied with an aspirating foam or nonaspirating
nozzle
(Continued)
39Aqueous Film Forming Foam (AFFF)
- Alcohol-resistant AFFF is available
- Store AFFF in a temperature controlled environment
40Regular Protein Foam and Fluoroprotein Foam
- Protein foam
- Used widely before the 1970s in ARFF
- No longer widely used in ARFF
- Fluoroprotein foam
- Not widely used in ARFF
- Used to protect fuel tanks and petroleum
processing facilities
41Film Forming Fluoroprotein Foam
- Incorporates benefits of aqueous film and
fluoroprotein foam - Available in alcohol-resistant formulation
- Effective agent on flammable liquid fires
(Continued)
42Film Forming Fluoroprotein Foam
- Available in 3 and 6 solutions
- Effectiveness depends on
- Application rate
- Density
- Blanketing of the fuel
- Not as effective as AFFF in foam stability
43High-expansion Foams
- Special-purpose foams detergent base
- Low water content
- Three basic applications
- Concealed spaces
- Fixed extinguishing systems
- Class A fire applications
- Varying expansion ratios
44How Foam Concentrates are Stored
- Pails
- Barrels
- Intermediate bulk containers
- Apparatus tanks
Courtesy of Doddy Photography.
45General Principles of Foam Proportioning
- Strict design specifications for equipment
- Failure to operate equipment
- Poor-quality foam
- No foam
(Continued)
46General Principles of Foam Proportioning
- Operate by one of two principles
- Venturi effect
- Injection into water stream
- Low-energy foam system uses a fire pump
- High-energy foam systems introduce compressed
air
47Foam Proportioning
- Proportioning mixing of water with foam
concentrate - Failure to proportion correctly
- Poor-quality foam
- Waste resources
(Continued)
48Foam Proportioning
- ARFF apparatus foam system testing
- FAA recommends at least twice a year
- Refractometer or conductivity meter
- Concentrates are mixed with 94 to 99.9 percent
water
(Continued)
49Foam Proportioning
- Selection of proportioner depends on several
factors - Four basic methods
- Induction
- Injection
- Batch mixing
- Premixing
50Foam Proportioning Induction
- Uses the pressure energy in stream of water to
induct foam concentrate into the fire stream - Stream of water passes through an eductor
- Examples In-line eductors and foam-nozzle
eductors
51Foam Proportioning Injection
- Uses an external pump or water pressure to force
foam concentrate into the fire stream - Used in apparatus-mounted or fixed-fire
protection systems - Examples Direct injection and balanced pressure
proportioners
52Foam Proportioning Batch Mixing
- Pouring an appropriate amount of foam concentrate
into a tank of water - Simplest method
- Used with regular AFFF and Class A
- Disadvantage all water is converted to foam
solution
53Foam Proportioning Premixing
- Premeasured portions of water and foam
concentrate are mixed - Commonly used
54Portable Foam Proportioners
- Simplest and most common foam proportioning
devices - Three common types
- In-line foam eductors
- Foam nozzle eductors
- Self-educting master stream nozzles
(Continued)
55Portable Foam Proportioners
- In-line eductors most common type in structural
fire service - Foam nozzle eductor eductor is built into the
nozzle - Self-educting master stream foam nozzle used
where flows in excess of 350 gpm (1 400 L/min)
are required
56Apparatus-mounted Foam Proportioning Systems
- Systems are commonly mounted on vehicles
- Fire boats
- Structural, industrial, wildland, and ARFF fire
apparatus - Majority can be used for both Class A and Class B
foam concentrates
(Continued)
57Apparatus-mounted Foam Proportioning Systems
- Installed in-line eductors
- Permanently attached to apparatus pumping system
- Same precautions as portable in-line eductors
- Supplied from pickup tubes or foam concentrate
tanks
(Continued)
58Apparatus-mounted Foam Proportioning Systems
- Around-the-pump proportioners
- Rated for specific flow
- Have disadvantages
(Continued)
59Apparatus-mounted Foam Proportioning Systems
- Balanced-pressure and direct-injection
proportioners - Used by most ARFF apparatus
- Various types of systems
- Each system has advantages and limitations
(Continued)
60Apparatus-mounted Foam Proportioning Systems
- Systems include
- Bypass-type balanced pressure proportioners
- Variable-flow demand-type balanced-pressure
proportioners - Variable-flow variable-rate direct-injection
systems
61High-energy Foam Generating Systems
- Introduce compressed air into foam solution prior
to discharge - Uses a standard centrifugal fire pump to supply
water
(Continued)
62High-energy Foam Generating Systems
- Called a compressed-air foam system (CAFS)
- Most commonly found on structural and wildland
fire apparatus
63Portable Foam Application Devices
- Foam solution must be mixed with air
- Low-energy foam systems aeration and discharge
accomplished by a fog nozzle or a foam nozzle
(Continued)
64Portable Foam Application Devices
- Low-expansion foams discharged through handline
nozzles or master stream devices
65Portable Foam Application Devices Handline
Nozzles
- Any nozzle that one to three firefighters can
safely handle and that flows less than 350 gpm (1
400 L/min) - Two most common
- Standard fog nozzles
- Air-aspirating foam nozzles
(Continued)
66Portable Foam Application Devices Handline
Nozzles
- Low-expansion, short lasting foam produced by
fixed-flow or automatic fog nozzles - Air-aspirating foam nozzle uses a venturi action
Courtesy of John Demyan, LVI Airport.
67Portable Foam Application Devices Turret Nozzles
- Large, pre-plumbed master stream appliances
- Capable of sweeping side to side and delivering
large volumes of foam or water
(Continued)
68Portable Foam Application Devices Turret Nozzles
- May be aspirating, nonaspirating, or combination
- Consider several factors when selecting
69Aspirating Versus Nonaspirating Nozzles
- Nonaspirating application only film forming
foams - Protein or fluoroprotein foams require
air-aspirating nozzles - AFFF aspirating or nonaspirating turrets and
nozzles
(Continued)
70Aspirating Versus Nonaspirating Nozzles
- Nonaspirating nozzles advantages and
limitations - Air-aspirating devices designed to produce a
good quality foam
71Foam Application Techniques
- Correct application as important as type of
agent - Principle of insulate and isolate
- Insulate the fuselage
- Separate fire from the fuselage
72Foam Application Techniques Roll-on Method
- Directs the foam stream on the ground near the
front edge of a burning liquid pool - Foam rolls across fuel surface
(Continued)
73Foam Application Techniques Roll-on Method
- Continue to apply foam across entire fuel surface
- Used only on a pool of liquid fuel on the ground
or pavement
Courtesy of James Mack, Richmond International
Airport
74Foam Application Techniques Deflection or
Bank-down Method
- Used when an elevated object is near a burning
pool of liquid or unignited spill - Direct the foam stream at the object
Courtesy of James Mack, Richmond International
Airport
75Foam Application Techniques Base-of-the-Fire
Method
- AFFF can be applied with a zero-degree
base-of-the-fire angle - Usually applied through a bumper turret
Courtesy of James Mack, Richmond International
Airport
76Foam Application Techniques Rainfall Method
- 40 degree rainfall method extends reach of foam
stream - Consider wind
- Used when other methods are not feasible
(Continued)
77Foam Application Techniques Rainfall Method
- Primary technique used on aboveground storage
tank fires
78Dry Chemicals
- Dry-chemical agents used on Class A, B, or C
fires - Dry-powder agents used only on Class D fires
(Continued)
79Dry Chemicals
- Effective
- For initial attack and quick knockdown of certain
fires - On three-dimensional or running fuel fires
- Not effective on large spill fires with
obstructions
(Continued)
80Dry Chemicals
- Do not have vapor-sealing properties or
flashback-preventive characteristics of foam - Inhibit chemical chain reaction
- Are nonconductive
- May contain a number of chemical compounds
(Continued)
81Dry Chemicals
- Compatible
- With film-forming foams
- With water and foam for master stream or turret
operations - Hydro-Chem use of dry chemical, water and AFFF
(Continued)
82Dry Chemicals
- Guidelines for applying
- Apply from upwind
- Apply so agent will blanket fire
- Be aggressive but do not splash or churn fuel
- Monitor fire area for reignition
(Continued)
83Dry Chemicals
- Are nontoxic, generally considered safe to use
- Cloud of chemicals may reduce visibility
- Respiratory irritant
- Wear SCBA
84Dry Chemicals Extinguishers
- Consult the UL listing for rating
- Two basic types
- Regular BC rated
- Multipurpose ABC-rated
- Additives are mixed with base
Courtesy of Doddy Photography
(Continued)
85Dry Chemicals Extinguishers
- Handheld and wheeled extinguishers
- Stored-pressure
- Cartridge operated
- Wheeled units are similar to handheld units but
larger
86Apparatus Mounted Units
- ARFF apparatus may be equipped with dry-chemical
or wet-chemical extinguishing systems - Consist of several components
(Continued)
87Apparatus Mounted Units
- FAR Part 139.317 lists requirements
- ARFF vehicles carry dry chemical as an auxiliary
agent - Usually Purple K
- Compatible with AFFF
- Systems start at 500 lb (227 kg)
(Continued)
88Apparatus Mounted Units
- Dry chemical is dispensed in three ways
- Handline
- Piggybacking systems
- Water stream injection systems
- Handlines and turrets must meet specific
requirements
89Clean Agents
- Designed to extinguish fires and leave little, if
no, residue - Traditional agents Halon 1211 and Halon 1301
- Halogens phased-out by 2000
- Exceptions for essential uses
(Continued)
90Clean Agents
- Clean agent systems are being replaced
- Because of high cost
- Changing to dry chemical or PKP systems
- Halon replacements often require higher
concentration
(Continued)
91Clean Agents
- Halotron I approved by FAA and EPA as a clean
agent replacement - Progress in replacing halogenated agents
92Characteristics of Halons
- Rapidly vaporize in fire
- Nonconductive
- Almost no flashback-preventive capabilities
(Continued)
93Characteristics of Halons
- Penetrate inaccessible areas
- Effective for fires in complex equipment
- Compatible with dry chemicals and AFFF
94Summary
- ARFF personnel should be familiar with the common
extinguishing agents they will use to fight
aircraft fires. - Water, foam, dry-chemical, dry-powder, and clean
agents all have specific uses in ARFF fire
fighting.
(Continued)
95Summary
- Foam applications are the most widely used due to
their greater ability to extinguish hydrocarbon
and polar solvent fuel fires.
(Continued)
96Summary
- Personnel should be familiar with the
proportioning process through which fuel
concentrate becomes finished foam. - Personnel should understand the four methods used
to apply foam as well as foam application
equipment.
(Continued)
97Summary
- Firefighters must have a working knowledge of
dry-chemical, dry-powder, and clean agent
extinguishing agents.
98Review Questions
- 1. Why is water alone not usually a suitable
extinguishing agent for large aircraft fuel
fires? - 2. What are the methods by which foam
extinguishes or prevents fire? - 3. How is foam induction achieved?
-
(Continued)
99Review Questions
- 4. Upon what variables does the rate of
application for fire fighting foam depend? - 5. What are the three basic applications of
high-expansion foam? - 6. How does an installed in-line eductor system
work?
(Continued)
100Review Questions
- 7. What is a handline nozzle?
- 8. How does the bank-down foam application
technique work? - 9. What are the two basic designs for handheld
dry-chemical extinguishers?
(Continued)
101Review Questions
- 10. Why are halogenated extinguishing agents
being replaced by alternative agents? -