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Aircraft Rescue and Fire Fighting,

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Preferred agent for Class A interior fires. ARFF. 6 7. Structural ... Class B Foam: Foam Expansion. Increase in volume of a foam solution when it is aerated ... – PowerPoint PPT presentation

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Title: Aircraft Rescue and Fire Fighting,


1
  • Aircraft Rescue and Fire Fighting,
  • 5th Edition

Chapter 6 Extinguishing Agents
2
Chapter 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.

3
Objectives
  • 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)
4
Objectives
  • 4. Describe foam proportioning systems.
  • 5. Discuss portable foam application devices.
  • 6. Explain foam application.

(Continued)
5
Objectives
  • 7. Describe dry chemicals and their
    applications.
  • 8. Describe clean agents and their applications.

6
Water 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)
7
Water 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

8
Structural Apparatus and Water
  • Guidelines when used for spilled fuel fire
  • 1 ½-inch (38 mm) or larger lines
  • Fog pattern
  • Avoid straight streams

(Continued)
9
Structural Apparatus and Water
  • Structural apparatus water supply
  • Does not carry as much water
  • Supply may last long enough for personnel to
    effect rescue

10
Hazards of Water
  • Excellent conductor of electricity
  • Steam can obscure vision, scald individuals

11
Water 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

12
Foam Use in Fire Fighting
  • Used to combat fires in hydrocarbon fuels
  • Lower specific gravity than hydrocarbon fuels
  • Floats on surface

(Continued)
13
Foam Use in Fire Fighting
  • Works by forming blanket
  • Excludes oxygen
  • Stops burning process
  • Water in foam
  • Slowly released
  • Provides cooling effect

14
Foam Extinguishing Methods
  • Separating
  • Smothering
  • Cooling
  • Suppressing

(Continued)
15
Foam Extinguishing Methods
16
Applying 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)
17
Applying 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

18
Critical 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

19
Foam 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)
20
Foam Proportioning
  • The foam tetrahedron

21
Terms
  • Foam concentrate
  • Foam proportioner
  • Foam solution
  • Finished foam

22
Using 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)
23
Using 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)
24
Using Foam Concentrates
  • Hydrocarbon fuels
  • Petroleum-based
  • Hydrophobic
  • Standard fire fighting foam
  • Effective agent and vapor suppressant
  • Float on surface of hydrocarbon fuels

(Continued)
25
Using Foam Concentrates
  • Polar solvents
  • Flammable
  • Hydrophilic

26
Class 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

27
Class 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)
28
Class B Foam
  • Do not mix different manufacturers foam
    concentrates
  • Military specifications AFFF is exception
  • Causes no adverse effects for military
    specification AFFF

(Continued)
29
Class B Foam
  • Chemical properties and environmental impact vary
  • Generally not good for environment
  • Use minimum needed
  • Contain and recover aircraft fuel and foam runoff

30
Class B Foam Proportioning
  • Mixed in proportions from 1 to 6
  • Some multipurpose foams used on both hydrocarbon
    and polar solvent fuels

31
Class 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)
32
Class B Foam Foam Expansion
  • Depending on its purpose foam is
  • Low-expansion
  • Medium-expansion
  • High-expansion

33
Class 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)
34
Class B Foam Rates of Application
  • NFPA 403 states application rates
  • Unignited spills do not require same
    application rates as ignited spills

35
Specific Foam Concentrates
  • Foams are selected based on
  • Properties
  • Performance
  • Consult the UL listing

36
Aqueous 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)
37
Aqueous Film Forming Foam (AFFF)
  • Available in 1, 3, or 6
  • Mixed with water
  • Resists breakdown by dry chemicals

(Continued)
38
Aqueous 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)
39
Aqueous Film Forming Foam (AFFF)
  • Alcohol-resistant AFFF is available
  • Store AFFF in a temperature controlled environment

40
Regular 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

41
Film Forming Fluoroprotein Foam
  • Incorporates benefits of aqueous film and
    fluoroprotein foam
  • Available in alcohol-resistant formulation
  • Effective agent on flammable liquid fires

(Continued)
42
Film 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

43
High-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

44
How Foam Concentrates are Stored
  • Pails
  • Barrels
  • Intermediate bulk containers
  • Apparatus tanks

Courtesy of Doddy Photography.
45
General Principles of Foam Proportioning
  • Strict design specifications for equipment
  • Failure to operate equipment
  • Poor-quality foam
  • No foam

(Continued)
46
General 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

47
Foam Proportioning
  • Proportioning mixing of water with foam
    concentrate
  • Failure to proportion correctly
  • Poor-quality foam
  • Waste resources

(Continued)
48
Foam 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)
49
Foam Proportioning
  • Selection of proportioner depends on several
    factors
  • Four basic methods
  • Induction
  • Injection
  • Batch mixing
  • Premixing

50
Foam 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

51
Foam 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

52
Foam 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

53
Foam Proportioning Premixing
  • Premeasured portions of water and foam
    concentrate are mixed
  • Commonly used

54
Portable 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)
55
Portable 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

56
Apparatus-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)
57
Apparatus-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)
58
Apparatus-mounted Foam Proportioning Systems
  • Around-the-pump proportioners
  • Rated for specific flow
  • Have disadvantages

(Continued)
59
Apparatus-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)
60
Apparatus-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

61
High-energy Foam Generating Systems
  • Introduce compressed air into foam solution prior
    to discharge
  • Uses a standard centrifugal fire pump to supply
    water

(Continued)
62
High-energy Foam Generating Systems
  • Called a compressed-air foam system (CAFS)
  • Most commonly found on structural and wildland
    fire apparatus

63
Portable 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)
64
Portable Foam Application Devices
  • Low-expansion foams discharged through handline
    nozzles or master stream devices

65
Portable 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)
66
Portable 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.
67
Portable 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)
68
Portable Foam Application Devices Turret Nozzles
  • May be aspirating, nonaspirating, or combination
  • Consider several factors when selecting

69
Aspirating 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)
70
Aspirating Versus Nonaspirating Nozzles
  • Nonaspirating nozzles advantages and
    limitations
  • Air-aspirating devices designed to produce a
    good quality foam

71
Foam Application Techniques
  • Correct application as important as type of
    agent
  • Principle of insulate and isolate
  • Insulate the fuselage
  • Separate fire from the fuselage

72
Foam 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)
73
Foam 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
74
Foam 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
75
Foam 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
76
Foam Application Techniques Rainfall Method
  • 40 degree rainfall method extends reach of foam
    stream
  • Consider wind
  • Used when other methods are not feasible

(Continued)
77
Foam Application Techniques Rainfall Method
  • Primary technique used on aboveground storage
    tank fires

78
Dry Chemicals
  • Dry-chemical agents used on Class A, B, or C
    fires
  • Dry-powder agents used only on Class D fires

(Continued)
79
Dry 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)
80
Dry 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)
81
Dry 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)
82
Dry 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)
83
Dry Chemicals
  • Are nontoxic, generally considered safe to use
  • Cloud of chemicals may reduce visibility
  • Respiratory irritant
  • Wear SCBA

84
Dry 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)
85
Dry Chemicals Extinguishers
  • Handheld and wheeled extinguishers
  • Stored-pressure
  • Cartridge operated
  • Wheeled units are similar to handheld units but
    larger

86
Apparatus Mounted Units
  • ARFF apparatus may be equipped with dry-chemical
    or wet-chemical extinguishing systems
  • Consist of several components

(Continued)
87
Apparatus 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)
88
Apparatus Mounted Units
  • Dry chemical is dispensed in three ways
  • Handline
  • Piggybacking systems
  • Water stream injection systems
  • Handlines and turrets must meet specific
    requirements

89
Clean 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)
90
Clean 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)
91
Clean Agents
  • Halotron I approved by FAA and EPA as a clean
    agent replacement
  • Progress in replacing halogenated agents

92
Characteristics of Halons
  • Rapidly vaporize in fire
  • Nonconductive
  • Almost no flashback-preventive capabilities

(Continued)
93
Characteristics of Halons
  • Penetrate inaccessible areas
  • Effective for fires in complex equipment
  • Compatible with dry chemicals and AFFF

94
Summary
  • 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)
95
Summary
  • Foam applications are the most widely used due to
    their greater ability to extinguish hydrocarbon
    and polar solvent fuel fires.

(Continued)
96
Summary
  • 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)
97
Summary
  • Firefighters must have a working knowledge of
    dry-chemical, dry-powder, and clean agent
    extinguishing agents.

98
Review 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)
99
Review 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)
100
Review 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)
101
Review Questions
  • 10. Why are halogenated extinguishing agents
    being replaced by alternative agents?
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