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?