Essentials of Fire Fighting,

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• Essentials of Fire Fighting,
• 5th Edition

Chapter 14 Fire Streams Firefighter II
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Chapter 14 Lesson Goal

• After completing this lesson, the student shall
  be able to effectively apply fire fighting foam
  using various foam types, concentrates, and
  delivery devices following the policies and
  procedures set forth by the authority having
  jurisdiction (AHJ).

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Specific Objectives

• 1. Describe the suppression characteristics of
  fire fighting foam.
• 2. Define terms associated with types of foam
  and the foam-making process.
• 3. Discuss how foam is generated.

(Continued)
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Specific Objectives

• 4. Discuss foam concentrates.
• 5. Describe methods by which foam may be
  proportioned.
• 6. Discuss foam proportioners.
• 7. Discuss foam delivery devices.

(Continued)
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Specific Objectives

• 8. List reasons for failure to generate foam or
  for generating poor-quality foam.
• 9. Describe foam application techniques.

(Continued)
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Specific Objectives

• 10. Discuss hazards associated with foam
  concentrates.
• 11. Place a foam line in service In-line
  eductor. (Skill Sheet 14-II-1)

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Ways Fire Fighting Foam Extinguishes/Prevents Fire

• Separating
• Cooling
• Smothering
• Penetrating

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Terms Associated With Foam

• Foam concentrate
• Foam proportioner
• Foam solution
• Foam (finished foam)

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How Foam is Generated

• Foams used today are of mechanical type and
  before use must be
• Proportioned
• Aerated

(Continued)
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How Foam is Generated

• Elements needed to produce fire fighting foam

(Continued)
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How Foam is Generated

• All elements must be present and blended in
  correct ratios
• Aeration produces foam bubbles to form effective
  foam blanket

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Foam Expansion

• The increase in volume of foam when aerated
• Method of aerating results in varying degrees of
  expansion
• Types of foam

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Foam Concentrates General Considerations

• Foam concentrates must match fuel to which
  applied
• Class A foams not designed to extinguish Class B
  fires
• Class B foams designed solely for hydrocarbon
  fires will not extinguish polar solvent fires

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Class A Foam

• Increasingly used in both wildland and structural
  fire fighting
• Special formulation of hydrocarbon surfactants

(Continued)
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Class A Foam

• Aerated Class A foam coats, insulates fuels,
  preventing pyrolysis and ignition
• May be used with variety of nozzles

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Class B Foam

• Used to prevent ignition of or extinguish fires
  involving flammable and combustible liquids
• Used to suppress vapors from unignited spills of
  these liquids
• Several types of Class B foam concentrates
  available

(Continued)
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Class B Foam

• Manufactured from synthetic or protein base
• May be proportioned into the fire stream through
  fixed system, apparatus-mounted system, or by
  portable foam proportioning equipment

(Continued)
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Class B Foam

• Foams such as AFFF and FFFP foam may be applied
  with standard fog nozzles or air-aspirating foam
  nozzles
• Rate of application depends on several factors

(Continued)
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Class B Foam

• Unignited spills do not require same application
  rates as ignited spills
• To be most effective, blanket of foam 4 inches
  (100 mm) thick should be applied to fuel surface

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Specific Application Foams

• Numerous types of foam available for specific
  applications
• Properties of foams vary

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Proportioning

• Mixing of water with foam concentrate to form
  foam solution
• Most concentrates can be mixed with fresh/salt
  water

(Continued)
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Proportioning

• For maximum effectiveness, foam concentrates must
  be proportioned at designated percentage
• Most fire fighting foams intended to be mixed
  with 94 to 99.9 percent water

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Proportioning Methods

• Induction
• Injection
• Batch-mixing
• Premixing

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Foam Proportioners General Considerations

• May be portable or apparatus-mounted
• Operate by one of two basic principles

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Portable Foam Proportioners

• Simplest, most common form of proportioning
  devices
• In-line foam eductors
• Foam nozzle eductors

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Apparatus-Mounted Proportioners

• Mounted on structural, industrial, wildland, and
  aircraft rescue and fire fighting apparatus, as
  well as on fire boats
• Three types

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Compressed-Air Foam Systems (CAFS)

• Newer structural engines are equipped with CAFS

(Continued)
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Compressed-Air Foam Systems (CAFS)

• Standard centrifugal pump supplies water,
  direct-injection foam-proportioning system mixes
  foam solution with water on discharge side of
  pump, onboard air compressor adds air to mix
  before discharging from engine

(Continued)
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Compressed-Air Foam Systems (CAFS)

• Unlike other systems, hoseline contains finished
  foam
• Advantages
• Disadvantages

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Handline Nozzles

• Solid-bore nozzles
• Fog nozzles
• Air-aspirating foam nozzles

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Medium- and High-Expansion Foam Generating Devices

• Produce foam that is semistable with high air
  content
• Medium-expansion foam
• High-expansion foam
• Water-aspirating type nozzle
• Mechanical blower generator

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Reasons for Poor-Quality Foam/Failure to
Generate Foam

• Eductor, nozzle flow ratings do not match so foam
  concentrate cannot induct into fire stream
• Air leaks at fittings cause loss of suction
• Improper cleaning of proportioning equipment
  causes clogged foam passages

(Continued)
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Reasons for Poor-Quality Foam/Failure to
Generate Foam

• Nozzle not fully open, restricting water flow
• Hose lay on discharge side of eductor is too long
• Hose is kinked and stops flow

(Continued)
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Reasons for Poor-Quality Foam/Failure to
Generate Foam

• Nozzle is too far above eductor
• Mixing different types of foam concentrate in
  same tank results in mixture too viscous to pass
  through eductor

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Roll-On Foam Application Method

• Directs foam stream on ground near front edge of
  burning liquid spill
• Foam rolls across surface of fuel

(Continued)
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Roll-On Foam Application Method

• Firefighters continue to apply foam until spreads
  across entire surface of fuel and fire
  extinguished
• Used only on pool of liquid fuel on open ground

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Bank-Down Foam Application Method

• May be employed when elevated object is
  near/within area of burning pool of liquid or
  unignited liquid spill
• Object may be wall, tank shell, similar vertical
  structure

(Continued)
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Bank-Down Foam Application Method

• Foam stream directed onto object, allowing foam
  to run down onto surface of fuel
• Used primarily in dike fires, fires involving
  spills around damaged/overturned transport
  vehicles

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Rain-Down Foam Application Method

• Used when other two methods not feasible because
  of size of spill area or lack of object from
  which to bank foam

(Continued)
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Rain-Down Foam Application Method

• Primary manual application technique on
  aboveground storage tank fires
• Directs stream into air above fire/spill, allows
  foam to float gently down onto surface of fuel

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Foam Hazards to Humans

• Foam concentrates pose minimal health risks to
  humans
• May be mildly irritating to skin, eyes

(Continued)
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Foam Hazards to Humans

• Affected areas should be flushed with water
• Some concentrates, vapors may be harmful if
  ingested/inhaled
• Consult MSDS for specific information

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Foam Hazards to Equipment

• Most Class A, Class B foam concentrates are
  mildly corrosive
• Follow proper flushing procedures to prevent
  damage

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Foam Hazards to Environment

• Primary impact is effect of finished foam after
  application to fire/liquid spill
• Biodegradability of foam determined by rate at
  which environmental bacteria cause decomposition

(Continued)
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Foam Hazards to Environment

• Environmental impact of foam concentrates varies
• In the U.S., Class A foams should be approved by
  USDA Forest Service

(Continued)
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Foam Hazards to Environment

• Chemical properties of Class B foams and
  environmental impact vary on type and
  manufacturer
• Protein-based foams safer for environment

(Continued)
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Summary

• Firefighters must know the differences between
  the classes of foam, how to generate foam, and
  how to apply foam most effectively

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Review Questions

• 1. What are the ways that fire fighting foam
  extinguishes and/or prevents fire?
• 2. Describe types of foam concentrates.
• 3. What are the methods by which foam may be
  proportioned?

(Continued)
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Review Questions

• 4. What are the types of portable foam
  proportioners and how do they work?
• 5. Describe the techniques used to apply foam.