Transcript Fire Streams

Intermediate
SFFMA Objectives: 6-02.01 – 6-02.06
8Hrs Received
Methods to Reduce Heat and
Provide Protection
 Applying water or foam directly onto burning material
to reduce its temperature
 Applying water or foam over an open fire to reduce the
temperature so firefighters can advance handlines
 Reducing high atmospheric temperature
(Continued)
Firefighter I
14–2
Methods to Reduce Heat and
Provide Protection
 Dispersing hot smoke and fire gases from a heated
area
 Creating a water curtain to protect firefighters and
property from heat
 Creating a barrier between a fuel and a fire by covering
the fuel with a foam blanket
Firefighter I
14–3
How Water Extinguishes Fire
 Primary way is cooling
 Smothering by diluting or excluding oxygen
Firefighter I
14–4
Heat Absorption
 When heated to boiling point, water absorbs heat
 Visible form of steam is called condensed steam
 Components of heat absorption
 Specific heat
(Continued)
Firefighter I
14–5
Heat Absorption
 Latent heat of vaporization
 Expansion capability
 Effective extinguishment with
water generally requires steam
production
(Continued)
Firefighter I
14–6
Heat Absorption
 Water absorbs more heat when converted to steam
than when heated to boiling point
Firefighter I
14–7
Characteristics of Water Valuable
for Fire Extinguishment
 Readily available, relatively inexpensive
 Has greater heat-absorbing capacity than most other
common agents
 Water changing to steam requires large amount of
heat
 Can be applied in variety of ways
Firefighter I
14–8
Solid Stream
 Produced from fixed
orifice, solid-bore
nozzle
 Has ability to reach
areas others might not; reach affected by several
factors
 Design capabilities
(Continued)
Firefighter I
14–9
Solid Stream
 Velocity of stream a result of nozzle pressure
 Nozzle pressure, size of discharge opening determine
flow
 Characteristics of effective fire streams
 Flow rate
Firefighter I
14–10
Advantages of Solid Streams
 May maintain better interior visibility than others
 May have greater reach than others
 Operate at reduced nozzle pressures per gallon (liter)
than others
 May be easier to maneuver
(Continued)
Firefighter I
14–11
Advantages of Solid Streams
 Have greater penetration power
 Less likely to disturb normal thermal layering of heat,
gases during interior structural attacks
 Less prone to clogging with debris
(Continued)
Firefighter I
14–12
Advantages of Solid Streams
 Produce less steam conversion than fog nozzles
 Can be used to apply compressed-air foam
Firefighter I
14–13
Disadvantages of Solid Streams
 Do not allow for different stream pattern selections
 Provide less heat absorption per gallon (liter) delivered
than others
 Hoselines more easily kinked at corners, obstructions
Firefighter I
14–14
DISCUSSION QUESTION
What type of fire situation would be ideal for a solidstream nozzle?
Firefighter I
14–15
Fog Stream
 Fine spray composed of tiny
water droplets
 Design of most fog nozzles
permits adjustment of tip to
produce different stream
patterns
(Continued)
Firefighter I
14–16
Fog Stream
 Water droplets formed to expose maximum water
surface for heat absorption
 Desired performance of fog stream nozzles judged by
amount of heat that fog stream absorbs and rate by
which the water is converted into steam/vapor
(Continued)
Firefighter I
14–17
Fog Stream
 Nozzles permit settings of straight stream, narrow-
angle fog, and wide-angle fog
 Nozzles should be operated at designed nozzle
pressure
(Continued)
Firefighter I
14–18
Fog Stream
 Several factors affect reach of fog stream
 Interaction of these factors on fog stream results in fire
stream with less reach than that of straight or solid
stream
(Continued)
Firefighter I
14–19
Fog Stream
 Shorter reach makes fog streams less useful for
outside, defensive fire fighting operations
 Well suited for fighting interior fires
Firefighter I
14–20
Fog Stream: Waterflow Adjustment
 Two types of nozzles control rate of water flow
through fog nozzle
 Manually adjustable nozzles
 Automatic nozzles
Firefighter I
14–21
DISCUSSION QUESTION
How should adjustments to the rate of flow be made?
Firefighter I
14–22
Fog Stream: Nozzle Pressure
 Combination nozzles designed to operate at different
pressures
 Designated operating pressure for most combination
nozzles is 100 psi (700 kPa)
(Continued)
Firefighter I
14–23
Fog Stream: Nozzle Pressure
 Nozzles with other designated
operating pressures available
 Setbacks of nozzles with lower
operating pressures
Courtesy of Elkhart
Brass Manufacturing
Company.
Firefighter I
14–24
Advantages of Fog Streams
 Discharge pattern can be adjusted for situation
 Can aid ventilation
 Reduce heat by exposing maximum water surface for
heat absorption
 Wide fog pattern provides protection to firefighters
Firefighter I
14–25
Disadvantages of Fog Streams
 Do not have as much reach/penetrating power as solid
streams
 More affected by wind than solid streams
 May disturb thermal layering
 May push air into fire area, intensifying the fire
Firefighter I
14–26
Ways Fire Fighting Foam
Extinguishes/Prevents Fire
 Separating
 Cooling
 Smothering
 Penetrating
Firefighter II
14–27
Terms Associated With Foam
 Foam concentrate
 Foam proportioner
 Foam solution
 Foam (finished foam)
Firefighter II
14–28
How Foam is Generated
 Foams used today are of mechanical type and before
use must be
 Proportioned
 Aerated
(Continued)
Firefighter II
14–29
How Foam is Generated
 Elements needed to produce fire fighting
foam
– Foam concentrate
– Water
– Air
– Mechanical agitation
(Continued)
Firefighter II
14–30
How Foam is Generated
 All elements must be present and blended in correct
ratios
 Aeration produces foam bubbles to form effective
foam blanket
Firefighter II
14–31
Foam Expansion
 The increase in volume of foam when aerated
 Method of aerating results in varying degrees of
expansion
 Types of foam
Firefighter II
14–32
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
Firefighter II
14–33
Class A Foam
 Increasingly used in both
wildland and structural fire
fighting
(Continued)
Firefighter II
14–34
Class A Foam
 Special formulation of hydrocarbon surfactants
 Aerated Class A foam coats, insulates fuels, preventing
pyrolysis and ignition
 May be used with variety of nozzles
Firefighter II
14–35
Class B Foam
 Used to prevent
ignition of or extinguish
fires involving
flammable and
combustible liquids
Courtesy of Williams Fire & Hazard Control,
Inc.
(Continued)
Firefighter II
14–36
Class B Foam
Used to suppress vapors from unignited spills
of these liquids
Several types of Class B foam concentrates
available
(Continued)
Firefighter II
14–37
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)
Firefighter II
14–38
Class B Foam
 Foams such as AFFF
and FFFP foam may
be applied with
standard fog nozzles
or air-aspirating
foam nozzles
Courtesy of Harvey Eisner.
(Continued)
Firefighter II
14–39
Class B Foam
 Rate of application depends on several factors
 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
Firefighter II
14–40
Specific Application Foams
 Numerous types of foam available for specific
applications
 Properties of foams vary
Firefighter II
14–41
Proportioning
 Mixing of water with foam
concentrate to form foam
solution
 Most concentrates can be
mixed with fresh/salt
water
(Continued)
Firefighter II
14–42
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
(Continued)
Firefighter II
14–43
Proportioning
Firefighter II
14–44
Proportioning Methods
 Induction
 Injection
(Continued)
Firefighter II
14–45
Proportioning Methods
 Batch-mixing
 Premixing
Courtesy of Ansul.
Firefighter II
14–46
DISCUSSION QUESTION
What proportion methods does your department use?
Firefighter II
14–47
Foam Proportioners — General
Considerations
 May be portable or apparatus-mounted
 Operate by one of two basic principles
Courtesy of Conoco/Phillips.
Firefighter II
14–48
Portable Foam Proportioners
 Simplest, most common
form of proportioning
devices
 In-line foam eductors
 Foam nozzle eductors
Firefighter II
14–49
Apparatus-Mounted
Proportioners
 Mounted on
structural,
industrial,
wildland, and
aircraft rescue
and fire fighting apparatus, as well as on fire boats
 Three types
Firefighter II
14–50
DISCUSSION QUESTION
What is the advantage of an apparatus-mounted proportioner?
Firefighter II
14–51
Compressed-Air Foam Systems
(CAFS)
 Newer structural engines are equipped with CAFS
(Continued)
Firefighter II
14–52
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)
Firefighter II
14–53
Compressed-Air Foam Systems
(CAFS)
 Unlike other systems, hoseline contains finished foam
 Advantages
 Disadvantages
Firefighter II
14–54
Handline Nozzles
 Solid-bore nozzles
 Fog nozzles
 Air-aspirating foam nozzles
Firefighter II
14–55
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
Firefighter II
14–56
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
(Continued)
Firefighter II
14–57
Reasons for Poor-Quality Foam/
Failure to Generate Foam
 Improper cleaning of
proportioning equipment causes
clogged foam passages
 Nozzle not fully open, restricting
water flow
(Continued)
Firefighter II
14–58
Reasons for Poor-Quality Foam/
Failure to Generate Foam
 Hose lay on discharge side of eductor is too long
 Hose is kinked and stops flow
 Nozzle is too far above eductor
(Continued)
Firefighter II
14–59
Reasons for Poor-Quality Foam/
Failure to Generate Foam
 Mixing different types of foam concentrate in same
tank results in mixture too viscous to pass through
eductor
Firefighter II
14–60
Roll-On Foam Application
Method
 Directs foam stream on ground near front edge of
burning liquid spill
 Foam rolls across surface of fuel
(Continued)
Firefighter II
14–61
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
Firefighter II
14–62
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)
Firefighter II
14–63
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
Firefighter II
14–64
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)
Firefighter II
14–65
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
Firefighter II
14–66
DISCUSSION QUESTION
What are some examples of when each of these techniques should be
used?
Firefighter II
14–67
Foam Hazards to Humans
 Foam concentrates pose minimal health risks to
humans
 May be mildly irritating to skin, eyes
(Continued)
Firefighter II
14–68
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
Firefighter II
14–69
Foam Hazards to Equipment
 Most Class A, Class B foam concentrates are mildly
corrosive
 Follow proper flushing procedures to prevent damage
Firefighter II
14–70
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)
Firefighter II
14–71
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)
Firefighter II
14–72
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)
Firefighter II
14–73