Pumping Apparatus
Driver/Operator — Lesson 15
Pumping Apparatus Driver/Operator
Handbook, 2nd Edition
Chapter 15 — Foam Equipment
and Systems
Learning Objectives
1. List the reasons why foam and durable
agents have increased in use in recent
years.
2. Match to their definitions terms associated
with the foam-making process.
3. Select facts about the principles of foam.
(Continued)
Pumping Apparatus
Driver/Operator
15–1
Learning Objectives
4. Explain how foam extinguishes and/or
prevents fire.
5. Answer questions about foam
proportioning.
6. List the four basic methods by which foam
may be proportioned.
(Continued)
Pumping Apparatus
Driver/Operator
15–2
Learning Objectives
7. Select facts about how foam is stored.
8. Answer questions about Class A foam.
9. Explain the common guidelines for
performing various applications with Class
A foams.
(Continued)
Pumping Apparatus
Driver/Operator
15–3
Learning Objectives
10. List the type of Class A foam required for
given situations.
11. Select facts about Class B foam.
12. List the variables that determine the rate of
application of Class B foam.
(Continued)
Pumping Apparatus
Driver/Operator
15–4
Learning Objectives
13. List the application rates of Class B foam
for common fire scenarios.
14. Explain how to determine the application
rate available from a nozzle.
15. Calculate foam application rates.
(Continued)
Pumping Apparatus
Driver/Operator
15–5
Learning Objectives
16. Select facts about specific foam
concentrates.
17. List the three things that happen when
Aqueous Film Forming Foam (AFFF) is
applied to a hydrocarbon fire.
18. List the three basic applications of highexpansion foams.
(Continued)
Pumping Apparatus
Driver/Operator
15–6
Learning Objectives
19. Describe the two principles by which foam
proportioning devices operate.
20. Answer questions about portable foam
proportioners.
21. List the operating rules when using
eductors.
(Continued)
Pumping Apparatus
Driver/Operator
15–7
Learning Objectives
22. Answer questions about apparatusmounted foam proportioning systems.
23. Distinguish between advantages and
limitations of compressed-air foam systems
(CAFS).
24. Identify characteristics of various portable
foam application devices.
(Continued)
Pumping Apparatus
Driver/Operator
15–8
Learning Objectives
25. Install an in-line foam eductor and operate
a high expansion foam generator.
26. Select from a list the reasons for failure to
generate foam or for generating poor
quality foam.
27. Match to their definitions various foam
application techniques.
Pumping Apparatus
Driver/Operator
15–9
(Continued)
Learning Objectives
28. Answer questions about the environmental
impact of foam concentrates and solutions.
29. Select facts about durable agents.
Pumping Apparatus
Driver/Operator
15–10
Why Foam and Durable Agents
Have Increased in Use Recently
• Magnitude and frequency of hazardous
materials incidents requiring foam for control
• New advances in foam concentrate
technology that have provided products which
are more easily used by municipal and
wildland firefighters
(Continued)
Pumping Apparatus
Driver/Operator
15–11
Why Foam and Durable Agents
Have Increased in Use Recently
• Technological improvements in foam
proportioning equipment and systems that
make their inclusion in the construction of
new fire apparatus, or the retrofitting of
existing apparatus, feasible for many fire
departments
Pumping Apparatus
Driver/Operator
15–12
Foam Terms
• Proportion — To mix with water
• Aerate — To mix with air
• Foam concentrate — The raw foam liquid in
its storage container before being combined
with air and water
(Continued)
Pumping Apparatus
Driver/Operator
15–13
Foam Terms
• Foam proportioner — The device that
introduces foam concentrate into the water
stream to make the foam solution
• Foam solution — The mixture of foam
concentrate and water before the introduction
of air
• Foam — The completed product after air is
introduced into the foam solution
Pumping Apparatus
Driver/Operator
15–14
Principles of Foam
• To produce quality fire fighting foam, foam
concentrate, water, air, and mechanical
aeration are needed.
(Continued)
Pumping Apparatus
Driver/Operator
15–15
Principles of Foam
• Proper aeration should produce uniform-sized
bubbles to provide a longer lasting blanket. A
good foam blanket must maintain cover over
either Class A or Class B fuels for the
required period of time.
(Continued)
Pumping Apparatus
Driver/Operator
15–16
Principles of Foam
• Some foams are now available that are rated
for use on fires in both Class A and Class B
fuels.
• If a department still has single-class foam
only, each must be matched to the fuel for
which it was formulated.
(Continued)
Pumping Apparatus
Driver/Operator
15–17
Principles of Foam
• Class B fuels
– Hydrocarbons — Petroleum based and float on
water; Class B foam is effective as an
extinguishing agent.
Examples: Crude oil, fuel oil, gasoline, benzene,
naphtha, jet fuel, and kerosene
(Continued)
Pumping Apparatus
Driver/Operator
15–18
Principles of Foam
• Class B fuels
– Polar solvents — Flammable liquids that mix with
water; foam can be effective, but only in special
alcohol-resistant formulations
Examples: Alcohol, acetone, lacquer thinner,
ketones, and esters
(Continued)
Pumping Apparatus
Driver/Operator
15–19
Principles of Foam
• Class B foams designed solely for
hydrocarbon fires will not extinguish polar
solvent fires regardless of the concentration
at which they are used. However, many
foams that are intended for polar solvents
may be used on hydrocarbon fires, but this
should not be attempted unless the
manufacturer of the particular concentrate
being used says this is permissible.
(Continued)
Pumping Apparatus
Driver/Operator
15–20
Principles of Foam
CAUTION! Failure to match the proper foam
concentrate with the fuel can result in an
unsuccessful extinguishing effort and could
endanger firefighters.
Pumping Apparatus
Driver/Operator
15–21
How Foam Extinguishes
and/or Prevents Fire
• Separating — Creates a barrier between the
fuel and the fire
• Cooling — Lowers the temperature of the fuel
and adjacent surfaces
(Continued)
Pumping Apparatus
Driver/Operator
15–22
How Foam Extinguishes
and/or Prevents Fire
• Suppressing (sometimes referred to as
smothering) — Prevents the release of
flammable vapors and therefore reduces the
possiblity of ignition or reignition
(Continued)
Pumping Apparatus
Driver/Operator
15–23
How Foam Extinguishes
and/or Prevents Fire
Pumping Apparatus
Driver/Operator
15–24
Foam Proportioning
• Describes the mixing of water with foam
concentrate to form a foam solution
• For maximum effectiveness, foam
concentrates must be proportioned at the
specific percentage for which they are
formulated. This rate is clearly marked on the
outside of the foam container.
(Continued)
Pumping Apparatus
Driver/Operator
15–25
Foam Proportioning
• Most fire fighting foam concentrates are intended to
be mixed with 94 to 99.9% water.
Example: When using 3% foam concentrate, 97
parts water mixed with 3 parts foam concentrate
equals 100 parts foam solution.
(Continued)
Pumping Apparatus
Driver/Operator
15–26
Foam Proportioning
• Class A foams are not proportioned as other
foams. Their percentage can be adjusted
(within limits) to achieve specific objectives.
– Dry (thick) foam suitable for exposure
protection and fire breaks require higher
percentage of foam.
– Wet (thin) foam that rapidly sinks into a
fuel’s surface can be adjusted to a lower
percentage.
(Continued)
Pumping Apparatus
Driver/Operator
15–27
Foam Proportioning
• The selection of a proportioner depends on
the foam solution, foam requirements,
available water pressure, cost, intended use,
and the agent to be used.
(Continued)
Pumping Apparatus
Driver/Operator
15–28
Foam Proportioning
• Proportioners and delivery devices are
engineered to work together. Using a foam
proportioner that is not compatible with the
delivery device can result in unsatisfactory
foam or no foam at all.
Pumping Apparatus
Driver/Operator
15–29
Methods by Which Foam
May be Proportioned
• Induction
• Injection
• Batch mixing
• Premixing
Pumping Apparatus
Driver/Operator
15–30
Induction
• Uses the pressure energy in the stream of
water to induct (draft) foam concentrate into
the fire stream
• Is achieved by passing the stream of water
through a venturi device called an eductor
Examples: In-line eductors and foam nozzle
eductors
(Continued)
Pumping Apparatus
Driver/Operator
15–31
Induction
Pumping Apparatus
Driver/Operator
15–32
Injection
• Uses an external pump or head pressure to
force foam concentrate into the fire stream at
the correct ratio in comparison to the flow
Pumping Apparatus
Driver/Operator
15–33
Batch Mixing
• Is the simplest method of mixing foam
concentrate and water
• Occurs when an appropriate amount of foam
concentrate is poured into a tank of water
• Is commonly used to mix foam within a fire
apparatus water tank or a portable water tank
(Continued)
Pumping Apparatus
Driver/Operator
15–34
Batch Mixing
• Is common with Class A foam but should only
be used as last resort with Class B foam
• May not be effective on large incidents
– When the tank becomes empty, the foam attack
lines must be shut down until the tank is filled with
water and more concentrate is added
• Requires that the pump and associated
piping must be thoroughly flushed after use
Pumping Apparatus
Driver/Operator
15–35
How Foam is Stored
• Foam concentrate is stored in a variety of
containers, depending on the procedural
manner in which the foam is generated and
delivered. The four common foam
concentrate storage methods include pails,
barrels, 275 gallon (1 100 L) tote tanks, and
apparatus tanks.
Pumping Apparatus
Driver/Operator
15–36
Pails
• Are usually 5-gallon (20 L), made of plastic
• Are perhaps the most common containers
used by the muncipal fire service to receive
and store foam concentrate
• Are durable and are not affected by the
corrosive nature of foam concentrates
(Continued)
Pumping Apparatus
Driver/Operator
15–37
Pails
• May be carried on the
apparatus in
compartments, on the
side of the apparatus, or
in topside storage areas
• May be airtight to prevent
a skin from forming on
the surface
Pumping Apparatus
Driver/Operator
15–38
Barrels
• Are used for larger quantities of concentrate
• Are usually 55-gallon (220 L) plastic or
plastic-lined barrels or drums
• Are most common in industrial applications
(Continued)
Pumping Apparatus
Driver/Operator
15–39
Barrels
• May be carried
directly to the
emergency scene or
may need to be
transferred to pails
or apparatus tanks
for transport to the
point of application
Pumping Apparatus
Driver/Operator
15–40
Totes
• Are 275-gallon (1 100 L) containers used for
bulk storage of foam concentrate
• Are used for large quantities of foam, such as
in aircraft rescue and fire fighting (ARFF),
industrial, or wildland firefighting applications
Pumping Apparatus
Driver/Operator
15–41
Apparatus Tanks
• Are found on municipal and industrial
pumpers, foam tenders, and ARFF apparatus
• Eliminate the need to use separate pails or
barrels
(Continued)
Pumping Apparatus
Driver/Operator
15–42
Apparatus Tanks
• Vary in type, location, and design
– Smaller foam tanks are located directly
above the fire pump area.
– Newer designs incorporate foam tanks as
an integral cell within the water tank
– Some apparatus have an additional pump
and connection nearer ground level for
refilling the concentrate tank.
(Continued)
Pumping Apparatus
Driver/Operator
15–43
Apparatus Tanks
• Vary in type, location, and design
– Large foam concentrate tanks may be
directly adjacent to the water tank.
– Foam tenders and some industrial foam
pumpers have a large tank that contains
foam concentrate and no water tank.
(Continued)
Pumping Apparatus
Driver/Operator
15–44
Apparatus Tanks
• Must be airtight
• Should have a pressure vacuum vent
• Range from 20 to 200 gallons (80 L to 800 L)
• May carry 8,000 gallons (32 000 L) or more of
concentrate
Pumping Apparatus
Driver/Operator
15–45
Class A Foam
• Is intended for use on Class A fuels
• Is effective for fires in structures, wildland
settings, coal mines, tire storage, and other
incidents involving deep-seated fuels
WARNING! Use Class A foam only on Class
A fuels. It is not specifically formulated for
fighting Class B fuels.
(Continued)
Pumping Apparatus
Driver/Operator
15–46
Class A Foam
• Is the formulation of hydrocarbon surfactants
that reduce the surface tension of the water in
the foam solution. Reducing the surface
tension provides better penetration of the
water, thereby increasing its effectiveness.
(Continued)
Pumping Apparatus
Driver/Operator
15–47
Class A Foam
• May be used with fog nozzles, aerating foam
nozzles, medium- and high-expansion
devices, and compressed-air foam systems
using almost any nozzle
• Has a shelf life of as much as 20 years if
properly stored
(Continued)
Pumping Apparatus
Driver/Operator
15–48
Class A Foam
• Is used in such small percentages in solution
that harm to the environment is not usually a
concern; however, there is some evidence
that the concentrate may slightly affect
aquatic life, so direct application into bodies
of water is not recommended
(Continued)
Pumping Apparatus
Driver/Operator
15–49
Class A Foam
• Has corrosive and supercleaning
characteristics, so direct skin contact should
be avoided. Properly flushing application
equipment after use is also recommended
Pumping Apparatus
Driver/Operator
15–50
Proportioning Class A Foams
• Some Class A foam concentrates are mixed
in proportions of 0.1% to 1.0%. As the
expansion ratios are increased, the
expansion and drainage characteristics of the
foam change.
(Continued)
Pumping Apparatus
Driver/Operator
15–51
Proportioning Class A Foams
• Most foam nozzles produce more stable
foams at 1.0% concentration than at 0.4% or
0.5% concentrations.
• Using percentages greater than 0.5% with
standard fog nozzles does not appear to
increase fire fighting performance.
Pumping Apparatus
Driver/Operator
15–52
Performing Various
Applications with Class A Foams
• Fire attack and overhaul with standard fog
nozzles
– 0.2% to 0.5% foam concentrate
• Exposure protection with standard fog
nozzles
– 0.5% to 1.0% foam concentrate
(Continued)
Pumping Apparatus
Driver/Operator
15–53
Performing Various
Applications with Class A Foams
• Any application with air aspirating foam
nozzles
– 0.3% to 0.7% foam concentrate
• Any application with compressed air foam
systems
– 0.2% to 0.5% foam concentrate
Pumping Apparatus
Driver/Operator
15–54
Application of Class A Foam
• Areas requiring maximum penetration
– Wet foam is very fluid and is desirable for
these areas.
• Vertical surfaces
– Dry foam is a rigid coat that adheres well.
Its slow drainage rate allows it to cling to
surfaces for extended periods.
(Continued)
Pumping Apparatus
Driver/Operator
15–55
Application of Class A Foam
• Areas requiring a balance of penetration and
clinging ability
– Medium foam has the ability to blanket and
wet the fuel equally well.
Pumping Apparatus
Driver/Operator
15–56
Class B Foam
• Is used to extinguish fires involving
flammable and combustible liquids
• Is used to suppress vapors from unignited
spills of flammable and combustible liquids
• May be applied either with standard fog
nozzles or with air-aspirating foam nozzles
(Continued)
Pumping Apparatus
Driver/Operator
15–57
Class B Foam
• May be proportioned into the fire stream via
apparatus-mounted or portable foam
proportioning equipment
• Is manufactured from either a synthetic or
protein base
(Continued)
Pumping Apparatus
Driver/Operator
15–58
Class B Foam
• Protein-based foams
– Are derived from animal protein
– Have a shelf life of about 10 years
– Are generally safer for the environment
• Synthetic-based foams
– Are made from fluorosurfactants
– Have a shelf life of 20 to 25 years
Pumping Apparatus
Driver/Operator
15–59
Proportioning Class B Foam
• Today’s Class B foams are mixed in
proportions from 1% to 6%.
• Some multipurpose foams designed for use
on both hydrocarbon and polar solvent fuels
can be used at different concentrations,
depending on which of the two fuels they are
used on.
(Continued)
Pumping Apparatus
Driver/Operator
15–60
Proportioning Class B Foam
• Older polar solvent mechanical foam
concentrates were designed to be used at
concentrations of 6% or greater. These
concentrates are not commonly found in use
today.
Pumping Apparatus
Driver/Operator
15–61
Foam Expansion
• The increase in volume of foam solution
when aerated
• The method of aerating results in varying
degrees of expansion, which depends on:
– Type of foam concentrate used
– Accurate proportioning of the foam concentrate in
the solution
– Quality of the foam concentrate
– Method of aspiration
Pumping Apparatus
Driver/Operator
15–62
Rate of Application
for Class B Foam
• Depends on
– Type of foam concentrate used
– Whether or not the fuel is on fire
– Type of fuel (hydrocarbon/polar solvent)
involved
– Whether the fuel is spilled or in a tank; if
the fuel is in a tank, the type of tank will
have a bearing on the application rate.
(Continued)
Pumping Apparatus
Driver/Operator
15–63
Rate of Application
for Class B Foam
• Hydrocarbon fuel spill fires (nondiked)
using portable extinguishing equipment
– Protein and fluoroprotein foams —
0.16 gpm/ft2 (6.5 [L/min]/m2) for 15 minutes
– ARFF and FFFP — 0.10 gpm/ft2
(4.1 [L/min]/m2) for 15 minutes
(Continued)
Pumping Apparatus
Driver/Operator
15–64
Rate of Application
for Class B Foam
• Polar solvent fuel spill fires (nondiked)
using portable extinguishing equipment
– Between 0.10 and 0.20 gpm/ft2
(4.1 [L/min]/m2 and 8.2 [L/min]/m2),
depending on the manufacturer’s UL listing
(Continued)
Pumping Apparatus
Driver/Operator
15–65
Rate of Application
for Class B Foam
• Hydrocarbon fuel fires in fixed roof storage
tanks using portable extinguishing equipment
– 0.16 gpm/ft2 (6.5 [L/min]/m2)
Pumping Apparatus
Driver/Operator
15–66
Determining the Application
Rate from a Nozzle
• Divide nozzle flow rate
by area of the fire
– A 250 gpm [1 000
L/min] nozzle on a
1,000-square-foot
(100 m2) fire equals a
rate of 0.25 gpm per
square foot
(10 [L/min]/m2)
Pumping Apparatus
Driver/Operator
15–67
Regular Protein Foams
• Are derived from naturally occurring sources
of protein such as hoof, horn, or feather meal
• Have good heat stability and resist burnback
• Are not as mobile or fluid on the fuel surface
as are other types of low-expansion foams
(Continued)
Pumping Apparatus
Driver/Operator
15–68
Regular Protein Foams
• Degrade faster in storage than do synthetic
foams
• Are rarely used in the fire service today
Pumping Apparatus
Driver/Operator
15–69
Fluoroprotein Foam
• Is derived from protein foam concentrates to
which fluorochemical surfactants are added
• Flows more easily than regular protein foam
(Continued)
Pumping Apparatus
Driver/Operator
15–70
Fluoroprotein Foam
• Provides a strong “security blanket” for longterm vapor suppression
• Can be formulated to be alcohol resistant by
adding ammonia salts; this foam maintains its
alcohol-resistive property for about 15
minutes
Pumping Apparatus
Driver/Operator
15–71
Film Forming
Fluoroprotein Foam (FFFP)
• Is based on fluoroprotein foam technology
with aqueous film forming foam (AFFF)
capabilities
• Incorporates AFFF benefits for fast fire
knockdown with the benefits of fluoroprotein
foam for long-lasting heat resistance
• Is available in an alcohol-resistant formulation
Pumping Apparatus
Driver/Operator
15–72
Aqueous Film
Forming Foam (AFFF)
• Is the most commonly used foam today
• Is completely synthetic
• Consists of fluorochemical and hydrocarbon
surfactants combined with high boiling point
solvents and water
(Continued)
Pumping Apparatus
Driver/Operator
15–73
Aqueous Film
Forming Foam (AFFF)
• When applied to a hydrocarbon fire, three
things occur:
– An air/vapor-excluding film is released
ahead of the foam blanket.
– The fast-moving foam blanket then moves
across the surface and around objects,
adding further insulation.
(Continued)
Pumping Apparatus
Driver/Operator
15–74
Aqueous Film
Forming Foam (AFFF)
• When applied to a hydrocarbon fire, three things
occur:
– As the aerated (7:1 to 20:1) foam blanket continues to
drain water, more film is released, giving AFFF the ability
to “heal” over areas where the foam blanket is disturbed.
Pumping Apparatus
Driver/Operator
15–75
Alcohol-Resistant AFFF
• Are usually used at 3% or 6% on polar
solvents and 1% or 3% on hydrocarbons
– Those used at 3% on hydrocarbons and 6% on
polar solvents are called 3 by 6 concentrates.
– Those used at 3% on both types of fuels are
called 3 by 3 concentrates.
– Those used at 1% on hydrocarbons and 3% on
polar solvents are called 1 by 3 concentrates.
(Continued)
Pumping Apparatus
Driver/Operator
15–76
Alcohol-Resistant AFFF
• Create a membrane over polar solvent fuels,
rather than a film; this separates the water in
the foam blanket from attack of the solvent
• Should be applied gently so that the
membrane can form first
• Should not be plunged into the fuel, but
sprayed over the top
Pumping Apparatus
Driver/Operator
15–77
High-Expansion Foams
• Are special-purpose foams
• Have a detergent base
• Have a low water content, which minimizes
water damage
(Continued)
Pumping Apparatus
Driver/Operator
15–78
High-Expansion Foams
• Have three basic applications:
– In concealed spaces such as basements,
coal mines, and other subterranean spaces
– In fixed-extinguishing systems for specific
industrial uses (rolled or bulk paper storage)
– In Class A fire applications
(Continued)
Pumping Apparatus
Driver/Operator
15–79
High-Expansion Foams
• Have expansion ratios of 200:1 to 1,000:1 for
high-expansion uses and 20:1 to 200:1 for
medium-expansion uses
Pumping Apparatus
Driver/Operator
15–80
Foam Proportioning Devices
• Although the process of foam proportioning
sounds simple, failure to operate even the
best foam proportioning equipment as
designed can result in poor quality foam or no
foam at all.
(Continued)
Pumping Apparatus
Driver/Operator
15–81
Foam Proportioning Devices
• In general, foam proportioning devices
operate by one of two basic principles:
– The pressure of the water stream flowing through
a restricted orifice creates a venturi action that
inducts (drafts) foam concentrate into the water
stream.
– Pressurized proportioning devices inject foam
concentrate into the water stream at a desired
ratio and at a higher pressure than that of the
water.
Pumping Apparatus
Driver/Operator
15–82
In-Line Foam Eductors
• Are the most basic type of foam proportioner
• Are designed to be either directly attached to
the pump panel discharge or connected at
some point in the hose lay
(Continued)
Pumping Apparatus
Driver/Operator
15–83
In-Line Foam Eductors
• Must follow manufacturer's instructions about
inlet pressure and the maximum hose lay
between the eductor and the appropriate
nozzle
• Use the Venturi Principle to draft foam
concentrate into the water stream
Pumping Apparatus
Driver/Operator
15–84
Venturi Principle
• As water at high-pressure passes through a
restriction, it creates a low-pressure area within
the eductor.
• The low-pressure area creates a suction effect
(called the Venturi Principle).
• The educator pickup tube is connected to the
eductor at this low-pressure point.
(Continued)
Pumping Apparatus
Driver/Operator
15–85
Venturi Principle
• Atmospheric
pressure forces
foam concentrate
into a pickup tube
and into the water
stream, creating a
foam/water solution.
Pumping Apparatus
Driver/Operator
15–86
Operating Rules to Observe
When Using Eductors
• The eductor must control the flow through the
system.
• The pressure at the outlet of the eductor must
not exceed 65 to 70 percent of the eductor
inlet pressure.
(Continued)
Pumping Apparatus
Driver/Operator
15–87
Operating Rules to Observe
When Using Eductors
• Foam solution concentration
is only correct at the rated
inlet pressure of the
eductor, usually 150 to 200
psi (1 050 kPa to 1 400
kPa).
• Eductors must be properly
maintained and flushed after
each use.
Pumping Apparatus
Driver/Operator
15–88
(Continued)
Operating Rules to Observe
When Using Eductors
• Metering valves must be
set to match foam
concentrate percentage
and the burning fuel.
• The foam concentrate
inlet to the eductor
should not be more than
6 feet (2 m) above the
liquid surface of the
foam concentrate
Pumping Apparatus
Driver/Operator
15–89
(Continued)
Operating Rules to Observe
When Using Eductors
• For nozzle and eductor to operate properly,
both must have the same gpm (L/min) rating.
• The eductor, not the nozzle, controls the flow.
• If the nozzle has a lower flow rating than the
eductor, the eductor will not flow enough
water to pick up concentrate.
• Using a nozzle with a higher rating than the
eductor also gives poor results.
Pumping Apparatus
Driver/Operator
15–90
Foam Nozzle Eductors
• Operate on the same principle as the in-line
eductor, but the eductor is built into the
nozzle rather than into the hoseline
• Require the foam concentrate to be available
where the nozzle is operated; if the foam
nozzle is moved, the foam concentrate also
needs to be moved
(Continued)
Pumping Apparatus
Driver/Operator
15–91
Foam Nozzle Eductors
• Compromise firefighter safety; firefighters
cannot move quickly, and they must leave
their concentrate behind if they are required
to back out for any reason
Pumping Apparatus
Driver/Operator
15–92
Self-Educting Master
Stream Foam Nozzles
• Are used where flows in excess of 350 gpm
(1 400 L/min) are required
• Are available with flow capabilities of up to
14,000 gpm (56 000 L/min)
• Use a modified venturi design to draw foam
concentrate into the water stream
(Continued)
Pumping Apparatus
Driver/Operator
15–93
Self-Educting Master
Stream Foam Nozzles
• Advantage — A much lower pressure drop
(10% or less) than typically associated with
standard foam nozzle eductors, allowing for
greater stream reach capabilities
• May use a jet ratio controller (JRC) to supply
foam concentrate to a self-educting master
stream nozzle
Pumping Apparatus
Driver/Operator
15–94
Jet Ratio Controller (JRC)
• A type of in-line eductor that allows the foam
concentrate supply to be as far away as
3,000 feet (900 m) from the self-educting
master stream foam nozzle
• Allows an elevation change of up to 50 feet
(15 m).
(Continued)
Pumping Apparatus
Driver/Operator
15–95
Jet Ratio Controller (JRC)
• Is supplied by a hoseline from the same fire
pump that is supplying other hoses to the
nozzle
• Flow of water to it represents about 2½
percent of the total flow in the system
(Continued)
Pumping Apparatus
Driver/Operator
15–96
Jet Ratio Controller (JRC)
• As with a standard in-line eductor, as water
flows through the JRC, a venturi draws
concentrate through the pickup tube and into
the hoseline. The difference is that the JRC
proportions the concentrate at a 66½ percent
solution.
(Continued)
Pumping Apparatus
Driver/Operator
15–97
Jet Ratio Controller (JRC)
• This rich solution is then pumped to a selfeducting master stream foam nozzle where it
is further proportioned with the water supplied
by the fire pump down to a discharge
proportion of 3%. To achieve a proper
proportion, it is important that the JRC and
nozzle match.
Pumping Apparatus
Driver/Operator
15–98
Installed In-Line Eductor Systems
• Use the same principles of operation as do
portable in-line eductors, but are attached to
the apparatus pumping system
• Should follow the same precautions as
portable in-line eductors regarding hose
lengths, matching nozzle and eductor flows,
and inlet pressures
(Continued)
Pumping Apparatus
Driver/Operator
15–99
Installed In-Line Eductor Systems
• Have foam concentrate supplied from either
pickup tubes inserted into 5 gallon (20 L)
pails or from foam concentrate tanks installed
on the apparatus
• Include a special version called a bypass
proportioner that is used to reduce the friction
loss across the eductor
(Continued)
Pumping Apparatus
Driver/Operator
15–100
Installed In-Line Eductor Systems
• Are most commonly used to proportion Class
B foams
Pumping Apparatus
Driver/Operator
15–101
Around-the-Pump Proportioners
• Are one of the most common types of built-in
proportioners installed in mobile fire
apparatus today
(Continued)
Pumping Apparatus
Driver/Operator
15–102
Around-the-Pump Proportioners
• Consist of a small return (bypass) water line
connected from the discharge side of the
pump back into the intake side of the pump
• Are rated for a specific flow and should be
used at this rate
Pumping Apparatus
Driver/Operator
15–103
Disadvantages of Around-thePump Proportioners
• The pump cannot take advantage of incoming
pressure. If the inlet water supply is any
greater than 10 psi (70 kPa), the foam
concentrate will not enter the pump intake.
Some newer units are capable of handling
intake pressures of up to 40 psi (280 kPa).
(Continued)
Pumping Apparatus
Driver/Operator
15–104
Disadvantages of Around-thePump Proportioners
• The pump must be dedicated solely to foam
operation. An around-the-pump proportioner
does not allow plain water and foam to
discharge from the pump at the same time.
(Continued)
Pumping Apparatus
Driver/Operator
15–105
Disadvantages of Around-thePump Proportioners
• When lines are shut down, water can still
circulate through the eductor adding more
concentrate than needed. To avoid this, the
bypass valve should be closed when no
water is flowing.
Pumping Apparatus
Driver/Operator
15–106
Bypass-Type Balanced
Pressure Proportioners
• Are one of the most accurate methods of
foam proportioning
• Are most commonly used in large-scale
mobile apparatus applications such as airport
crash vehicles and refinery fire fighting
apparatus
(Continued)
Pumping Apparatus
Driver/Operator
15–107
Bypass-Type Balanced
Pressure Proportioners
(Continued)
Pumping Apparatus
Driver/Operator
15–108
Bypass-Type Balanced
Pressure Proportioners
• Advantages
– Its ability to monitor the demand for foam
concentrate and to adjust the amount of
concentrate supplied.
– Its ability to discharge foam from some
outlets and plain water from others at the
same time.
(Continued)
Pumping Apparatus
Driver/Operator
15–109
Bypass-Type Balanced
Pressure Proportioners
• Apparatus equipped with these proportioners
have a foam concentrate line connected to
each fire pump discharge outlet.
• This line is supplied by a foam concentrate
pump separate from the main fire pump.
(Continued)
Pumping Apparatus
Driver/Operator
15–110
Bypass-Type Balanced
Pressure Proportioners
• The foam concentrate pump draws the
concentrate from an onboard tank.
• This pump is designed to supply foam
concentrate to the outlet at the same
pressure at which the fire pump is supplying
water to that discharge.
(Continued)
Pumping Apparatus
Driver/Operator
15–111
Bypass-Type Balanced
Pressure Proportioners
• The pump discharge and the foam
concentrate pressure from the foam
concentrate pump are jointly monitored by a
hydraulic pressure control valve that ensures
the concentrate pressure and water pressure
are balanced.
(Continued)
Pumping Apparatus
Driver/Operator
15–112
Bypass-Type Balanced
Pressure Proportioners
• The orifice of the foam concentrate line is
adjustable at the point where it connects to
the discharge line.
• If 3% foam is used, the orifice is set to 3% of
the total size of the water discharge outlet.
• If 6% foam is used, the orifice is set to 6% of
the total size of the water discharge outlet.
(Continued)
Pumping Apparatus
Driver/Operator
15–113
Bypass-Type Balanced
Pressure Proportioners
• Limitations
– Its need for a foam pump with PTO or
other power source
– Bypass of concentrate in this system can
cause heating, turbulence, and foam
concentrate aeration
Pumping Apparatus
Driver/Operator
15–114
Variable-Flow Variable-Rate
Direct Injection Systems
• Operate off power supplied from the
apparatus electrical system
• Are controlled by monitoring the water flow
and controlling the speed of a positive
displacement foam concentrate pump, thus
injecting concentrate at the desired ratio
(Continued)
Pumping Apparatus
Driver/Operator
15–115
Variable-Flow Variable-Rate
Direct Injection Systems
• Allow full flow through the fire pump
discharges because there are no flowrestricting passages in the proportioning
system
• Provide foam concentrate rates from 0.1% to
3%
(Continued)
Pumping Apparatus
Driver/Operator
15–116
Variable-Flow Variable-Rate
Direct Injection Systems
• Have a control unit with a digital display that
shows the current water or foam solution flow
rate, the total amount of water or solution
flowed to this time, the current foam
concentrate flow rate, and the amount of
foam concentrate used to this time
(Continued)
Pumping Apparatus
Driver/Operator
15–117
Variable-Flow Variable-Rate
Direct Injection Systems
• Can be used with all Class A foam
concentrates and many Class B concentrates
• CANNOT be used with alcohol-resistant foam
concentrates
Pumping Apparatus
Driver/Operator
15–118
Advantages of Variable-Flow VariableRate Direct Injection Systems
• Their ability to proportion at any flow rate or
pressure within the design limits of the
system
• The system automatically adjusts to changes
in water flow when nozzles are either opened
or closed
(Continued)
Pumping Apparatus
Driver/Operator
15–119
Advantages of Variable-Flow VariableRate Direct Injection Systems
• Nozzles may be either above or below the
pump, without affecting the foam
proportioning
• May be used with high-energy foam systems
Pumping Apparatus
Driver/Operator
15–120
Disadvantage of Variable-Flow
Variable-Rate Direct Injection Systems
• The foam injection point must be within the
piping before any manifolds or distribution to
multiple fire pump discharges. This means
that if foam solution is flowing through one
pump discharge, only foam solution can be
flowed through any other discharge that is
plumbed to that discharge manifold.
Pumping Apparatus
Driver/Operator
15–121
Variable-Flow Demand-Type
Balanced Pressure Proportioners
• Are versatile systems
• Have a variable-speed mechanism, which is
either hydraulically or electrically controlled,
that drives a foam concentrate pump; the
pump supplies concentrate to a Venturi-type
proportioning device built into the water line
(Continued)
Pumping Apparatus
Driver/Operator
15–122
Variable-Flow Demand-Type
Balanced Pressure Proportioners
Pumping Apparatus
Driver/Operator
15–123
Advantages of Variable-Flow DemandType Balanced Pressure Proportioners
• The foam concentrate flow and pressure
match system demand
• No recirculation back to the foam
concentration tank
(Continued)
Pumping Apparatus
Driver/Operator
15–124
Advantages of Variable-Flow DemandType Balanced Pressure Proportioners
• System is maintained in a ready-to-pump
condition and requires no flushing after use
• Water and/or foam solution can be
discharged simultaneously from any
combination of outlets up to rated capacity
Pumping Apparatus
Driver/Operator
15–125
Limitation of Variable-Flow DemandType Balanced Pressure Proportioners
• The fire pump discharges have ratio
controllers, thus pressure drops across the
discharge are higher than those on standard
pumpers.
Pumping Apparatus
Driver/Operator
15–126
Batch-Mixing
• Is the simplest means of proportioning foam
• Is simply pouring an appropriate amount of
foam concentrate into a tank of water
(Continued)
Pumping Apparatus
Driver/Operator
15–127
Batch-Mixing
• Occurs when the driver/operator pours a
predetermined amount of foam concentrate
into the tank via the top fill opening at the time
foam is needed; the pump is operated
normally, and foam is discharged through any
hoseline that is opened
(Continued)
Pumping Apparatus
Driver/Operator
15–128
Batch-Mixing
• Means that the size of the water tank and the
proportioning percentage of the foam
concentrate dictate how much concentrate
must be poured into the water tank
• Is only used with regular AFFF (not alcoholresistant AFFF concentrates) and Class A
concentrates
(Continued)
Pumping Apparatus
Driver/Operator
15–129
Batch-Mixing
• Can be done at any time, anywhere, and with
any equipment, and eliminates the need for
costly foam proportioning equipment
(Continued)
Pumping Apparatus
Driver/Operator
15–130
Batch-Mixing
Note: Apparatus water tanks, pumps, and
associated piping should be thoroughly
flushed with fresh water after any pumping
operation in which a foaming agent was
batch-mixed in the vehicle’s water tank. The
flushing operation must be conducted
according to the MSDS supplied by the foam
manufacturer.
Pumping Apparatus
Driver/Operator
15–131
Disadvantages of Batch-Mixing
• Class A foam solutions do not retain their
foaming properties if mixed in the water for
more than 24 hours, and there may be further
degradation, depending on the product used
• Froth may form when the water tank is refilled
(Continued)
Pumping Apparatus
Driver/Operator
15–132
Disadvantages of Batch-Mixing
• Foam solutions are solvents, so they can
remove lubricants from ball valve seals
• All the water onboard the apparatus is
converted to foam solution
(Continued)
Pumping Apparatus
Driver/Operator
15–133
Disadvantages of Batch-Mixing
• Does not allow for continuous foam discharge
because the stream has to shut down while
the apparatus tank is refilled
• It is difficult to maintain the concentrate ratio
unless the water tank is completely emptied
each time
Pumping Apparatus
Driver/Operator
15–134
History of Compressed-Air
Foam Systems (CAFS)
• Instead of using air cylinders, as was popular
in the 1970s, the U.S. Bureau of Land
Management added a rotary air compressor
to a standard fire department pumper.
(Continued)
Pumping Apparatus
Driver/Operator
15–135
History of Compressed-Air
Foam Systems (CAFS)
• This system uses a standard centrifugal fire
pump to supply the water. Once the foam
concentrate and water are mixed to form a
foam solution, compressed air is added to the
mixture before it is discharged from the
apparatus and into the hoseline.
Pumping Apparatus
Driver/Operator
15–136
Advantages of CAFS
• A considerably longer fire stream than
streams from low-energy systems
• Produce uniformly sized, small air bubbles
that are very durable.
• The foam adheres to the fuel surface and
resists heat longer than low-energy foam.
(Continued)
Pumping Apparatus
Driver/Operator
15–137
Advantages of CAFS
• Hoselines containing high-energy foam
solution weigh less than hoselines containing
low-energy foam solution or plain water.
• A CAFS provides a safer fire suppression
action that allows effective attack on the fire
from a greater distance.
Pumping Apparatus
Driver/Operator
15–138
Disadvantages of CAFS
• A CAFS adds expense to a vehicle and adds
to the maintenance that must be performed
on the vehicle.
• Hose reaction can be erratic if foam solution
is not supplied to the hoseline in sufficient
quantities.
(Continued)
Pumping Apparatus
Driver/Operator
15–139
Disadvantages of CAFS
• The compressed air accentuates the hose
reaction in the event the hose ruptures.
• Additional training is required for personnel
who are expected to make a fire attack using
a CAFS or who will operate CAFS equipment.
Pumping Apparatus
Driver/Operator
15–140
Characteristics of CAFS
• Most apparatus equipped with a CAFS are
also designed to flow plain water should the
choice be made to do that.
• The fire pump used on a CAFS-equipped fire
vehicle is a standard centrifugal fire pump.
(Continued)
Pumping Apparatus
Driver/Operator
15–141
Characteristics of CAFS
• The foam proportioning system is a type of
automatic, discharge-side proportioning
system.
• Foam eductors are typically not used
because they are not designed to work at
either the 0.1% or 1% eduction rates or the
variable flow rates required for Class A
foams.
(Continued)
Pumping Apparatus
Driver/Operator
15–142
Characteristics of CAFS
• Variable-flow rate sensing proportioners are
necessary to ensure that foam concentrate is
supplied to the fire stream at the proper rate.
• In general, 2 cubic feet per minute (cfm)
(0.06 m3/min) of airflow per gallon minute of
foam solution flow produces a very dry foam
at flows of up to 100 gpm (400 L/min) of foam
solution.
(Continued)
Pumping Apparatus
Driver/Operator
15–143
Characteristics of CAFS
• Most structural and wildland fire attacks using
CAFS are done with an air flow rate of 0.5 to
10.5 cfm (0.015 m3/min to 0.03 m3/min).
CAUTION! To protect fire attack teams,
nozzle flow rates (gpm, L/min) should be the
same for Class A foam application as for plain
water.
Pumping Apparatus
Driver/Operator
15–144
Portable Foam
Application Devices
• While standard fire fighting nozzles can be
used for applying some types of lowexpansion foams, it is best to use nozzles
that produce the desired result (such as fastdraining or slow-draining foam).
Pumping Apparatus
Driver/Operator
15–145
Handline Nozzles
• Any nozzle that one to three firefighters can
safely handle and that flows less than 350
gpm (1 400 L/min)
• Smooth bore nozzles
• Fog nozzles
• Air-aspirating foam nozzles
Pumping Apparatus
Driver/Operator
15–146
Smooth Bore Nozzles
• Are limited to Class A, CAFS applications
• Provide an effective fire stream that has
maximum reach capabilties
• When using, disregard the standard rule that
the discharge orifice of the nozzle be no more
than one-half the diameter of the hose
Pumping Apparatus
Driver/Operator
15–147
Fog Nozzles
• Break the foam solution into tiny droplets and
use the agitation of water droplets moving
through air to achieve the foaming action
• Have expansion ratios between 2:1 and 4:1
(Continued)
Pumping Apparatus
Driver/Operator
15–148
Fog Nozzles
• Are best when used with regular AFFF and
Class A foams, but may be used with alcoholresistant AFFF foams on hydrocarbon fires
• Cannot be used with protein and fluoroprotein
foams and should not be used on polar
solvent fires
(Continued)
Pumping Apparatus
Driver/Operator
15–149
Fog Nozzles
• Some have foam aeration attachments that
can be added to the end of the nozzle to
increase aspiration of the foam solution
• Some have an adjustable sleeve that allows
them to convert to air-aspirating nozzles
Pumping Apparatus
Driver/Operator
15–150
Air-Aspirating Foam Nozzles
• Induct air into the foam solution by a venturi
action
• Are the only type of nozzles that can be used
with protein and fluoroprotein concentrates
(Continued)
Pumping Apparatus
Driver/Operator
15–151
Air-Aspirating Foam Nozzles
• May also be used with Class A foams in
wildland applications
• Provide maximum expansion of the agent
• Have less stream reach than that of a
standard fog nozzle
Pumping Apparatus
Driver/Operator
15–152
Master Stream Foam Nozzles
• Large-scale flammable
and combustible liquid
fires are beyond the
capabilities of
handlines. Master
stream nozzles are
required to deliver
adequate amounts of
foam in these
situations.
Pumping Apparatus
Driver/Operator
15–153
(Continued)
Master Stream Foam Nozzles
• Standard fixed-flow or automatic-fog master
stream nozzles may be used to deliver foam,
when necessary.
• Large-scale industrial foam apparatus and
AFFF vehicles may be equipped with special
aerating foam master stream nozzles.
Pumping Apparatus
Driver/Operator
15–154
Medium- and High-Expansion
Foam Generating Devices
• Produce a high-air-content, semistable foam
– Medium-expansion — Air content ranges from 20
parts air to 1 part foam solution (20:1) to 200 parts
air to 1 part foam solution (200:1)
– High-expansion — Ranges from 200:1 to 1,000:1
• Water-aspirating type
• Mechanical blower type
Pumping Apparatus
Driver/Operator
15–155
Water-Aspirating Type
• Is similar to other foam-producing nozzles
except that it is much larger and longer
• Has a back that is open to allow airflow
• Pumps foam solution through the nozzle in a
fine spray that mixes with air to form a
moderate-expansion foam
(Continued)
Pumping Apparatus
Driver/Operator
15–156
Water-Aspirating Type
• Has a screen on the
end that further breaks
up the air and mixes it
with water
• Typically produces a
lower-air-volume foam
than do mechanical
blower generators
Pumping Apparatus
Driver/Operator
15–157
Mechanical Blower Type
• Is similar in appearance to a smoke ejector
• Operates on the same principle as the wateraspirating nozzle except that the air is forced
through the foam spray by a powered fan
instead of being pulled through by water
movement
(Continued)
Pumping Apparatus
Driver/Operator
15–158
Mechanical Blower Type
• Produces foam with a high air content and is
typically associated with total-flooding
application
• Is limited in use to high-expansion foams
Pumping Apparatus
Driver/Operator
15–159
Reasons for Failure to Generate Foam
or for Generating Poor Quality Foam
• Failure to match eductor and nozzle flow,
resulting in no pickup of foam concentrate
• Air leaks at fittings that cause loss of suction
• Improper cleaning of proportioning equipment
that results in clogged foam passages
(Continued)
Pumping Apparatus
Driver/Operator
15–160
Reasons for Failure to Generate Foam
or for Generating Poor Quality Foam
• Partially closed nozzle that results in a higher
nozzle pressure
• Too long a hose lay on the discharge side of
the eductor
• Kinked hose
(Continued)
Pumping Apparatus
Driver/Operator
15–161
Reasons for Failure to Generate Foam
or for Generating Poor Quality Foam
• Nozzle too far above eductor (results in
excessive elevation pressure)
• Mixing different types of foam concentrates in
the same tank, which can result in a mixture
too viscous to pass through the eductor
Pumping Apparatus
Driver/Operator
15–162
Various Foam
Application Techniques
• Direct-application method
– Finished Class A foam in applied directly
onto the material that is burning.
(Continued)
Pumping Apparatus
Driver/Operator
15–163
Various Foam
Application Techniques
• Roll-on method
– Directs Class B foam stream on the ground
near the front edge of a burning liquid pool
or spill. The foam then rolls across the
surface of the fuel. Foam application
continues until it spreads across the entire
surface of the fuel and the fire is
extinguished or the vapors suppressed.
(Continued)
Pumping Apparatus
Driver/Operator
15–164
Various Foam
Application Techniques
• Roll-on method
(Continued)
Pumping Apparatus
Driver/Operator
15–165
Various Foam
Application Techniques
• Bank-down method
– Class B foam
stream is directed
onto a vertical
surface, allowing
foam to run down
onto and spread
across surface of
the fuel.
Pumping Apparatus
Driver/Operator
15–166
(Continued)
Various Foam
Application Techniques
• Rain-down method
– Directs stream of
Class B foam into
the air above fire
and allows foam
to gently rain
down onto
surface of fuel.
Pumping Apparatus
Driver/Operator
15–167
Environmental Impact of Class A and
Class B Foam Concentrates and Solutions
• The primary concern is the impact of finished
foam after it has been applied to a fire or spill.
• The biodegradability of these foams in either
solution or concentrate is determined by the
rate at which environmental bacteria dissolve
or degrade the foam.
(Continued)
Pumping Apparatus
Driver/Operator
15–168
Environmental Impact of Class A and
Class B Foam Concentrates and Solutions
• The decomposition of these foams results in
the consumption of oxygen. In waterways, a
reduction in oxygen can kill water-inhabiting
creatures and vegetation.
• Foam concentrates, solutions, or finished
foam should not be discharged into any body
of water.
Pumping Apparatus
Driver/Operator
15–169
Environmental Impact
of AFFF Concentrate
• Environmental issues revolve around glycol
ethers and perfluoroctylysulfonates (PFOS).
Foam manufacturers are trying to find
alternatives to these chemicals.
Pumping Apparatus
Driver/Operator
15–170
Durable Agents
• Are the term used for a number of different
water additives used as extinguishing agents
and for pretreating structures threatened by
fires spreading toward them
• Retain their fire retarding properties longer
than Class A foam
(Continued)
Pumping Apparatus
Driver/Operator
15–171
Durable Agents
• Are also known as gelling agents, fire
blocking gels, and aqueous fire fighting gels
• Are used in the same way as Class A foam,
but are chemically and structurally quite
different
(Continued)
Pumping Apparatus
Driver/Operator
15–172
Durable Agents
• Are different from Class A foam in that they:
– Are water-absorbent polymers rather than
hydrocarbon-based surfactants like Class A foams
– When mixed with water, form minute polymer
bubbles that are filled with water; Class A foams
form tiny water bubbles that are filled with air
– Are considerably more expensive
– Make surfaces to which applied very slippery
(Continued)
Pumping Apparatus
Driver/Operator
15–173
Durable Agents
• Are normally siphoned from a container with
an eductor, but in an emergency can be
batch-mixed in the apparatus water tank
• Can be used for fire extinguishment, line
construction, or structure protection
(Continued)
Pumping Apparatus
Driver/Operator
15–174
Durable Agents
• Can be applied through hoselines with any
standard fire nozzle, including master stream
appliances, or dropped by air tankers or
helicopters
• Are normally applied at a ratio of 1:100 or a
1 percent solution in water for fire
extinguishment
(Continued)
Pumping Apparatus
Driver/Operator
15–175
Durable Agents
• Are normally applied at 1½ to 2 percent for
line construction; at 2 or 3 percent for
structure protection
• Can be repeatedly rehydrated with a fine
water mist to extend their protection for
several days
Pumping Apparatus
Driver/Operator
15–176
Summary
• Advances in foam technologies combined
with a greater need for foam application have
increased the use of foaming agents by fire
departments throughout North America.
(Continued)
Pumping Apparatus
Driver/Operator
15–177
Summary
• Regardless of the type of foam system used
by a particular fire department, it is the
responsibility of the driver/operator to deliver
properly proportioned foam solution to the
nozzle or nozzles applying the foam.
(Continued)
Pumping Apparatus
Driver/Operator
15–178
Summary
• To fulfill this responsibility, driver/operators
must be familiar with the type of foam system
their department uses, along with its
capabilities and limitations.
(Continued)
Pumping Apparatus
Driver/Operator
15–179
Summary
• Driver/Operators must know how to introduce
foam into the system, maintain its flow for as
long as necessary, and troubleshoot any
problems that develop while the system is in
operation.
(Continued)
Pumping Apparatus
Driver/Operator
15–180
Summary
• In addition, the driver/operator must know
how to properly flush the system after use,
and maintain the foam system in a state of
constant readiness.
Pumping Apparatus
Driver/Operator
15–181
Discussion Questions
1. Why have foam and durable agents
increased in use in recent years?
2. Name the three ways in which foam
extinguishes and/or prevents fire.
3. What are the four basic methods by which
foam may be proportioned?
4. Name various ways in which foam is
stored.
(Continued)
Pumping Apparatus
Driver/Operator
15–182
Discussion Questions
5. Explain how to determine the application
rate available from a nozzle.
6. What are the three things that happen
when AFFF is applied to a hydrocarbon
fire?
7. What are the three basic applications of
high-expansion foams?
8. Describe some reasons for failure to
generate foam or for generating poor
quality foam.
Pumping Apparatus
Driver/Operator
15–183