LTT 300

LTT 300
Class A Foam
Awareness and Operations Level
Workbook and Glossary
Foam Concentrate
Air
Mechanical Agitation
Water
The Foam Tetrahedron
COURSE CURRICULUM CREATED BY: Rod Carringer
National Sales Manager for Task Force Tips, Inc.
26 Year member of Center Fire and Rescue, LaPorte, Indiana
This Page
Intentionally
Left Blank
Class A Foam Course Outline
Course Objectives
1) Explain the concept and chemistry of foam as an enhancement to fire suppression.
2) Identify the types of mechanical foams and explain benefits and limitations of each.
3) Define proportional and non-proportional concentrate injection systems, batch mixing,
eductors, and discharge side injection systems.
4) Understand operational characteristics using foam, critical application rates, and initial
attack strategies.
5) Understand operations and performance of fog/combination nozzles, low and medium
expansion foam tubes (Low Energy Foam Delivery Systems), and CAFS (High Energy
Foam Delivery Systems).
6) Present application techniques and strategies for structural and wildfire suppression
responsibilities.
7) Provide current research and reports on the use of Class A foaming agents for wildfire
and structural suppression.
Classroom Activities
1) Overview of surface activate agents (surfactants) in the fire environment. Class A and
Class B foaming agents.
2) Evaluation of mechanical foam generating systems and concentrate delivery systems.
3) Discuss operational techniques and strategies for successful applications.
4) Study of safety and environmental concerns when using foam agents.
5) Understanding of application rates and critical flow rates for Class A and Class B fuels.
6) Demonstrations and hands-on evaluations of systems and equipment used in
fireground applications.
Live Fire Demonstration Exercise (if appropriate)
In order to conduct any live fire or demonstration fire training exercise, a burn location should be
determined by the local agency having jurisdiction in advance and be in close proximity to the classroom
activities. For wildfire fuels, the location should be representative of the problems encountered by the local
agency. If an acquired structure or debris is to be burned, the agency having jurisdiction and the instructor
should inspect the site well in advance of the demonstration burn.
All fire training and demonstrations shall be in complete compliance with all applicable local, state, federal,
and jurisdiction policies. The NFPA standard 1403 for conducting live fire training exercises shall be
followed.
All participating members in either demonstration or live fire operations will wear complete NFPA
approved protective clothing, including, but not limited to, full bunker clothing (coat and pants), gloves,
boots, helmets, and hoods. Any attendee participating in live structural training shall be in
compliance with the local use of SCBA and be under the direction of Fire Ground Command.
The demonstration/training exercise will focus on the use of foaming agents on structural attack, exposure
protection, and application techniques and tactics for the range of foaming agents.
2
• Review of Course Content
• Course Objectives
• Classroom Activities...
Awareness and
Operations Level
Slides, Demonstrations, and
Video Presentations
Class A Foam
Applications
• Glossary of Common Terms
• Foam vs Fire, CAFS,
Proportioners
• Live Fire Exercise (Operations Level)
• Review of NFPA 1403
• Summary and Review
• Test
• Course Evaluation
Class A Foam Applications
Course Objectives
l The
Concept and Chemistry of Foams
l Proportional and Non-Proportional
Injection
l Low Energy Foam Delivery Systems
l High Energy Foam Delivery Systems
l Application Tactics and Strategies
l Current Research
• Explain the concept and chemistry
of foam for fire suppression.
• Define proportional and non-proportional injection systems, batch mixing,
eductors and the benefits and limitations of each.
• Understand the operations and performance of nozzles, aspirating nozzles
and foam tubes (Low Engery Systems).
• Understand the operations and performance of CAFS (High Energy Systems).
• Present tactical and strategic considerations of foam applications.
• Provide current research and reports on the use of Class A foam agents for
Forestry/Rural and Intermix responsibilities.
3
• Class A combustibles include wood,
Combustible Materials
paper, fabrics, and other deep-seated
fuels that leave an ember.
l Class
A: Woody, cellulose
materials
l Class B: Flammable Liquids
l Class C: Electrical
l Class D: Flammable Metals
• Class B flammable liquids include
both hydrocarbon and alcohol-based
fuels.
• Class C fires are Class A or Class B
fires with energized electricity
involved.
• Class D flammable metals like
magnesium and others require
specialty agents for effective
extinguishment.
• NOTE: Tires can be Class A until
they melt into a liquid state and
become Class B flammable liquid
hydrocarbon.
Fire Tetrahedron
•Fuel
•Oxygen
• The basic Fire Tetrahedron and how
it interacts.
•Heat
• Fuel, anything flammable that, when
•Chain Reaction
heated, will produce a vapor that will
burn when contacting a source of
ignition.
• Oxygen, necessary for combustion, will vary on enclosed fires, providing
different stages to a structure fire. Smoldering or free burning, it can also be
an indicator of life safety within a confined space.
• Heat, a source of ignition and the preheating of the fuels to provide vapors
that will ignite.
• Remove or modify any side of the tetrahedron and complete combustion will
cease to exist, including the interruption of the chemical chain reaction
(i.e. the use of Halons, Shock waves and Ion separation).
4
• Typically, initial structural attack
Methods of Fire
Extinguishment
concentrates on the removal of heat
with the application of water spray.
Primary
l Remove
Heat
Fuel
l Remove Oxygen
• Structurally, removal of fuel is not
l Remove
appropriate, but in wildfire
suppression removal of fuel in
advance of a fire is common. This is
known as indirect attack.
Secondary
l Interrupt
Chemical Chain
Reaction
• Removal of oxygen happens in the
later stages of the compartment-type
unvented fire, but is not practical for
initial attack, unless a door can be
closed on a room of involvement.
• Interruption of the chemical chain
reaction of fire is accomplished by
the use of shock waves, critical
vibrations or ion separation in some
combination. A good example is how
Halon works on a fire.
• Discuss the objectives of the awareness
The Concept of Foam
Applications
and operational level of foam applications.
• Understand the limitations of foam.
l The
Properties of Foam in the
Fire Environment
l Differences in Mechanical Foams
l The Reduction of the Surface
Tension of Water
l Class A Foam’s Role in Initial
Attack
Foam is not a good tool for three
dimensional Class B fires, or fires
involving pressurized flammable
liquids or gases. For Class B fires,
the use of chemical powder is best for
three dimensional fires and foam for
fires on pooled liquids.
• Provide an overview of the most commonly used mechanical foams.
• Offer discussion and present demonstrations of the reduction in the surface
tension of water and how this enhancement will relate to initial fireground
attack and suppression activities.
• Overview the main benefits of using not only Class B foam but Class A foam
for structural initial attack, pretreatment and exposure protection.
• As a water enhancement, Class A foam has many variables from a tactical
standpoint. Discussion will be provided to offer strategies and tactics to fit
most needs, whether structural or wildfire.
5
There are four separate qualities that make
a good foam blanket. Each must be in the
proper proportion to generate a quality
finished foam.
the Foam Tetrahedron
Foam Concentrate
Mechanical Agitation
Water as supplied by the pumper (or water
flow + pressure) is not only the transfer of
the water, but the supplier of the energy to
make a finished foam as well. The energy
that is put into the line in the form of flow
(gpm) and pressure (psi) is used at the nozzle
tip to help generate a finished foam. This is
true of “low” energy systems only.
Water
Air
The foam concentrate must be added into the water stream to create a foam solution. This
can be done in a number of ways. As simple as batch mixing in a tank to as complex as an
around-the-pump proportioning system. There are eductors, automatic discharge side injection
systems, suction side injectors, and balanced pressure systems. But, they all do one thing, mix
foam concentrate into the water in a controlled accurate manner. This finished foam solution
is used to make a final foam blanket.
Air, or some other inert gases, when made available for mixing, will provide one part of this
tetrahedron. The mechanical agitation that is created by the nozzle tips, foam attachments,
or foam tubes draws the air into the foam solution, and tumbles and mixes the solution with air.
The final outcome, if all items are added properly to the tetrahedron, is a finished foam of some
quality and quantity.
How a Foam Acts on a Fire
In some form, a foam blanket will do the
following:
Smothering - The use of a foam
blanket will provide an excellent
covering that can be used to surround
a fuel thereby breaking a side of the
tetrahedron. This smothering ability
will act to isolate the fuel from other
sides of the tetrahedron.
3Smothers
3Suppresses
3Separates
3Cools
Suppressing - Foams, especially Class A, are extremely effective at allowing
water to penetrate into the fuel upon which it is applied either absorbing heat
or generating a film.
Separates - A layer of foam in blanket form will accomplish several things. A
key factor of both Class A and B fuels is the ability to separate the fuel from the
air and heat. Again, this will break the tetrahedron.
Cools - Still 99% or more water, a foam blanket will have all the cooling
characteristics of plain water applications. In exposure protection the holding
benefits will be extended when using a foam blanket.
6
Protein has been used extensively since
WWII and its base composition is hydrolyzed
waste protein materials.
Types of Mechanical Foams
l Protein
l Syndet,
High Expansion
Film Forming Foam (AFFF)
l Fluoroprotein
l Film Forming Fluoroprotein (FFFP)
l Alcohol Resistant Concentrates
(ARC)
l Polar Solvents and HazMat Foams
l Syndet, Class A
Syndet, High Expansion is a combination
of synthetic foaming agents and stabilizers
used to provide vast quantities of finished
foam to fill cavities (i.e. coal mines, shipboard
and enclosed areas) and locations of potential
firefighter life safety. A drawback can be
lightness of the finished product.
l Aqueous
Aqueous Film Forming Foam is a combination of fluorochemical surfactants and synthetic
foaming agents that form a thin film layer for vapor suppression.
Fluoroprotein is a combination of fluorochemical surfactants and protein foam. It has
increased fluidity and better fuel tolerance.
Film Forming Fluoroprotein, a combination of fluorochemical surfactants and protein
that combines the burn-back resistance of protein with film forming capability.
ARC and Polar Solvent Foams consist of synthetic stabilizers, foaming agents, fluorochemicals, and alcohol resistant membrane forming additives that combine to provide the
most versatile foam available today. Individual HazMat foams are designed for specific
chemicals and their vapor suppression.
Syndet, Class A combines surfactants, stabilizers, and corrosion inhibitors to provide a
biodegradable, high bubble producing, concentrated product for Class A combustible products.
Protein Foam
PROS
l Long
Lasting
Heat Resistance
l Stable and Relatively Inexpensive
l Excellent
CONS
l Messy
and Poor Flowing
Knockdown and Low Fuel
Tolerance
l High Concentrations 3% and 6%
l Slow
• 3% or 6% concentration ratios.
• Effective on hydrocarbon fires, but ineffective on polar solvent (alcohol).
• Typical usable temp. is 20 degrees F. up to 120 degrees F. Cold protected foams will go as
low as -20 degrees F.
• Protein foams will produce a homogenous, stable foam blanket that has excellent burn-back
resistance.
• Protein foams have low knockdown, but relatively inexpensive post fire security.
• May be used with either fresh or saltwater.
• Mechanical aspiration is mandatory for application.
7
Syndet, High Expansion Foam
PROS
l Good
l Excellent
Wetting Capability
Bubble Producer for Filling
Cavities
CONS
l Low
Tactical Stability
l High Concentration Ratio 3% and
6%
• These foams are composed of synthetic
foaming agents and additional stabilizers.
• High expansion is designed to produce a
stable foam blanket and is resistant to
flammable product pickup.
• Some drawbacks include its high expansion
ratio and light weight. In unconfined
spaces, wind renders it useless.
• It is ideally suited for compartment-type fires and areas of concern for firefighter safety,
i.e. mine shafts, shipboard fires, and, as taught many years ago, for basement fires in
structural attack.
• Avoid the use of this type of application if there is any consideration the source of the fire
may be an electrical problem. The foam is still 94% to 97% water.
• Some Hazmat foams fall into this category.
Film Forming Process
• Finished Foam
• Flammable Vapors
• Film
• As a finished foam covers and works to smother the fire, the unique film-forming ability
works to provide a thin layer of solution that prevents vaporization of the flammable liquid.
• The surfactants and films are stored in the shell of the bubble.
When the bubble breaks,
the solution drains out to become this layer.
• An increase in 1/4 drain time means a slowing of the amount of solution draining out of the
finished bubble blanket.
• The finished foam also works to exclude air from the flammable vapors, separate the flames
from the fuel surface, and cool the fuel surface and surrounding metal surfaces.
8
• A combination of fluorochemical surfactants
Aqueous Film Forming Foam
(AFFF)
and synthetic foaming agents create a
unique characteristic, an aqueous film.
PROS
l Low
Surface Tension (16 dynes cm/2)
Spreads Across Surface
l High Burn Back Resistance / Quick
Knockdown
• The thin layer spreads rapidly across the
l Rapidly
surface blocking flammable vapors.
• Most effective on hydrocarbon fuels with
CONS
l High
Concentration Ratio (3%, 6%)
l High Cost (Flourine)
l Does Not Biodegrade
higher surface tensions such as kerosene,
diesel and jet fuels and less effective on
fuels with lower surface tensions like
hexane and gasolines.
• Concentration ratios of 1, 3, 6% are common and must be understood when mixing or
using an eductor.
• 1% = 1 gal. + 99 gal. of water to make 100 gal. 1% solution.
• 3% = 3 gal. + 97 gal. of water to make 100 gal. 3% solution.
• 6% = 6 gal. + 94 gal. of water to make 100 gal. 6% solution.
• The reason for not training more often with department application equipment is usually
cost, but the fact that it doesn’t biodegrade is becoming more and more important as
departments are legally being held responsible for the products they put on the ground.
• FP
Fluoroprotein foams are a combination
of protein foam and the addition of special
fluorochemical surfactants to provide
increased fluidity to the concentrate and
increases the foam’s ability to produce
faster knockdowns and improved fuel
tolerances.
Fluoroprotein Foams (FP,
FFFP)
l Fluoroprotein Foam (FP)
l Fluorochemical
Surfactants + Protein
l Increased Concentrate Fluidity
l Faster Knockdown
l Film
Forming Fluoroprotein
Foam (FFFP)
• FFFP
Film Forming Fluoroprotein foams
have all of the properties of fluoroprotein
and also provide the vapor suppression
characteristics of an aqueous film.
l Fluoroprotein
+ Aqueous Film
Forming
9
Alcohol Resistant AFF Foams
l Extremely
Versatile 3X3 % and
3X6 %
l Excellent Burn-back Resistance
l Fast Knockdown
l Excellent Fuel Tolerance on both
Hydrocarbon and Alcohol Based
Fires
• Alcohol Resistant Concentrates (ARC) and
AFFF-AR all are terms for a foam that
combines synthetic stabilizers, foaming
agents, fluorochemicals, and alcohol
resistant membrane forming additives.
• Since polar solvents and
alcohols are
destructive to non-alcohol resistant foams,
an ARC foam must be used for vapor
suppression and extinguishment. The
alcohol aggressively mixes with the water
in the foam bubble, destroying it.
• Typically, these foams will have a dual percent rate, i.e. 3X3% or 3X6%.
The lower ratio is
used on a standard hydrocarbon based fire and the higher ratio is used for the alcohol
based fire.
• The film formed when alcohol is present is a tough polymeric membrane, occasionally
called mucouloid, which separates the alcohol from the foam blanket.
• The higher the alcoholic level of the fuel the better the creation of the membrane.
• When a polar solvent foam is used, and the polymeric membrane has been created for
suppression, care must be taken to not disturb the foam blanket in any way. This type of
foam, unlike most AFFF concentrates, does not heal itself when disturbed. If the foam
blanket is somehow broken, a reapplication will be necessary.
Fuel and Heat Tolerance of
Finished Foams
Fuel Tolerance
The ability of the finished foam bubble
to shed the fuel it is applied to.
Heat Tolerance
The ability of the finished foam bubble
to withstand radiant and direct flame
impingement without degradation.
When a foam blanket is applied to a fuel
spill, either burning or as a vapor
suppression operation, fuel tolerance is a big
concern. It is the foam blanket's job to
prevent vaporization. Foams that have very
low fuel tolerance will pick up the fuel and
carry it on the outer shell of the bubble
structure. This will allow for little or no
vapor or fire suppression.
When the finished foam is plunged into the
fuel, its ability to drop off or shed the fuel as
it rises to the surface is a key factor in the
suppression effort. This is how sub-surface injection systems work. Expanded foam is
injected under pressure into the bottom of a storage tank, rises to the surface, and covers
the top providing suppression. The choice of foams is based on fuel tolerance of the
Another term that is used is HEAT TOLERANCE. This refers to a finished foam’s ability to
resist and not degrade when placed in contact with either direct flame impingement or
radiant heat. The finished foam blanket must be of a slow draining nature to hold up to
high temperatures. The more rigid and stable the finished foam blanket, the better its heat
resistance. This is important for all foams. Flammable liquids spills and fires being attacked
with Class B foams, and pretreatment of exposures with Class A foams both need the
blanket for resistance to the high radiant heat or direct flame impingement.
10
These rates come from NFPA 11 for spill
fires of shallow depth. More application rate
will reduce suppression time, but too little
application rate and the potential for the
fire not to go out is possible.
Class B Flammable Liquids
lHydrocarbon
Fire
l 0.1 GPM of Foam Solution Per
Square Foot of Burning Liquid for a
Minimum of 15 Minutes
lPolar
Solvent Fire
(Alcohol Base)
l 0.2
GPM of Foam Solution Per Square
Foot of Burning Liquid for a
Minimum of 15 Minutes
Remember, your limits of application rate
(i.e. a 95 gpm eductor will limit your
application to only 95 gpm of solution).
Hydrocarbon fires require 0.1gpm per sq ft of burning liquid for a minimum of 15 minutes.
EXAMPLE 2000 square feet of gasoline
.1 x 2000 sq. ft. = 200 gpm of solution (not expanded foam)
.03 x 200 gpm = 6 gallons of 3% foam concentrate per minute
6 gal. x 15 minutes = 90 gallons of 3% concentrate to control, extinguish,
and initially secure 2000 sq. ft. of hydrocarbons burning.
Polar Solvent fires require 0.2 gpm per sq ft of burning liquid for a minimum of 15 minutes.
EXAMPLE 1000 square feet of alcohol based fire
.2 x 1000 sq. ft. = 200 gpm of solution (not expanded foam)
.06 x 200 gpm = 12 gallons of 6% foam concentrate per minute
12 gal. x 15 minutes = 180 gallons of 6% concentrate to control, extinguish,
and initially secure 1000 sq. ft. of polar solvents burning.
MTBE and other Additives
Gasoline Additives May Change
Intial Attack Procedures
The U.S. EPA in its attempt at helping to provide
cleaner burning fuels throughout the United Sates
has mandated the use of alcohol based additives to
make the fuel burn cleaner and reach even stricter
emission standards.
4 M.T.B.E.
(methyl tertiary butyl
ether) added to Allow Fuels to
Burn Cleaner
MTBE or methyl tertiary butyl ether, in the past a
by-product of the fuel processing industry, is now
present in fuels in levels above 15% of total volume.
The challenge to the fire service surfaces as these
chemicals are more understood. They are polar
solvents, and as such must be treated in a different
way. As we have learned in the past, foams must be
designed to work on alcohol. Because of its tremendous affinity for water, alcohol tends to destroy the foam
l Future
Use of Methyl Tertiary Amyl
Ether, Ethyl Tertiary Butyl Ether, and
Di-isopropyl Ether Will Present
Special Dangers
The level of MTBE in a fuel may require the initial attack strategy to deal with vapor suppression or
mitigation of a fire as a polar solvent. This is done when using the higher % number on the dual purpose foam
concentrates. Typically, we have used universal 3/6% foams, and now more 3/3% foams are available.
Unlike traditional AFFF applications, putting a finished foam down on this type of fire requires a higher level
of aeration. For fire fighting efforts normally a 7 to 10 : 1 expansion ratio is necessary and for vapor
suppression a 10 to 30 : 1 ratio is preferred. This higher expansion will provide a greater level of post fire
security.
Pre-planning for this type of fire is necessary. A survey of local distributors and terminals within your
jurisdiction will provide additional information on the extent of these additives in use in your area of response.
11
HAZMAT foams are designed to deal with
those chemicals that produce fuming vapors.
These foams are not designed in any way to
neutralize the chemical, but to provide an
immediate suppression of the potential
hazardous vapors being given off by the spill.
They aren’t designed for fire suppression and
many times will degrade other finished foams.
Hazardous Material Foams
A specialty Foam or Stabilizer
used to deal specifically with
fuming chemicals in a vapor
suppression operation.
A finished foam blanket on fuming chemicals
will not only suppress vapors being given off,
but protect the chemical from the outside
atmospheric changes as well.
To be effective HAZMAT foams need to be well expanded. Typically, 30:1 + expansion ratios
with extended quarter drain times work the best for these operations. Since no real standards
exist for these types of foams, your local supplier of concentrates would be your best resource
for information on their use.
Foam Stabilizers are additives used to make an existing blanket much more resistant to some
chemicals. Normally, the stabilizer is added to the finished foam blanket with special
equipment. The finished product exhibits a rubbery plastic type coating that protects the foam
from degradation.
Again, consult the manufacturer in the use of these additives.
Syndet, Class A Foam
PROS
at Reducing Surface
Tension
l Low Concentrate Mix Ratio 0.1 to 1%
l Tremendous Bubble Producer
l Biodegrades Quickly
• Class A foam does some things very well.
Reduction of the surface tension of water
has a tremendous effect on the ability of
water to soak into deep-seated Class A fuels.
l Excellent
• Class A foam will increase the effectiveness
of water. In certain instances from three to
five times more.
CONS
l Detergent
Base Will Attack
Lubricants
• It will extend the useful life of water as it
resists quick evaporation in a hot
environment.
• Will provide a short term fire barrier.
• This foam will operate effectively on all Class A fuels.
• Easy to use and mix, the foam is visible upon application.
Some drawbacks involved include:
• Eye and skin irritation
• Corrosion on some metals and may speed up deterioration of some gasket materials.
• High concentrations (outside the envelope of testing) can be environmentally harmful.
• Reduced life expectancy of leather goods and possible increase in pump lubrication
requirements.
12
Foam Mix Ratios
lClass
B Foam Concentrates
1% = 1 Gallon Concentrate + 99 Gallons
Water
3% = 3 Gallons Concentrate + 97 Gallons
Water
6% = 6 Gallons Concentrate + 94 Gallons
Water
l Class
A Foam Concentrates
0.1% = 1 Gallon Concentrate + 999 Gallons
Water Up To
1% = 1 Gallon Concentrate + 99 Gallons Water
Mix Ratios for Flammable Liquid Foams
(Class B)
Protein Foams - 3% or 6% listings for Underwriters
Laboratories, U. S. Coast Guard, Factory Mutual,
and the New York Board of Standards
Fluoroprotein Foams - 3% or 6% listings for
Underwriters Laboratories, U.S. Coast Guard,
Factory Mutual, FAA, and New York Board of
Standards
Standard AFFF - 1%, 3% or 6% listings for
Underwriters Laboratories (1%, 3% & 6%), Factory
Mutual (3% & 6%), N.Y. Board of Standards (6%)
Universal AFFF - 3% by 3% and 3% by 6% listings
Mix Ratios for Class A Foam Concentrates - Mix Ratios on Class A foam can vary greatly on the type of
application, outside weather and temperature conditions, and necessary longevity of the foam blanket. The
use of High Energy Delivery Systems will require a lower concentration to make a quality foam blanket.
Typical Application Rates:
0.1% up to 0.3% will provide a wet foam through low expansion nozzles, moderately wet foam through a
medium expansion nozzle, and dry foam through a High Energy Delivery System.
0.3% up to 0.6% will provide a much dryer foam through low and medium expansion nozzles, and extremely
dry foam with High Energy Systems.
0.6% up to 1% will offer only minimally more foam quantity, but will provide more surfactant in the bubble
shell for a longer lasting foam blanket in low and medium expansion nozzles.
Important Foam Properties
Performance
lSurface
Tension
Ratio
l Drain Time
lFoam Viscosity
lExpansion
Handling
lConcentrate
l Toxicity
Viscosity
& Biodegradability
Foam Performance issues
Surface Tension is the elastic force of a liquid
which tends to minimize the surface area thus
causing droplets to form. The demonstrated
high surface tension of water is a hindrance in
firefighting.
Expansion Ratio is the ratio of the volume of
finished foam to the original volume of nonaspirated solution. The Quantity of bubbles.
Drain Time is the rate at which the foam
solution is released from the bubble structure
of a finished foam. The Quality of bubbles.
Finished Foam Viscosity is the fluidity of foam. An indication of foam’s ability to cling and stick
to a surface. This attribute is important in pre-treatment and exposure protection.
Handling Characteristics
The concentrate viscosity is important especially during cold weather when foam concentrate
can become too thick to proportion properly.
Toxicity is measured on plant, fish and animals to ensure a safe usable product that can be
applied in the environment and can come into contact with users without the need for special
equipment.
Biodegradation has become more of an issue than ever before with the renewed environmental
interests. A fire department is responsible for the products it puts on the ground.
13
Surface Tension
Water, long used in fire suppression due to
its readily available nature, inherently has
“high surface tension” characteristics that
hinder its ability to soak and penetrate into
deep-seated Class A combustibles.
l The
Elastic-like Force at the
Surface of a Liquid which
Tends to Minimize the
Surface Area.
l Indicates the Ability to
Penetrate and Spread
Regardless of Drain Time
and Expansion Ratio.
A Surface Active Agent, when added to the
water, will reduce the surface tension to a
level that will allow faster penetration.
Typical surface tension of water (measured in dynes) is about 70 dynes per centimeter.
When just 0.1% of Class A foam (surfactant) is added, it will reduce the tension to as little
as 30 dynes. A dyne is the amount of force required to move one gram of weight the
distance of one centimeter. This measurement is calculated using a tensiometer. (A sphere
has the least amount of surface area.)
The reduced surface tension will allow water to spread and form a film which will coat and
cling to hot fuels and convert to steam more quickly.
Smaller water droplets will also convert to steam more quickly than larger drops = Faster
Absorption of BTUs.
Reduction of Surface Tension = Reduction of Rekindles.
Water & Water with
Surfactant
•Water
•Water
molecule
•Surfactant
molecule
• Water with Surfactant
Hydrocarbon surfactant molecules tend to be water shedding and oil loving.
Oil loving allows it to be good at spreading and excellent at wetting.
Fluorocarbon surfactant molecules tend to be water shedding and oil indifferent.
Oil shedding allows it to be excellent at spreading, but poor at wetting.
Other names include “wet” water, “slippery” water, but it will always have the same
extinguishing characteristics as plain water.
High specific latent heat of vaporization of water will not be affected by the addition of
surfactants.
Decrease in the surface tension of water increases the amount of free surface of water
available for absorption of heat.
14
Since it takes energy to produce a finished
foam, it follows that, the more energy used
to aspirate foam solution, the higher the
volume of finished foam.
Expansion Ratio
Volume of Finished Foam
-------divided by-------- = Expansion Ratio
Volume of Foam Solution
A law of Mother Nature dictates that in
Low Energy Delivery Systems (nozzle
aspirated), you can have reach or expansion.
The same energy that is taken from the
velocity of the fire stream for reach is also
used to draw air into the stream and
produce expanded foam.
l LOW
1:1 up to 20:1
l MEDIUM
20:1 up to 200:1
l HIGH above 200:1
NFPA 11 calls out the ranges of specific equipment.
Low expansion, up to 20:1, commonly will refer to common combination nozzles. Most
typical selectable or automatic nozzles will do 5 or 6 to 1 expansion.
Medium expansion, up to 200:1, can be produced with the use of larger aspirating tubes
or attachments to nozzles. Increased expansion, but reduced reach.
High expansion, over 200:1, is only produced with fan-type attachments and netting. The
resulting foam is very light and has little reach. These foams, created from Hi X foam
concentrates, will fill large cavities with highly expanded foam.
Foam Solution + Energy =
Finished Foam
l
1 Gallon Solution
l Aspirated ( Added Energy)
Will Produce 10 Gallons of
Finished Foam
Expansion ratios and applications
Foam Solution - no bubble structure, wet
water, immediately runs off a vertical
surface. Used for immediate penetration
into dry fuels, on deep-seated fires, and mop
up. Conventional nozzles, with limited
expansion. (1:1 to 3:1 expansion)
Final Result will be
a 10:1 Expansion Ratio
l
Wet Foam - watery foam, runny on vertical surfaces, fast draining, no “body”, great
variations in bubble size. Direct initial attack on fine fuels, deep-seated fires, mop up. Low
expansion nozzles, CAFS with “stripping” nozzle. (3:1 to 5:1 expansion)
Fluid Foam - watery shaving cream consistency, flows over vertical surface, medium to
small consistency bubble size, medium to fast drain rate. Exposure protections, wet line,
(less than 30 minutes). CAFS and low expansion nozzles. (6:1 up to 10:1 expansion)
Dry Foam - shaving cream and medium to small bubble structure. Clings readily to vertical
surfaces, makes foam barriers for exposure and wet lines that will hold over 30 minutes.
Mostly air, slow drain time, CAFS and low expansion nozzles. (over 10:1 expansion ratios)
15
The QUALITY of the foam blanket.
Drain Time
Indicates Foam’s
Measured in 1/4 drain time typically with foams
for flammable liquids. The amount time it takes
for 25% of the solution to drain out of the
finished foam blanket. EXAMPLE: A finished
foam has a 3 minute 1/4 drain time. If that is
accurate, for safety purposes, when a foam
blanket is drained down by 50%, a reapplication
will be necessary. Therefore, within 6 minutes,
for maximum vapor suppression, there should
be an additional application.
Durability
lLongevity
lRate of Solution Release
from the Bubble Structure
l
Drain time with Class A foams shows the
stability of the foam blanket. The rate that the
solution drains down and soaks into the Class A fuels upon which it was applied. Cold water tends to
decrease the drain time, and salt water will increase drain time.
Foams with high drain times release their water slowly, making them best suited for exposure
protection and pretreatment of structures.
Foams with faster drain times are ideally suited for initial attack and applications requiring quick
soaking of the fuels. A good example is a large hay bale. The use of a slow draining foam isn’t
tactically the best choice for fast suppression, and inversely a wet, fast draining foam isn’t best
suited for exposure protection.
Be aware of a dried foam blanket that leaves only a foam skeleton. It gives the appearance of a foam
blanket, but the water has long since drained from the bubbles leaving only a skeleton. Reapply as
needed.
Finished Foam Viscosity
l Indicates
a Finished Foam’s Ability
to Spread Across a Surface
l Protein
Based
l AFFF
l Class
A
Viscosity is foam’s inherent property to coat and cling to the surface upon which it is applied.
Especially important to Class A foam applications, the foam viscosity is key to the quality of
sticking to vertical surfaces.
Viscosity also describes the ability to surround fuels when only applied to one side. The foam
will move around and cover areas that cannot be reached from the applicator’s angle.
Viscosity is the FLUIDITY OF THE FOAM. More viscous / less fluid, less viscous / more fluid.
16
Standards for performance, storage,
compatibility and others are listed in UL
and Canadian UL specifications.
Foam Specifications
l AFFF,
ARC, PROTEINS,
SYNDET
AFFF, ARC, and newer proteins have good
storage characteristics, good compatibility
among their groups and meet or exceed very
specific performance criteria on test fires.
l Underwriters
Laboratories
l Mil. Specs. & FAA
l CLASS
A FOAM CONCENTRATE
l USDA-USFS
Missoula, MT, Fire
Sciences Lab
l NFPA Standard 298
Military specifications demand very rigid
performance as does the FAA for airports of
a certain size that require suppression
equipment.
Class A foams in the U.S. rely on the testing done in Missoula, MT, USFS/USDA Labs, and
the standards currently presented in NFPA 298.
Key Items tested for by the USDA:
• Corrosion...Minimum criteria
• Flash Point of Concentrate
• Viscosity and Solubility
• Surface Tension
• Density of Finished Foam / Specific Gravity • Storage Capabilities
• Biodegradation
• Toxicity
Foam Test / Corrosion
Approval Will Mean Acceptable
Corrosion on :
l Aluminum
l Mild Steel
l Yellow Brass
l Copper
l For
Corrosion with Class A foam concentrate is
greatly reduced from what AFFF would be,
but when routinely tank mixed, some
corrosion can be seen on susceptible metals.
Aircraft, Tests are also Conducted
on Magnesium
Typically, corrosion is not nearly the issue,
as the cleaning and rinsing that goes on
with repeated tank mixing is. The slight amount of foam concentrate in the water acts as a
detergent removing tank scale left by the last tank load of water. Over a period of time this
process can lead to tank leakage.
Current approvals can be checked with the Labs in Missoula. The labs test the physical
properties, storage etc. over an extensive 18 month trial. Actual foaming performance is not
measured currently.
Stainless and polypropylene tanks seem to offer the best in foam concentrate storage.
NFPA 1906 standard also specifies that any foam concentrate tank must be protected from
the outside atmosphere with a pressure/vacuum vent. This protection will prevent the
17
Acute Oral LD50 >500 mg/kg
Foam Tests / Toxicity
HEALTH AND SAFETY
Acute Dermal LD50 >2000 mg/kg
l Acute
Oral and Acute Dermal Limits
l Primary Dermal and Eye Irritation
Limits
l Acute Inhalation Tests
Primary Dermal Irritation Mildly Irritating
Primary Eye Irritation Score <5.0
Acute Inhalation LC50 >2.0
ENVIRONMENTAL SAFETY
Toxicity
l Plant Toxicity
Aquatic Toxicity: Rainbow Trout, Fathead
Minnows, Daphnia magna, and Algae are all
tested and must provide acceptable results
for USDA/USFS approval.
Foam Tests / Biodegradation
USFS/USDA Missoula Lab tests require a minimum
50% ultimate biodegradation within 28 days.
l Aquatic
This degradation is necessary since a huge volume
of these foam agents are dispersed into the
environment, and into some environmentally
sensitive areas, via aircraft, helicopter and ground
applications each fire season.
Population
Number
0
Lag Growth
Phase
Phase
This ultimate environmental safety is only certified
on federally approved Class A foam concentrates.
Die Off
(O2)
AFFF and ARC foams do not biodegrade and are
considered and classified as non-biodegradable
waste and when applied on the ground, must be
cleaned up by a licensed disposal company. Not a
great idea for training.
A fire department is liable for the foams it puts on the ground. Training can only be safely done with an
approved Class A foam.
The reason this has not been a big issue in the past is due partly because when a department is called to
apply foam, there usually is a bigger problem to be cleaned up.
A sample of responses of typical fire departments: Source NFPA.
Only 5% of all fire related responses involve some sort of flammable liquid.
Of this 5%, only 5% of these require the involvement of suppression activities on a live fire. Most foam
applications are for vapor suppression to prevent an ignition of the vapors.
95% of fire related calls involve Class A combustibles in some form. This group is a potential target for
Class A foam applications. This volume of use absolutely dictates an environmentally approved concentrate
18
Storage of Foam Concentrates
Storage of Foam Concentrates
All federally approved Class A concentrates are
evaluated on ability to maintain performance
characteristics over time. Production of foam is
evaluated after 12 months of storage as it
compares to foam production of original fresh
concentrate.
l Follow
Manufacturer’s
Recommended Instructions for
Storage
l Use USDA Approved Class A
and UL/FM Approved Class B
Foams
l Avoid
Extreme Temperature
Conditions
l Keep Concentrates in Original
Containers
General storage for both Class A and B
concentrates suggests avoiding below freezing
or above 100 degrees F storage. Immediate use
of concentrates that have been stored in cold
(below 45 degrees F) conditions, may have an
effect on eduction, injection, or mixing of these
concentrates with water. Eductors and some injection equipment are sensitive to the viscosity of cold
concentrates.
Storage of concentrates in their original containers is suggested. When concentrates are placed in
on-board storage tanks, the use of polyethylene, polypropylene, fiberglass storage tanks are
suggested. Storage in mild steel, aluminum, and even 304L and 316L stainless steel tanks may cause
product degradation.
Foam solutions should not be stored any longer than necessary in any container. Water impurities
and temperature will tend to speed the biodegradation process. Batch mixing should take place as
close to the time of application as possible and complete flushing of equipment should be completed
as soon as possible afterwards.
All on-board foam concentrate storage tanks should be protected from the outside atmosphere by a
pressure/vacuum valve. This protection will prevent the volatile active ingredients from vaporizing
Personal Safety Considerations When
Working with Concentrates:
Personal Safety with Foams
l Follow
ALL Manufacturer’s
Recommendations When
Working with Concentrates
l Keep a Current MSDS Sheet of
All Products Being Mixed
l Use Required Personal Protective
Equipment
l Follow Stated Hygienic
Precautions
Beware of any written evidence of health effects
of inhalation or contact of the concentrates.
Involvement in mixing, handling, or application
of foam agents must require the use of
necessary protective equipment. Skin, eye, and
inhalation protection will be stated in MSDS
sheets. Personnel should be aware of and
practice the procedures stated in the
manufacturer’s operational procedures.
Failure to follow the stated protection and application requirements may lead to
unnecessary health risks.
* Goggles, waterproof gloves, disposable coveralls, and rubber boots are required items.
* Soaked clothing should be properly disposed of.
* Eyewash equipment should be available for splash protection.
* Skin contact should be flushed immediately.
* Respirators should be used as recommended in confined spaces.
* Ingestion of concentrate or solution may be harmful and should be avoided.
* Spills can be slippery and should be cleaned up quickly to avoid falls.
* Avoid flushing spills. Use an absorbent and dispose of properly.
* Report any spills or contact immediately to a supervisor.
19
Class A foam concentrates, though tested
and approved, have a window of testing.
This means that from 0.1% up to 1% it is
tested and approved to be within the
established biodegradation requirements.
Environmental Safety with Foams
l Class A Foams Designed to
Biodegrade within Window
of Testing
l Protein Foams Biodegrade
within Reasonable Time
l Film Forming Foams Do Not
Biodegrade Well
Class B foam concentrates that form films
(Flourine) do not biodegrade well and must
be considered as a hazardous material when
spilled and cleaned up with care following
recommendations of the manufacturer.
Considerations when using concentrates:
* Inform personnel of potential problems when concentrates get into waterways.
* Locate foam mixing areas well away from watershed area.
* Exercise care during mix procedures to avoid spills.
* Avoid applications that will put solution into surrounding waterways and watersheds.
* Notify a supervisor should any spill occur.
* Make safe handling a part of training with foam applications.
* Flushing of equipment after use should be done with care to avoid further
contamination of the fireground area.
* Build a good working relationship with local environmental authorities.
(DEM, DNR, EPA)
Foam Solution Accuracy Testing
NFPA Standard #11
l Refractive
Index and
Refractometer
Other Methods in Use Today
l For
Abstract from “Fire Technology”
February 1990
authors G. Timms and P. Haggar
AFFF a Test of Total Flourine
Content
“Three types of foam concentration
measurement techniques are examined: total
fluorine content, optical absorption, and
specific conductivity. Specific conductivity was
found to be the most useful for field
measurements and was therefore compared with the traditional refractive index approach. It was
found that electrical conductance provides a more accurate method of estimating the
concentration of AFFF solution than does the refractive index technique described in NFPA 11.”
l For
Class A Foams Conductivity
of TSD (Total Dissolved Solids)
Refractive index uses a subjective visual meter and a fixed solution to determine accuracy. Total
fluorine content is used specifically for foams that have a fluorine content i.e. AFFF.
Most tests are arranged to use the water at the test location and the foam concentrate to be
tested in the temperature to be used. To take any accurate measurements, no matter which test
is used, all of these considerations must be looked at.
Current trends indicate, for field tests, that the testing of conductivity of a solution, or the value
of total dissolved solids, has the simplest temperature compensating meters available.
20
There are many ways of creating a foam
solution, or the addition of foam
concentrate into the water stream.
Making a Foam Solution:
(Water + Concentrate = Solution)
l Batch
Mixing (Tank Mix)
l Suction Side Regulator
l In-Line (Eductor)
l Around the Pump Proportioning
l Discharge-Side Foam Injection
The choice of the proportioning method will
have to be determined by the local agency
after determining and accessing the use of
foams within their department’s tactical
procedures.
Manual Regulation
•Batch Mixing
•Suction Side Proportioner
•In-line Proportioners and Eductors
•Around the Pump Proportioning Systems
Automatic Regulation
•Discharge Side Foam Injection Systems
•Balanced Pressure Bladder Tank
•Balanced Pressure Pump
•Electronically Controlled Direct Injection
* Flow Sensing
* Conductivity Sensing
Each version does expose equipment to foam concentrate and solution. Good maintenance
procedures need to be followed by flushing and lubricating critical parts.
Batch Mixing
Advantages
l Unlimited
Hose Lengths
Choice of Hose Lines
l Minimal Investment
l Unlimited
Disadvantages
l Tank
and Pump Corrosion
Generation in Tank
l Removes Lubricants
l Bubble
Advantages of Batch Mixing:
•Premix will maintain the desired ratio over the length of the mix.
•The use of unlimited hoseline lengths and choices of attack lines.
•Not flow or pressure sensitive and relatively inexpensive.
•No moving parts or additional equipment needed.
Disadvantages of Batch Mixing:
•Corrosion problems in pump, tank, and plumbing.
•Possible pump cavitation and level sensor error.
•Refilling of water tank will cause a mess of bubbles from tank fill.
•Foam solution will degrade over time and contaminates other water supplies.
•Excessive concentrate may be used and cleaning is required after every use.
21
Disadvantages
of a Suction Side Regulator:
Suction Side Regulator
Advantages
•Only a single flow and single mix ratio may
be used and changes in flow or ratio require
operator adjustments.
l Unlimited
Hose Lengths
l Unlimited Choice of Hose Lines
l Adjustable Mix Ratios
•Contamination of pump water supply and
waste of foam concentrate as water is
bypassed during standby operations.
Disadvantages
l
lTank,
Pump and Plumbing Corrosion
on Pump Vacuum
l Concentrate Viscosity Sensitive
l Dependent
•Corrosion problems in pump, tank and
plumbing.
•Pump priming and cavitation problems.
•Removal of lubricants throughout the
pumping systems. Concentrate viscosity
sensitive and reliant on vacuum created on
the suction side of the pump.
Advantages
of a Suction Side Regulator:
•The use of unlimited hoseline lengths and
choices of attack lines.
•No loss in water pressure or flow and no
moving parts.
•Adjustable mix ratios and minimal cost of
equipment.
Disadvantages of Eductors:
In-Line Proportioning (Eductors)
Advantages
•Limited hose lay lengths (typically 150 to
200 feet) restrict operational flexibility.
l No
Moving Parts
to Most Structural Engines
l Capable of 1%, 3%, 6% Mix Ratios
•High inlet pressures. Most current models
require nearly 200 psi inlet pressure. There
are some forestry and European versions that
require less.
l Common
Disadvantages
l Limited
Hoselays and Elevation
Losses
l High Inlet Pressures (200psi)
l Matching of Nozzle to Specific Flows
•Limited flexibility in percentage choices.
•When selectable gallonage nozzles are used,
nozzle flow must be matched to the flow of
the eductor, typically 60gpm, 95gpm, or
125gpm, and 240gpm with 2 1/2” hose. When
automatic nozzles are used, providing a fully
opened valve will allow the flow to match the
eductor.
Advantages of Eductors:
•Most structural engines that have AFFF or
protein foams on board typically carry either
an eductor as loose equipment or it is
plumbed into the trucks pumping system.
These units can also be modified to work with
the lower injection rate of Class A foam
agents.
•Nozzle must always be used in a full open
position to be effective.
Rule of Thumb = For Hydrocarbon based fuel
fires, use a factor of 10 for the coverage rate (a 95
gpm eductor can cover about 950 sq ft). For
alcohol based fires, the number is 1/2 that, or a
factor of 5 (a 95 gpm eductor will cover 475 sq ft).
•Eductors, being fixed orifice type units, are
relatively simple in design, though restrictive
in operation.
22
Advantages
of an In-Line Pump Proportioner:
In-Line Proportioning (Pump)
Advantages
•It will keep all foam concentrate away
from the pump and tank.
l Discharge
Side Injection
l No Loss of Pressure or Flow
•There is minimal or no loss of pressure or
flow.
Disadvantages
l Single
Flow / Single Mix Ratio
l Electronic Flow Meter Components
l Concentrate Viscosity Sensitive
Disadvantages
of an In-Line Pump Proportioner:
•Single set flow rate and single set mix ratio
allow for no flexibility in initial attack. To
change either, the system must be shut
down and recalibrated.
•Systems use electronic flow sensing
equipment to drive an electric motor and
positive displacement pump.
•System is very sensitive to corrosion and
viscosity of foam concentrates.
Advantages
of Around the Pump Proportioning:
Around the Pump Proportioners
Advantages
•Unlimited use of hose lengths and choices
is possible.
l Unlimited
Hose Lengths
l Easily Adjusted Mix Ratios
l No Moving Parts
•There are no moving parts and mix ratios
are easily adjusted.
Disadvantages
l Tank,
Pump and Plumbing Corrosion
l Removes Lubricants
l Excessive Foam Concentrate Use
Disadvantages
of Around the Pump Proportioning:
•Corrosion problems in the tank, pump and
truck plumbing.
•Possible pump cavitation, refill problems,
and tank level indicator errors.
•Excessive concentrate is used and will
require thorough flushing.
•Removal of lubricants throughout the
system.
23
Advantages
of Discharge Side Injection Systems
Discharge Side Foam Injection
•These systems will maintain the desired mix
ratio over a wide variety of pressures and flows.
l Automatically
Injects Concentrate on the
Discharge Side of the Pump
l Engine Pressures, Hose Choice, Length, or
Nozzle Choice Have No Effect on Injection
l Automatically Adjusts for Changes in Flows
l Minimal Losses in Pressure and Flow
l Automatic Mix Ratios from 0.1% to 1%
•Unlimited use of hose lengths and choices is
possible.
•They will keep all concentrate away from
pump and water tank.
•Multiple hose lines, nozzles, and applicators
may be used simultaneously.
•Simple pump operator procedures to use.
Disadvantages of Discharge Foam
Injection Systems
•Requires an outside power source (water, electrical, hydraulic or four cycle engine) to drive
concentrate injection.
•Requires an investment and installation for truck mounted units.
Types of injection systems (general)
Bladder Type - uses the pressure of the water in the hoseline to surround and squeeze a bladder with foam
concentrate through a metering valve into a low pressure area created by a differential valve.
Direct Injection - Flow Meter based - Uses an electronic flow meter and receiving device to direct a
concentrate pump and motor to inject a metered amount of foam that corresponds to the flow.
Direct Injection - Venturi based - Uses a venturi to create a low pressure area that is sensed and mechanically
transmitted to a pilot valve. More differential in the venturi, more foam will be injected proportionally.
Critical Application Rate or Rate of
Flow is all important to those involved in
initial attack operations. It is this set of
formulas, some created long ago, that
determine success of suppression activities.
Tactical Considerations with Foams
l
l
Critical Application Rates
Low Energy Delivery Systems
Low Energy Foam Delivery Systems
include the use of conventional fog and
straight stream nozzles to apply product.
Typical nozzles will provide a certain level
of application and aspirating nozzles
another.
Conventional or Aspirating Nozzles
l
High Energy Delivery Systems (CAPS)
High Energy Delivery Systems cover systems that will use an additional source of
energy, typically a compressor, or compressed air tank to provide an additional source of
energy for delivery.
24
The basic importance of the critical application
rate or basic rate of flow cannot be overlooked
on any initial fire attack. Listed below are a
couple of the more commonly accepted rules of
thumb for figuring these rates.
Critical Application Rate
(rate of flow)
BTU’s
Generated
The Old Iowa Formula:
Length of area x Width of area x Height
100
Time
equals GPM FLOW
Rule of thumb...the length x width x height
of the room divided by 100 would give the necessary rate of flow for initial attack. Within thirty
to sixty seconds of this application, the fire should darken down.
Another commonly accepted formula states that application rate needs to be three to four gallons
per minute rate for each 100 cubic feet of involvement. A room 10x10x8 would be 800cu.ft.
divided by 100 x three to four gpm flow...24 to 32 gpm rate of flow.
NFPA provides Standard 1231 which also helps determine critical application rates needed for
structures and also takes into account exposures, building classification, and construction.
National Fire Academy, Factory Mutual, and Underwriters Laboratories have all done lengthy
studies on critical application rates for fixed systems and initial attack in compartment fires.
Foam enhancement of the water has no effect on critical application rate!
The ISO formula for insurance rating
purposes gets quite complicated as it takes
into account design density and the greatest
available fire flows. Not practical for fire
ground operations, it is ideal for the purposes
for which it was designed, insurance rating.
Fire Flow Formulas
•ISO Formula - for Insurance Purposes
•Iowa Formula - for Compartment Fires
•NFA Formula - for Daily Structural
Suppression Operations
The Iowa formula has been taught
extensively for years as an easy size up tool
for first arriving engine companies with fire
showing.
L x W x H divided by 100 = Needed Fire Flow
The flow determined by this formula is ideal for a single compartment type fire. Exactly the
scenarios Keith Royer and Chief Lloyd Layman worked with on shipboard firefighting
activities. The NFA formula takes much more into account the actual fireground
operational needs for critical application rates.
[( L x W) divided by 3 + Exposure Charge]
x % Involvement equals the needed for flow
This process led to the more easily used (LxW) divided by 3. As materials have changed in
the construction of homes and fire loads have increased in commercial structures, the more
realistic flows afforded by this formula have proven effective.
25
Latent Heat of Vaporization
l Water
is the Agent of Choice for Fire
Suppression because of the High
Amount of BTU’s Absorbed
From 60 degrees F. to Steam, One Pound of
Water will Absorb 1,122 BTUs
l The
Use of Steam to Cool and
Smother a Fire Can Be a Tactical
Consideration
One Cubic Foot of Water will turn to 1700
Cubic Feet of Steam (@ 212 degrees)
Technical Data Used When Working with
Water as a Fire Suppression Agent
•One pound of ice needs 143 BTUs to convert
water.
•One pound of water at 60 degrees F. will need
1,122 BTU’s to convert to steam.
•In general..one gallon of water will absorb
8,000 BTUs.
•Heat of combustion generally states that one
pound of Class A combustibles will generate
8,000 BTUs, and Class B flammable liquids will
generate 16,000 BTUs per pound.
•One cubic foot of water (7.5 gal.) will convert to 1700 cubic feet of steam at 212 degrees (much
more in higher fire compartment fires).
Factors Affecting Heat Transfer during Initial Attack
•Best maximization of transfer is accomplished with fog pattern.
•The more surface area exposed to the heat the better the transfer.
•Maximum transfer is affected by distance and velocity of the stream.
•Droplet size must be sufficient to provide reach, overcoming distance, air resistance,
and convective actions.
The Use of Class A foam as an enhancement to the water has no affect on the heat of
vaporization, but only on the ability to hold the water to the surface of the fuel and the
ability to provide increased surface area for more complete vaporization.
Class A Foam Characteristic Rate
l Solution - Clear milky fluid lacking
any bubble structure (wet water)
l Wet - Watery, inconsistent bubble
structure, lacking any body, very fast
drain time
l Fluid - Watery shaving cream
consistency, medium to small
bubbles, moderate drain time
l Dry - Similar to shaving cream,
medium to small bubbles, mostly air,
slow drain time
Tactical Uses of the Different Foam
Characteristics (USFS/BLM Rating)
Solution: Typically, called wet water, foam
solution has virtually no bubble structure and
will work only as a soaking type application.
The reduced surface tension of the solution is
ideal for soaking applications (coal bunkers,
peat bogs, saw dust piles, dumps, rag houses,
hay bales, grain fires, cotton bales, structural
overhaul).
Wet: A wet sloppy foam, this type application
will have a minimal inconsistent bubble
structure that tactically can be used the same way a solution is, but will provide a little
smothering ability for short term applications. Quick drain times restrict the use of this type
foam for exposure pretreatment.
Fluid: A wet shaving cream type consistency, this application is ideally suited for blanketing
and smothering. With the moderate drain out time, limited success can be achieved in exposure
pretreatment. Ideally, this type foam works well in hay bale attack, tire fires, and other attacks
that will need water drain out for deep-seated suppression and some medium term smothering
characteristics.
Dry: Shaving cream consistency allows this type foam to be used primarily for long term foam
blanket application. Exposure protection, pretreatment, long term wet lines, and long term
smothering can all be easily achieved. Because of the long drain out time of moisture in this
26
The use of finished foam as a tool for exposure
protection and pretreatment has gained wide
acceptance for three main reasons:
Exposure Pretreatment
Radiant Heat
#1. Since finished foam is nothing more than
water with some surfactants added, its ability
to coat and cling allows water to hold and soak
into the fuels to be protected. As long as the
exposure is wet (water must boil off the
exposure before the fuel can be preheated to
ignition point), the chance to burn is limited.
The reduced surface tension will hold and
allow the water to completely soak into the
fuel.
Reflected Radiant Heat
#2. Finished foam bubbles are one of the best insulators. Encapsulating air, foams will insulate
the fuel from the radiant and convective forces of the fire, again preventing the fuel from
preheating to the point of ignition.
#3. Because it is white in color, the foam blanket will also provide reflective protection from the
radiant heat being generated. In some cases as much as 70% of the radiant heat may be reflected
away from the fuels to be protected.
Tactically, the use of foam for this type of application relies heavily on the quality of the foam
blanket generated. A wet sloppy foam will not have the success of a dry sticky foam. Though
wetting will be achieved, the long term insulating and reflective capabilities will be diminished.
Reapplication of a foam blanket under heavy fire or extreme weather conditions may need to be
considered for the necessary long term exposure protection.
The Structure of bubbles in the finished foam
blanket can best be tactically characterized in three
categories:
Bubble Structure
l Very
Consistent
Inconsistent bubble structure is typically produced
with Low Energy Delivery Systems (i.e. regular fog
nozzles and low expansion foam tubes, or a fog
nozzle on a High Energy Delivery System). The
l Moderately Consistent
bubble structure tends to break down quickly
Medium Term
releasing either the film forming characteristics of an
AFFF or the water in a Class A foam blanket into (or
l Very Inconsistent
onto) the fuel beneath. Faster drain out time of this
Short Term
type of foam is ideally suited for deep-seated fires
when quick soaking is needed. Initial attack and
overhaul operations are well suited for this type of
bubble structure with Class A foams. Fast draining
foam is not desirable with AFFF due to the need to reapply the foam blanket for continued vapor suppression
and security more often.
Long Term
A moderately consistent bubble structure is normally produced with some low and, more often, medium
expansion foam tubes. With Class A foams the longer drain down time of this type application makes it well
suited for the construction of “wet” line, smothering foam for tire or railroad tie fires, and for short term
exposure protection and pretreatment. The less consistent the structure, the faster the drainout rate. With
Class B foams the necessity of a more consistent bubble structure is part of reapplication and long term vapor
suppression. Different types of foam concentrates will produce differing structures even through the same
application devices.
Highly consistent structures are best used for exposure pretreatment and any area where a “dry” long
lasting, slow draining foam is needed. Typically produced with a High Energy Foam Delivery System, these
structures aren’t well suited with the use of AFFF due to the extremely slow drain out of the solution. CAFS
has produced this type of foam blanket using only an open butt ball valve. Any restrictions in a High Energy
27
Low Energy Foam Delivery Systems, or
nozzle aspirated foam, take the energy from
the horsepower of the truck engine,
transferred through the fire pump,
throughout the hose line to the end of the line
at the nozzle.
Low Energy Foam Delivery
Truck Pump
Foam Solution
The velocity of the fire stream (nearly 65 mph
at 100 psi nozzle pressure) is nothing more
than transferred energy that is being used up
at the nozzle.
Aspiration Device
Expansion {- reach and expansion -} reach
Foam may be tank mixed, injected, or used
with an eductor to create solution. The nozzle entrains the air to provide a finished foam.
Combination fog nozzles entrain enough air to produce approximately a 5 to 8 to 1 expansion
ratio.
Attachments, the most common method, are the most versatile way of increasing expansion to
provide greater volume. Many of these are capable of as much as 20 to 1 expansion, but with
limited reach.
THREE TYPES OF FOAM APPLICATION TECHNIQUES
BOUNCE OFF TECHNIQUE - straight stream for reach
BANK IN TECHNIQUE - roll foam over the surface
RAIN DOWN TECHNIQUE - expansion down through thermal
Avoid PLUNGING of streams into the flammable liquid!!!
Though 95% of initial attacks on structural
fires use the first two lines off the engine,
these limitations have not been greatly
discussed. On initial interior attack, extensive
foam creation is not necessary. The “wet”
solution type of foam is ideal for the soaking
and coating need of this type attack. Overhaul
operations actually begin upon initial attack.
The soaking ability immediately reduces the
opportunity for rekindle.
Conventional Combination
Nozzles
Advantages
l Standard
Equipment Used on Initial
Attack
l No Modification to S.O.Gs
Disadvantages
l Restricted
to Solution or Wet Foam
Performance Only
l May Require Higher Foam Ratio for
Longevity
Tactically, water savings in attacks are noted
as personnel realize that if it’s “white” they
don’t have to reapply to that area. The foam is
there sticking and clinging and soaking into that fuel. Any reapplication to this area would be a
waste. Now that there is a cost to the application agent, this needs to be taught. The “paint
brush” effect of an interior attack has proven to be very productive. A 15 degree fog pattern
provides the best coverage.
The drawbacks of a conventional nozzle tend to arise when the need to do exposure protection
or pretreatment of a structure is necessary. Conventional nozzles just don’t aspirate the foam
enough to provide a long lasting white blanket.
Piercing applicators, and specialty nozzles can be effectively used with Class A foaming agents
to reach hard to get to areas (hay bales, cotton bales, rag houses, car fires, coal bunkers).
Conventional Fog/Straight stream Nozzles are designed only to provide a limited amount of air
28
Low Expansion Aspirating Nozzles, and/or
attachments are designed to provide a higher
level of foam expansion by using energy of the
fire stream. That higher expansion does come
with a price. An increase in expansion will
provide a decrease in stream reach.
Low Expansion Aspirating Nozzles
Advantages
l Will
Provide “Wet” and “Fluid” Foam
Performance
l Inexpensive, Simple, and Easy to Use
Disadvantages
The performance of a low expansion nozzle or
attachment may very well limit its total use as
an initial attack tool. Many have limits on how
the fog pattern can be adjusted, or limits in the
ability to provide reach or pattern changes.
These restrictions limit these nozzles or
attachments to the truck compartment where
they wait for use during a specialty application. Tactically, this group of nozzles is well designed for
building wet line in wildfire applications, and for short term exposure protection and pretreatment.
The quality and longevity of the foam blanket created by these nozzles is certainly better than a
conventional nozzle, but lacks in long term applications.
l Limited
Discharge Distance and Foam
Variability
l Incompatibility of Equipment
Needed for Initial Attack
An example of multiple tactical considerations is a tire fire. Two items need to take place: #1. A wet
sticky water needs to be applied to absorb heat. #2. A wet sloppy foam needs to be added to provide
the necessary smothering blanket. A low expansion nozzle or attachment can do both effectively.
There are some low expansion nozzles that can provide a protective fog pattern, as well
as low expansion foam. These nozzles have a better opportunity of being in first line
operation because of their versatility and safety. There are also attachments to
conventional nozzles that will provide the same versatility.
Medium Expansion Aspirating Nozzles
and/or attachments are designed to use the
maximum amount of energy from the fire stream
for conversion of solution to a finished foam.
This use of energy will severely limit the reach of
these nozzles.
Medium Expansion Nozzles
Advantages
l Will
Provide “Medium” to “Dry”
Foam Performance
l Simple and Easy to Use
The limits of reach of these tools relegate them
to the truck compartment and are rarely used on
an initial attack. These nozzles and attachments
are normally used tactically on the building of
wet lines in wild fire operations or for building a
long term foam blanket for vapor suppression of
flammable liquids and smothering of problem
deep-seated Class A fuel fires.
Disadvantages
l Requires
Higher Mix Ratio for
Longevity of Foam Blanket
l Discharge Distance is Limited
Best performance, or highest expansion, is
achieved with a somewhat reduced nozzle pressure (reduced velocity). The faster the stream is
traveling through the medium expansion nozzle (screen), the less time is available to create bubble
structure. This is called “shear” factor. Reduced velocity will provide more time to create a more
consistent and highly aspirated bubble structure. Many medium expansion nozzles are rated for 6080psi operation. This may become a problem when an attachment is used on a conventional fog
nozzle rated at 100psi nozzle pressure.
There are some medium expansion attachments that can be used variably on a conventional nozzle.
These can be adjusted for reach or expansion or a moderate combination of each. Also, some
automatic nozzles have a normal (100psi) and low pressure (75psi) selection. This combination
tactically will provide the highest degree of versatility.
29
High Expansion Systems are designed to
produce a highly expanded foam (200:1 +
expansion). These systems use a fan and
netting to add energy to the foam solution.
Once aspirated, it is also directed through
tubing with the energy of the fan pushing
the foam into the cavity to be filled.
High Expansion Delivery Systems
Advantages
l Will
Provide Extremely “Dry” Foam
Performance
l Ideally Suited, Tactically, for Life
Safety Applications
Disadvantages
l Requires
Large Amounts of
Equipment
l For Compartment Type Situations
The theory of these type applications is to
fill a burning cavity with foam and smother
the fire. It is used extensively in areas
where there is a life safety hazard for the
fire suppression forces (coal mine fires,
shipboard compartment fires, telephone vault fires, and, for some time, has shown
effectiveness on basement fires).
Regular pumping operations and injection of the foam concentrate still need to take place
up to the fan and netting location. The energy is then injected into the solution from the
four cycle or electrically powered fan. The netting acts as a location for agitation of the
solution, and, finally, the tubing directs the foam to the area of application.
The light finished products are so unstable in the outside environment, due to wind
currents, that, tactically, little use has been found. This tends to be an extremely specialized
High Energy Foam Delivery Systems, or
CAFS (compressed air foam systems), do
not use the energy transferred to the
hoseline from the fire pump. Instead, a
third component, an air compressor, is
mounted on board the apparatus and adds
compressed air (energy) in the form of
pressure (psi) and flow (cfm). This energy
is transferred into the hose line, which
holds it in the form of stored energy
awaiting release at the tip.
High Energy Foam Delivery
Truck
Pump
Compressed Air Source
(Energy)
Water doesn’t compress, but compressed air
foam will compress in the hoseline holding a tremendous amount of “stored” energy for use.
This additional energy will translate into additional reach, and a high quality, very
consistent bubble structure in the finished foam.
High energy systems use 1 cfm of air matched to 1 gpm of fire flow, at the same pressure,
for tactical applications.
Constant foam injection is imperative for effective applications. Inconsistent injection will
allow slug flow to hamper operations.
30
Most compressed air systems use an on-board
air compressor either powered directly from the
truck drive train or via some sort of secondary
power source. Other types of systems also will
use pressurized tanks to supply energy. These
may be used in a fixed system or portably.
High Energy Foam Delivery
Systems
Advantages
l
l
Requires Less Water and has Greater Discharge
Distances than Low Energy Systems
Stored Energy in the Hose will More Completely
Convert Solution to Finished Foam
Disadvantages
The choice of components is important to
system longevity, maintainability, and
performance. Many varieties are coming into
the marketplace on a monthly basis. The use of
“totally” engineered packages offer more long
term results than component buildup systems.
More Mechanical Components Lead to More Complex
Operating Procedures
l Misunderstanding of Fire Ground Hydraulics and the
Inclusion of Pneumatics
l
The foam quality and reach associated with
these high energy systems provide tremendous tactical consideration for use in exposure protection
and pretreatment of structures in advance of fires.
The choice of nozzles is unusual for initial attack. Typically, only a ball valve is used to achieve best
foam performance. The addition of a nozzle will have an adverse affect on the quality of the foam,
stripping out the bubbles generated in the hose line. This will give versatility in the quality of the
foam. Different nozzle choices will provide differing types of foam from “wet” to “dry”.
Hose lines are extremely lightweight. Though deceptive, because of the amount of stored energy in
the line, hose lines are filled with mostly air and bubbles allowing for easy movement of hose lines in
initial attack.
High Energy systems make best use of foam concentrate. Typically, 0.2% to 0.4% is all that is needed
to create excellent quality foam. With low energy systems, it may vary from 0.2% up to 1%
Discussion of National Usage
Examples of Current National Usage in:
lUrban
Structural Initial
Attack
lWildfire / Structural
Intermix Responsibilities
lForestry and Wildfire
Responsibility
Discussion of current activity of usage in the U.S. and Canada by agencies involved in:
•Structural Initial Attack
•Car Fires
•Deep-Seated Problem Fires
•Industrial Use
•Coal Fired Facilities
•Grain and Fabric Processing
•Wildfire Structural Intermix
•Exposure Protection and Pretreatment
•Wildfire and Forestry Applications
•Pretreatment
•Mop up Operations
31
Discussion of current activity of testing in
the U.S. and Canada:
Overview of National Testing
Examples of Current National Studies:
NFPA activity including pending standards
and work of the research and development
group at the foundation
l Initiatives
from the National Fire
Protection Association
l Initiatives Under the USDA,
BLM and USFS
l Testing Underway with
Underwriter’s Laboratory
l Independent Evaluations
Current work from the Missoula Fire
Sciences Laboratories, Equipment
Development Group in San Dimas, CA, and
the National Interagency Fire Center in
Boise, ID
Testing underway and proposed by Underwriter’s Lab, the insurance industry, Factory
Mutual, and Southwestern Labs
Independent testing being conducted by the Canadian government, foam companies, and
independent consultants
Summary of
Course Material
lQuestions
lWritten Quiz
lCourse Evaluation
l
32
Glossary of Foam Terminology
Absorption: The act of absorbing or being absorbed.
AFFF (Aqueous Film Forming Foam): A foam concentrate containing fluorocarbon surfactants that
control the physical properties of water so that it is able to float and spread across the surface of the
hydrocarbon liquid.
AFFF - Polar (ATC): An AFFF that contains a plastic material that forms a polymeric layer only on
polar solvents to separate and protect the finished foam.
Adhesive Qualities: The ability to bind together substances of unlike composition. When a foam blanket
clings to a vertical surface, it is said to have adhesive qualities. This is required to prevent vapor release
at a tank shell fire, or to describe Class A foam applications to exposures.
Airfoam: Foam produced by the physical agitation of a solution of water and foaming agent and air.
Also called mechanical foam.
ARC - Alcohol Resistant Concentrate: See AFFF Polar.
Aspirate: To draw in air; nozzle aspirating systems (low energy delivery) draw air into the nozzle to mix
with the foam solution.
Batch Mix: Manual addition of foam concentrate to a water storage container or to make a foam
solution.
Barrier: Any physical obstruction that impedes the spread of the fire; an area or strip devoid of
flammable fuels
Biodegradation: Decomposition by microbial action as with synthetic detergent based agents.
Boilover: The violent ejection of flammable liquid from its container caused by the vaporization of
water beneath a body of liquid. It may occur after a lengthy burning period of products such as crude oil
when the heat wave has passed down through the liquid and reaches the water bottom in the storage
tank. It will not occur to any significant degree with water soluble liquids or light products, such as
gasoline.
Bubble: The building block of foam; bubble characteristics of water content and durability influence
foam performance.
Bareback Resistance: The ability of the finished foam to resist direct flame impingement such as would
occur with partially extinguished petroleum fire or with Class A foam in exposure protection and
pretreatment.
Carcinogenic: Cancer causing.
Class "A " Fire: A fire in combustibles that exhibit deep-seated burning characteristics such as wood,
paper, fabric, tires and peat, where the cooling, smothering and soaking ability of Class A foam and
water are best utilized.
Class "B" Fire: A fire involving any type of flammable liquid, where blanketing and smothering for
vapor suppression is of the first importance.
Class "C" Fire: A fire in "live" electrical equipment, where the use of non-conducting fire suppression
agents is of prime importance.
Cohesive Quality: The ability to bind together substances of like composition. A good foam blanket is
held together by its cohesive qualities.
Combustible Liquid: Any liquid having a flash point at or above 100°F (37.8°C).
33
Compatibility: The ability or inability of extinguishing agents to be mixed together or used
simultaneously.
Compressed Air Foam System (CAFS): A generic term used to describe high energy foam delivery
systems consisting of an air compressor (or air source), a water pump (or pressurized water), and foam
injection equipment (or foam solution).
Concentration: The amount of foam concentrate contained in a given amount of foam solution. The
type of foam used determines the foam concentration used (i.e. AFFF 1%, 3%, or 6%, and Class A
foams from 0.1% up to l%).
Corrosion: Resulting chemical reaction between a metal and its environment (i.e. air, water and
impurities).
Degradation: A negative change in the characteristics of qualities of a foam.
Density: The weight of a specific volume of solution.
Discharge Device: A fixed or portable device which directs the flow of solution or finished foam onto
the hazard (example: fixed master stream device or an aspirating handline).
Downstream: The direction to which the water is flowing.
Drainage (Dropout) Rate: The rate at which bubbles from a finished foam blanket burst and release
their solution; generally measured as quarter drain time.
Expansion Ratio: The ratio of volume of foam formed to the volume of solution used to generate the
foam (example: an 8:1 expansion ratio means 800 gallons of finished foam were created from 100
gallons of foam solution). Expansion ration is determined by the use of different aspiration devices, low
energy and high energy delivery.
Eductor: A proportioning device which uses the vacuum created by the water moving through a venturi
to draw concentrate into the hose line.
Environment: The complex surrounding an area such as water, air and natural resources and their
physical conditions (temperature, humidity, etc.).
Film Forming Fluoroprotein- FFFP: A foam concentrate composed of protein and film forming
fluorinated surface active agents, which makes it capable of forming a water solution film on the surface
of a flammable liquid, and conferring a fuel shedding property to the finished foam blanket. See also
Oleo phobic.
Fluoroprotein Foam - FP: A foam concentrate composed of protein polymers and fluorinated surface
active agents to confer a fuel shedding property to the finished foam blanket. See Oleo phobic.
Fire Retardant: Any substance that by its chemical nature or physical action reduces or impedes the
flammability of a combustible.
Flammable Liquid: A substance that is liquid at ordinary temperatures and pressures and has flash
point below 100ºF (38°C).
Flash Back: Re-ignition of a flammable liquid caused by the exposure of its vapors to a source of
ignition, such as a hot metal surface or spark.
Flash Point: The point at which a flammable liquid gives off enough vapor to ignite.
Fluorocarbon: An inert organic compound in which fluorine replaces hydrogen.
Foam - (Finished): A homogeneous blanket obtained by mixing water, foam concentrate, and the
addition of air or an inert gas by the use of energy.
Foam - (Concentrate): The foaming agent for mixing in the right proportion with water and air to
produce finished mechanical foam.
34
Foam Maker: A device designed to introduce air into a pressurized foam solution stream (i.e.
low/medium expansion nozzle, high expansion nozzle, or compressed air foam system).
Foam Solution: A homogeneous mixture of water and foam concentrate.
Foam Stability: The relative ability of a finished foam to withstand spontaneous collapse or breakdown
from external causes, such as heat, chemical reaction, or weather factors.
Friction Loss: The loss of pressure in a flowing stream resulting from resistance to flow imposed by the
inside of the pipe or hose and by changes in flow direction such as elbows and tees, and also elevation.
Heat Resistance: The ability of a finished foam to withstand exposure to heat (radiant, convective or
conductive).
High Energy System: A foam generating system that adds the energy of the air source to the energy of
the water pump. CAFS is a high energy foam delivery system.
High Expansion Foam: Special foam designed for high air-to-solution ratios with 200 parts air to
each part foam solution.
Hydrocarbon: An organic compound containing only carbon and hydrogen.
Hydrocarbon Pickup: The characteristic of a fuel that is suspended or absorbed by expanded foam.
Hydrophobic: Water-hating; having the property of not mixing with water.
Hydrophilic: Water-liking; having the property of mixing with water readily.
Ingestion: To take things into the body as by swallowing, breathing, or absorbing.
Line Proportioner: A device that siphons foam from a container to make a foam solution (i.e. an
eductor).
Low Energy System: A foam generation system that uses the energy of the velocity of the water stream,
delivered from the water pump, to mix air at the nozzle tip with the solution to deliver a finished foam.
An aspirating foam tube is a low energy delivery system.
Minimum Operative Temperature: The lowest temperature a foam concentrate will proportion with
venturi devices in accordance with UL and USDA/USFS requirements.
NFPA - Requirements / Recommendations: Standards established for foam extinguishing systems as
outlined in Standard #11 and Standard #298.
Oleo Phobic: Oil - hating; having the ability of shedding gasoline, oil and similar products.
Pickup: The induction of foam concentrate into the water stream by the use of a venturi or suction side
injection system.
Polar Solvent: In fire fighting, any flammable liquid which destroys regular foams. The alcohol
aggressively attacks the bubble by mixing with the water in the bubble structure. Polar solvents require
special foam agents and mix ratios. Examples: esters, ethers, alchohols, aldehydes, and keytones.
Polymeric Membrane: A thin, durable, plastic layer formed by the application of an alcohol resistant
foam on a polar solvent fuel surface protecting the foam cells from destruction by the fuel.
Pour Point: The lowest temperature at which a foam concentrate is fluid enough to pour, generally
about 5 degrees F above the freezing point.
Pressure Drop: The net loss in flowing water pressure between any two points in a hydraulic system. It
is the sum of friction loss, head loss, or other losses due to the insertion of an orifice plate, venturi, or
other restriction into a section of pipe or hose.
35
Product: Another name that may be applied to flammable liquids.
Proportioner: The device where foam concentrate and water are proportionally mixed to form a foam
solution. Also a unit that pumps foam concentrate, as demanded, into the attack hose line.
Protein: Complex nitrogen containing compounds derived from natural vegetative and animal sources.
Hydrolysis products of protein provide exceptionally stable, cohesive, adhesive, and heat resistant
properties to foam.
Protein Foam Concentrate: Concentrated solution of hydrolyzed protein to which chemicals are added
to obtain fire resistance and other desirable characteristics.
Quarter-life (Drain Time): The time required in minutes for one-fourth of the total liquid solution to
drain from the finished foam. Also referred to as 25% drainage time.
Residual Pressure: The pressure existing in a line at a specific flow (as opposed to static pressure).
Short Term Retardant: A viscous, water based substance wherein water is the suppressing agent.
Skin Fire: A flammable liquid fire, such as a spill on a solid surface where the liquid is not present in a
depth exceeding one inch.
Slug Flow: In CAFS only, when the foam solution is not rich enough or unevenly mixed with air,
inadequate mixing occurs. This sends pockets, or slugs, of water and air to the nozzle.
Soluble: The ability to become readily dissolved or mixed with.
Spray Pattern: The pattern produced by a divergent flow of fully formed subdivided foam; the pattern
varying with the nozzle pressure and the adjustment of the spray creating device.
Static Pressure: The pressure existing in a line during a no flow situation. This can be considerably
higher than residual pressure.
Submergence: Plunging of foam beneath the surface of burning liquid resulting in a partial breakdown
of the foam structure and coating of the foam with the burning liquid.
Suppressant: An agent used to extinguish flaming or glowing phases of combustion by direct
application to the burning fuel.
Surface Active Agent (Surfactant): A chemical that lowers the surface tension of a liquid.
Syndet: Synthetic detergent or cleaning agent.
Upstream: In the direction from which the water is flowing.
Venturi: A constricted portion of a pipe or tube which increases water velocity, thus momentarily
reducing its pressure. It is in this reduced pressure area that foam concentrate is introduced in many
types of proportioning equipment.
Viscosity: The fluidity of a foam. An indication of the foam's ability to spread and cling.
Wetting Agent: A chemical that, when added to water reduces the surface tension of the solution and
causes it to spread and penetrate exposed objects more effectively. A wetting agent may not be a foam
concentrate.
36
Class A Foam Awareness Level Test
1) Match the correct Material to the correct Combustible Classification.
A) Class A
_____ Electrical Source
B) Class B
_____ Flammable Metals
C) Class C
_____ Woods, Paper and Fabrics
D) Class D
_____ Flammable Liquids
2) The Four sides of the Fire Tetrahedron are _______________, _______________, _______________
and Chemical _______________ _______________.
3) What side of the Fire Tetrahedron does a typical structural attack with water try to interrupt?
_____________________________
4) Match the Classification of Foam Concentrate with the statement that describes one of its
characteristics.
A) Protein Foam
_____ Forms as aqueous film
B) Syndet, High Expansion _____ Used in fighting Class A combustibles
C) Alcohol Resistant
_____ Hydrolyzed proteins
D) Syndet, Class A
_____ Used for filling a cavity with foam
E) Fluoroportien
_____ Foam concentrate for keytones and polar solvents
F) AFFF
_____ Fluorochemical surfactants and protein
5) The film created on a flammable liquid surface by AFFF prevents what from happening?
_____________________________________________________________________________
_____________________________________________________________________________
6) Can a Class A foam safely be used on a flammable liquid fire? _____ yes
_____ no
7) What is the minimum application rate for a hydrocarbon fuel fire per square foot of burning liquid for
a minimum of 15 minutes?
(1 gpm), (0.3 gpm) or (0.1 gpm)
__________
8) Class A form solution is ideal for reducing the surface tension of water.
9) Which Class B foam concentrate is most concentrated? _____ 1%
_____ yes
_____ 3%
_____ no
_____ 6%
10) You have attacked a pile of burning hay bales. You put hundreds of gallons of water on them, but it
just runs off on the ground. Which attribute of Class A foam could work for you?
A) Expansion Ratio B) Drain Time C) Viscosity D) Reduced Surface Tension
11) A low expansion nozzle can provide up to 50:1 expansion ratio._____ yes
_____ no
12) It takes a foam solution plus ____________________ to make a finished foam.
13) A foam with a short drain time means that the water drains (quickly) or (slowly) out of the bubble
structure into the fuel? _________________________
14) Foam concentrates are corrosive.
_____ yes
15) Which one of these foams is designed to biodegrade quickly and safely?
A) Protein B) Fluoroprotein C) AFFF D) Class A E) Syndet, High Expansion
37
_____ no
_____
This Page
Intentionally
Left Blank
For additional information please contact:
Task Force Tips, Inc
800-348-2686
TASK FORCE TIPS, Inc.
MADE IN USA •www.tft.com
©Copyright Task Force Tips, Inc. 2002-2004
2800 E. Evans Ave, Valparaiso, IN 46383-6940 USA
800-348-2686 • 219-462-6161 • Fax 219-464-7155
LTT-300 September 30, 2004 Rev02
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement