Foam Fighting

Pumping Apparatus Driver/Operator Lesson 15Pumping Apparatus Driver/Operator Handbook, 2nd Edition

Chapter 15 Foam Equipment and Systems

Pumping Apparatus Driver/Operator

Pumping Apparatus Driver/Operator15*Learning Objectives1.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/Operator15*Learning Objectives4.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/Operator15*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/Operator15*Learning Objectives10.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/Operator15*Learning Objectives13.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/Operator15*Learning Objectives16.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 high-expansion foams.(Continued)


Pumping Apparatus Driver/Operator15*Learning Objectives19.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/Operator15*Learning Objectives22.Answer questions about apparatus-mounted 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/Operator15*Learning Objectives25.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.(Continued)


Pumping Apparatus Driver/Operator15*Learning Objectives

28.Answer questions about the environmental impact of foam concentrates and solutions.

29.Select facts about durable agents.


Pumping Apparatus Driver/Operator15*Why Foam and Durable Agents Have Increased in Use RecentlyMagnitude 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/Operator15*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/Operator15*Foam TermsProportion 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/Operator15*Foam TermsFoam 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/Operator15*Principles of FoamTo produce quality fire fighting foam, foam concentrate, water, air, and mechanical aeration are needed.

(Continued)


Pumping Apparatus Driver/Operator15*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/Operator15*Principles of FoamSome 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/Operator15*Principles of FoamClass B fuelsHydrocarbons 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/Operator15*Principles of FoamClass B fuelsPolar solvents Flammable liquids that mix with water; foam can be effective, but only in special alcohol-resistant formulationsExamples: Alcohol, acetone, lacquer thinner, ketones, and esters

(Continued)


Pumping Apparatus Driver/Operator15*Principles of FoamClass 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/Operator15*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/Operator15*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)



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/Operator15*Foam ProportioningDescribes 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/Operator15*Foam ProportioningMost 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/Operator15*Foam ProportioningClass 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 fuels surface can be adjusted to a lower percentage.(Continued)


Pumping Apparatus Driver/Operator15*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/Operator15*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/Operator15*Methods by Which Foam May be ProportionedInduction

Injection

Batch mixing

Premixing


Pumping Apparatus Driver/Operator15*InductionUses 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/Operator15*Induction


Pumping Apparatus Driver/Operator15*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/Operator15*Batch MixingIs 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/Operator15*Batch MixingIs 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/Operator15*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/Operator15*PailsAre 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/Operator15*PailsMay 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/Operator15*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/Operator15*BarrelsMay 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/Operator15*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/Operator15*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/Operator15*Apparatus TanksVary in type, location, and designSmaller foam tanks are located directly above the fire pump area.Newer designs incorporate foam tanks as an integral cell within the water tankSome apparatus have an additional pump and connection nearer ground level for refilling the concentrate tank.(Continued)


Pumping Apparatus Driver/Operator15*Apparatus TanksVary in type, location, and designLarge 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/Operator15*Apparatus TanksMust 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/Operator15*Class A FoamIs 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 fuelsWARNING! Use Class A foam only on Class A fuels. It is not specifically formulated for fighting Class B fuels.(Continued)


Pumping Apparatus Driver/Operator15*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/Operator15*Class A FoamMay 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)



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)



Has corrosive and supercleaning characteristics, so direct skin contact should be avoided. Properly flushing application equipment after use is also recommended


Pumping Apparatus Driver/Operator15*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/Operator15*Proportioning Class A FoamsMost 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/Operator15*Performing Various Applications with Class A FoamsFire attack and overhaul with standard fog nozzles0.2% to 0.5% foam concentrate

Exposure protection with standard fog nozzles0.5% to 1.0% foam concentrate(Continued)


Pumping Apparatus Driver/Operator15*Performing Various Applications with Class A FoamsAny application with air aspirating foam nozzles0.3% to 0.7% foam concentrate

Any application with compressed air foam systems0.2% to 0.5% foam concentrate


Pumping Apparatus Driver/Operator15*Application of Class A FoamAreas requiring maximum penetrationWet foam is very fluid and is desirable for these areas.

Vertical surfacesDry 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/Operator15*Application of Class A Foam

Areas requiring a balance of penetration and clinging abilityMedium foam has the ability to blanket and wet the fuel equally well.


Pumping Apparatus Driver/Operator15*Class B FoamIs 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/Operator15*Class B FoamMay 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/Operator15*Class B FoamProtein-based foamsAre derived from animal proteinHave a shelf life of about 10 yearsAre generally safer for the environment

Synthetic-based foamsAre made from fluorosurfactantsHave a shelf life of 20 to 25 years


Pumping Apparatus Driver/Operator15*Proportioning Class B FoamTodays 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/Operator15*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/Operator15*Foam ExpansionThe increase in volume of foam solution when aeratedThe method of aerating results in varying degrees of expansion, which depends on:Type of foam concentrate usedAccurate proportioning of the foam concentrate in the solutionQuality of the foam concentrateMethod of aspiration


Pumping Apparatus Driver/Operator15*Rate of Application for Class B FoamDepends onType of foam concentrate usedWhether or not the fuel is on fireType of fuel (hydrocarbon/polar solvent) involvedWhether 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/Operator15*Rate of Application for Class B Foam

Hydrocarbon fuel spill fires (nondiked) using portable extinguishing equipmentProtein and fluoroprotein foams 0.16 gpm/ft2 (6.5 [L/min]/m2) for 15 minutesARFF and FFFP 0.10 gpm/ft2 (4.1 [L/min]/m2) for 15 minutes(Continued)



Polar solvent fuel spill fires (nondiked) using portable extinguishing equipmentBetween 0.10 and 0.20 gpm/ft2 (4.1 [L/min]/m2 and 8.2 [L/min]/m2), depending on the manufacturers UL listing(Continued)



Hydrocarbon fuel fires in fixed roof storage tanks using portable extinguishing equipment0.16 gpm/ft2 (6.5 [L/min]/m2)


Pumping Apparatus Driver/Operator15*Determining the Application Rate from a NozzleDivide nozzle flow rate by area of the fireA 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/Operator15*Regular Protein FoamsAre 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/Operator15*Regular Protein Foams

Degrade faster in storage than do synthetic foams

Are rarely used in the fire service today


Pumping Apparatus Driver/Operator15*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/Operator15*Fluoroprotein Foam

Provides a strong security blanket for long-term 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/Operator15*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/Operator15*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/Operator15*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/Operator15*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/Operator15*Alcohol-Resistant AFFFAre usually used at 3% or 6% on polar solvents and 1% or 3% on hydrocarbonsThose 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/Operator15*Alcohol-Resistant AFFFCreate 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/Operator15*High-Expansion Foams

Are special-purpose foams

Have a detergent base

Have a low water content, which minimizes water damage(Continued)



Have three basic applications:In concealed spaces such as basements, coal mines, and other subterranean spacesIn fixed-extinguishing systems for specific industrial uses (rolled or bulk paper storage)In Class A fire applications(Continued)



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/Operator15*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/Operator15*Foam Proportioning DevicesIn 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/Operator15*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/Operator15*In-Line Foam EductorsMust 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/Operator15*Venturi PrincipleAs 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/Operator15*Venturi Principle

Atmospheric pressure forces foam concentrate into a pickup tube and into the water stream, creating a foam/water solution.


Pumping Apparatus Driver/Operator15*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/Operator15*Operating Rules to Observe When Using EductorsFoam 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.

(Continued)


Pumping Apparatus Driver/Operator15*Operating Rules to Observe When Using EductorsMetering 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(Continued)


Pumping Apparatus Driver/Operator15*Operating Rules to Observe When Using EductorsFor 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/Operator15*Foam Nozzle EductorsOperate 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/Operator15*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/Operator15*Self-Educting Master Stream Foam NozzlesAre 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/Operator15*Self-Educting Master Stream Foam NozzlesAdvantage 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/Operator15*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/Operator15*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 2 percent of the total flow in the system(Continued)


Pumping Apparatus Driver/Operator15*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 66 percent solution.(Continued)


Pumping Apparatus Driver/Operator15*Jet Ratio Controller (JRC)

This rich solution is then pumped to a self-educting 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/Operator15*Installed In-Line Eductor SystemsUse 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/Operator15*Installed In-Line Eductor SystemsHave 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/Operator15*Installed In-Line Eductor SystemsAre most commonly used to proportion Class B foams


Pumping Apparatus Driver/Operator15*Around-the-Pump ProportionersAre one of the most common types of built-in proportioners installed in mobile fire apparatus today

(Continued)


Pumping Apparatus Driver/Operator15*Around-the-Pump ProportionersConsist 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/Operator15*Disadvantages of Around-the-Pump 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)



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)



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/Operator15*Bypass-Type Balanced Pressure ProportionersAre 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/Operator15*Bypass-Type Balanced Pressure Proportioners(Continued)


Pumping Apparatus Driver/Operator15*Bypass-Type Balanced Pressure ProportionersAdvantagesIts 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/Operator15*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/Operator15*Bypass-Type Balanced Pressure ProportionersThe 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)



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/Operator15*Bypass-Type Balanced Pressure ProportionersThe 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)



LimitationsIts need for a foam pump with PTO or other power sourceBypass of concentrate in this system can cause heating, turbulence, and foam concentrate aeration


Pumping Apparatus Driver/Operator15*Variable-Flow Variable-Rate Direct Injection SystemsOperate 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/Operator15*Variable-Flow Variable-Rate Direct Injection SystemsAllow full flow through the fire pump discharges because there are no flow-restricting passages in the proportioning system Provide foam concentrate rates from 0.1% to 3%(Continued)


Pumping Apparatus Driver/Operator15*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/Operator15*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/Operator15*Advantages of Variable-Flow Variable-Rate Direct Injection SystemsTheir 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/Operator15*Advantages of Variable-Flow Variable-Rate Direct Injection SystemsNozzles may be either above or below the pump, without affecting the foam proportioning

May be used with high-energy foam systems


Pumping Apparatus Driver/Operator15*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/Operator15*Variable-Flow Demand-Type Balanced Pressure ProportionersAre 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/Operator15*Variable-Flow Demand-Type Balanced Pressure Proportioners


Pumping Apparatus Driver/Operator15*Advantages of Variable-Flow Demand-Type Balanced Pressure Proportioners

The foam concentrate flow and pressure match system demand

No recirculation back to the foam concentration tank

(Continued)


Pumping Apparatus Driver/Operator15*Advantages of Variable-Flow Demand-Type 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/Operator15*Limitation of Variable-Flow Demand-Type 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/Operator15*Batch-Mixing

Is the simplest means of proportioning foam

Is simply pouring an appropriate amount of foam concentrate into a tank of water(Continued)



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/Operator15*Batch-MixingMeans 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 alcohol-resistant AFFF concentrates) and Class A concentrates(Continued)



Can be done at any time, anywhere, and with any equipment, and eliminates the need for costly foam proportioning equipment(Continued)


Pumping Apparatus Driver/Operator15*Batch-MixingNote: 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 vehicles water tank. The flushing operation must be conducted according to the MSDS supplied by the foam manufacturer.


Pumping Apparatus Driver/Operator15*Disadvantages of Batch-MixingClass 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/Operator15*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/Operator15*Disadvantages of Batch-MixingDoes 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/Operator15*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/Operator15*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/Operator15*Advantages of CAFSA 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/Operator15*Advantages of CAFSHoselines 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/Operator15*Disadvantages of CAFSA 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/Operator15*Disadvantages of CAFSThe 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/Operator15*Characteristics of CAFSMost 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/Operator15*Characteristics of CAFSThe 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/Operator15*Characteristics of CAFSVariable-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/Operator15*Characteristics of CAFSMost 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/Operator15*Portable Foam Application Devices

While standard fire fighting nozzles can be used for applying some types of low-expansion foams, it is best to use nozzles that produce the desired result (such as fast-draining or slow-draining foam).


Pumping Apparatus Driver/Operator15*Handline NozzlesAny 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/Operator15*Smooth Bore NozzlesAre 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/Operator15*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/Operator15*Fog NozzlesAre best when used with regular AFFF and Class A foams, but may be used with alcohol-resistant 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/Operator15*Fog NozzlesSome 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/Operator15*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/Operator15*Air-Aspirating Foam NozzlesMay 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/Operator15*Master Stream Foam NozzlesLarge-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.(Continued)


Pumping Apparatus Driver/Operator15*Master Stream Foam NozzlesStandard 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/Operator15*Medium- and High-Expansion Foam Generating DevicesProduce a high-air-content, semistable foamMedium-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/Operator15*Water-Aspirating TypeIs 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/Operator15*Water-Aspirating TypeHas 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/Operator15*Mechanical Blower TypeIs similar in appearance to a smoke ejector

Operates on the same principle as the water-aspirating 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/Operator15*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/Operator15*Reasons for Failure to Generate Foam or for Generating Poor Quality FoamFailure 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/Operator15*Reasons for Failure to Generate Foam or for Generating Poor Quality FoamPartially 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/Operator15*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/Operator15*Various Foam Application Techniques

Direct-application methodFinished Class A foam in applied directly onto the material that is burning.(Continued)


Pumping Apparatus Driver/Operator15*Various Foam Application TechniquesRoll-on methodDirects 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/Operator15*Various Foam Application TechniquesRoll-on method(Continued)


Pumping Apparatus Driver/Operator15*Various Foam Application TechniquesBank-down methodClass B foam stream is directed onto a vertical surface, allowing foam to run down onto and spread across surface of the fuel.(Continued)


Pumping Apparatus Driver/Operator15*Various Foam Application TechniquesRain-down methodDirects stream of Class B foam into the air above fire and allows foam to gently rain down onto surface of fuel.


Pumping Apparatus Driver/Operator15*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/Operator15*Environmental Impact of Class A and Class B Foam Concentrates and SolutionsThe 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/Operator15*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/Operator15*Durable AgentsAre 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/Operator15*Durable AgentsAre 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/Operator15*Durable AgentsAre different from Class A foam in that they:Are water-absorbent polymers rather than hydrocarbon-based surfactants like Class A foamsWhen mixed with water, form minute polymer bubbles that are filled with water; Class A foams form tiny water bubbles that are filled with airAre considerably more expensiveMake surfaces to which applied very slippery(Continued)


Pumping Apparatus Driver/Operator15*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/Operator15*Durable AgentsCan 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/Operator15*Durable AgentsAre normally applied at 1 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/Operator15*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)



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)



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)



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)



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/Operator15*Discussion Questions1.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/Operator15*Discussion Questions5.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.


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Foam Fighting