Fire Apparatus Driver/Operator Chapter 14: Effective Foams for Polar Solvents Quiz and Flashcards

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Questions and Answers

What elements are needed to produce finished foam according to the foam tetrahedron?

Water, foam concentrate, air, mechanical agitation (correct)

Water, foam concentrate, heat, chemical reaction

Water, air, chemical reaction, mechanical agitation

Water, foam concentrate, fuel, air

How does foam extinguish flammable liquid fires?

By forming a blanket on the surface to separate the fuel from the air and lower the temperature of the fuel (correct)

By evaporating the flammable liquid

By increasing the temperature of the fuel to a level where it cannot burn

By creating a chemical reaction with the flammable liquid

What are the two basic types of foam?

Chemical foam and mechanical foam (correct)

Wet foam and dry foam

Fast foam and slow foam

Thick foam and thin foam

What is essential for the expansion of foam solution?

Good mechanical agitation and effective aeration Signup and view all the answers

What is the primary reason hydrocarbon fuels separate from water when mixed?

Hydrocarbon fuels have a lower surface tension than water Signup and view all the answers

Which type of fires are Class A foams effective on?

Ordinary combustibles and organic materials Signup and view all the answers

How does a wetting agent differ from foam in combating fuel fires?

A wetting agent enhances penetration into burning fuel by reducing water's surface tension Signup and view all the answers

Why are Class B foams ineffective on polar solvent and water-miscible fuels like acetone?

Polar solvents readily mix with water, degrading the foam's effectiveness Signup and view all the answers

What does fuel resistance refer to in the context of foam?

The ability of foam to minimize fuel pickup Signup and view all the answers

What are Class A foams primarily used for extinguishing?

Ordinary combustibles like wood and paper Signup and view all the answers

What type of fires are Class B foams designed to extinguish?

Hydrocarbon and polar solvent fires Signup and view all the answers

What is film-forming fluoroprotein foam able to do?

Form a vapor-sealing film on nonpolar solvents Signup and view all the answers

What is the purpose of aqueous film-forming foam?

Be compatible with dry chemical agents Signup and view all the answers

What is the composition of fluoroprotein foam?

Hydrolyzed protein, stabilizers, preservatives, and synthetic fluorocarbon surfactants Signup and view all the answers

What type of nozzle should be used with protein foams?

Aspirating nozzle Signup and view all the answers

What is the primary source of protein for protein foams?

Keratin protein derived from chicken feathers Signup and view all the answers

What type of foam can be used on both hydrocarbon and water-soluble fuels?

Alcohol-resistant film-forming fluoroprotein foam Signup and view all the answers

What is the primary purpose of AR-AFFF foam?

Providing good knockdown and burnback resistance on polar solvent and hydrocarbon fires Signup and view all the answers

What is the recommended range for foam concentrate ratios for Class B foams?

1 to 6% Signup and view all the answers

What does the foam expansion rate measure?

The ratio of finished foam to foam solution after mixing with water Signup and view all the answers

Why are high expansion foams highly effective in confined space firefighting operations?

They achieve extinguishment and fire control by rapid smothering and cooling Signup and view all the answers

What is the foam expansion ratio of low-expansion foam?

Up to 20:1 Signup and view all the answers

What is the expansion ratio range of medium-expansion foam?

20:1 to 200:1 Signup and view all the answers

What is the expansion ratio range of high-expansion foam?

200:1 to 1,000:1 Signup and view all the answers

What is the primary problem with batch mixing of foam concentrate?

All of the above Signup and view all the answers

Which type of eductor is permanently mounted to the fire pump and dedicated to producing foam from a single discharge?

Pump mount eductor Signup and view all the answers

What is the necessary inlet pressure for an eductor to overcome friction loss through the eductor and between the nozzle and eductor?

200 psi Signup and view all the answers

What is the adjustable range of settings for metering devices controlling the flow of concentrate into the eductor?

0% - 6% Signup and view all the answers

Where should an in-line eductor be attached to the hoseline in relation to the nozzle and surface of the foam concentrate?

No more than 150 ft from the nozzle and no more than 6 ft above the surface of the foam concentrate Signup and view all the answers

What is a key advantage of around-the-pump proportioning systems (AP systems) for foam application?

Variable flow discharge rate allows for adjustment of the foam depending on the specific application Signup and view all the answers

What is the maximum inlet pressure to the water pump on an AP system?

10 psi Signup and view all the answers

What type of system uses a diaphragm-type pressure control valve to balance pressures in foam concentrate and water lines?

Balanced pressure system Signup and view all the answers

What is the range of injection rates for foam concentrate in injection systems?

0.1 to 10% Signup and view all the answers

How is foam concentrate injected in injection systems?

At only one point in the discharge manifold Signup and view all the answers

What is a benefit of a CAFS system?

Foam produced works 4 - 5 times faster than water in suppressing a fire Signup and view all the answers

What is a potential problem with CAFS?

Foam must be present in the stream prior to injecting air, if no foam is present the line will act erratically Signup and view all the answers

What is a characteristic of the attack line in a CAFS system?

Contains approximately 30% compressed air Signup and view all the answers

What is the shelf life range of protein concentrate?

7 - 10 years Signup and view all the answers

When should the sweep (roll-on) method be used?

On a pool of flammable product located on the ground Signup and view all the answers

In which scenario is the raindown method used?

When there is no vertical object to use and it would be too dangerous to get close and use the roll-on method Signup and view all the answers

Study Notes

The Foam Tetrahedron

Four elements are required to produce finished foam: a surfactant, a fuel, air, and water.

Foam Extinguishment

Foam extinguishes flammable liquid fires by creating a barrier between the fuel and oxygen, smothering the fire.
Foam also cools the fuel, reducing the likelihood of re-ignition.

Types of Foam

There are two basic types of foam: Class A and Class B.
Class A foams are used for extinguishing fires involving ordinary combustibles, such as wood, paper, and cloth.
Class B foams are used for extinguishing fires involving flammable liquids, such as gasoline, oil, and paints.

Expansion of Foam Solution

Water is essential for the expansion of foam solution.

Hydrocarbon Fuels

Hydrocarbon fuels separate from water when mixed because they are non-polar and do not mix with water.

Class A Foams

Class A foams are effective on fires involving ordinary combustibles.
Class A foams are primarily used for extinguishing fires involving wood, paper, and cloth.

Wetting Agents vs. Foam

A wetting agent differs from foam in combating fuel fires because it reduces the surface tension of water, allowing it to penetrate and cool the fuel more effectively.
Foam, on the other hand, creates a barrier between the fuel and oxygen, smothering the fire.

Class B Foams

Class B foams are designed to extinguish fires involving flammable liquids.
Class B foams are ineffective on polar solvent and water-miscible fuels like acetone because they do not form a stable foam blanket.

Fuel Resistance

Fuel resistance refers to the ability of a fuel to resist the extinguishing properties of foam.

Fluoroprotein Foam

Film-forming fluoroprotein foam is able to form a thin, insoluble film on the surface of the fuel, preventing re-ignition.
The composition of fluoroprotein foam includes a mixture of protein and fluorinated surfactants.

Aqueous Film-Forming Foam (AFFF)

The purpose of AFFF is to create a thin, insoluble film on the surface of the fuel, preventing re-ignition.
AFFF is primarily used for extinguishing fires involving hydrocarbon fuels.

Protein Foams

Protein foams should be used with a low-expansion nozzle.
The primary source of protein for protein foams is animal by-products, such as hydrolyzed protein or keratin.

AR-AFFF Foam

AR-AFFF foam is a type of foam that can be used on both hydrocarbon and water-soluble fuels.
The primary purpose of AR-AFFF foam is to provide a versatile and effective firefighting agent for a wide range of fuels.

Foam Concentrate Ratios

The recommended range for foam concentrate ratios for Class B foams is between 1% and 6%.

Foam Expansion Rate

The foam expansion rate measures the volume of foam produced per unit of foam concentrate.

High-Expansion Foams

High-expansion foams are highly effective in confined space firefighting operations because they can fill a large volume of space quickly.
The expansion ratio of high-expansion foam is typically above 200:1.

Low-Expansion Foams

The foam expansion ratio of low-expansion foam is typically below 20:1.

Medium-Expansion Foams

The expansion ratio range of medium-expansion foam is between 20:1 and 200:1.

Batch Mixing of Foam Concentrate

The primary problem with batch mixing of foam concentrate is that it can lead to inconsistent foam quality and quantity.

Eductors

A fixed eductor is permanently mounted to the fire pump and dedicated to producing foam from a single discharge.
The necessary inlet pressure for an eductor to overcome friction loss through the eductor and between the nozzle and eductor is typically between 50 and 100 psi.
The adjustable range of settings for metering devices controlling the flow of concentrate into the eductor is typically between 1% and 6%.

In-Line Eductors

An in-line eductor should be attached to the hoseline between the nozzle and the surface of the foam concentrate.

Around-the-Pump Proportioning Systems (AP Systems)

A key advantage of AP systems is that they provide a consistent and accurate foam concentrate ratio.
The maximum inlet pressure to the water pump on an AP system is typically 100 psi.

Pressure-Controlled Systems

This type of system uses a diaphragm-type pressure control valve to balance pressures in foam concentrate and water lines.

Injection Systems

The range of injection rates for foam concentrate in injection systems is typically between 1% and 6%.
Foam concentrate is injected in injection systems through a metering valve that controls the flow of concentrate into the water stream.

Compressed Air Foam Systems (CAFS)

A benefit of CAFS is that it provides a high-volume, high-pressure foam solution that can be used for a wide range of firefighting applications.
A potential problem with CAFS is that it can be difficult to maintain the proper foam concentrate ratio.
A characteristic of the attack line in a CAFS system is that it uses a compressed air source to generate foam.

Protein Concentrate

The shelf life range of protein concentrate is typically between 5 and 10 years.

Sweep (Roll-On) Method

The sweep (roll-on) method should be used when the fire is located at a distance from the nozzle.

Raindown Method

The raindown method is used when the fire is located above the nozzle, such as in a fuel tank or on a roof.

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Fire Apparatus Driver/Operator Chapter 14

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