Fire Apparatus Driver/Operator Chapter 14

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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?

<p>Good mechanical agitation and effective aeration (A)</p> Signup and view all the answers

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

<p>Hydrocarbon fuels have a lower surface tension than water (B)</p> Signup and view all the answers

Which type of fires are Class A foams effective on?

<p>Ordinary combustibles and organic materials (D)</p> Signup and view all the answers

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

<p>A wetting agent enhances penetration into burning fuel by reducing water's surface tension (D)</p> Signup and view all the answers

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

<p>Polar solvents readily mix with water, degrading the foam's effectiveness (C)</p> Signup and view all the answers

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

<p>The ability of foam to minimize fuel pickup (B)</p> Signup and view all the answers

What are Class A foams primarily used for extinguishing?

<p>Ordinary combustibles like wood and paper (D)</p> Signup and view all the answers

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

<p>Hydrocarbon and polar solvent fires (A)</p> Signup and view all the answers

What is film-forming fluoroprotein foam able to do?

<p>Form a vapor-sealing film on nonpolar solvents (D)</p> Signup and view all the answers

What is the purpose of aqueous film-forming foam?

<p>Be compatible with dry chemical agents (B)</p> Signup and view all the answers

What is the composition of fluoroprotein foam?

<p>Hydrolyzed protein, stabilizers, preservatives, and synthetic fluorocarbon surfactants (D)</p> Signup and view all the answers

What type of nozzle should be used with protein foams?

<p>Aspirating nozzle (A)</p> Signup and view all the answers

What is the primary source of protein for protein foams?

<p>Keratin protein derived from chicken feathers (A)</p> Signup and view all the answers

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

<p>Alcohol-resistant film-forming fluoroprotein foam (C)</p> Signup and view all the answers

What is the primary purpose of AR-AFFF foam?

<p>Providing good knockdown and burnback resistance on polar solvent and hydrocarbon fires (C)</p> Signup and view all the answers

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

<p>1 to 6% (B)</p> Signup and view all the answers

What does the foam expansion rate measure?

<p>The ratio of finished foam to foam solution after mixing with water (A)</p> Signup and view all the answers

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

<p>They achieve extinguishment and fire control by rapid smothering and cooling (A)</p> Signup and view all the answers

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

<p>Up to 20:1 (C)</p> Signup and view all the answers

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

<p>20:1 to 200:1 (A)</p> Signup and view all the answers

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

<p>200:1 to 1,000:1 (A)</p> Signup and view all the answers

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

<p>All of the above (D)</p> 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?

<p>Pump mount eductor (C)</p> 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?

<p>200 psi (B)</p> Signup and view all the answers

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

<p>0% - 6% (D)</p> 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?

<p>No more than 150 ft from the nozzle and no more than 6 ft above the surface of the foam concentrate (D)</p> Signup and view all the answers

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

<p>Variable flow discharge rate allows for adjustment of the foam depending on the specific application (D)</p> Signup and view all the answers

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

<p>10 psi (D)</p> 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?

<p>Balanced pressure system (C)</p> Signup and view all the answers

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

<p>0.1 to 10% (D)</p> Signup and view all the answers

How is foam concentrate injected in injection systems?

<p>At only one point in the discharge manifold (D)</p> Signup and view all the answers

What is a benefit of a CAFS system?

<p>Foam produced works 4 - 5 times faster than water in suppressing a fire (A)</p> Signup and view all the answers

What is a potential problem with CAFS?

<p>Foam must be present in the stream prior to injecting air, if no foam is present the line will act erratically (C)</p> Signup and view all the answers

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

<p>Contains approximately 30% compressed air (B)</p> Signup and view all the answers

What is the shelf life range of protein concentrate?

<p>7 - 10 years (D)</p> Signup and view all the answers

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

<p>On a pool of flammable product located on the ground (A)</p> Signup and view all the answers

In which scenario is the raindown method used?

<p>When there is no vertical object to use and it would be too dangerous to get close and use the roll-on method (B)</p> Signup and view all the answers

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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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