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Essentials of Fire Fighting > Foam Fire Fighting, Liquid Fires, and Gas Fires > Flashcards

Foam Fire Fighting, Liquid Fires, and Gas Fires Flashcards

1
Q

In what four ways does foam extinguish/prevent reignition of flammable liquid fires and flammable gas fires?

A
  • Seperating, by creating a barrier between fuel gases and ignition souces
  • Cooling, lowers temperature of fuel
  • Smothering, prevents oxygen from contacting fuel
  • Penetrating, lowers surface tension of water to ease penetration.
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2
Q

What is Class A foam used for?

A

It is used on ordinary combustibles and as a preventative agent.

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3
Q

What are Class B foams used for?

A

They are used to extinguish flammable liquid fires by preventing the release of flammable vapors. They are especially good at suppressing hydrocarbons and polar solvents.

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4
Q

How is foam generated?

A

A foam proportioner mixes the foam concentrate with water and then it is aerated to create the bubbles. if the ratio of foam concentrate to water is incorrect the foam will lose affectiveness.

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5
Q

When would you want to use a Low-expansion foam?

A
  • On most Class B fires

- Class A fires

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6
Q

When would you want to use a Medium-expansion foam?

A

When you need to suppress vapors from hazardous material spills.

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7
Q

When would you want to use a High-expansion foam?

A

In confined spaces like mines and basements

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8
Q

What four factors affect the degree of expansion of foam?

A
  • Type of foam concentrate used
  • Accurate proportioning
  • Quality of the foam concentrate
  • Method of aeration.
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9
Q

What are the three primary types of nozzles used in the application of type A and B foams?

A
  • Fog
  • Air aspirating
  • Medium expansion
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10
Q

What is a surfactant?

A

Chemical that lowers the surface tension of a liquid. Class A foam is a surfactant.

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11
Q

True or false, You can use Class B foam designed for polar solvants on hydrocarbon fires, but you cannot use Class B foam designed for hydrocarbons on polar solvants.

A

True

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12
Q

True or false, never apply foam to an unignited flammable liquid spill as it will just spread it around and make clean up more difficult.

A

False, by applying foam to the unignited spill, you prevent potential ignition.

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13
Q

True or false, Foam exposure can lead to increased rates of cancer in firefighters.

A

False, it is mostly harmless. Only slight iritation if it gets in the eyes. It can also degrade PPE.

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14
Q

True or false, Foam can harm water ecosystems by preventing oxygen from entering the water.

A

True, firefighters must ensure that foam will not enter water bodies.

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15
Q

If you have 5 liters of a 6% foam, how many liters of water do you need to pass through the hose to use up all the foam concentrate?

A
  1. 94/0.06=15.66 (15.66L of water per 1 liter of foam concentrate)
  2. 66X5L=78.33L
  3. 33 liters of water + 5 liters of foam + 83.33 total liters

If you have 5 liters of foam concentrate, you need 78.33 liters of water to create a 6% proportion. In total, 83.33% of foam water mix is used.

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16
Q

What is the typical foam to water concentration of Class A foams?

A

One percent or less.

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17
Q

What is the typical foam to water concentration of Class B foam?

A

One to six percent

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18
Q

True or false, all foam proportioning equipment is intended to be used on mobile apparatus.

A

False, there are also fixed fire protection systems, and portable.

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19
Q

What four factors determine the selection of proportioners?

A
  • Foam solution flow requirements
  • Available water pressure
  • Intended use of the foam
  • Foam agent to be used
20
Q

What are the three methods by which foam can be proportioned?

A
  • Eduction - Uses an eductor and the venturi effect to draw foam up through a tube in the foam container
  • Injection - Uses a pump to force the foam into the water.
  • Premixing - The foam and water are premixed in a pressurized tank like an extinguisher. If unused for too long the foam can go bad.
21
Q

List the four essential pieces of equipment in the application of foam.

A
  • Pump
  • Hose
  • Proportioner
  • Foam delivery device
22
Q

What are the four kinds of foam proportioners?

A
  • In-line foam eductors - Foam in introduced to the hoseline at the pump.
  • Foam nozzle eductors - Foam is introduced to the hoseline at the nozzle. Rarely used
  • Apparatus-mounted proportioners - Are present on the apparatus
  • Compressed air foam systems - Mixes water, air and foam at the same time on the apparatus
23
Q

What are the advantages of using a fog nozzle over a foam nozzle?

A

Fog nozzles do not aerate the foam before it exits the nozzle, rather it becomes aerated once it travels through the air.

  • Widely available
  • Quicker set-up when using preconnected hose
  • Greater reach
24
Q

What are the disadvantages of using a fog nozzle for foam application over a foam nozzle?

A
  • More difficult to correctly apply foam to the fire.
  • Longer to set up properly
  • Lower quality foam
25
Q

How does a foam nozzle work?

A

It draws foam into the water stream through the venturi effect, and aeration to create optimal foam.

26
Q

Name the three foam application methods

A
  • Roll-on
  • Bank-down
  • Rain-down
27
Q

When do you us a roll-on method?

A

Only for small pools of ignited or unignited flammable liquid fire that are not near a structure or wall.

28
Q

When do you us the bank-down method?

A

When there is an ignited or unignited pool of flammable liquid near a wall or structure.

29
Q

When do you us the rain-down method?

A

On ignited or unignited flammable liquid fires that are too large for roll-on and bank-down methods. Also on elevated fires.

30
Q

Where should the safety area be in relation to the flammable liquid fires?

A

uphill upwind

31
Q

What is the flashpoint of flammable liquids?

A

Less than 38C

32
Q

What is the flashpoint of combustible liquids?

A

Greater than 38C

33
Q

True or false, a HAZMAT team must be called to an incident with spilled Flammable or combustible gas.

A

True

34
Q

True or false, in an incident that includes a propane leak, the propane company should be called as they are trained to identify and fix leaks.

A

True

35
Q

True or false, it is a myth that propane tanks explode if they catch fire. Still caution is required when working around them.

A

False, they certainly explode.

36
Q

True or false, the best way to control a flammable liquid leak fire is often to seperate the fuel from the flames by closing the open valve. If you see that a valve is open, you should report it to your supervisor and proceed to shut it off.

A

While it is true that you can control the fire by turning off the valve, and that you should report a valve to your supervisor, no valve can be touched by firefighters, even those with training, without the supervision of facility personel.

37
Q

What defines a pressurized vessel?

A

One with at least 15 psi

38
Q

What is a BLEVE?

A

Boiling Liquid Expanding Vapor Explosion

39
Q

When does a BLEVE occur?

A

When the liquids or liquified gases in pressure vessels boil and vaporize, which causes massive expansion and explosions.

40
Q

True or false, pressure relief valves are often enough to relieve the pressure inside a pressure vessel if it is in direct contact with fire.

A

False

41
Q

Describe the safest way to fight fire under a pressure vessel

A

-Fight the fire as far away from it as you can get. This means applying water to the top of the vessel with a master stream from long distances or with an unattended stream device. Spray the containers with cool water even after the fire is out to cool the liquid or gas inside. Don’t spray the leaking area. If you hear the venting devices begin to rapidly increase in pitch, an explosion is likely and you should evacuate immediately.

42
Q

Why is it harder to fight a fire involving a transport truck with a load of liquid flammable gas than at a storage facility?

A
  • Danger to firefighters from traffic
  • Danger to motorists
  • Less available water
  • Harder to identify the product burning
  • Difficulty controling run-off
43
Q

Where can you find information about the product being transported on a transport truck?

A

Manifest, placards, or driver of the transport. If these are unavailable, you can call the manufacturer

44
Q

If a transport cylinder explodes, where is the safest place to be?

A

During explosions, fragments will fly in every direction, so the best place to be is far away behind a barrier.

45
Q

True or false, you should not extinguish a compressed natural gas fire, instead protect the surrounding area and have the manufacturer turn off the gas line.

A

True

Essentials of Fire Fighting (26 decks)

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