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IFSTA Pumping Apparatus, Driver Operator > Chapter 15, Foam Equipment And Systems > Flashcards

Chapter 15, Foam Equipment And Systems Flashcards

1
Q

What are the 3 main reasons why the use of foam has increased dramatically?

A
  • frequency of hazmat incidents
  • new advances in foam concentrate technology
  • improvements in foam proportioning equipment
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2
Q

The majority of foams used today are the mechanical type. What 2 steps need to take place to mechanical foams before they can be used as fire fighting foam?

A
  • proportioned (mixed with water)

- aerated (mixed with air)

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3
Q

To produce quality foam, what 4 things are needed?

A
  • foam concentrate
  • air
  • water
  • mechanical aeration
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4
Q

What is foam concentrate?

A

Raw liquid foam (before combined with water and air).

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5
Q

What is a foam proportioner?

A

The device that introduces foam concentrate into a water stream to create foam solution.

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6
Q

What is foam solution?

A

The mixture of foam concentrate into water before introduction of air.

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7
Q

What is foam?

A

The completed product after air is introduced to foam solution (finished foam).

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8
Q

What are the 2 categories of Class B foam?

A
  • hydrocarbons (gas, crude oil, jet fuel)

- polar solvents (alcohol, lacquer thinner)

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9
Q

Class B foam is effective as an extinguishing agent and vapor suppressant because it can do what?

A

Float on the surface of hydrocarbon fuels.

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10
Q

By what method does foam extinguish/prevent fire?

A
  • separating (create barrier between fuel and fire)
  • cooling (lowers temp of fuel and adjacent surfaces)
  • suppressing (prevents release of vapors; smothers)
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11
Q

What is the difference in proportioning Class B foams, compared to Class A foams?

A

Class B foams MUST be proportioned in the specific percentage they are designed for; Class A foams can be adjusted to higher or lower percentages.

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12
Q

What happens when you vary the proportioning percentages of class A foam?

A
  • to produce a dry (thick) foam, adjust concentrate to a higher percentage
  • to produce a wet (thin) foam, adjust concentrate to a lower percentage
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13
Q

What are the 4 basic methods in which foam may be proportioned?

A
  • induction (water passes through educator, pulls concentrate into water stream
  • injection (external pump forces foam concentrate into water stream at the correct ratio)
  • batch mixing (appropriate amount of concentrate is poured directly into tank)
  • premixing (premeasured water and foam concentrate mixed into a container; portable extinguisher)
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14
Q

What are the 4 common methods of storing foam concentrate for municipal/wild land fire?

A
  • pails (5 gallon plastic, airtight)
  • barrels (plastic, airtight)
  • totes (for bulk purchasing, reduces cost)
  • apparatus tanks (piped directly to foam delivery system)
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15
Q

Mechanical foam is technically divided into what 2 categories?

A
  • Class A (ordinary combustibles)

- Class B (flammable/combustible liquids)

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16
Q

When performing fire attack and overhaul with standard fog nozzles, what percentage of Class A foam concentrate do you use?

A

.2% to .5%

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17
Q

When providing exposure protection with standard fog nozzles, what percentage of Class A foam concentrate do you use?

A

.5% to 1.0%

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18
Q

When using any application of Class A foam with air aspirating nozzles, what percentage of Class A foam concentrate do you use?

A

.3% to .7%

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19
Q

What percentage of Class A foam concentrate is used for any application with compressed air foam system (CAFS)?

A

.2% to .5%

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20
Q

When using Class A foam, areas requiring maximum penetration need what consistency of foam?

A

Wet foam (high water content, very fast drainage).

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21
Q

When using Class A foam for vertical surfaces, what foam consistency is needed?

A

Dry foam (slow drainage rate makes it cling, resembles shaving cream).

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22
Q

When using Class A foam in areas requiring a balance of penetration and clinging ability, what foam consistency is needed?

A

Medium foam (blankets and wets foam equally well).

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23
Q

Class B foam concentrates are manufactured out of what type of materials?

A

Either a protein base or synthetic base.

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24
Q

What percentages are Class B foams proportioned in?

A

1% to 6% (normally 1 to 3 for hydrocarbons, and 3 to 6 for polar solvents).

25
Q

What is foam expansion?

A

The increase in the volume of foam solution when it is aerated.

26
Q

What factors play a role in the varying degrees of Class B foam expansion?

A
  • type of foam concentrate used
  • accurate proportioning of concentrate in the solution
  • quality of foam concentrate
  • method of aspiration
27
Q

What variables determine the rate of application of fire fighting foam?

A
  • type of concentrate used
  • whether or not the fuel is on fire
  • type of fuel (hydro or polar)
  • whether fuel is spilled or in a tank
28
Q

What is the most commonly used foam today?

A

AFFF (completely synthetic).

29
Q

What 3 things occur when AFFF is applied to a hydrocarbon fire?

A
  • vapor-excluding film is released ahead of foam blanket
  • fast moving foam blanket moves across surface and around objects (more insulation)
  • as foam blanket continues to drain water, more film is released
30
Q

What are concentrations for alcohol-type AFFF when used on polar solvents?

A

3% to 6% (create a membrane over fuel instead of a film).

31
Q

How should alcohol type AFFF be applied to the fuel?

A

Gently, so that membrane can form first (sprayed over top of fuel, not plunged into the fuel).

32
Q

What are high-expansion foams?

A

Special purpose foams with a detergent base (low water content minimizes water damage).

33
Q

What are the three applications of high-expansion foams?

A
  • in concealed spaces, such as basements
  • in fixed-extinguishing systems for industrial use (bulk paper storage)
  • class A fire applications
34
Q

Foam proportioning devices operate under what 2 principles?

A
  • pressure of water streaming through a restricted orifice creates venture action (pulls foam into the stream)
  • pressurized proportioning devices inject foam concentrate into water stream (at a chosen ratio)
35
Q

How does low-energy foam system operate?

A

Introduces air into the solution when it reaches, or is discharged from, the nozzle.

36
Q

How does high-energy foam system operate?

A

Introduces compressed air into the solution before its discharged from the hose line.

37
Q

What are the 3 common types of portable foam proportioners?

A
  • in-line eductors
  • foam nozzle eductors
  • self-educting master stream nozzles
38
Q

How does in-line eductor work?

A

Either directly attaches to pump panel discharge or connected at some point in the hose lay (uses venture to pull foam concentrate into water stream).

39
Q

On the in-line eductor, back pressure must not exceed how much of the eductor inlet pressure?

A

67 to 70 percent.

40
Q

In order for the eductor and the nozzle to operate correctly, both must have the same gpm rating. Which controls the flow, the eductor or the nozzle?

A

The eductor controls the flow.

41
Q

How does foam nozzle eductor work?

A

It is built into the nozzle, instead of the hose line (foam concentrate has to be where the nozzle is operated).

42
Q

How does self-educting master stream nozzle work?

A

Used where flows in excess of 350 gpm are needed.

43
Q

How does the installed in-line educator system operate?

A

These are permanently attached to the apparatus pumping system (operates same as portable in-line educator).

44
Q

How does the bypass-type balanced pressure proportioner operate?

A

Usually found on large scale mobile trucks (airport trucks). Can flow foam and water at the same time.

45
Q

How does variable-flow variable-rate direct injection operate?

A

Operates off power supplied from trucks electrical system.

46
Q

What is the unique difference with the variable-flow demand-type balanced pressure proportioner?

A

It is maintained in a ready-to-pump state, requires no flushing after use, water and foam discharged at same time.

47
Q

How does batch-mixing work?

A

Pour appropriate amount of concentrate into tank (simplest form).

48
Q

What are some advantages of using CAFS?

A
  • much longer reach than low-energy foam
  • sticks to fuel surface longer, resists heat longer
  • allows application from a greater distance
  • hose lines weigh less
49
Q

What type of pump is used foe CAFS system?

A

A standard centrifugal pump.

50
Q

With LOW ENERGY foam systems, how is aeration and foam discharge accomplished?

A

By the foam nozzle.

51
Q

How does IFSTA define a hand line nozzle?

A

Any nozzle that 1 to 3 fire fighters can safely handle and that flows under 350 gpm.

52
Q

What foam applications can smoothbore nozzles be used on?

A
  • class A

- CAFS

53
Q

What types of foam provides the best application when used with fog nozzle?

A
  • AFFF

- Class A

54
Q

How does an air-aspirating foam nozzle operate?

A

It inducts air into the foam solution by a venture action.

55
Q

What are the 2 basic types of medium and high-expansion foam generators?

A
  • water-aspirating type: large nozzle with screen at the end to further break up foam and mix it with air
  • mechanical blower: air forced through foam spray by a powered fan (total flooding app, huge discharge)
56
Q

What are the 4 types of foam application methods?

A
  • direct application (Class A foam)
  • roll-on (direct on ground near front edge of burning spill: Class B foam)
  • bank-down (spray on wall, flows down wall onto surface of spill; Class B)
  • rain-down (use on above ground storage tanks; Class B)
57
Q

What is the primary environmental concern of finished foams?

A

Its impact after it applied to a spill (Class A foams are lethal to fish).

58
Q

What are durable agents?

A

Water additives used to aid in extinguishment (water wetter), as well as a pretreat for structures threatened by fires.

IFSTA Pumping Apparatus, Driver Operator (7 decks)

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