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Apparatus Tech > IFSTA Chapter 14 Foam Equipment > Flashcards

IFSTA Chapter 14 Foam Equipment Flashcards

1
Q

How is Firefighting foam produced

A

Foam Concentrate, water and air must be educted or injected at the correct ratios

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2
Q

Foam Concentrate

A

Raw foam liquid in its storage container before being combined with water and air

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3
Q

Foam Proportioner

A

Device that injects the correct amount of foam concentrate into the water stream

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4
Q

Foam Solution

A

Mixture of foam concentrate and water without air

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5
Q

Foam

A

Completed product after air is introduced into the foam solution

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6
Q

What are class B fires divided into

A

Hydrocarbons: Crude Oil, Fuel Oil, Gasoline, Benzene and Kerosene (Specific gravity <1)

Polar Solvents: Alcohol, Acetone, ketones, and esters (miscible)

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7
Q

Class B foams are designed solely for use on ____________ and are not effective on ____________ regardless of concentration

A

Hydrocarbon fuels not effective on polar solvents

some foams intended for polar solvents may be used on hydrocarbon fuels under manufacturer instructions

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8
Q

What is Proportioning

A

The act of mixing of fresh/salt water with foam to form a solution

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9
Q

Most firefighting foams are formulated to mix with what percent water

A

94 to 99.9

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10
Q

Four Basic methods of proportioning foam

A

Inductions

Injection

Batch Mixing

Premixing

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11
Q

What is Class A foam concentrate composed of

A

Hydrocarbon surfactants that reduce the surface tension of water allowing penetration

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12
Q

Properly stored foam has a shelf life of?

A

20 years

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13
Q

Commonly used percentages for different scenarios when proportioning Class A foam

Fire Attack and Overhaul:
Exposure Protection:
Any Application with air aspirating Nozzle:
CAFS:

A

Fire attack and overhaul .2 to .5% with Fog Nozzle

Exposure Protection .5 to 1% with fog nozzle

Any Application with Air Aspirating Nozzle: .3 to .7%

CAFS: .2 to .5%

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14
Q

What Does application rate refer to

A

Minimum amount of foam solution that must be applied to a fire per minute per square foot

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15
Q

What is Synthetic Class B foam made out of

A

Fluorosurfactants

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16
Q

What shelf life does Class B foam have

A

20 to 25 years

17
Q

To what percentages are Class B foams proportioned to

A

One to Six Percent

Hydrocarbon Fuels: 1 to 3%

Polar Solvents: 3 to 6%

18
Q

What is Foam Expansion

A

Increase in volume of foam solution once it has been aerated

19
Q

Per NFPA 11 what do the different foam expansion ratios contain?

A

Low: 20:1 finished foam to foam solution

Medium: 20:1 to 200:1

High: 200:1 to 1000:1

20
Q

Formula to calculate the application rate available from a specific nozzle

A

Nozzle Flow Rate / by the area of the fire

21
Q

When AFFF is applied to a hydrocarbon fuel what occurs
How does the foam HEAL

A

Air/Vapor excluding film is released ahead of the foam blanket

Blanket of Foam spreads across surface providing insulation

As water is released from the aerated foam blanket more film is released giving the foam the ability to “HEAL”

22
Q

How does AR-AFFF foams work

How should it be applied

A

Applied to polar solvents, a membrane is created over the fuel which separates the water into the foam blanket.

Should be applied gently to a fuel product in order to allow the membrane to form

23
Q

Different types of foam proportioning eductors

A

In-Line Eductors

Foam Nozzle Eductors

Self Educting master stream nozzles

24
Q

When using an In-line Eductor what pressure percent must not be exceeded on the discharge side of the eductor

A

Discharge pressures must not exceed 70% of the eductor inlet pressure. This creates back pressure

25
Q

How do you calculate back pressure on an in-line eductor

A

Nozzle Pressure + FL between eductor and nozzle + elevation pressure

26
Q

Step to take after a foam operation using an inline eductor

A

Use a bucket of water to immerse the foam pick up tube and induct water for atleast 1 minute

27
Q

What height should the foam concentrate inlet to the eductor be from the liquid surface of the concentrate

A

should not be more than 6 feet between foam inlet and liquid surface of concentrate

28
Q

What must be the same between the nozzle and the eductor to operate successfully

A

Attack nozzle and eductor must have the same GPM

29
Q

How does a bypass proportioning system work

A

In bypass mode a valve directs water through a second chamber of the eductor that contains no orifice or restrictions

To activate foam being used a valve is directed to divert water through the eductor

30
Q

In a bypass proportioning system what is included in the system to ensure proper foam concentrates are applied

A

A metering valve is present at the valve that activates with water running through eductor

31
Q

How is an around the pump system built
How many gpms of water is allowed to flow to create the foam drawing Venturi effect

A

A small return water line containing an eductor and a control valve is connected to the discharge side of the pump back to the intake side.

The valve allows between 10 to 40 gpm to flow through the piping creating a Venturi that draws foam from onboard tank

Once mixed it enters the intake side of the pump

32
Q

(CAFS) system contains what type of air compressor, pump and proportioner

how does it operate

A

Rotary Air Compressor, a standard centrifugal pump, a direct injection proportioner is attached to the discharge side of the pump

Once concentrate is mixed with water compressed air is added before being discharged from the apparatus to the hose line

33
Q

Benefits of CAFS generated foam

A

Reach of the fire stream is longer

Produces small uniform air bubbles (very durable)

Adheres to fuel surfaces

resists heat longer

34
Q

What airflow from compressor when using CAFS produces dry foam of up to 100 gpm?

A

2 cubic ft/minute of airflow per gpm

Apparatus Tech (58 decks)

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