IFSTA Chapter 14 Foam Equipment

Question 1

How is Firefighting foam produced

Answer 1

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

Question 2

Foam Concentrate

Answer 2

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

Question 3

Foam Proportioner

Answer 3

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

Question 4

Foam Solution

Answer 4

Mixture of foam concentrate and water without air

Question 5

Foam

Answer 5

Completed product after air is introduced into the foam solution

Question 6

What are class B fires divided into

Answer 6

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

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

Question 7

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

Answer 7

Hydrocarbon fuels not effective on polar solvents

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

Question 8

What is Proportioning

Answer 8

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

Question 9

Most firefighting foams are formulated to mix with what percent water

Answer 9

94 to 99.9

Question 10

Four Basic methods of proportioning foam

Answer 10

Inductions

Injection

Batch Mixing

Premixing

Question 11

What is Class A composed of

Answer 11

Hydrocarbon surfactants that reduce the surface tension of water allowing penetration

Question 12

Properly stored foam has a shelf life of?

Answer 12

20 years

Question 13

Commonly used percentages for different scenarios when proportioning Class A foam

Answer 13

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%

Question 14

What Does application rate refer to

Answer 14

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

Question 15

What is Synthetic Class B foam made out of

Answer 15

Fluorosurfactants

Question 16

What shelf life does Class B foam have

Answer 16

20 to 25 years

Question 17

To what percentages are Class B foams proportioned to

Answer 17

One to Six Percent

Hydrocarbon Fuels: 1 to 3%

Polar Solvents: 3 to 6%

Question 18

What is Foam Expansion

Answer 18

Increase in volume of foam solution once it has been aerated

Question 19

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

Answer 19

Low: 20:1 finished foam to foam solution

Medium: 20:1 to 200:1

High: 200:1 to 1000:1

Question 20

Formula to calculate the application rate available from a specific nozzle

Answer 20

Nozzle Flow Rate / by the area of the fire

Question 21

When AFFF is applied to a hydrocarbon fuel what occurs

Answer 21

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”

Question 22

How does AR-AFFF foams work

Answer 22

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

Question 23

Different types of foam proportioners

Answer 23

In-Line Eductors

Foam Nozzle Eductors

Self Educting master stream nozzles

Question 24

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

Answer 24

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

Question 25

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

Answer 25

Nozzle Pressure + FL between eductor and nozzle + elevation pressure

Question 26

Step to take after a foam operation using an inline eductor

Answer 26

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

Question 27

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

Answer 27

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

Question 28

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

Answer 28

Attack nozzle and eductor must have the same GPM

Question 29

How does a bypass proportioning system work

Answer 29

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

Question 30

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

Answer 30

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

Question 31

How is an around the pump system built

Answer 31

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

Question 32

What does (CAFS) system contain and how does it operate

Answer 32

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

Question 33

Benefits of CAFS generated foam

Answer 33

Reach of the fire stream is longer

Produces small uniform air bubbles (very durable)

Adheres to a fuel surface and resists heat longer

Question 34

What measurements when using CAFS produce dry foam of up to 100 gpm?

Answer 34

2 cubic feet per minute of airflow per gallon per minute