09 Foam

Question 1

Foam

Answer 1

Was developed during the twentieth century as a way to fight flammable liquid fires.

Question 2

Foam is made to

Answer 2

float on top of flammable liquids - preventing vapors from burning.

Question 3

Finished foam is a combination of

Answer 3

1. Foam Concentrate
2. Water
3. Air
   (Mechanical Agitation “rounds” out the Foam Tetrahedron)

Question 4

Foam extinguishes flammable or combustible liquid fires in four ways:

Answer 4

1. Excludes air from the flammable vapors
2. Does not allow fuel to release vapors
3. Separates the flames from the fuel surface, stopping burning process
4. Cools the fuel surface and the surrounding areas

Question 5

Foams are effective on Class B fires by

Answer 5

suppressing their vapors.

Question 6

Class B fires are

Answer 6

fires involving flammable or combustible liquids

Question 7

Flammable liquids can be divided into two categories:

Answer 7

1. Hydrocarbons
2. Polar Solvants

Question 8

Hydrocarbons

Answer 8

By Products of crude oil or have been extracted from vegetable fiber
- Have a specific gravity less than 1.0

Question 9

Examples of hydrocarbons

Answer 9

1. Gasoline
2. Diesel
3. Heptane
4. Kerosene
5. Jet fuel (JP4)

Question 10

Polar Solvents

Answer 10

Products that have been synthetically produced and are not found in nature.

Question 11

Polar Solvents and water

Answer 11

They mix.

Question 12

Polar Solvents are found in

Answer 12

dry cleaning products, paint thinners, nail polish removers, glue solvents, and even perfumes.

Question 13

Examples of polar solvents

Answer 13

1. Alcohol (inc. ethyl alcohol)
2. Methyl tertiary-butyl ether (MTBE)
3. Acetone
4. Ethanol
5. Paint thinners

Question 14

When is foam not effective?

Answer 14

1. Electrical fires (Class C)
2. Three-dimensional Fires
3. Pressurized Gases
4. Combustible metals

Question 15

Electrical Fires

Answer 15

Best extinguished using dry chem agents, carbon dioxide, or halon.

Question 16

Three-dimensional Fires

Answer 16

Liquid fuel fire is being discharged from an elevated position or under pressure.
Best extinguished by controlling the flow of the liquid then using foam on spill.

Question 17

Pressurized Gases

Answer 17

Best to cool the tank and let the gas burn until the flow can be controlled.
Examples:
- Propane
- Butane
- Acetylene
- Nitrogen
- Argon

Question 18

Combustible Metals

Answer 18

Class D fires
- Aluminum
- Magnesium
- Sodium
- Potassium
Best extinguished with Class D Powder

Question 19

Protein Foam

Answer 19

Intended for hydrocarbons only.

Question 20

Types of Foam

Answer 20

1. Protein Foam
2. Fluoroprotein Foam
3. Film-Forming Fluoroprotein (FFFP) Foam
4. Aqueous film-forming foam (AFFF)
5. Alcohol-resistant aqueous film-forming foam (AR-AFFF)
6. Synthetic detergent foam

Question 21

Fluoroprotein Foam

Answer 21

Add fluorochemicals to lower surface tension and allow foam to flow more freely.

Question 22

Film-Forming Fluoroprotein (FFFP) Foam

Answer 22

Same as Fluroprotein foam with added chemical surfactants.
Excellent for subsurface injection

Question 23

Aqueous film-forming foam (AFFF)

Answer 23

Use air-aspirating nozzles
Works by spreading a strong foam blanket over the fuel, smothering the fire. Also form vapor barrier

Question 24

Alcohol-resistant aqueous film-forming foam (AR-AFFF)

Answer 24

Combo of foaming agents, synthetic stabilizers, fluorochemicals, and synthetic polymers
- For use on Polar Solvants
Most versatile foam (covers polar solvents and hydrocarbons)

Question 25

Synthetic Detergent Foam

Answer 25

Work on Class A and Class B fires

Question 26

Foam Proportioning Devices

Answer 26

Effectiveness of foam depends on proper proportioning and the ability to deliver the finished foam where it is needed.

Question 27

Two principle ways to add foam to water:

Answer 27

1. Induction (Venturi principle) 2. Injection

Question 28

Proportioning Devices

Answer 28

Inline eductors Balanced pressure systems Around the pump system Foam nozzles

Question 29

Inline Eductors

Answer 29

Most common type; Work on Venturi principle Rules for eductors: 1. Have a set GPM flow rate (typical: 60-250 gpm) 2. Require adequate inlet pressures (180-200 psi) 3. Do not like back pressure (can handle 65% of inlet pressure)

Question 30

Backpressure rules for eductors

Answer 30

1. Nozzle must be fully open or fully closed 2. No kinks in the hose between eductor and nozzle 3. Do not elevate nozzle higher than eductor 4. Don't exceed hoselay length 5. Keep pickup tube short. (no longer than 6ft) 6. Keep eductor clean 7. Flush eductor, nozzle, and hose for 5 min. 8. Allow transit time of foam (20-40 seconds)

Question 31

When determining pump discharge pressures, the ____________________ should be treated as the nozzle pressure.

Answer 31

Eductor Inlet Pressure

Question 32

Around the pump systems use eductor on the discharge side of the pump. Advantages:

Answer 32

1. Variable flow rate 2. Variable pressure 3. No back pressure restrictions 4. No nozzle restrictions

Question 33

Around the pump restrictions:

Answer 33

1. Minimum pressure of 10 psi 2. Important to flow water and foam at same time. 3. Continually monitor proportioning valve to correspond with GPM flow 4. Clean up is more difficult - all discharges need to be flushed

Question 34

Foam Nozzles

Answer 34

Foam-aspirating nozzles use the Venturi principle and have the pickup tube connected to the nozzle.

Question 35

Advantages of foam nozzles

Answer 35

1. Deliver large amounts of finished foam 2. Easy to operate 3. Easy to clean 4. No moving parts 5. No additional foam equipment needed

Question 36

Foam nozzles produce expansion ratio between ____ and _____, producing good-quality, low-expansion foam.

Answer 36

8:1 and 10:1