Foam

Question 1

When would foam be used?

Answer 1

On fires involving flammable liquids or liquefiable solids.

Question 2

What does foam do? (basic description)

Answer 2

It creates a smothering blanket, cutting of the flammable materials supply of oxygen.

Question 3

How exactly does foam extinguish a fire? (list of 5)

Answer 3

DILUTES the surrounding air

ISOLATES fuel from oxygen

FORMS a sealing blanket, enclosing vapour

INTERCEPTS radiant heat

COOLS the fuel

Question 4

What are the three concentrates of foam?

Answer 4

Low expansion (usually between 5:1 and 15:1)
Medium expansion (20-1 and 200-1 -not used by LFB)
High expansion (usually 1200:1)

Question 5

When would a 3% concentration of high expansion foam be used?

Answer 5

For fires involving hydrocarbons

Question 6

When would a 6% concentration of high expansion foam be used?

Answer 6

For fires involving polar solvents

Question 7

What three factors can be varied when producing foam?

Answer 7

1- The volume of air mixed with the volume of solution
2- The quantity of foam concentrate
3- The size of the bubbles

Question 8

What 4 factors affect the effectiveness of foam produced

Answer 8

1- Good condition concentrate
2- Correct mixture of concentrate
3- Good maintenance of equipment
4- Correct pump pressure

Question 9

What should the RB101 branch settings be when using foam?

Answer 9

6 bar pressure (from the pump)

400 litres per minute (branch flow ring)

Question 10

What is the flow rate of the ground monitor when using foam?

Answer 10

950 litres per minute.

Question 11

What bar pressure should the ground monitor operate at when using foam?

Answer 11

7 bar pressure

Question 12

What are the four methods of application when using foam?

Answer 12

1- Gentle application
2- Raindown
3- Rolling on
4- Off wall (Indirect)

Question 13

What considerations must be taken when applying foam? (list of 7)

Answer 13

1- Never apply water to a burning liquid
2- Open the branch away from the fire until there is a consistent supply of foam
3- Apply foam to the furthest point of burning liquid
4- Ensure that there is enough foam to blanket the fuel
5- Combat surrounding risks with covering jets
6- Water will break a blanket of foam
7- Do not walk or drag hose on foam

Question 14

What piece of equipment is used for high expansion foam?

Answer 14

The Angus Turbex MK2

Question 15

What are the hazards associated with high expansion foam?

Answer 15

Claustrophobia.
Disorientation.
Severely affected light penetration.
Limited audibility (Speech, ADSU, warning whistles).
Mini backdraughts and fire gas explosions.
Difficult to determine the location of fire.
Surrounding damage may be obscured.

Question 16

What must always be used when working in high expansion foam?

Answer 16

Guidelines and communication equipment

Question 17

How much foam can be stored on the appliance tank?

Answer 17

127 litres (the tank should only be filled to 90 litres)