Ventilation

Question 1

Ventilation is defined as

Answer 1

“The removal of heated air, smoke or other airborne contaminants from a structure, and their replacement with a supply of fresher air”

Question 2

What are 3 ways fires can be ventilated?

Answer 2

Self ventilation

Automatic ventilation

Tactical ventilation

Question 3

When tactical ventilation is effectively used, it can…

6

Answer 3

Assist the escape of occupants and firefighters by restricting the spread of smoke

Improve conditions for firefighters and trapped occupants

Speed up rescue operations and fire attack by reducing heat and smoke

Increase the safety of firefighters by reducing the risk of flashover, backdraught and fire gas explosion

Reduce fire spread and property damage by controlling the movement of hot smoke and gases

Improve visibility

Question 4

What are the principles of tactical ventilation?

4

Answer 4

The high level vent should be downwind of the low level vent to take advantage of wind induced air flow

The high level vent should be made before the low level vent

If conditions indicate signs of potential backdraught, the compartment should be ventilated from outside the building

Outlet vents should be protected by Firefighters with BA with charged branches

Question 5

Tactical ventilation can be used at various stages of the fire which are?

(3)

Answer 5

After the arrival of LFB but before control is achieved

After control but before fire extinction

After fire extinction

Question 6

What are the two types of tactical ventilation?

Answer 6

Defensive ventilation

Offensive ventilation

Question 7

Vertical ventilation is most appropriate when:

2

Answer 7

The fire is in or has spread to the roof space or structural voids

Where there are tall vertical shafts within the building

Question 8

What are the advantages of vertical ventilation?

3

Answer 8

It minimises the risk of a backdraught, as the overpressure in the compartment will drive out the hot gases

It minimises fire spread, as the hot gases travel the shortest route before leaving the building

It provides rapid smoke clearance because of the velocity of the hot gases through the vent

Question 9

What are the main disadvantages of vertical ventilation?

2

Answer 9

Firefighting operations may be required on the roof above the fire, which can be extremely hazardous

There are fewer opportunities to make a vertical vent