Ventilation

Front 1

WHAT IS
VENTILATION?

Back 1

Planned and systemative removal of smoke, heat and superheated gases and replacement with coolor cleaner air.

Front 2

WHAT IS THE

PURPOSE OF VENTILATION?

Back 2

Purpose of ventilation is

• improve the safety of people trapped in the building
• reduce damage to the structure and its contents from heat and smoke
• proivde exposure protection to uninvolved areas or adjoining structures
• prevent or reduce the spread of fire due to a build-up of heat
• improve firefighting conditions by

- increasing visibility in the structure

- providing a non-toxic atmosphere

- reducing temperature inside the structure

Front 3

WHAT ARE THE
TYPES OF
VENTILATION? (4)

Back 3

1. Natural (open a window)
2. Manual - Vertical and Horizontal
3. Mechanical - Positive and Negative Pressure
4. Hydraulic - hose stream

Front 4

WHY VENTILATE?

Back 4

To avoid extreme fire behaviour (EFB) events an other hazardous situations/environments correct ventilation techniques must be taken.

Front 5

FLASHOVER

Back 5

Occurs where large amounts of combustible gas is produced in an environment with oxygen supply and where these gases are subsequently heated to their ignition temperature.

Front 6

BACKDRAUGHT

Back 6

Results from a fire that is depleted of adequate air. It is the sudden introduction of oxygen in a burning room full of unignited super-heated gas which has been starved of oxygen (below 15%). The oxygen cobimes with the superheated gases creating an explosion of fire.

Front 7

VENTILATION TECHNIQUES

Back 7

Important factors to consider are

• availability of existing openings, such as skylights, windows doors, elevator and ventilator shafts, stairways and chimneys
• location of the fire
• the path for combustion products to be vented
• the strucutre's construction and condition
• wind direction
• exposure protection
• Air handling system
• Vertical and Horizontal ventilation

Front 8

HORIZONTAL

VENTILATION

Back 8

Creation of openings at about the same level as the fire. It has the advantage that it can often be achieved without the need for ladders because you do not need to be above the fire.

In the context of horizontal ventilation

• Natural Ventilation
  Opening doors to take advantage of normal
  air currents
• Negative pressure ventilation
  refers to the reduction of air pressure in the

burning structure, thus drawing smoke
from it

• Positive pressure ventilation involves the
  atmospheric pressure in the structure to
  the extent that smoke is forced from it

Front 9

VERTICAL

VENTILATION

Back 9

Vertical ventilation is the making of openings above the fire, usually at roof level. A decision on when and where to commence vertical ventilation is a part of size-up.

Vertical ventilation needs to be considered when:

• heat, smoke and gases rising from the fire create a life hazard for the occupants.
• firefigthers are unable to gain entry
• smoke is damaging the structure and its contents
• the fire cannot be located
• a backdraught or flashover situation occurs
  
  
  

Front 10

NATURAL

VENTILATION

Back 10

• Uses natural air currents

.