Tactical Ventilation Flashcards
What is the definition of ventilation?
Ventilation is de ned as:
‘The removal of heated air, smoke or other airborne contaminants from a structure, and their replacement with a supply of fresher air.’
What are the three ways a fire can be ventilated?
There are three ways a re can be ventilated:
• Self-ventilation: Occurs when the re damages the structure of the premises, so that increased ventilation occurs. For example
when a roof collapses or a window breaks.
• Automatic ventilation: Occurs when pre-installed vents operate, usually in the early stages of a re. They can be operated by the re detection
system or fusible link devices. Some can also be controlled by the re service at the scene. This can be a powered ventilation system or roof lights that open at ceiling level.
• Tactical ventilation: Is used to assist re ghting operations and requires re ghters to release the products of combustion and allow fresher air to
enter.
What are the benefits to tactical ventilation?
• 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.
What are the 5 basic principles of tactical ventilation?
The basic principles of ventilation are:
• Hot gases should be released from the area at the greatest height possible and replacement fresh air should be allowed to enter at low level. This takes full advantage of the buoyancy of the hot gases and minimises mixing.
• The high level vent should be downwind of the low level vent to take advantage of wind induced air flows.
• The high level vent should be made before the low level vent.
• If conditions indicate signs of a potential backdraught, the compartment should be ventilated from outside the building when possible.
• Outlet vents should be protected by firefighters in breathing apparatus (BA) with charged branches. Hot gases emitting from the vent can be cooled to prevent their ignition and fire spread.
Tactical ventilation can be defensive or offensive, what is the difference?
Defensive ventilation involves venting the adjoining smoke logged areas but not the fire compartment itself.
Offensive ventilation is ventilating the fire compartment itself.
What are the advantages of vertical ventilation?
The advantages of vertical ventilation are:
• 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.
When is vertical ventilation most appropriate?
Vertical ventilation is most appropriate when:
• The fire is in or has spread to the roof space or structural voids
• Where there are tall vertical shafts within the building.
What are the disadvantages of vertical ventilation?
The main disadvantages of vertical ventilation are that:
• Firefighting operations may be required on the roof above the re, which can be extremely hazardous.
• There are fewer opportunities to make a vertical vent.
What are the two types of tactical ventilation?
Vertical
Horizontal
Name 5 of the control measures when ventilating?
Before tactical ventilation can be undertaken the IC must:
• Undertake a dynamic risk assessment.
• Make sure adequate resources are available.
• Identify the wind direction.
• Decide whether vertical or horizontal ventilation is more appropriate.
• Select inlet and outlet vents and decide how they will be made.
• Make sure the outlet vent is covered by a charged 45mm hoseline.
• Make sure there is effective communication between firefighters performing other activities inside the building, the IC, and firefighters conducting ventilation activities.
• Consider withdrawing any firefighters inside the building while ventilation takes place.
• Notify all crew members of the intention to start ventilation.
• Make an outlet vent rst, followed by an inlet vent as soon as possible (this may already be the point of access).
• Closely supervise the effects of ventilation and make sure progress and conditions within the building are reported.
