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What is tactical ventilation
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When should tactical ventilation be performed
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Structure CH13
| Question | Answer |
|---|---|
| What is tactical ventilation | The planned, systematic, and coordinated removal of heated air, smoke, gases, or other airborne contaminants from a structure |
| When should tactical ventilation be performed | Fire attack hoselines/teams are in place and ready to advance toward the fire |
| What must occur for a successful tactical ventilation | Careful planning Knowledge of building construction Knowledge of fire behavior Systematic application of procedures/techniques Coordination with other fire ground activities |
| What are some reasons tactical ventilation would be performed | Reduce interior heat Decrease rate of fire spread/extreme fire behavior Improve visibility, efficiency, victim survival potential Reduce smoke damage and property damage |
| How can tactical ventilation improve life safety for firefighters and occupants | Increase oxygen concentration Reduce toxic products of combustion concentration Reduce temperature Increase visibility Create smoke free egress paths |
| What factors should be considered when assessing the use of tactical ventilation | Risks to occupants/firefighters Building construction Fire behavior indicators Location/extent of fire Type/location of ventilation Weather Exposures Staffing/available resources |
| What hazards can be expected from the accumulation of smoke and fire gases | Visual impairment Lack of oxygen Presence of toxic gases Presence of flammable gases Possibility of rapid fire development |
| What building characteristics should be considered when assessing the use of tactical ventilation | Occupancy type Construction type Floor area and compartmentation Ceiling heaight Number of stories above/below fire floor Number, size, and location of exterior openings |
| What observations of smoke can create a clear picture of interior fire conditions | Volume of smoke Location of smoke Smoke color, density, and pressure Movement of smoke |
| What are air flow indicators the you should pay attention to when using tactical ventilation | Velocity Turbulence Direction Movement of neutral plane |
| What is air flow caused by | Pressure differentials inside/outside a compartment Differences in density between hot smoke and cool air |
| What must be present in order for a flow path to be present | Vent inlet Vent outlet |
| What is a flow path | The path air travels between the inlet and outlet vents |
| What are some visual indicators to watch for from heat | Blistering paint Bubbling roofing tar Crazed glass |
| What can flames provide an indication of | Size and location of the fire |
| What are the different types of ventilation | Vertical and horizontal |
| What are the available means of ventilation | Natural, mechanical, and hydraulic |
| What are some factors that effect where to ventilate | Location of occupants and fire Desired flow path Condition of building, building construction, openings Effect ventilation could have on fire, egress, exposures |
| What factor should the means of tactical ventilation work with | Prevailing wind |
| What are some internal exposures | Occupants Contents Uninvolved rooms/area of building |
| What risk does ventilation below the highest point of a building increase | Ignite portions of the exterior building Heat/gases drawn into openings Ignite exposures |
| What are some things that external exposures can be affected by | Radiation Direct flame contact Heat/smoke drawn in through openings/HVAC Ignition from convection embers |
| What indicates the need to used mechanical or hydraulic ventilation | Location/size of fire have been determined Layout of building won’t work with natural ventilation Natural ventilation becomes ineffective Fire burning below ground Fire so large natural ventilation isn’t efficient |
| What structure work well with horizontal ventilation | Buildings that fire has not involved attic/cockloft Involved floors of multistory structures are below top floor Building is weak and threat of collapse |
| Where should a fan be positioned for mechanical horizontal ventilation | At an opening on the leeward side |
| What should be done when using a smoke ejector | Sealed the area around the opening to prevent recirculating |
| What can atmospheric pressure cause when using horizontal ventilation | Recirculate air by pushing smoke and heat back into openings |
| What is a best practice for having effective horizontal ventilation | Keep the flow path as straight as possible |
| How far away should a fan be positioned from a door for PPV | 4 to 6 feet |
| For PPV what area of the opening being used should be covered by the fan cone | All of it |
| Where should positive pressure be applied when ventilating a multi story building | Apply at the lowest point |
| What is the main issues with PPV In above ground operations | Coordinating the opening and closing of the doors in the stairwell being used to ventilate the building |
| What actions should be taken to ensure PPV is successful | Exhaust opening is sufficient Monitor PPV fan Maintain communications Take advantage of existing openings Cover inlet vent with air cone Avoid creating unintended outlets |
| What are some advantages of PPV to NPV | Don’t have to enter IDLH More efficient Little effect on smoldering debris Less cleaning/maintenance PPV effective in all types of structures Heat and smoke can be directed |
| What are some disadvantages of PPV | Structure must be intact Carbon monoxide levels may be increased Hidden fires can accelerate |
| How is hydraulic ventilation performed | Fog nozzle directed out an opening and covering 85-90 percent of the opening and the nozzle should be at least 2 feet away from opening |
| What are some disadvantages of hydraulic ventilation | Increase in water damage Excessive use of water Increase in ice in freezing temperatures Firefighters must remain in IDLH Operations interrupted when air supply low |
| What are some advantages of using mechanical ventilation | Supplements and enhances natural ventilation Ensures more control of air flow Speeds the removal of contaminants Reduces smoke damage Promotes good public relations |
| What can occur if improper mechanical advantage occurs | Fire intensifies Has to have a power source Special equipment needed Need additional resources/personnel |
| When will vertical ventilation occur | When ic determines the need, safety, and effectiveness Considered age/type of building construction Observed safety precautions Identified escape routes Selected pace to ventilate Considered location, duration, and extent of fire |
| What risks are increased when vertical ventilation occurs | Placing personnel above ground level Working on both peaked and flat surfaces Working above fire Working on roofs that could have been weakened |
| How should roofs with tile and slate be sounded | They can’t |
| What are some signs of an unsafe Roof | Melting asphalt Spongy roof Smoke coming from roof Fire coming from roof |
| What should happen before cutting a ventilation hole | Cut a inspection hole |
| What are the primary types of inspection holes | Kerf cut and triangle/A cut |
| What is offensive ventilation | Making an opening over the seat of the fire at or near the highest point of the roof |
| What are two critical points to remember when ventilating any roof | Square/rectangular opening is easier to cut One large opening is better than multiple small ones |
| Where should flat roof openings be located | Between roof trusses or with the truss in the middle of the opening |
| What cut is used when a truss is in the middle of an opening | Louver cut |
| Where should a ventilation opening be made on shingle covered pitched roofs | A few inches below the peak on the leeward side |
| How are slate and tile roofs be ventilated | Remove tiles/slate and cut sub roof under it as a standard roof |
| What should be done whenever ventilating an arched roof | Make a kerf cut to locate arches, observe truss space, determine fire involvement |
| Where should you walk whenever ventilating a roof | On trusses or strong points |
| What a trench cut strictly used for | Defensive operation/ventilation |
| What does a trench cut create | A firebreak that stops the spread of fire in common attics or large structures |
| Where should a trench cut be located | 30 feet ahead of the advancing fire |
| What should happen before a trench cut occurs | An offensive ventilation opening is made |
| What does the offensive ventilation opening allow when making a trench cut | Heat and smoke escape allowing the trench cut to be made safely |
| What would happen if an offensive ventilation opening was not made before a trench cut is performed | Fire will quickly be drawn to new opening Fire will burn past trench cut Endanger firefighters |
| How is a trench cut made | Two parellel cuts far enough apart to stop the fire but it compromise roof integrity that extends from one exterior wall to the opposite exterior wall. |
| What are some factors that reduce the effectiveness of vertical ventilation | Improper use of mechanical ventilation Indiscriminant window breaking Fire stream directed into exhaust openings Explosions Burn through of structural components Improper location of ventilation openings |
| How do you ventilate a basement with windows | Horizontal ventilation |
| What is the best practice to ventilate a basement without windows | Vertical ventilation using natural flow paths from the basement |
| What is a last resort to ventilate a basement | Cut an opening in the floor near a ground level opening and use fans to push heat and smoke out of the building |
| How are windowless buildings usually ventilated | Mechanical ventilation |
| When can horizontal smoke spread and hot gas layers occur in multi story buildings | Vertical exhaust opening isn’t large enough to exhaust smoke and gases |
| What stair well can be used to ventilate a multistory building | The stair well that penetrates the roof |
| How can a stairwell be used to ventilate a building | Chimney with the roof door open and a PPV fan located at the base of the stair well. |
Created by:
Kab731