Deputy Chief Jim Murtagh
Fire Department of New York (FDNY)
Response: At the current time, FDNY does not make widespread use of positive-pressure ventilation as a primary attack strategy or tactic. The underlying concepts of PPV are to use high-pressure airflow to create a positive stream of air from outside the fire area, causing the gases produced by the fire to be pushed away from the advancing firefighters. PPV assumes the presence of the following: (1) ventilation holes (open windows or doors) that will allow the gases to flow from the high-pressure zone to a lower-pressure zone (outside the building), (2) a fire area that will not channel the gases into other uninvolved areas or significant voids, and (3) an attack team that will be able to reach the fire area rapidly and control the main body of fire.
In large metropolitan areas like New York City, the vast majority of buildings are multistory and multitenant occupancies. Getting high-pressure fans into an effective position (the door to the apartment), controlling for inappropriate openings (in walls, floors, and ceilings; hidden shafts; and voids), controlling the actions of the occupants as they exit on fire escapes, and controlling the dangerous effects of the ball of flame that often erupts outside the window when hot fire gases are pushed out are almost impossible.
An effective attack strategy in these buildings, given the limiting factors mentioned above, is to use a well-timed, concurrent, and somewhat simultaneous deployment of handlines and ventilation (vertical and horizontal) to achieve an aggressive attack and control of the fire. Fans and fog streams are used to assist in ventilation and to improve the interior conditions for firefighters and occupants; however this is generally not implemented until effective attack and control strategies have been made operational.
The use of PPV in multistoried, multioccupancy buildings has been considered time and time again. However, long-term fire suppression experience and knowledge of the diversity and complexity of the structures, the wide variations in occupancies, and the inability to have control of these factors make it is very difficult to control effectively and safely the unwanted effects of the use of air under high pressure (PPV). While PPV can be implemented effectively in smaller, limited-occupancy buildings, its use in diverse multistoried, multioccupancy buildings is not considered an initial operational tactic.
