Evaluation of Fire Service Positive Pressure Ventilation Tactics on High-Rise Buildings.
Evaluation of Fire Service Positive Pressure Ventilation
Tactics on High-Rise Buildings.
Interflam 2007. (Interflam '07). International
Interflam Conference, 11th Proceedings. Volume 2.
September 3-5, 2007, London, England, 1289-1300 pp,
smoke movement; fire departments; ventilation; high rise
buildings; NFPA 92A; pressure differential; smoke
barriers; experiments; fans; structures; pressure; fuel
load; smoke; stairwells; fire fighters; effectiveness;
Positive Pressure Ventilation (PPV) is a ventilation
technique used by the fire service to remove smoke,
heat and other combustion products from a structure.
This allows the fire service to perform tasks in a
more tenable environment. PPV fans are commonly powered
with an electric or gasoline engine and range
in diameter from 0.30 m to 0.91 m (12 in to 36 in). More
recently fans up to 2.1 m (84 in) have been
manufactured and mounted on trucks and trailers.
Typically, a PPV fan is placed about 1.2 m to 3.0 m (4
ft to 10 ft) outside the doorway of the structure. It is
positioned so that the "cone of air" produced by the
fan extends beyond the boundaries of the opening. With
the doorway within the cone of air, pressure
inside the structure increases. An exhaust opening in
the structure, such as an opening in the roof or an
open window, allows the air to escape due to the
difference between the inside and outside air pressure.
The smoke, heat and other combustion products are pushed
out of the structure and replaced with ambient
air. Another use of PPV is to increase the pressure in a
portion of a structure by not providing a vent location.
This increase in pressure, if adequate, will prevent
smoke flow to a "protected" area. This is most useful
in larger structures such as schools, hospitals and
high-rise buildings. In a high-rise building it is
to increase the pressure of a stairwell to prevent the
infiltration of smoke if the fans are properly
configured. Two sets of experiments were conducted in
high-rise buildings to analyze the impact of fire
service PPV tactics.