Effect of Positive Pressure Ventilation on a Room Fire.
Effect of Positive Pressure Ventilation on a Room Fire.
(1858 K)
Kerber, S.; Walton, W. D.
NISTIR 7213; 54 p. March 2005.
Keywords:
room fires; ventilation; fuel load; heat release rate;
gas temperature; pressure; gas velocity; uncertainity;
rooms; doorways; windows; corridors
Abstract:
Fire departments may use ventilation blowers or fans to
pressurize a structure prior to suppressing a fire. This
pressurization or positive pressure ventilation (PPV)
tactic can assist in the venting of smoke and high
temperature combustion products and make attacking the
fire easier than without PPV. However, this tactic also
provides additional oxygen to the fire and can increase
the rate of heat and energy being released. PPV has not
been characterized carefully enough to establish
specific guidelines for optimum use. This study examined
gas temperatures, gas velocities and total heat release
rate in a series of fires in a furnished room. The use
of the PPV fan created slightly lower gas temperatures
in the fire room and significantly lower gas
temperatures in the adjacent corridor. The gas
velocities at the window plane were much higher in the
PPV case than in the naturally ventilated scenario. This
higher velocity improved visibility significantly. PPV
caused an increase in heat release rate for 200 seconds
following initiation of ventilation but the heat release
rate then declined at a faster rate than that of the
naturally ventilated experiment.
