This article will focus on the practical results of the studies. The results will be listed with the title of the report they came from and the Web link if you want to download and review it for further information.
- Regardless of size, portable PPV fans should be placed so that the cone of air “seals” or extends over the open inlet doorway. In these experiments 1.2 m (4 ft) to 1.8 m (6ft) set back from the doorway and angled back at least 5 degrees maximized the flow through
- the fan shroud and air entrainment around the fan shroud as it reaches the doorway.
- Placing fans in a V-shape is more effective than placing them in series, Figure 3.
- When attempting to pressurize a tall stairwell, portable fans at the base of the stairwell or at a ground floor entrance alone will not be effective. Placing portable fans inside the building below the fire floor is a way to generate pressure differentials that exceed the NFPA 92A minimum requirements. For example, if the fire is on the 20th floor, placing at least one fan at the base of the stairwell and at least one near the 18th floor blowing air into the stairwell could meet the NFPA 92A of 25 Pa for most of the stair, Figure 4.
- Fans used inside the building should be set back and angled just as if it were positioned at an outside doorway, Figure 5.
- Placing a large trailer mounted type fan at the base of the stairwell is another means of generating pressure differentials that exceed the NFPA 92A minimum requirements of 25 Pa., Figure 6.
In this series of experiments the fans increased the pressure sufficiently to reduce temperatures throughout the hallways even up to the fire room as shown in Figure 8. The PPV fans would provide occupants a more survivable environment and increase firefighter safety, limit smoke spread, keep additional parts of the structure safe for occupants and undamaged and reduce the scale of the emergency for the firefighters, and increase visibility.
(8) The thermal gradient from the ceiling to the floor, in the hallway just outside the open classroom doorway is shown. As the fire develops the hot gas layer in the hallway develops and reaches a steady state at approximately 400 seconds. This is followed by the fire department opening a remote door to the hallway and then starting the PPV fans with using the remote doorway as an outlet vent. That had very little effect on the temperature. It did not make conditions worse, but close to the fire room it did not improve them. After 800 seconds, the window to the classroom was vented. The remote door was closed and the PPV fans were turned on first one then another was added. The impact on the fans on the temperature in the hall is clear.