Positive Pressure Ventilation

This week I am pleased to present a short inservice drill about positive pressure ventilation. My thanks go out to my colleague Deputy Chief Fred LeBlanc of the Leominster Massachusetts Fire Department.

This is not a complete class or text on positive pressure and much needs to be discussed, but if you have equipment and wish to do some training and review here is a simple drill format you can use.

Positive Pressure Ventilation
Station Drill


A simple drill to demonstrate the effectiveness of Positive Pressure Ventilation (PPV) can be conducted in most fire stations. This drill would simulate a large open area such as a warehouse or commercial building. A class review of the principle elements of use should be conducted prior to the practical demonstration. Keeping in mind the four basic components of PPV. The four points are: Entry Point, Effective Path of Travel, Exit Point, and Cone of Air.

Utilizing an overhead door at an apparatus bay, open this door approximately one third to one half its height (Entry Point). Place two positive pressure fans side by side facing away from the door at a 90 degree angle. Open one or two man doors at the rear of the station (Exit Point) insuring that a flow of air can be reached from the front overhead doors (Path of Travel). Once this is complete start the fans and while idling turn towards the overhead doors. Once blowing in direction of doors feel for complete air flow around edge of doors by using hand to feel air pressure (Cone of Air). Bring fans to full speed and recheck cone of air. To further enhance the visual demonstration, place streamers (tape or paper) from bottom edge of overhead door, at top of exit door, and in middle of apparatus bay from ceiling. The entry and exit streamers should be moving inward at entry and outward at exit if a good air flow has been established while the streamer in the apparatus bay should barely show movement.

Another drill to simulate removing smoke from a single room can be conducted in most stations as well. Locate a room remote from the main entry door to your station and open a window. This will become your Exit Point. Work back towards the main entry door to your station (Path of Travel) opening doors along the way. Position a positive pressure fan outside at this door (Entry Point). In the same manner as the previous drill place the fan at a 90 degree position to the door and start fan running it on idle. Once running turn fan towards door and feel for air flow around door frame (Cone of Air). Once you determine the air is sealing the doorway increase to full throttle. Using streamers at top of entry point and window at exit point will once again show the dramatic air flow created by the positive pressure. Hanging streamers in the path of travel will show little movement. This will illustrate that fire is not pushed around a room.