Positive Pressure Ventilation Fan
Getting rid of all the smoke
A Positive Pressure Ventilation (PPV) Fan is used to push fresh air into a compartment which may be full of smoke or other fumes to force them out of that compartment, (eg a building). It is used as a means of ventilation in combination with other openings, and causes the compartment to be raised to a higher pressure than that of the outside air.
While this may be used to good advantage in a structure fire, care must be taken to ensure the fresh air pushed in does not fan the fire, making it dangerous to BA operators inside. The use of the fan is different in all incidents, but can assist in the search and rescue of casualties if they are suspected of being inside a structure, by clearing the smoke more quickly, enabling firefighters to see more easily, and potentially being able to locate any casualties more quickly, and to locate the seat of the fire.
Many Urban and urban fringe brigades carry this type of fan, as well as brigades in strategic rural areas.
The majority of fans used in the CFS are petrol operated, and are lightweight and highly portable. In some circumstances, such as toxic fumes, gas or areas which cannot be exposed to ignition sources, a PPV fan powered by water is used instead. It is coupled up to a pressurised water source, which spin the blades around, and can also induce water mist via sprays into the air stream from the unit. The water droplets provide cooling and well as diluting any vapours.
While specified as a positive pressure device, it can also be used to produce a negative pressure in a structure by placing the fan inside and facing the exit. This creates a negative pressure behind the fan enabling smoke to be drawn out.
Photographs on this page taken by Ashley Hosking, CFS Promotions Unit