Polk Township Vol. Fire Dept.

Using a fan to fight a fire?


Up until about just a few short years ago, if you had asked any veteran firefighter to use a fan to fight a fire, they would have laughed you out of the firehouse. 'What's next a billows?' they would ask. But today, one of our most innovative new tools is just that, a high powered fan. Now sure we have had the exhaust or 'ejector' fans for years. But pushing air into a fire was unheard of.

When a fire breaks out in a room of the home, the heat, smoke and toxic gases spread quickly to fill the room. They will also continue spread to other accessible areas and rooms as well. This produces a very deadly situation not only for any victims inside but also for the responding firefighters. The areas can become so super-heated that a quick draft of air from the outside could easily spark a backdraft or flashover and ignite the entire area into a raging inferno.

But the use of proper ventilation techniques by firefighting crews greatly reduces the risk of backdraft and flashover. Ventilation will allow the heat, smoke and toxic gases to escape through a path of least resistance. Firefighters can use many different techniques of ventilation from opening windows and doors, gable vents and even roof cuts.

Principles of PPV

To speed up the ventilation process, a new technique was developed called Positive Pressure Ventilation (PPV). PPV is a forced ventilation technique that uses the principle of creating pressure differentials. By using high volume blowers, a higher pressure is created inside a building than that of the outside environment. As long as the pressure is higher inside the building, the smoke, heat and toxic gases within the building will seek an outlet to a lower pressure zone through ventilation openings controlled by the firefighter.

There are many advantages of PPV

  • Firefighter can set up forced ventilation procedures without entering the smoke-filled building.
  • PPV supplements the natural ventilation currents.
  • PPV allows more efficient removal of smoke, heat and toxic gases from the building.
  • The velocity of air currents within the building have little effect on smoldering debris or contents.
  • Heat and smoke can be directed away from unburned areas, thus cutting down on losses.
  • The fans don't interfere with the firefighter's access to and from the building.

PPV in action

The positive pressure is created by using the high volume blowers to blow fresh air into the structure. The PPV fan is usually placed several feet outside an external doorway. The fan is placed far enough away from the door so that the 'cone' of air from the fan completely covers the door opening. By closing doors within the building and pressurizing a room at a time, the process of removing the smoke, heat and toxic gases is speeded up because the velocity of the air movement is increased. If none of the interior doors are closed, the process will still work, but it will take more time.

This new breakthrough technique, unheard of just years ago, is another useful weapon in our firefighting aresenal. PPV allows us to enter a building quicker and safer. In the tense, stressful first minutes of a house fire, every second counts!

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John D. Einhorn
Sources: Fire Fighting Essentials