FAQ: NEGATIVE PRESSURE VENTILATION

Do you recommend Negative Pressure Ventilation?

VENTRY Fans are designed for positive pressure ventilation and attack. PPV is simply more effective than negative for aggressive, coordinated attack. This can be easily observed: Stand in front of a fan and you will notice lots of air flow; stand on the other side and there is very little airflow. The same observation is apparent at a fire by observing how fast positive pressure pushes smoke and heat out of a structure versus how long it takes using negative pressure. Using a smoke ejector to ventilate a structure is like using a wagon to drive across the country.

Though we do not advocate negative pressure for attack, it is very helpful for cleanup and overhaul. Click here for how.

On attack: Unlike negative pressure and vertical ventilation, PPV can be accomplished without entering the structure, requires fewer people, and takes much less time to implement. PPV does not damage your fan by sucking hot gases through the engine, as can be the case with negative pressure ventilation. Vertical ventilation requires a team on the roof of a burning building; that takes lots of time and manpower plus the roof of a burning building is an extremely dangerous location. Although negative pressure ventilation can be accomplished from outside a building, in practice it is usually set up from inside, which again puts the ventilation crew at risk.