Basic Firefighter Written Practice Exam

At what distance should a PPV fan be placed from the entrance opening to ensure a full cone seal?

1. 1-3 feet

2. 4-10 feet

3. 11-15 feet

4. 16-20 feet

The correct answer is: 4-10 feet

To achieve a full cone seal when using a Positive Pressure Ventilation (PPV) fan, it's essential for the fan to be placed at the appropriate distance from the entrance opening. The distance of 4-10 feet is optimal because this range allows for the fan to produce an effective airflow pattern while minimizing turbulence. At this distance, the air being pushed into the structure can effectively fill the space, ensuring that the ventilation covers the entire volume within, maximizing the removal of heat and smoke. If a fan is placed too close, it may disrupt the airflow and create a chaotic pattern that does not enhance the ventilation effort. Conversely, if a fan is placed too far away, it may not generate enough pressure to establish a proper flow into the structure, reducing its effectiveness in clearing smoke and heat. Thus, positioning the PPV fan within the 4-10 feet range provides a good balance, creating a successful seal and facilitating efficient ventilation operations.