What is one way to eliminate recirculation during smoke ejection?

To eliminate recirculation during smoke ejection, completely blocking the opening around the fan is an effective method. This action creates a sealed environment that ensures smoke is drawn directly out of the structure rather than allowing it to circulate back into the area from which it was expelled. When the fan has a tight seal, it optimally draws in smoke and particulates without having the contaminated air recirculate through the opening, thereby improving the overall efficiency of smoke clearance.

In contrast, if the fan is pulled back from the opening or if exhaust openings are not adequately sized or positioned, there is a higher likelihood that some smoke will return to the work area. Raising the fan can assist in positioning but does not effectively seal the area around it, which is crucial for controlling airflow and preventing recirculation.

Understanding how airflow dynamics work in smoke ejection contexts is key to successful ventilation operations during fire suppression. By ensuring an airtight fit around the fan, firefighters can significantly enhance visibility and oxygen levels within the affected environment.