To operate smoke ejectors efficiently during negative pressure ventilation, where should they be placed?

When conducting negative pressure ventilation, placing smoke ejectors in a doorway or window opening is optimal because it allows for the most effective removal of smoke and heat from the structure. This strategic placement creates a negative pressure zone inside the building by exhausting air out, which in turn helps pull fresh air in from other openings. The placement in these openings ensures that the smoke ejectors are directly and effectively channeling the smoke toward the outside, thereby enhancing the airflow and maximizing the efficiency of the ventilation process.

Positioning the smoke ejectors in a compartment can limit their effectiveness as the airflow may not be directed efficiently towards the source of smoke. Similarly, placing them near an open window, while seemingly logical, does not optimize the airflow needed to create the negative pressure effect essential for effective smoke removal. In contrast, the guideline about positioning them no closer than ten feet from a door opening is not conducive to the immediate expulsion of smoke which is required in emergency scenarios. Hence, placing the smoke ejectors in a doorway or window optimally supports the dynamic of negative pressure ventilation.