Smoke ejectors function efficiently during negative pressure ventilation, you should:

• A. In a compartment
• B. Near an open window
• C. In a doorway or window opening
• D. No closer than ten feet from a door opening

Answer: (C)

Smoke ejectors pull smoky air out of a structure by creating a negative pressure that draws interior air toward an exterior opening. To maximize this effect, place the ejector at a doorway or window opening that leads directly outside. This gives the exhaust a clear exit path and establishes a strong draft that pulls smoke from the interior through the opening and out, improving visibility and air quality inside.

If the ejector is placed inside a compartment, the negative pressure can’t effectively move smoke out of the building; the flow becomes confined and less efficient. Positioning near a window without a proper exterior opening or too far from the door reduces the draft and can cause recirculation or insufficient exterior outlet flow. Therefore, the best setup is at a doorway or window opening to the outside.