Which device is used to produce negative-pressure ventilation?

Which device is used to produce negative-pressure ventilation?

• A. Smoke ejector
• B. Fan
• C. Oxygen bottle
• D. Fire hose

Answer: (B)

Negative-pressure ventilation works by pulling air out of the burning space, so the pressure inside becomes lower than outside. A device that can exhaust air serves this purpose, and a fan used as an exhaust pulls smoky air out of the room and vents it outside, creating that negative pressure. As air is expelled, fresh air can enter through openings, helping to push smoke and hot gases out. A smoke ejector is a specialized exhaust device, but it is essentially a type of fan; the general term that describes the mechanism here is a fan. The other options don’t move air to remove smoke or create a draft: an oxygen bottle provides breathing gas, and a fire hose delivers water.