Fire spread through a ventilation duct system is generally controlled by what architectural feature?

• A. Fire dampers
• B. Smoke vents
• C. Fire doors
• D. Automatic shutters

Answer: (A)

Fire dampers are the architectural feature that stops fire from spreading through ductwork. They’re installed in the ventilation ducts at the boundaries of fire-rated compartments and are designed to close automatically when heat is detected (often via a fusible link or actuator). By sealing off the ducts, they prevent flames and smoke from riding the air currents into other parts of the building, helping to preserve compartment integrity and buy time for occupants to evacuate.

Smoke vents are meant to vent smoke from a space, not to seal off duct passages. Fire doors help isolate spaces at openings between rooms but don’t address the movement of air and fire through a building’s duct system. Automatic shutters may close openings, but the standard feature used specifically to control fire spread through ducts is the fire damper.