What devices are used to control the flow of smoke and fire within ducts?

The correct answer is smoke and fire dampers because they are specifically designed to control the movement of smoke and flames within ductwork. These devices play a critical role in fire protection systems by automatically closing when they detect heat or smoke, thereby preventing the spread of fire and smoke from one area of a building to another through the duct system. This containment is vital to maintaining safe egress routes and protecting occupants during a fire event.

Smoke alarms, while important for detecting smoke, do not actively control its movement. Fire extinguishers are used for manually suppressing fires but do not have a role in managing smoke flow within duct systems. Ventilation fans can help manage airflow but cannot close off ducts to prevent smoke or fire from passing through them. Therefore, understanding the function of each device helps clarify why smoke and fire dampers are the correct choice in this context.