Automatic fire dampers in ventilation systems are operated by use of

Automatic fire dampers are operated by A. Heat or smoke detectors or D. Fusible links, as both are designed to close the damper upon detecting high temperatures, which indicates a fire. Heat or smoke detectors provide an electrical signal, while a fusible link melts when a certain temperature threshold is reached, triggering the damper to close and prevent the spread of fire and smoke through ductwork.