Overview of Emergency Control Functions
Chapter 21 of NFPA 72 addresses emergency control functions (ECFs), which are the interfaces between the fire alarm system and other building systems. These functions ensure that building systems respond appropriately during a fire emergency to support occupant safety, facilitate evacuation, and assist firefighting operations. Emergency control functions are activated automatically by the fire alarm system based on predefined input signals and sequences.
Elevator Recall and Shutdown
One of the most critical emergency control functions is elevator recall. When smoke detectors in elevator lobbies, hoistways, or machine rooms activate, the fire alarm system must initiate elevator recall to bring elevators to a designated floor and take them out of normal service. This prevents occupants from being delivered to a fire floor and ensures elevators are available for firefighter use. Elevator shutdown may also be required when heat or smoke is detected in the machine room or hoistway.
Door Release and HVAC Control
Fire alarm systems commonly interface with magnetic door holders to release fire doors upon alarm activation, allowing them to close and compartmentalize the building. HVAC shutdown or smoke control activation is another critical function. The fire alarm system may shut down air handling units to prevent smoke spread or activate dedicated smoke control systems to maintain tenable conditions in egress paths and areas of refuge.
Suppression System Interfaces
Chapter 21 also addresses the interface between fire alarm systems and fire suppression systems, including pre-action sprinkler systems, deluge systems, and clean agent systems. The fire alarm system may provide the detection input that triggers suppression system activation, and proper coordination between detection and suppression is essential. All emergency control functions must be documented in the system’s sequence of operations and tested during system acceptance and at required intervals.
