What is a key function of smoke detectors on an initiating device circuit?

Smoke detectors play a crucial role in the initiating device circuit of a fire alarm system, primarily by serving as early warning devices that detect smoke from a fire. The function of signaling temperature fluctuations is not exclusive to smoke detection, as other devices may monitor temperature, but smoke detectors are designed specifically for detecting the presence of smoke particles in the air, indicating combustion.

In relation to the operation of elevators and the shut down of fans, this is a significant safety measure in fire protection protocols. When smoke is detected, the alarm system can automatically initiate control responses, such as recalling elevators to a designated floor for safe evacuation or shutting down smoke-control fans to prevent the spread of smoke throughout a building. This capability is essential for enhancing life safety and property protection during a fire incident.

While smoke detectors may have different operational modes, including manual activation, they are primarily designed to function automatically. Their reliance on the presence of smoke to trigger an alarm underscores their vital role in fire detection, rather than requiring manual intervention in every instance.