What activates the sprinkler heads in a fire suppression system?

The activation of sprinkler heads in a fire suppression system is primarily based on the detection of heat. Sprinkler systems are designed to respond to an increase in temperature, indicative of a fire. Each sprinkler head is equipped with either a glass bulb filled with a heat-sensitive liquid or a fusible link—a metal element that melts at a predetermined temperature. When the temperature around the sprinkler head rises to the point where it exceeds this threshold, the heat either causes the glass bulb to shatter or the fusible link to melt. This process results in the release of water from the sprinkler head to help extinguish or control the spread of fire.

While smoke and flame are associated with fire conditions, they do not trigger the sprinkler activation directly. Smoke detectors and flame sensors serve different functions in fire safety, typically providing alarms rather than direct suppression. Water pressure is crucial for the delivery of water through the system, but it does not activate the sprinkler heads. Therefore, heat is the correct factor that activates the sprinkler heads in a fire suppression system.