What type of system operates only when the temperature exceeds a certain set point?

A heat-activated sprinkler system is designed to function automatically when the temperature in the environment reaches a specific set point. This system typically utilizes heat-sensitive elements, such as a glass bulb filled with a liquid or a fusible link, which respond to changes in temperature. When the ambient temperature rises to the predetermined threshold, the protective element breaks or melts, allowing water to flow from the sprinkler heads to combat the fire.

This mechanism ensures that the system activates only in response to a fire's heat, rather than other events that may trigger unwanted activation, which is an important aspect of fire protection systems. The system's reliance on temperature makes it suitable for various applications, particularly in areas where overheating can occur without an actual fire.

Other types of sprinkler systems may respond to different triggers, such as manual activation or specific electrically controlled functions, which is why they do not fall under the description of operating solely based on temperature set points.