Which type of heat detectors activate when the component melts at a preset temperature?

Fixed-temperature heat detectors are designed to activate when the temperature in the surrounding area rises to a predetermined level, which causes the detector's sensing element to melt. This melting triggers the alarm, indicating that a specified temperature threshold has been exceeded, typically associated with a fire condition.

These detectors are commonly used in various settings because they provide a reliable way to monitor for high temperatures that are indicative of fires. The melting point is specifically set according to the requirements of the environment where the detector is installed, making them suitable for many applications.

In contrast, rate of rise heat detectors activate based on a rapid increase in temperature over a short period rather than a specific melting point. Laser and photoelectric heat detectors are based on different operational principles and do not function by melting components to signal a fire condition.