Fire sprinklers will be activated at what degrees?

Fire sprinklers typically activate at temperatures ranging from 135°F to 165°F (57°C to 74°C), depending on the specific type of sprinkler head and its intended use. The temperature at which they activate is determined by the glass bulb or fusible link within the sprinkler, which breaks or melts to release water when exposed to heat. In some specialized applications, higher or lower activation temperatures may be used.