Detector spot fire fixed temp, 65 degree c.

Spot Heat Detectors are mounted on exposed ceiling surfaces or on a sidewall near the ceiling. When two metals with different coefficients of thermal expansion are bonded together and then heated, differential expansion causes bending or flexing toward the metal having the lower expansion rate. This action closes a normally open circuit. The mechanism of this fixed temperature type fire detector triggers the fire alarm, when the temperature rises at a rate exceeding a predetermined value.