Which type of detector is characterized as self-resetting?

The type of detector characterized as self-resetting is the bimetallic detector. Bimetallic detectors function based on the principle of two metals with different thermal expansion rates bonded together. When exposed to heat, the bimetallic strip bends as one metal expands more than the other. This bending action can trigger an alarm or activate a fire safety system. Once the heat source is removed and temperatures return to normal, the bimetallic strip returns to its original position, effectively resetting the detector without the need for manual intervention or replacement.

This self-resetting feature makes bimetallic detectors especially useful in certain environments as they can respond to heat without requiring a reset process. On the other hand, while ionization and photoelectric detectors are effective in detecting smoke and certain types of flames, they do not reset themselves automatically in the same way. Thermal detectors are designed to respond to temperature changes, but they will not automatically reset unless the system is designed to do so electronically or manually.