How is a frangible bulb heat detector activated?

A frangible bulb heat detector is activated specifically when a small glass vial, or bulb, filled with a liquid temperature-sensitive substance breaks due to heat. As the temperature rises, the liquid inside the bulb expands. Once the temperature reaches a predetermined threshold, the pressure from the expanded liquid causes the glass to fracture. This rupture allows the detection system to trigger an alarm or activate suppression equipment, signaling that a fire condition may exist.

This activation method allows for a quick response to increasing temperatures, which is crucial in fire situations. The design of frangible bulbs is reliable due to the clarity of the temperature threshold at which the detector will respond, making it an effective tool for early fire detection. Other methods of detection, such as pressure increase or vapor detection, are not applicable to frangible bulb detectors, as their activation mechanism relies solely on the physical breaking of the glass bulb in response to high temperatures.