Which sprinkler release mechanism is activated by heat causing a fusible link to melt?

• A. Fusible links
• B. Frangible bulbs
• C. Chemical pellets
• D. Magnetic triggers

Answer: (A)

In sprinkler systems, activation is triggered by heat, using a small heat-sensitive element that holds the sprinkler in place until conditions rise high enough. A fusible link is a metal alloy designed to melt at a specific temperature. When fire heat reaches that point, the link melts and releases the sprinkler head, allowing water to flow. This is the mechanism described by the scenario.

Frangible bulbs are a different heat-activated path: a glass bulb containing a liquid expands with heat and breaks at a set temperature, releasing the mechanism. Magnetic triggers rely on removing a magnetic hold rather than melting due to heat, and chemical pellets are part of other types of suppression systems and don’t operate by melting a fusible link.