Which type of sprinkler head relies on thermal activation to release water?

A frangible bulb sprinkler relies on thermal activation to release water, making it an effective fire suppression system in many settings. The frangible bulb is filled with a liquid that expands when heated. As the temperature rises due to a fire, the liquid in the bulb expands until the bulb shatters. This breaking of the glass allows the water to flow through the sprinkler head and onto the fire, effectively suppressing it. This automatic response to heat makes frangible bulb sprinklers reliable for providing immediate fire protection.

In contrast, the other types of sprinklers have different activation mechanisms or functions. A soaked head sprinkler might refer to those designed for specific applications but does not operate on thermal activation like frangible bulbs. An electromechanical sprinkler typically relies on electrical systems rather than thermal-sensitive elements to activate. Finally, a dry pipe sprinkler is designed to operate in environments where pipes may freeze; it uses a valve system that fills the pipes with air until a fire activates the system, but it does not rely on thermal activation in the same manner as frangible bulb sprinklers. Each of these alternatives has its own unique operational principles that differentiate them from the frangible bulb design.