Which type of sprinkler head uses a plunger mechanism?

The correct answer is chemical pellet sprinkler heads, which utilize a plunger mechanism to activate the sprinklers. In these types of sprinkler heads, a chemical pellet, often made from a heat-sensitive material, reacts to heat by expanding and ultimately triggering the plunger. This mechanism is designed to provide quick activation in response to elevated temperatures, resulting in effective water discharge over a fire area.

Chemical pellet sprinkler heads are specifically engineered for certain applications where rapid activation is crucial, and they effectively address specific fire hazards. Other types of sprinkler heads, such as frangible bulb heads, rely on glass bulbs filled with liquid that shatter when heated, and deluge heads are typically used in systems designed to deliver water over a large area without individual activation, functioning via a water supply directly upon activation of the system. Pendant sprinkler heads are designed to hang from a ceiling and typically operate using similar mechanisms to frangible bulbs rather than a plunger. Thus, the distinctive plunger mechanism specific to chemical pellet sprinkler heads marks their effectiveness in certain fire suppression scenarios.