Sprinkler Components

An automatic fire sprinkler is a thermally actuated valve assembly designed to remain closed under normal system pressure and open when exposed to fire conditions. The frame or body forms the structural backbone of the sprinkler. It includes the threaded inlet for connection to the piping system and supports all operating components while withstanding continuous hydraulic pressure. Opposite the inlet, the deflector is positioned to shape and distribute the discharged water into a prescribed spray pattern, ensuring effective coverage of the protected area.

At the orifice, the sealing assembly—comprised of a cap and gasket— retains water within the system. The gasket provides a watertight seal against the machined seat, while the cap transfers load from the thermal element to keep the orifice closed until operation.

One primary distinction between designs lies in the thermal release mechanism. In a glass bulb sprinkler, a glass ampoule is the thermal trigger element for the sprinkler. A hermetically sealed liquid expands as the temperature in the bulb increases, so that the internal pressure in the ampoule increases until the ampoule bursts into tiny fragments at a defined trigger temperature. With no bulb (ampoule) holding the seal in place, pressurized water is allowed to flow through and out of the sprinkler orifce. In a metallic fusible alloy (solder-link) sprinkler, a eutectic solder joint melts at a predetermined temperature, allowing a lever-and-strut assembly to separate and release the sealing cap. In both cases, once the thermal element releases, water flows through the orifice and is distributed by the deflector.