Ventilating, air-conditioning, and heating ducts provide a path for fire and smoke, which can travel throughout a building. The ordinary types of dampers that are often installed in these ducts depend on gravity-close action or spring-and-level mechanisms. When their releases are activated, they are freed to drop inside the duct.
A fusible link attachment to individual registers also helps control fire and smoke. Figure 17-12 shows a fusible- link-type register. The link is available with melting points of 160°F (71.1°C) or 212°F (100°C). When the link melts, it releases a spring that forces the damper to a fully closed position. The attachment does not interfere with damper operation.
Smoke dampers for high-rise buildings
Fire and smoke safety concepts in high-rise buildings are increasingly focusing on providing safety havens for personnel on each floor. This provision is to optimize air flow to or away from the fire floor or adjacent floors. Such systems require computer-actuated smoke dampers. Dampers are placed in supply and return ducts that are reliable. They must be tight closing, and offer minimum flow resistance when fully open.