The Broan® RD1 Radiation Damper prevents the rapid spread of fire to other areas of a home during a fire. Many codes require that exhaust fans installed in multi-family homes, with fire-rated ceilings, must be protected by radiation dampers. When the air temperature passing through the damper exceeds 212°F, the fusible link melts, triggering the thermal fabric to automatically close across the damper. Airflow is interrupted by a flame and heat barrier, preventing the rapid spread of fire to other areas of the home.The Broan® RD1 Radiation Damper prevents the rapid spread of fire to other areas of a home during a fire. Many codes require that exhaust fans installed in multi-family homes, with fire-rated ceilings, must be protected by radiation dampers. When the air temperature passing through the damper exceeds 212°F, the fusible link melts, triggering the thermal fabric to automatically close across the damper. Airflow is interrupted by a flame and heat barrier, preventing the rapid spread of fire to other areas of the home.