UL 555S BULLETIN

Abstract

These requirements cover smoke dampers intended for use in heating, ventilating, and air conditioning (HVAC) systems. Smoke dampers are intended: <br>a) To restrict the spread of smoke in HVAC systems that are designed to be automatically shut down in the event of a fire, or <br>b) To assist with the control of pressure differentials across smoke barriers when the HVAC system is part of an engineered smoke control system. <br>Dampers covered by these requirements are evaluated for use as either: <br>a) Smoke Dampers &#8211; For use in HVAC systems where ducts pass through smoke barriers. <br>b) Combination Fire and Smoke Dampers &#8211; For locations in HVAC systems where a fire damper and a smoke damper are required at a single location. <br>Smoke dampers are used for the protection of openings in smoke barriers or in engineered smoke control systems in accordance with the Standard for Installation of Air Conditioning and Ventilating Systems, NFPA 90A. These damper assemblies are intended for installation in accordance with codes such as the BOCA National Mechanical Code, the SBCCI Standard Mechanical Code, the ICBO Uniform Mechanical Code, and the International Mechanical Code. <br>Combination fire and smoke dampers shall also comply with the applicable requirements in the Standard for Fire Dampers, UL 555.