UL 555S

Standard for Smoke Dampers

1.1 These requirements cover smoke dampers intended for use in heating, ventilating, and air conditioning (HVAC) systems. Smoke dampers are intended:

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

b)    To assist with the control of pressure differentials across smoke barriers when the HVAC system is part of an engineered smoke control system.

1.2 Dampers covered by these requirements are evaluated for use as either:

a)    Smoke Dampers - For use in HVAC systems where ducts pass through smoke barriers.

b)    Combination Fire and Smoke Dampers - For locations in HVAC systems where a fire damper and a smoke damper are required at a single location, or

c)    Corridor Dampers - For locations in HVAC Systems where air ducts penetrate or terminate at openings in the ceilings of interior corridors when permitted by authority having jurisdiction.

1.3 The smoke dampers covered by these requirements are intended for installation in accordance with the National Fire Protection Association Standard for Installation of Air Conditioning and Ventilating Systems, NFPA 90A, the International Mechanical Code and the Uniform Mechanical Code.

1.4 Combination fire and smoke dampers and corridor dampers shall also comply with the applicable requirements in the Standard for Fire Dampers, UL 555.


  • Edition Number: 5
  • Edition Date: 02/13/2014
  • Price Code: B
  • Type: ulstd
  • ANSI Approved: 02/13/2014
  • DOD Approved: 07/29/1994