1 Scope

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

1. 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

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

Summary of Topics

This new Sixth Edition of ANSI/UL 555S dated June 26, 2025 includes the following changes in requirements:

– Expanded Referenced Documents; 1.3

– Formatting and Typo Corrections; 13.3.1.1, 13.3.2.5