What is the minimum damper rating for penetrations of less than 3-hour fire-resistance-rated assemblies?

In the context of fire-resistance-rated assemblies, it's essential to understand the purpose of dampers and their ratings. Dampers are used in mechanical systems to prevent the spread of fire and smoke through ductwork or other openings that penetrate fire-rated walls or floors.

The minimum damper rating for penetrations of less than 3-hour fire-resistance-rated assemblies is 1.5 hours, which aligns with the intent of providing sufficient protection while ensuring that the fire-resistive integrity of the assembly is maintained. This duration allows the damper to function effectively in a fire situation, holding back flames and smoke for the necessary period to help protect life and property, ensuring compliance with fire safety regulations.

Understanding this minimum rating is crucial for ensuring proper design and installation of HVAC systems in buildings that are subject to fire safety codes, particularly in scenarios where there are less than 3-hour rated assemblies. It underscores the overall goal of minimizing the risks associated with fire spread and enhancing building safety standards.