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

A fire damper is an essential component used in HVAC systems to prevent the spread of flames and smoke through ducts in fire-rated walls and floors. When it comes to the fire damper rating for penetrations into assemblies with less than a 3-hour fire resistance rating, the requirement is typically 1.5 hours.

This rating is established to ensure that if a fire occurs, the damper can withstand the heat and pressure for a sufficient amount of time to maintain the integrity of the fire-rated barrier. A 1.5-hour rating provides a level of protection and allows for adequate time for occupants to evacuate and for emergency services to respond.

In environments where assembly areas have fire resistance ratings under 3 hours, utilizing a fire damper with a 1.5-hour rating ensures compliance with building codes and safety standards, thereby reducing the risk of fire spreading through ductwork and improving the overall fire safety of the structure.

Higher ratings, such as those indicated in the other choices, are intended for use in assemblies that require more stringent protection, which may not be applicable in this specific context of less than 3-hour rated assemblies.