The hourly F and FH Ratings of the firestop system are equal to the hourly fire rating of the wall in which it is installed. Any batt or blanket meeting the above specifications and bearing the UL Classification Marking with a Flame Spread Index of 25 or less and a Smoke Developed Index 50 or less may be used. The appearance of a company's name or product in this database does not in itself assure that products so identified have been manufactured under UL's Follow-Up Service. Always look for the Mark on the product. UL permits the reproduction of the material contained in the Online Certification Directory subject to the following conditions: 1.
Firestopping non-dampered heating, ventilation, and air-conditioning HVAC duct penetrations in fire-rated walls is more involved than installing that ubiquitous red caulk into the space between the duct and the periphery of the opening. Because of the nature of thin sheet metal ductwork and the physics that come into play during the course of a fire, additional steps are required to ensure that such penetrants are properly protected. Today, a search would yield total systems for HVAC duct penetrations through walls. In just 7 years, the industry has more than 3.
Improving Firestopping for HVAC Duct Penetrations in Fire-Rated Walls
Fire Technology. There is a continuing debate among fire protection specialists on the value and role of fire dampers in preventing fire spread via HVAC duct systems. It has been recognized that fire dampers are not required under all circumstances. For example, NFPA 90A, Standard for the Installation of Air Conditioning and Ventilation Systems, does not require the installation of fire dampers in ducts penetrating one-hour fire-rated walls and partitions. Additionally, there are circumstances where the closure of dampers may affect critical environmental air systems.
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