What is Class 0?
Class 0 refers to a material that shall have surface burning characteristics of zero. (Flame spread / Smoke developed).
What is U.L. 181?
U.L. 181 is the standard that has been used for over 30 years for evaluating safety. The testing procedures were developed by taking a wide range of safety-related installation situations into consideration, including structural integrity and flammability characteristics. Four (4) fire tests are used to investigate the flammability and burning characteristics of flexible ducts.
What is Class 1?
Class 1 represents a material which shall have a flame spread rating of not over 25 without evidence of continued progressive combustion and a smoke-developed rating of not over 50.
What is “Listed”?
A published list by a recognized approving agency acceptable to the authority having jurisdiction stating the flexible duct, tape and mastic has been tested to and complies with the applicable Standards UL 181 / UL 181B and maintains periodic inspection to assure production of the listed products are in accordance with the listing. Factory made air ducts must be tested and listed in accordance with (U.L.) Underwriters Laboratories Standard for Factory-Made Air Ducts UL-181.
Who is U.L.?
U.L. (Underwriters Laboratories) is an independent, not-for-profit product safety testing and certification organization, founded in 1894.
Why does U.L. require labelling of Air Ducts and Air Connectors?
Labelling is required because this certifies the compliance with the U.L. standards. In some cases the label also contains recommendations of installation or conditions of use.
