UL 181C:2020 PDF Download

UL 181C:2020 is an outline of investigation that applies to non-metal accessories used to join or attach flexible air ducts and air connectors. These accessories, such as collars and sleeves, are intended to be installed in accordance with various codes and standards related to the installation of air-conditioning and ventilating systems, such as the International Mechanical Code, International Residential Code, Uniform Mechanical Code, and NFPA 90A.

It is important to note that this outline is not intended for metal joining accessories. Requirements for metal accessories can be found in the SMACNA HVAC Duct Construction Standards - Metal and Flexible, 3rd edition, 2005.

Furthermore, the non-metal accessories covered by this outline have not been evaluated for use with rigid factory-made air ducts and connectors or sheet metal ducts that comply with the SMACNA HVAC Duct Construction Standards - Metal and Flexible, 3rd edition, 2005.

If there are any conflicts between the installation instructions of the flexible air ducts and the use of these non-metal joining accessories, the accompanying installation instructions are intended to take precedence.