UL 181B:2021 PDF Download

UL 181B:2021 standard specifies the requirements for pressure-sensitive tapes, mastic systems, and non-metallic mechanical fasteners used as part of the closure system for factory-made flexible air ducts or air connectors. This standard complements the requirements outlined in UL 181, the Standard for Factory-Made Air Ducts and Air Connectors.

The standard covers pressure-sensitive tapes used for core to fitting attachment and outer moisture barrier applications. When used at the core to fitting attachment, a mechanical fastener must be installed over the tape to ensure a secure connection. Tapes may be used at the outer moisture barrier with or without mechanical fasteners.

Mastic systems covered by the standard are intended for joints of flexible non-metallic air ducts or air connectors that use mechanical fasteners. The joints, without mastics, must comply with the requirements of UL 181. Mastic closure systems provide an additional seal at the attachment of the flexible non-metallic air duct cores, ensuring a tight and reliable connection without disrupting mechanical fasteners.

Non-metallic mechanical fasteners specified in the standard are intended for use at the core to fitting attachment and outer moisture barrier of flexible non-metallic air ducts or air connectors. These fasteners require beaded fittings and are limited to a maximum positive operating pressure of 6 inches water column (1.5 kPa). Multiple lengths of fasteners can be joined to achieve longer lengths.

The pressure-sensitive tapes, mastic closure systems, and non-metallic mechanical fasteners covered by the standard are designed to be used with flexible air ducts and air connectors installed in accordance with various building codes such as the International Mechanical Code (IMC), International Residential Code (IRC), International Energy Conservation Code (IECC), Uniform Mechanical Code (UMC), NFPA 90A, and NFPA 90B, among others.