What marking is used for pressure-sensitive tape in ductwork compliant with UL 181B?

The correct marking for pressure-sensitive tape in ductwork compliant with UL 181B is 181B-FX. This designation indicates that the tape has passed specific tests for use in HVAC applications, particularly for sealing and maintaining duct integrity under varying pressure conditions.

UL 181B is a standard that outlines the safety and performance requirements for various products used in duct systems, including tapes. The "FX" suffix signifies that the tape is intended for applications requiring stronger adhesion and durability, making it suitable for sealing joints and seams in duct systems, which is critical for maintaining system efficiency and air quality. Other markings, while they denote compliance with UL 181B, apply to different types of products or applications, rather than specifically indicating the properties of pressure-sensitive tape designed for ductwork.