In some HVAC applications, UL listings are critical for code compliance. This means the HVAC tape used has the proper adhesion and exceptional shear strength needed to stay in place effectively for the life of the HVAC system.

In order to receive a UL 181 listing, tapes that are used to seal air duct and air connectors are subjected to a battery of tests, including: Flame Resistance, Mold Growth & Humidity, Temperature, Static Load, Impact, Pressure, Collapse, Tension, Torsion and Leakage Test.

This testing determines if an HVAC tape will be able to receive a UL listing. Two commonly used on HVAC tapes are UL 181A-P and UL 181B-FX. So what’s the difference?

UL 181A-P

UL 181A-P is the standard for HVAC tapes used to seam, seal and join rigid ductwork (or duct board).

This listing has more stringent testing requirements that must be passed in order to be approved and must be made of either aluminum or aluminum alloy foil with a minimum width of 2.5 inches. These tapes must also be constructed with a release liner.

UL 181B-FX

UL 181B-FX is the standard for HVAC tapes used to seam, seal and join Class 1 Flex Duct.

Products meeting this listing are required to meet a minimum width of 1.825 inches, and can be made from a variety of materials such as foil, film or cloth.