HVAC tape ratings ul-181 a-p and ul181b-fx explained

UL-181A-P and UL181B-FX are important ratings for HVAC tapes, indicating their compliance with specific Underwriters Laboratory (UL) standards:

1. UL-181A-P:
   • Used for seaming, sealing, and joining rigid fiberglass ductwork (duct board) and sheet metal13.
   • Made of aluminum or aluminum alloy foil with a minimum width of 2.5 inches13.
   • Features an aggressive acrylic adhesive and often includes a release liner3.
   • Designed to withstand the thermal cycles of HVAC systems3.
2. UL181B-FX:
   • Specifically used for Class 1 flexible air ducts and connectors123.
   • Can be made of foil, film, or cloth with a maximum width of 1.88 inches3.
   • Some UL181B-FX tapes can be used as alternatives to traditional paint-on mastic3.

Both ratings ensure that the tapes have passed rigorous testing for flame resistance, mold growth, humidity resistance, temperature performance, and other critical factors1. These certifications are crucial for code compliance and guarantee that the tape will effectively seal HVAC systems for their intended lifespan when properly installed3.

It’s worth noting that a UL181A-P certified product is always certified to UL181B-FX as well, and may carry the designation UL181A-P/B-FX2