For sealing HVAC insulation fiberglass duct work and flexible duct joint systems, tapes must meet UL 181 A/B-FX standard. 3M(TM) Foil Tape 3340 meets these UL standards, which include specifications for tensile, adhesion, shear holding as well mold growth resistance.
For general duct sealing and MRO repair applications, 3M(TM) Foil Tape 3380 is an excellent choice. This tape is UL 723 classified, which specifies burning characteristics of flame spread and smoke development. This is a standard important to the construction industry.
UL identification printed on the 3326 tape: Ensures that correct tape is used and is recognized by those who may be inspecting the installation.
Linered tapes: Easy to use; protects the integrity of the adhesive and allows user to put tape through narrow gaps.
Acrylic adhesive on 3340 and 3380 tape: Has very long life and is not readily degraded by high temperature.