Standard Duct Wrap is FSK which means that it’s jacket is alumimum foil with scrim threads.
Duct Wrap Installation
This FSK jacket also provides a fire resistant surface and a vapor barrier which allows it to meet ASTM and NFPA90 specs and prevents sweating. Commercial insulators use an ASJ (all service jacket) on pipe coverings and occasionally they use an ASJ white vinyl wrap to match the pipe coverings on boilers.
