Air Duct Covering

Air Duct Covering: Materials such as insulation and
banding used to cover the external surface of a duct.
Air Duct Lining: Generally refers to fiber glass or other
matting affixed to the interior surfaces of the air ducts for
thermal insulation and noise attenuation.
Air Filtration Device (AFD): A portable or transportable,
self-contained blower assembly designed to move a
defined volume of air equipped with one or more stages
of particulate filtration. Depending on the mode of use,
an AFD that filters (usually HEPA) and re-circulates air is
referred to as an "air scrubber." One that filters air and
creates negative pressure is referred to as a "negative
air machine."
Air-handling Unit (AHU): A packaged assembly, usually
connected to ductwork, that moves air and may also
clean and condition the air.