Hinged -

Hinged - fabricated door and doorframe attached
together with a hinge.
Sandwich - two-part closure device in which the two
sides are mechanically fastened together on both
sides of the duct wall at the perimeter of the service
opening.
Spin Door - round access door and door frame
installed by spinning the door frame into a round
opening.
Ductwork: A system of passageways for distribution and
extraction of air, excluding plenums not installed in
accordance with SMACNA Standards (See ASHRAE
Terminology of Heating, Ventilation, Air Conditioning &
Refrigeration, 1991).
EPA: United States Environmental Protection Agency.
Flame Spread Index: The Flame Spread Index refers to
the sustained combustion classification of a material as
listed in NFPA 255, Standard Method of Test of Surface
Burning Characteristics of Building Materials.