Abstract: A duct system comprising duct sections which are factory manufactured and field modifiable. The field modifiable duct system comprises fire resistant materials and is fire-rated. The duct sections when assembled create a continuous conduit that allows air to flow from a fresh air source to the required area of the building.

Abstract: An access panel assembly for providing access to a duct through an opening in the duct. The access panel assembly comprises a sealing member, a cover member and fasteners. The sealing member fits around the opening in the duct and the cover member fits over the sealing member and coupled to the duct by the fasteners. The cover member may comprise a fire resistant panel and is formable to the shape of the duct thereby allowing the access panel assembly to be fitted to irregular shaped ducts or openings in the ducts. The access panel assembly allows easy and ready access to the interior of ducts or other air handling equipment to permit the inspection and cleansing of the interior surfaces and other interior components of any contaminants.