Abstract: A light fixture, for a ceiling plenum system defining an upstream space and a downstream space, includes a light-fixture base defining a light-fixture axis. First and second side walls extend toward the downstream space and are sealingly attached to the base plate and to first and second end plates. First and second legs are sealingly attached to the light-fixture base by one of a first-leg continuously welded joint and a first-leg monolithic connection. A downstream end of each leg forms a knife portion. First and second gas filters each comprise an orthogonal gas-filter frame defining an interior perimeter and an exterior perimeter. A trough with sealant affixed therein is sealingly attached to and surrounds a portion of the exterior perimeter. A trough opening faces the downstream space, with the knife portions penetrating surfaces of the sealant, forming a seal between the light-fixture base and each gas filter.

Abstract: A method of constructing a cleanroom pass-thru chamber includes bending a single sheet of material into a monolithic frame having a first side, an opposing second side, a third side extending between the first and second sides, an open front end and an open rear end. The first side defines a first lip at a free end thereof and the second side defines a second lip at a free end thereof. The monolithic frame is bent to form four coved internal corners. The first lip and the second lip define an open portion therebetween. A first plate is attached to the two opposing lips and extends therebetween, closing the open portion of the monolithic frame, thereby forming an inner shell. The inner shell is positioned within, and attached to, an outer frame.