Abstract: A safety enclosure is disclosed which provides a portable self-contained ultra clean enclosed space environment, with easy access to the interior of the enclosure and which can be operated at relative positive, zero or negative pressure, depending on the usage conditions required so as to provide biological protection for an animal handler or investigator, to reduce contamination of the material inside the enclosure, and to prevent escape of noxious material to the outside.

Abstract: An air distribution ceiling for clean rooms is disclosed which includes a first or primary plenum chamber at the top of a room with a clean air supply communicating with it, the top of this chamber being bounded by the room ceiling and the bottom being bounded by a plurality of vertically spaced horizontal interlocked upper panels, a second plenum chamber bounded at the top by the upper panels and at the bottom by lower horizontal interlocked panels and forming the ceiling of the room. The panels are carried on spaced parallel supporting bars suspended from the top wall of the room and extending therealong, the supporting bars being held in spaced relation by spacer bars extending therebetween and having ledges to carry the upper and lower plates and to permit the insertion and removal of the lower panels from below. The panels each has a plurality of nozzle holes therethrough for downward air delivery and to provide for uniform air displacement within the room.