Abstract: An airlock (purge chamber) which functions as an intermediate area between a contaminated area and a clean area where contaminated air may be purged before a person enters the clean area. The airlock (10) is a double-walled circular structure having an outside wall (20) with a single air intake (31) at its top and multiple air discharge ducts (37) spaced around the full 360 degree circumference of its base. The airlock (10) has an inner wall (24) with multiple air intake openings (perforations) (38) across its inner ceiling (26) and around its sides (24), providing a primary purge air flow (34) into the ceiling (26) of the inner wall (24) and down through the airlock (10) and a secondary air flow (32) into the side air intake openings (perforations) (38) and down through the airlock (10). Outgoing purge air (36) flows down through the floor (28) of the inner wall (24) and out the discharge ducts (37) at the base (27) of the outer wall (20) of the airlock (10).

Abstract: A gas particulate filter system is provided for supplying clean heated air o an operator subjected to ambient environments containing nuclear, biological or chemical contaminants. The filter unit includes replaceable radial flow canister means, centrifugal blower/heater means, continuously variable electronic control means for regulating air temperature and air flow, and clamping means for easy assembly of the components under adverse field conditions.