A filter unit barrier system

The present invention proposes a method for loading into the isolator or a clean room or the return air passage in the exhaust passage a filter unit (1), comprising: a filter enclosing means (22) for communicating with a separator (2) or the purification chamber connected; the filter with a closure means (22) filter (20) is connected, wherein the filter enclosing means (22) having at least one opening (50) with at least one filter flange (24); at least a cover for opening and closing (40) said opening (50), wherein movement of the lid to (40), said filter unit (1) internally comprises at least one piston receiving portion (26) and at least one can in this relative movement of the piston (34), the piston is movably mounted in the piston receiving portion (26).