Abstract: The invention relates to a closure device (28) for a filter unit (1) for the mutual and releasable insertion into a return air duct or exhaust air duct (2) of a barrier system (3), comprising a main body (30), an opening (6) in the main body (30) that can be peripherally bounded by an annular seal (11), a lid (10) that can be switched between an open position in which the opening (6) is open and a closed position in which it bears in a sealing manner against the annular seal (11) in order to selectively open and close the opening (6) and that has passing through it an imaginary longitudinal axis (A), wherein the lid (10) is connected in an articulated manner to the main body (30) so as to be able to pivot by means of at least one rotary articulation (40) through which there passes a pivot axis (S).

Abstract: The invention relates to a closure device (28) for a filter unit (1) for the mutual and releasable insertion into a return air duct or exhaust air duct (2) of a barrier system (3), comprising a main body (30), an opening (6) in the main body (30) that can be peripherally bounded by an annular seal (11), a lid (10) that can be switched between an open position in which the opening (6) is open and a closed position in which it bears in a sealing manner against the annular seal (11) in order to selectively open and close the opening (6) and that has passing through it an imaginary longitudinal axis (A), wherein the lid (10) is connected in an articulated manner to the main body (30) so as to be able to pivot by means of at least one rotary articulation (40) through which there passes a pivot axis (S).