Patent ID: 7527663

Claim:
Ventilation system ( 10 ) providing NBC protection for at least one closed security space and/or protection space ( 12 ) with constant slight excess pressure, which ventilation system ( 10 ) substantially comprises an air inlet ( 16 ) and air outlet ( 18 ), an explosion protection valve ( 28 ), a prefilter ( 26 ), a filter ( 38 ) for suspended matter, an activated carbon filter ( 40 ) and an air conveying device for sucking in the air to be purified and for distributing the purified air, wherein the ventilation system ( 10 ) comprises an explosion protection valve ( 28 ) which is combined with and cooperates with the prefilter ( 26 ); wherein the explosion protection valve ( 28 ) comprises an impact-resistant plate ( 30 ) having a first perforation ( 32 ), rigidly mounted prior to the filter ( 38 ) for suspended matter, a prefilter pad ( 26 ) which can be elastically compressed and is held upstream from this stationary plate ( 30 ) and a moveable plate ( 34 ) having a second perforation ( 36 ), which can be displaced in the direction (L) of the stationary plate ( 30 ).