Abstract: The invention relates to the filtration of air according to the N.B.C. method. A filtering unit (1) adapted to be incorporated in a casing of a filtering equipment comprises, in a housing, a filtering stage employing "filter paper" superimposed on a filtering stage based on "activated charcoal", an inlet passage (12) for gas to be filtered on the upstream side of the "paper" stage and a discharge passage (4) for filtered gas on the downstream side of the "charcoal" stage, one (12) of the passages being equipped with a peripheral sealed junction device (13,13') adapted to cooperate with a wall of the casing. The inlet and discharge passages (12,16) of the filtering unit are closed by sealed closure members (15,16) peripherally connected to the walls (7) of the housing and manually disengageable.

Abstract: This invention describes apparatus for pressurization and filtration of contaminated air for a vehicle or mobile dwelling capable of containing several persons, especially if the contamination is of nuclear, biological and chemical origin. The apparatus comprises an air loop extending between a contaminated air intake and a processed air outlet, comprising two cyclone precleaners, a filter and an air circulation blower. The apparatus also comprises a dust loop extending between the dust outlets of the prefilters and a dust outlet and comprising a dust discharge blower. In this apparatus, the blowers are coupled to an identical driving device, and the intake of the first blower is situated close to the air outlets of the cyclone precleaners.

Abstract: A pressurization and filter installation for shelters, notably of the substantially horizontal tubular tunnel type, comprises at least one entry-exit section communicating with a respective entry-exit airlock. This is adapted to be pressurized, in use, to a pressure higher than the normal external pressure. There is an armored door on the outside of the airlock. There is a sealed door on the inside of the airlock, controlling access to the shelter interior. The shelter interior is pressurized to a pressure higher than that in the airlock. Filter units are disposed in the airlock. Each filter unit comprises at least one absolute filter and at least one activated carbon filter. The shelter provides protection against the effects of nuclear, biological and chemical weapons.