Abstract: A double floor for removing air from rooms, particularly clean rooms, which are connected to the air supply system of a ventilating and/or air-conditioning unit. The double floor has an upper floor plane formed by perforated plates. The perforated plates are supported by support members. On the underside of the perforated plates is provided a stiffening system composed of stiffening members. Cover members are provided on portions of the stiffening system facing away from the perforated plates. The cover members form at least in the regions of the edges of the stiffening members nozzle openings which project beyond the lower plane of the stiffening system. All the nozzle openings open in the same direction.

Abstract: A laminarizer or arrangement for producing laminar flow, particularly for ceilings and walls of clean rooms or the link formed of filter modules. The laminarizer is suspended or held spaced from a cover supporting mechanical filters. The laminarizer is composed of rectangular frames with fabric sheets stretched onto the rectangular frames. The side members of the rectangular frames are hollow sections or angle sections of triangular cross-section. The fabric sheets rest against and are aligned by the surfaces of the side members facing the rooms are only as narrow and/or rounded-off alignment contacts for the fabric sheets, while the fastening of the fabric sheets is provided at the outer surfaces of the side members extending perpendicularly to the plane of the frame and/or on the rear surfaces of the side members extending in the plane of the frame.

Abstract: An impact mill in which the pins of the milling tools are provided with pocket-forming vanes which are oriented substantially radially or tangentially with respect to the rotation circle of the respective tool and, downstream of the pin forming the tool, a streamlined profile is provided to reduce vortex formation and turbulence and thereby improve the energetic efficiency of the mill.