Abstract: In a method for checking filters for permeability, in particular for the presence of leaks or other faulty zones which have increased permeability in comparison with other filter zones for particles to be filtered from an air or gas stream, air or gas charged with such particles as applied to one surface of the filter and the other side of the filter is scanned with an indicator system indicating the penetration of particles. The method is arranged in such manner that zonewise scanning of the reverse filter surface takes place by means of a suction nozzle, that upon entrance of a particle flow into the suction nozzle a measuring device arranged in the flow path is separately influenced by the particle flow for each scanned region, and that the result for each scanned region emitting a particle flow is indicated separately.

Abstract: A modular frame arrangement suspendable from the ceiling of a room is proposed for receiving filters having fluid seals for clean room ceilings, which consists of structural rails having U-section channels for receiving the fluid, the rails being provided with a central web. Lying parallel to the ceiling, the webs of the rails and the central webs are constructed as hollow sections, the hollow section of the web being formed of two hollow chambers and a T-section groove lying between these hollow chambers. For connection of the rails, connection members are provided which have a square central part and integral arms offset in height at the lower side. The connection members are inserted with their arms in the rails so that the respective U-section channels are extended around the corner.

Abstract: Ceiling construction for clean rooms in which beneath a main ceiling (3) a lower ceiling (18) is mounted which is formed by a light and air permeable capillary structure (19), so that, with a high light transmission factor in respect of optimal and simultaneously dazzle free illumination of the clean room a turbulence-free laminar air flow is possible in the clean room.