Abstract: A ventilation system for a multi-storey building, which system comprises a ventilation apparatus mounted on a roof and provided with fans for generating an inlet air flow and a distributing channel for supplying the inlet air flow to various intermediate levels of the building. A service shaft of the building serves as an inlet air flow channel, which shaft forms a flow path for the inlet-air flow directed from the fans downwards, whereby the service shaft has deflecting means for passing a part of the air flow to each intermediate level of the building.

Abstract: The invention relates to an apparatus for the separation of edge trimmings, in connection with a pulper. The upper portion of the jacket of the pulper (1) serves as a jacket of a first cyclone (5), a second cyclone (8) opposite in direction being provided within said cyclone (5). When the air flow enters the second cyclone and the direction thereof is reversed, it is essentially retarded, whereby also light paper particles fall into the stock contained in the pulper. The object is to provide an efficient device for the separation of edge trimmings, which device does not spread dust in the surroundings.