Abstract: An arrangement to counteract or prevent spreading of fire, smoke or undesired gases through at least one passage, such as a ventilating duct, in a building. Said arrangement comprises a device adapted to keep the passage open normally but to close the passage when there is a risk of said spreading to occur. Said passage comprises at least one portion running in a drain trap-like path and said device comprises at least one supply means to supply, when there is a risk of said spreading to occur, a fluid to said drain trap-like portion in order to completely or partly fill the same while providing said closure of the passage.

Abstract: An arrangement to counteract or prevent spreading of fire, smoke or undesired gases through at least one passage, such as a ventilating duct, in a building. Said arrangement comprises a device adapted to keep the passage open normally but to close the passage when there is a risk of said spreading to occur. Said passage comprises at least one portion running in a drain trap-like path and said device comprises at least one supply means to supply, when there is a risk of said spreading to occur, a fluid to said drain trap-like portion in order to completely or partly fill the same while providing said closure of the passage.

Abstract: This invention is related to an arrangement in fans, compressors, turbines, pumps or the like, comprising at least one wheel, which is provided with vanes and through which a fluid is intended to pass at least partially in an essentially axial direction, and at least one inlet and one outlet opening. The main object of the invention is to improve this arrangement so that higher pressures may be obtained when used for driving a fluid and so that a better energy absorption from a fluid may be obtained when the fluid is driving the wheel. This object is achieved in that said wheel is arranged in a housing formed by a mantle provided at least partially about the periphery of the wheel and at least two side walls provided on opposite sides of the wheel, said housing and/or one or more parts associated therewith extending to the vicinity of the wheel on at least one side thereof.

Abstract: Recuperative heat exchangers are disposed in the supply and exhaust ducts of a ventilating system. To reduce frost build-up at the exit end of the exhaust-duct heat exchanger, the heat exchanger is disposed so that the exhaust air flows through it alternately from one end to the other, and vice-versa, when the temperature is below freezing. The reversal of flow of the exhaust air is accompanied by a reversal of the flow of heat exchange medium so that the efficiency of heat exchange is not adversely affected. Several systems of heat exchange are disclosed.

Abstract: Recuperative heat exchangers are disposed in the supply and exhaust ducts of a ventilating system. To reduce frost build-up at the exit end of the exhaust-duct heat exchanger, the heat exchanger is disposed so that the exhaust air flows through it alternately from one end to the other, and vice-versa, when the temperature is below freezing. The reversal of flow of the exhaust air is accompanied by a reversal of the flow of heat exchange medium so that the efficiency of heat exchange is not adversely affected. Several systems of heat exchange are disclosed.