Abstract: A method and system for testing airtightness of a building envelope (10). An air flow generator (21) is provided that is switchable between at least two different flow rates (Q0,Q1). The air flow generator (21) is repeatedly switched between a first flow rate (Q0) and a second flow rate (Q1) for modulating the building pressure (P1) as a function of time (t) between respective equilibrium pressure values at the first flow rate (Q0) and the second flow rate (Q1). The relative building pressure (?P) is measured by a differential pressure transducer (31) and recorded as a function of time (t). A pressure modulation amplitude (?Pmodulation) is calculated for providing a measure of the airtightness.

Abstract: A method and system for testing airtightness of a building envelope (10). An air flow generator (21) is provided that is switchable between at least two different flow rates (Q0,Q1). The air flow generator (21) is repeatedly switched between a first flow rate (Q0) and a second flow rate (Q1) for modulating the building pressure (P1) as a function of time (t) between respective equilibrium pressure values at the first flow rate (Q0) and the second flow rate (Q1). The relative building pressure (?P) is measured by a differential pressure transducer (31) and recorded as a function of time (t). A pressure modulation amplitude (?Pmodulation) is calculated for providing a measure of the airtightness.

Abstract: Welding torch system for use in welding or cutting operations during which fume is created. The welding torch system has a welding torch comprising a contact tip holder and a coaxial nozzle comprising an inner shield gas conduit having a shield gas outlet for supplying a shield gas. The inner shield gas conduit surrounds the contact tip holder. An outer shell at least partly surrounds said inner shield gas conduit. The welding torch system further comprises a shield gas generator and supply unit for supplying shield gas through the shield gas outlet and a fume extracting assembly for extracting fume and ambient air. The welding torch system is arranged for—during operation—supplying shield gas through the shield gas outlet at a velocity between about 1.5 m/s and 10 m/s. By operating the fume extracting assembly to generate a flow of between 10 and 100 m3/h, preferably a flow of about 55 m3/h a reduction in the area of 90%-95% of hazardous fumes can then be realized.

Abstract: Welding torch system for use in welding or cutting operations during which fume is created. The welding torch system has a welding torch comprising a contact tip holder and a coaxial nozzle comprising an inner shield gas conduit having a shield gas outlet for supplying a shield gas. The inner shield gas conduit surrounds the contact tip holder. An outer shell at least partly surrounds said inner shield gas conduit. The welding torch system further comprises a shield gas generator and supply unit for supplying shield gas through the shield gas outlet and a fume extracting assembly for extracting fume and ambient air. The welding torch system is arranged for—during operation—supplying shield gas through the shield gas outlet at a velocity between about 1.5 m/s and 10 m/s. By operating the fume extracting assembly to generate a flow of between 10 and 100 m3/h, preferably a flow of about 55 m3/h a reduction in the area of 90%-95% of hazardous fumes can then be realized.

Abstract: Ventilation system for ventilating especially classrooms (1) and similar rooms, comprising a lowered ceiling (3) and means, e.g. a ventilator (5), for forced air inlet from the outside air (6) into the room (2) above the lowered ceiling, and air outlet openings (7) mainly evenly spaced over the whole surface of the lowered ceiling. The exhaust air may be led via an HR unit (12-16) to preheat the supply air. Blowing the supply air along the underside of the concrete upper floor (4) enables cooling that floor at night. By day this cold may be used to cool the supply air.

Abstract: The present invention relates to a device for performing welding operations, comprising: a core member in which can be guided a welding wire connectable to a voltage source; an extraction member arranged on the outside of the core member for extracting substances inconvenient to the welder; a gas supply member arranged on the outside of the extraction member for supplying gas. The invention also relates to an assembly for welding a weldment, comprising: a device as claimed in any of the claims 1-9, welding wire supply means for supplying welding wire; gas supply means for supplying gas via the gas supply member; a voltage source for applying electrical voltage between the welding wire and the weldment; pumping means for exhausting substances inconvenient to the welder via the extraction member.