| 摘要 |
The invention concerns a method and an arrangement for controlling, regulating and indicating the flow of ventilation air in ventilated rooms, such as an exhaust hood 2 at laboratory work stations and the like. At each exhaust hood 2, a first position pickup 15 is arranged to put out information as to how open or closed the shutters 3 of the exhaust hood 2 are. A second position pickup 13 is arranged to put out information on the degree of opening of the shutter 3. The information, in the form of electric or pneumatic signals, is taken to a control unit in which the signals are processed and some of them displayed on an indicator 18, others detected by a limit value circuit 29. The signal quantities thus shown on the indicator 18 are proportional to the air flow speed in the shutter opening of the exhaust hood and when this signal falls below a limit value previously set at the limit value circuit 29, i.e., when the air flow speed in the shutter opening falls below a lowest tolerable value, an optical and/or acoustical alarm is given off by an alarm unit 29, 30, 19, 21. <IMAGE> |
