| 摘要 |
PURPOSE:To obtain easy, fine control over the pressure in a negative pressure chamber, which maintains a predetermined negative pressure state, by providing in the negative pressure chamber an sub-system with a negative pressure controlling duct. CONSTITUTION:Negative pressure chambers 10 and 12 are connected to each other by means of a relief valve 32. As the main systems for the negative pressure chambers 10 and 12, an air inlet duct 22 consisting of an air conditioner 14, an air delivery fan 16, a constant airflow valve 26, and filters 20 and 20 is used in addition to an exhaust duct 30 consisting of a constant airflow valve 26, a filter 24, and exhaust fans 28 and 29. However, since it is not easy to control the pressure in the negative pressure chambers 10 and 12 because of plugging or the like in the filters 20 and 24, a negative pressure regulating duct 34 consisting of an air delivery fan 36, a constant airflow valve 38, and a filter 40 is provided. This duct 34 is connected to a by-pass duct 42 to form a sub-system. And the by-pass valve 44 in the by-pass 42 is controlled by a signal that is output from a regulator 46 after comparing the pressure in the negative pressure chamber 12 with the standard pressure. |
