| 摘要 |
PURPOSE:To make it possible to put a room into a negative pressure in a manner almost the same as the case of a normal operation, to prevent the inside of the room from being put into an extraordinary negative pressure and also to prevent a precise and airtight housing and a duct system from being damaged by stopping an air feed fan when power supply is stopped, and operating an exhaust fan at a speed which is lower than that at a normal operation time by a power source for emergency use. CONSTITUTION:An air feed fan 9 is stopped when power supply is stopped, and power supply to a changeover damper 13 is stopped to close the same. At the same time, an exhaust fan 15 is operated at a low speed to reduce the capacity of an emergency power source 20. At the time of stoppage in power supply,the changeover damper 13 is closed and exhaustion of air from an auxiliary exhaust duct 14 is stopped. An exhaustion route from the air feed fan 9 to the exhaust fan 15 via an air feed port 7, a laboratory 1a, a safe cabinet 2a, and an opening and closing valve 6, is set. The laboratory 1a is put into a negative pressure, and the safe cabinet 2a is put into a more negative pressure. Thus, the negative pressure is increased according to the degree of danger thereby to prevent bacteria arrested by a filters 5 from re-scattering into the laboratory 1a and further dispersing to outside the laboratory 1a to maintain a desired cleanliness degree.
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