| 摘要 |
PURPOSE:To prevent the discharge of water in an air blow-off tank by making the maximum suction pressure larger than pressure converted into a water column corresponding to difference between the highest level of the surface of the water in an overpressure preventive pipe inserted into the tank and the lowest level of the surface of the water in the tank. CONSTITUTION:Water 8 is supplied previously into the air blow-off tank 3 up to a level L2. When air in a covering body 1 is discharged forcedly by means of a blower 2' and the inside of the covering body 1 is brought to negative pressure, water in the tank 3 is pulled up to a level L1 through the overpressure preventive pipe 4 while water in the tank 3 drops up to L3. Here, let it be supposed that volume in the overpressure preventive pipe 4 between the level L1 and the level L3 is equal to volume in the tank 3 between the level L2 and the level L3 and the suction pressure of the blower 2' is equivalent to the water column section h3. Accordingly, the discharge of water in the tank 3 can be prevented by settting length h3 to length more than the sucking capacity of the blower 2'. |
