| 摘要 |
PURPOSE:To prevent the intrusion of foreign matters into the air supply and discharge systems by a method in which the inside of the film dam is provided with a partition wall to divide it into two compartments vertically, an air supply tube is connected to the upper compartment, and the lower compartment is connected with the upstream side of the film dam through an opening. CONSTITUTION:The inside of a rubber dam 1 is divided into upper and lower compartments 3 and 4 by a partition wall 2, an air supply tube 13 from which air is supplyed or discharged is connected to the upper compartment 3, and an exhaust pipe 15 with an exhaust valve 16 on the tip of its mid-branched portion is provided to the pipe 13. The lower compartment 4 is provided with another opening 25 connected to a drain pipe 26 with a drain valve 27. When raising the rubber dam 1, the exhaust pipe 16 and the drain valve 27 are closed and air is charged into the dam 1 through the compartment 3 by means of the blower 14. Also, when falling down the dam 1, the exhaust valve 16 and the drain valve 27 are both opened manually. By this, the intrusion of foreign matters, e.g., water, soil, sand, etc., into the air supply and discharge systems can be completely prevented. |
