| 摘要 |
PURPOSE:To decrease weight or the like of a pressure reducing device, by arranging a pipe of the suction side port of a pump under a level of water in a water tank and connecting a delivery side to an injection nozzle of a jet pump. CONSTITUTION:Water in a water tank 3 is supplied to a jet pump 4 by a submergible pump 2, if the water is injected into a delivery pipe 5, whose opening end is closed by water to prevent a reverse flow of air, delivery negative pressure in the delivery pipe is generated in a suction pipe 15. In this way, pressure in a vacuum tank 1 is reduced, and an ultra-high vacuum can be obtained without causing the necessity for using a vacuum pump of large weight at high cost. |
