| 摘要 |
PURPOSE:To improve the safety and reliability of a vacuum container by vacuum-sealing, permitting the rectilinear motion, by a double structure bellows between a vacuum container and a driving member and substituting the airtight space between the inside and outside bellows by a specific kind of gas under normal pressure. CONSTITUTION:A vacuum container 1 and a driving member 12 fixed onto a flange 13 are held airtightly in free shift between advance and retreat by a double bellows part 4 installed between the flanges 3 and 13. The airtight space 11 between the inside and outside bellows 6 and 7 of the double bellows part 4 is substituted by a specific kind of gas under normal pressure such as N2 gas by a feeding means 19, in consideration of safety and the easiness for detecting leak, and the pressure is monitored by a pressure detecting means 20. Therefore, the trouble of sharp destruction of vacuum in the vacuum con tainer 1 due to the leak in the both bellows 6 and 7 is prevented, and the leak in one of the bellows can be detected in an early stage. Thus, the safety and reliability of the vacuum container can be improved markedly.
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