| 摘要 |
PURPOSE:To prevent the deterioration of an O ring by setting a beltlike shielding plate at the inside of an O ring fixing position. CONSTITUTION:A groove for an O ring 3 and a groove for a shielding plate 4 are cut in the periphery of the body 1 of a vacuum vessel. The shielding plate 4 is set in the groove for the plate, an upper lid 2 for shielding the body 1 of the vessel is joined to the plate 4 and the O ring 3 is fixed in the groove for the ring. The O ring for airtightness can be protected from the reactive atmosphere in the vacuum vessel and the vessel can be kept airtight over a long period of time. |
