Patent ID: 8807531

Claim:
An apparatus comprising: a vacuum valve in which an inside pressure is an atmospheric pressure and an outside pressure is a vacuum, the vacuum valve including a main flow path that is opened or closed by a disc-shaped valve member coming into contact with or moving away from a valve seat and a driving part for driving the valve member via a rod, so as to surround the rod to separate the main flow path from the driving part; and a vacuum valve bellows attached to the vacuum valve, wherein the bellows includes ring-shaped valley portions swelling inward of a metal pipe and ring-shaped peak portions swelling outward of the metal pipe alternately and continuously in a peripheral wall of the metal pipe in an axial direction of the metal pipe, and wherein valley R is larger than peak R and valley R/peak R, which is a ratio of valley R to peak R, is in the range of 1.15 to 1.52, where valley R is a radius of curvature of the valley portions in cross section, and peak R is a radius of curvature of the peak portions in cross section, in a state in which no external force from the rod acts on the bellows.