| 摘要 |
PURPOSE:To simplify the structure of a vacuum seal-off portion by sealing off vacuum by means of a veneer-like seal-off plate. CONSTITUTION:A notch portion 15 is disposed on the outer periphery of a seal- off plate 5 in such a manner as to pierce in the radial direction. In this arrangement, even if the seal-off plate 5 is positioned below a discharge port 3a, air is continuously forced to escape from a system 1. After an O-ring 7 of a valve seat 2b is fastened by the seal-off plate 5, air exhaust for a vacuum is stopped to restore a space above the seal-off plate 5 to atmospheric pressure, a valve rod 10 is pulled up above the seal-off plate 5 without rotating a handle 12 of the valve rod 10. Subsequently, an operator 4 is unscrewed to be detached from a body 2, and a cap 6 is screwed into the body 2 to fasten an O-ring 8 of an upper valve seat 2c of the body 2 and the seal-off plate 5. |
