To solve the problem of the conventional method for releasing vacuum equipment to atmospheric pressure that, since high-pressure nitrogen gas filled in a cylinder is used, the vacuum equipment after released to the atmosphere is contaminated with a stain (particularly a small amount of dust, oil or the like) in the cylinder, it is necessary to install a filter at a port for introducing the nitrogen gas into the vacuum equipment to remove this strain and it is necessary to insure safety when the cylinder is handled.
Liquid nitrogen is used as a nitrogen source instead of the high-pressure nitrogen gas filled in the cylinder, a high-purity nitrogen gas obtained by evaporating the liquid nitrogen is introduced directly into the vacuum equipment, and then the vacuum equipment is released to the atmospheric pressure. Since the vacuum equipment is replaced with the high-purity nitrogen and released to the atmospheric pressure under the condition of no water, no oil and no dust, the time to alter and maintain the vacuum equipment can be shortened remarkably.
SHIMURA TAKAYOSHI
SUMITANI KAZUTSUGU
Tadashi Masui
Yasushi Kobayashi
Akio Chiba
Hiroyuki Tomita
Shurin Sakurai