| 摘要 |
PURPOSE: An exhaust pipe of a cryo pump is provided to exhaust nitrogen gas when the nitrogen gas is sufficiently diluted with process gas after a desired uniform pressure of gas is maintained. CONSTITUTION: A piston(110) moves backward/forward, installed in the exhaust pipe of the cryo pump. A pressure detecting unit(120) detects the pressure of gas induced from the exhaust pipe, installed in the piston. A signal detected by the pressure detecting unit is delivered to the first valve(132) to introduce air to the first air line(130) that is perpendicularly installed in the exhaust pipe so as to make the piston move forward due to the introduced air. A release signal form the pressure detecting unit is delivered to the second valve(142) to introduce air to the second air line(140) that is installed in the end surface of the exhaust pipe so as to make the piston move backward due to the introduced air. A plurality of piston guides(160) support and seal the piston, installed in the piston and the exhaust pipe. A stopper(170) controls movement of the piston, installed in the exhaust pipe corresponding to the rear end of the piston. A gas exhausting pipe(150) is perpendicularly installed in the exhaust pipe. Process gas is exhausted through the gas exhausting pipe according to the forward movement of the piston.
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