| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and a device for selecting and supplying self-supplied air or backup gas as seal gas or instrumentation air while surely preventing the mixture of the self-supplied air into a backup gas supply source. SOLUTION: The device comprises a self-supplied air passage 1 in which a pressure monitoring device 8 and a first check valve 4 are provided in sequence ranging from the upstream side to the downstream side, a backup gas passage 2 in which a selector three-way valve 7 and a second check valve 5 are provided in sequence ranging from the upstream side to the downstream side and which has a downstream end connected to the downstream end of the self-supplied air passage 1, a seal gas passage 3 which has an upstream end connected to a connection point between the passages, and a control means for changing over the selector three-way valve 7 in accordance with a value measured by the pressure monitoring device 8. When the value measured by the pressure monitoring device 8 is greater than a specified value, the selector three-way valve 7 is changed over to supply the self-supplied air so that a portion of the backup gas passage 2, on the downstream side of the selector three-way valve 7, is communicated with outside air. COPYRIGHT: (C)2007,JPO&INPIT
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