| 摘要 |
PURPOSE:To wash the external surface of an observation window and to prevent the external surface after washing from the residual of water drops by movably arranging a valve body in a fluid feeding valve room so that the valve body is separated from a valve hole to open the hole at the time of fluid feeding, and at the normal state, the valve body is moved so as to close the valve hole by the feeding pressure of the washing solution. CONSTITUTION:In a switching valve device for blowing off the mixed fluid of a washing solution fed through a feed line 13 with a gas from a blow off nozzle 10 to the external surface of an observation window formed on an insertion part, the fluid feeding valve room 39 is connected to a washing solution feeding source and connected also to the feed line 13 through the valve hole 27 and the valve body 42 to be moved to a fluid feeding position by opening the valve hole 27 by a switching means 37, and at the normal disconnection, moved so as to close the valve 27 by the feeding pressure of the washing solution is movably arranged in the valve room 39.
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