| 摘要 |
PURPOSE:To permit easy opening and closing operation of a valve and securely seal a pipe, by providing a guide rail for guiding at least one of an upper valve plate and a lower valve plate. CONSTITUTION:An upper seal member 23 and a lower seal member 24 are provided at end portions of an upstream pipe 21 and a downstream pipe 22 over a circumference thereof, respectively. An upper guide rail 34 is fixed to the outside of the upstream pipe 21 having a substantially rectangular section, and a front roller 33 and a front upper guide rail 34 are arranged at a position higher than a rear roller 33 and a rear upper guide rail 34. When a valve is opened, an upper valve plate 25 and a lower valve plate 26 are slided in separation from the upper seal member 23 and the lower seal member 24, and accordingly friction in valve opening and closing operation may be reduced. |
