| 摘要 |
PROBLEM TO BE SOLVED: To prevent an exposing part of a valve rod from decreasing thickness by erosion in a butterfly valve having a part of the valve rod exposing to a flow passage. SOLUTION: A non-penetrating part 3b not engaging with a protrusion 4a of a valve element 4 of the valve rod 3 is formed in a small size and covered by a rubber cylinder 15. Since the rubber cylinder 15 is little influenced by erosion, it has a long life. And the rubber cylinder 15 can be easily replaced. Accordingly maintenance costs of the butterfly valve original from the erosion can be saved.
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