| 摘要 |
PROBLEM TO BE SOLVED: To provide a coupling capable of detecting a case where a push ring is not screwed to a specified position of a coupling body as liquid if leaked out and eliminating nonconformity caused by insufficient screwing. SOLUTION: The coupling 12 is mainly constituted of the coupling body 13, an inner cylinder part 14, a pressurizing ring 15, the push ring 17 and a seal ring 33, and a recessed groove 14a extending spirally is formed on an outer peripheral surface of the inner cylinder part 14. Additionally, it is constituted so that hydraulic pressure directly works on the seal ring 33 from the recessed groove 14a by water circulating in a coupler 14 when the push ring 17 is not screwed to the specified position of the coupling body 13 and fastening of the pressurizing ring 15 to the outer peripheral surface of the resin pipe 11 is insufficient. Consequently, the seal ring 33 is elastically deformed by the hydraulic pressure and a sealing function between the resin pipe 11 and the inner cylinder part 14 is lowered, and water is leaked out from the coupling 12.
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