| 摘要 |
A diaphragm valve comprises: a body (1) having an inflow passage (1a), an outflow passage (1b), a concave valve chamber (1c) and a valve seat (1d); a metallic main diaphragm (2) which holds airtightness of the valve chamber (1c) and makes contact with and separates from the valve set (1d) directly or indirectly; a bonnet (4) which securely holds an outer circumferential edge portion of the main diaphragm (2) between the body 1 and the bonnet 4; and a stem 5 which causes the main diaphragm (2) to be deformed elastically. At the top surface side of the aforementioned main diaphragm (2) there is arranged a metallic sub-diaphragm (3) whose outer circumferential edge portion can be elastically deformed in a vertical direction. A center portion of the aforementioned sub-diaphragm (3) is fixed to a center portion of the main diaphragm (2), so that the sub-diaphragm (3) comes in contact with the top surface side of the main diaphragm (2) to support a bend thereof when the main diaphragm is deformed elastically.
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