| 摘要 |
PURPOSE:To obviate mutual control interference of respective characteristic portions in control to provide predetermined continuous flow characteristics securely by providing two characteristic portions independent from each other and continuously controllable between a valve plug and a valve seat ring. CONSTITUTION:A tubular valve seat 11 is provided in the center with two large and small inner holes 12, 13 having different bores, and between the hole walls of these inner holes are provided a valve seat 14. A valve plug 15 having a seating portion 16 capable of being seated on the valve seat 14 is movably disposed in a valve seat ring 11 to be moved vertically by the automatic or manual movement of a valve shaft. When the valve plug 15 is moved upward from the fully closed condition, first between it and the valve seat 14 is controlled flow by the lower side characteristic portion 18 and then between it and the opening end of the inner hole 12 is controlled the flow by the upper side characteristic portion 17. |
