| 摘要 |
A ball valve assembly and method in which a ball valve (10) is rotatable in a conduit section (14,16) to selectively permit fluid flow through a bore of the ball valve to control the flow of the fluid through the conduit section. An insert (30) is disposed in the valve bore and has a plurality of small diameter passages (38) and a large diameter passage (36) extending therethrough. The valve is rotated from its closed position to a first, partially-opened position where the small diameter passages are in the flow path of the fluid to reduce the flow rate and the noise caused by the fluid flow. The valve can be rotated to a fully opened position in which the large diameter passage is in the flow path of the fluid to achieve relatively high flow rates. The insert forms an airfoil surface (32a,32b) to prevent separation of the fluid as it passes through the large diameter passage. <IMAGE> |
