| 摘要 |
A ball valve (1) has a housing (H) in which is mounted for rotation about an axis of operation (A), a valve member which is a ball (2), the ball (2) having a passage (P) through which fluid flows from an inlet (I) of the housing (H) to an outlet (O) of the housing (H), and the ball (2) has at one end of the passage (P) a metering opening (4) for the fluid, the ball (2) being rotatable about the axis of operation (A) between a first closed position in which the opening (4) is concealed by an adjacent housing wall and fluid flow through the passage (P) is prevented, and a fully open position in which the opening (4) is aligned with one of the inlet (I) and outlet (O) of the housing (H) to permit of maximum fluid flow through the passage (P), and characterised in that the opening (4) in the ball (2) at the one end of the passage (P) is provided by removing material by high pressure fluid jetting.
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