| 摘要 |
<p>The valve includes a tubular housing member that is connected in a string of a tubing that extends into an oil or gas well. The upper end of the tubular housing member is rotatable and is connected through actuators to a valve member that is pivotally supported in the tubular housing member. Rotation of the upper end of the tubular housing causes the actuators to pivot the valve member between open and closed positions.</p> |
