| 摘要 |
PURPOSE:To easily carry out fine adjustment of conductance, by forming a groove at a sealing portion of a valve whose opening angle is adjustable. CONSTITUTION:A gate valve 2 is formed with a groove 5 extending in a direction of thickness of the valve, but not passing through the thickness. The groove 5 is located at one end or both ends of a diameter perpendicular to a driving shaft 3 of the gate valve 2. When the gate valve 2 is rotated a very small angle in a direction as depicted by an arrow a from a full closed condition where the entire inner circumference is closed by an outer circumferential sealing portion of the gate valve 2, a gas starts gradually flowing through the groove 5. Upon further rotation of the gate valve 2, the outer circumferential sealing portion of the gate valve 2 is separated from the gas passage, thus obtaining an open condition of the valve. Accordingly, it is possible to obtain a gradual change in conductance in a small opening area, thereby attaining flow control with a high accuracy.
|
