| 摘要 |
PURPOSE:To protect a manometer from a high pressure, by providing a change- over valve between the manometer of a pressure source and the pressure source itself to close the communication between the pressure source and the manometer with the movement of the valve disc thereof against a spring when the pressure exceeds a specified level. CONSTITUTION:When the working pressure of a fluid in a pipeline 5 is below a specified value, a change-over valve 4 allow the working pressure in the pipeline 5 to lead to a manometer 1 for low temperature through a bore 41, a cylinder 4h, a valve seat ;4f, a bore 4k and a pipeline 2. As the working pressure in the pipeline 5 rises, the working pressure at a bore 4j goes up in the change-over valve 4 so high as to push up a piston 4b against the charged forces of springs 4c and 4g, bringing the dvalve disc 4e close to the valve seal 4f through a seat 4d. Thus, when the pressure of the pipeline 5 reaches a specified level, the pressure of the fluid leading to the manometer 1 through the bore 4i, the cylinder 4h, the valve seat 4f, the bore 4k and the pipeline 2 from the pipeline 5 is fully closed at the valve body 4e. |
