The tightness of the self-operated regulating valve aff […]
The tightness of the self-operated regulating valve affects the performance of the self-operated regulating valve. Therefore, the sealing performance of the self-operated regulating valve should be continuously improved. The sealing performance of the self-operated regulating valve can be improved by the following five methods:
1) Grinding method: fine grinding, eliminating traces, reducing or eliminating the sealing gap, improving the smoothness of the sealing surface to improve the sealing performance.
2) Using the unbalanced force to increase the sealing specific pressure method: the sealing pressure generated by the actuator on the valve core is certain, and when the unbalanced force causes the opening of the valve core, the sealing force of the valve core is reduced by two forces, and vice versa. The core produces a pressure-closing tendency, and the sealing force of the valve core is added by the two forces, which greatly increases the sealing specific pressure, and the sealing effect can be increased by 5 to 10 times or more than the former. The general single-sealing valve of dg ≥ 20 is the former. In one case, it is usually a flow-open type. If the sealing effect is not satisfactory, the flow-closing type will be multiplied. The two-type shut-off control valve should generally be used in a flow-closed type.
3) Improve the sealing force method of the actuator: Improve the sealing force of the actuator to the valve core, and also be a common method to ensure the valve is closed, increase the sealing specific pressure, and improve the sealing performance. Common methods are:
1 moving spring working range;
2 use a small stiffness spring;
3 add accessories, such as with a positioner;
4 increase the pressure of the gas source;
5 Switch to an actuator with greater thrust.
4) Adopt single seal and soft seal method: For the double seal, the control valve can be changed to a single seal, which can generally improve the sealing effect by more than 10 times. If the unbalanced force is large, the corresponding measures should be added to the hard seal. The valve can be replaced with a soft seal, which can increase the sealing effect by more than 10 times.
5) Switch to a valve with good sealing performance: If it is unavoidable, consider using a valve with better sealing performance. For example, if you change the ordinary butterfly valve to an elliptical butterfly valve, you can also use a cut-off butterfly valve or an eccentric rotary valve. Ball valves and shut-off valves specially designed for them.