As we all know, special valves rely on the pressure and temperature of the medium in the valve as the energy source to drive the valve to work automatically. Its sealing directly affects the performance of self operated control valves. Therefore, to improve the performance of special valves, it is necessary to continuously improve their sealing performance in use. Here are some ways to improve the sealing performance of special valves.
1. Fine grinding, eliminating traces, reducing or eliminating sealing clearance, and improving the smoothness of sealing surface to improve sealing performance.
2. By improving the sealing force of the actuator on the valve core, ensure that the special valve is closed, increase the sealing pressure and improve the sealing performance. By moving the working range of the spring, increasing the accessories such as the positioner, using the actuator with greater thrust, and increasing the air source pressure, the sealing force of the actuator on the valve core can be improved.
3. For special valves with double seals, single seal can improve the sealing effect by more than 10 times. If the unbalance force is large, corresponding measures shall be added. The hard seal valve can be soft sealed, and the sealing effect can be improved by more than 10 times.
4. Special valves can use unbalanced force to increase the sealing specific pressure: the sealing pressure generated by the actuator on the valve core is constant, and when the unbalanced force pushes the valve core open, the sealing force of the valve core is the subtraction of the two forces; On the contrary, the valve core is more inclined to be closed under pressure. The sealing force of the valve core is the sum of these two forces, which greatly increases the sealing pressure and can improve the sealing effect by more than 5~10 times. If the sealing effect is not ideal, it will be changed to closed type, and the sealing performance will be doubled. In particular, the two position stop regulating valve shall be generally used according to the flow closing type.
The so-called preventive maintenance is to take some preventive measures for special valves before the failure occurs. It is equivalent to unscheduled maintenance of special valves, specifically including stress release, removal or prevention of foreign matters, inspection of supports, inspection of safe operation, regular maintenance and refueling, regular inspection of air and power sources, transportation and storage, etc.
Fault maintenance, as the name implies, is the maintenance of special valves in case of failure. In case of failure of special valves, the following measures are usually taken for maintenance.
1. Thoroughly clean the regulating valve. Special valves are easy to be polluted by process fluid, and parts immersed in process medium must be cleaned by special methods. Avoid repeated pollution during cleaning, and conduct it in a safe place. All cleaning tools, such as containers, heating equipment, steam hoses, cleaning equipment, etc. Be prepared in advance.
2. Disassemble the regulating valve and check whether the inner wall of the valve body, valve seat, valve element, sealing packing and gasket are intact. After disassembling the actuator, carefully check the bracket, diaphragm, spring, push rod, threaded joint, etc. No matter what kind of parts are corroded or rusted, replace them with new ones.
3. Reassemble after repairing all parts and components.