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Recently, clients have frequently reported that their electrical valve positioners suddenly start to leak air while in use, which severely affects the proper functioning of these positioners. Generally, when an electrical valve positioner experiences valve air leakage, it refers to air leakage from the pneumatic actuator and its accessories. So today, the technical editor from Xi’an Pride Instruments will introduce to you the common causes of air leakage in the cylinders of electrical valve positioners, as well as the solutions for these issues. 1. Air leakage from the solenoid valve on the cylinder. There are mainly two reasons for the air leakage. One reason is that the seal ring at the position where the solenoid valve is installed on the cylinder is damaged, and the other reason is that the solenoid valve itself leaks air. This requires performing the venting action several times at the bottom of the solenoid valve; sometimes it may also be necessary to replace the solenoid valve, or to realign the seal ring between the solenoid valve and the cylinder before reinstalling the solenoid valve. 2. Cylinder leakage may also be caused by the drilling of holes in the cylinder being too deep, resulting in a connection between the outside of the cylinder and its internal bore. At this point, the cylinder needs to be replaced or discarded. 3. Air leakage in the three-piece assembly. At this point, we need to check the sealing performance of the triple union, and replace it if necessary. 4. The inner wall of the cylinder is scratched. This is because some cylinders have not undergone hard anodizing; repeated switching causes wear on the inner walls of these cylinders, which in turn leads to damage to the piston O-rings and results in air leakage inside the cylinders. We can solve this by replacing the cylinder. 5. The exhaust port of the cylinder is leaking. This may be due to air leakage inside the cylinder, which in turn causes leakage at the exhaust port ； It is also possible that the hole in the air inlet was drilled too deep, penetrating the cylinder directly, which caused a leak in the air path between cylinder B and cylinder A. We can apply for scrapping it or replace it with a new cylinder. 6. Air leakage at the upper and lower parts of the cylinder shaft. This is mainly due to insufficient smoothness in the machining of the upper and lower shaft holes in the cylinder, as well as wear of the sealing ring after repeated opening and closing, which causes air leakage ； It is also possible that the fit between the cylinder and the shaft is too tight, causing the sealing ring to wear out easily. Therefore, we need to replace the upper and lower shaft seals and improve the surface finish of the holes. The above has introduced to you the common causes of air leakage in the cylinders of electrical valve positioners and the corresponding solutions. However, in practical operation, we still need to take specific actions based on the actual working conditions. We also have to consider the surrounding environment as well as the condition of the cylinders in order to find solutions. It is hoped that through today’s learning, it will be possible to assist users in the event of air leakage in electrical valve positioners in the future.