Causes of failure and solutions for pneumatic ball valve actuators

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　　A pneumatic ball valve is a type of ball valve that combines a pneumatic actuator with the ball valve itself; the pneumatic actuator controls the valve stem, which in turn rotates the ball 90 degrees to open or close the valve. It is widely used in industries such as petroleum refining, long-distance pipelines, chemicals, papermaking, pharmaceuticals, water management, power generation, municipal services, and steel manufacturing, and holds a pivotal role in the national economy. Reasons for air leakage in the actuator of a pneumatic ball valve: 1. The solenoid valve on the cylinder is leaking air, possibly due to excessive pressure in the pressure reducing valve. 　　 　　 2. The exhaust port of the cylinder is leaking, as the sealing rings at the seals between the two moving parts inside the cylinder and the cylinder block have worn out. 3. Air leakage at the upper and lower parts of the cylinder occurs because the sealing rings at the seal between the actuator and the cylinder fail to provide a proper seal due to the frequent movement of the actuator. 　　 　　 4. Apart from the 3 situations mentioned above, there is another scenario that can cause air leakage in the cylinder: damage to the spring inside the cylinder, resulting from insufficient force application, which may also lead to improper closure of the valve. When addressing air leakage issues in cylinders, it is essential to consider the actual circumstances, such as whether the valve operates on an air-open or air-close principle. For valves that operate on an air-open principle, we can first close the manual valves at both ends, then have the control system open the valve. Next, we disassemble the connecting pieces at the joints and cut off the air supply; at this point, the gas in the pressure regulator should be released. Note that the actuator will rotate by 90° at this time, and after making the necessary adjustments, it is important to return the actuator to its original position. Solution: 　　 　　 1. Replace the seal ring of the actuator. 　　 　　 2. Replace the seal ring at the cylinder. 　　 　　 3. Adjust the air pressure of the pressure relief valve to 3-5 kilograms, or disconnect the venting mechanism at the bottom of the solenoid valve several times; in some cases, it may also be necessary to replace the solenoid valve. 4. Replace the spring in the cylinder.