Why Your Pneumatic Ball Valves Won't Close Properly?
Posted Aug 25, 2025

Why Your Pneumatic Ball Valves Won't Close Properly?

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In industrial production, pneumatic ball valves play a crucial role, acting like a loyal goalkeeper that precisely controls the flow of fluids. However, when a pneumatic ball valve fails to close properly, it is akin to a goalkeeper making a mistake, which can not only affect production efficiency but also pose safety hazards. Don't worry, today we will delve into the reasons why a pneumatic ball valve may not close properly and provide a series of practical solutions to help you tackle this issue with ease.

Insufficient Air Supply Pressure

A stable air supply pressure is essential for the normal operation of a pneumatic ball valve, much like how a car needs sufficient fuel to run. If the air supply pressure is insufficient, the valve will lack the necessary power to close completely. Generally, the rated working pressure for a pneumatic ball valve should be between 5-7 bar. If the actual pressure falls below this range, it is necessary to adjust the air supply pressure promptly or replace the air supply device to ensure the valve receives adequate power.

In large-scale applications where compressed air is extensively used, the air supply may sometimes be insufficient, leading to unstable power during the valve's closing process. This is similar to a relay runner suddenly losing strength and being unable to pass the baton smoothly. Therefore, it is important to check the stability of the air supply to ensure that the air pressure remains constant during the valve's closing process. If issues with the air supply are detected, consider increasing the air supply or optimizing its distribution to provide stable power support for the pneumatic ball valve.

Misadjusted Stroke Control Switch

The stroke control switch is an integral part of a pneumatic ball valve, functioning like a "navigator" that controls the degree of valve opening and closing. If the stroke control switch is not properly adjusted, the valve may fail to open or close fully. This is similar to a car's navigation system malfunctioning, preventing the vehicle from reaching its destination accurately.

Checking the settings of the stroke control switch is key to resolving this issue. First, ensure that the stroke control switch is adjusted to the correct position. If the switch position is inaccurate, loosen the valve stem connection nut and rotate the valve stem outward or inward to adjust the valve's stroke. After adjustment, be sure to tighten the nut to secure the valve stem firmly. This will enable the valve to open and close in the correct direction and degree, achieving complete closure.

Damaged Seals

Seals are the "guardians" of a pneumatic ball valve, effectively preventing fluid leakage and ensuring the valve's sealing performance. However, seals may fail due to wear and tear or aging over time, creating a breach in the defense and causing the valve to fail to close completely. Therefore, it is crucial to regularly inspect the condition of the seals.

If signs of damage or aging are detected in the seals, such as cracks, deformation, or severe surface wear, it is necessary to replace them with new seals promptly. When replacing seals, choose high-quality seals that match the valve model and follow the installation instructions carefully to ensure that the seals fit tightly against the sealing surface and restore the valve's sealing performance.

Internal Valve Contaminants

Contaminants or foreign objects inside the valve are a common cause of a pneumatic ball valve failing to close properly. These contaminants can clog the sealing surface of the ball valve, acting like obstacles in a passage and hindering the valve's normal closure. In some industrial environments, fluids may contain particulate matter, rust, or other contaminants that can enter and accumulate inside the valve during the opening and closing process.

The solution to this problem is to regularly clean the inside of the valve. Use professional cleaning tools or cleaning agents to remove contaminants from within the valve. During the cleaning process, take care not to damage the internal components of the valve. If a significant amount of contaminants is found, multiple cleanings may be necessary until the inside of the valve is clean. After cleaning, ensure that the inside of the valve is dry to prevent the formation of new contaminants from residual moisture.

Pneumatic Actuator Malfunction

The pneumatic actuator is the power core of a pneumatic ball valve, responsible for driving the valve's opening and closing. If the pneumatic actuator malfunctions, the valve will not be able to rotate or close properly. This is similar to a car's engine failing, rendering the vehicle unable to operate normally.

Inspecting the working condition of the pneumatic actuator is key to diagnosing the problem. Check whether components such as the actuator's diaphragm, rolling diaphragm, and gaskets are aged or ruptured, causing air leaks. If any issues are found with these components, it is necessary to replace the damaged parts promptly, or even the entire actuator if needed. When replacing parts, ensure that the new components meet the required quality and performance standards and follow the installation steps carefully to ensure the actuator functions properly.

Improper Operation

Improper operation of the pneumatic ball valve can also lead to the valve not closing properly. For example, if the operator does not correctly operate the control device or does not follow the correct operating procedures, the valve may fail to close completely. This is similar to operating a precision machine without following the instructions, resulting in the machine malfunctioning.

To avoid problems caused by improper operation, operators should receive professional training to become familiar with the operating procedures and precautions for pneumatic ball valves. During operation, strictly follow the operating regulations and avoid impatience or carelessness. Additionally, regularly train and assess operators to ensure they can operate the pneumatic ball valve correctly and proficiently.

Regular Maintenance and Inspection

Regular maintenance and inspection of pneumatic ball valves are essential for their normal operation, much like how a car requires regular servicing. Regular maintenance can help identify potential issues early, reduce the likelihood of malfunctions, and extend the valve's service life.

Maintenance tasks include inspecting seals, cleaning the inside of the valve, and adjusting the air supply pressure. Regularly check the condition of the seals and replace any that are damaged or aged; clean the inside of the valve to remove contaminants and dirt; and check the air supply pressure to ensure it is within the normal range. Additionally, lubricate the valve's moving parts to reduce friction between components and improve the valve's operating efficiency.

Other Common Issues and Solutions

In addition to the aforementioned common causes, there are other issues that may cause a pneumatic ball valve to fail to close properly. For example, if there are contaminants on the valve's sealing surface, adjust the valve to a larger opening and then close it repeatedly. This can use the fluid's impact force to remove the contaminants. If the valve stem threads are rusted, it is recommended to adjust the valve's opening and closing several times to remove the rust through movement. If this does not work, the valve stem may need to be inspected or the sealing surface replaced. Adjusting the valve's opening and closing flexibility and adding an appropriate amount of lubricating oil can also help solve the problem of the valve not closing properly.

In actual operation, the following points should also be noted: First, signal issues may cause the switch to display a state of not being properly closed, even though the valve is actually closed. This is not a problem with the valve itself but rather with the signal. Therefore, it is necessary to check whether the sensor is working properly and replace any faulty sensors in a timely manner. Second, if there are contaminants in the pipeline, such as on the sealing surface, it can easily lead to the valve not closing properly. It is recommended to open the valve wider and then slowly close it, repeating this process several times to solve the problem, but be careful not to apply too much force. Third, the power to drive the valve comes from the actuator. If its output torque does not conform to the closing pattern and the medium pressure is too high, the valve will not close properly. Therefore, attention should be paid to adjustment during selection. Finally, damage or rust on the valve stem can also cause the valve to fail to close properly. In such cases, try several times, and if the problem cannot be resolved, repair or replace the sealing surface is necessary.

Additionally, the following points should be noted: The angular stroke of the pneumatic actuator is usually 90°. If the positioning bolts or limit blocks are not properly adjusted, it will result in insufficient opening and closing angles of the ball valve. When the air supply pressure is lower than the actuator's design requirements, the valve's operating force is insufficient, making it prone to not closing tightly. After long-term frequent opening and closing, wear or contaminants trapped between the valve core and seat can cause poor sealing. If the actuator is not properly aligned with the valve, it will lead to uneven torque transmission, affecting the proper closure. Therefore, regularly inspect the air supply system to prevent water or oil contaminants from entering the actuator; lubricate and replace seals according to the manufacturer's recommended schedule; and avoid forced switching under pressure to reduce impact wear on the seat.

Conclusion

In conclusion, the issue of a pneumatic ball valve not closing properly is a relatively complex problem that can be caused by various factors. When encountering this situation, do not panic. Instead, calmly analyze the cause and take the corresponding solution. By inspecting the working conditions of the air supply pressure, stroke control switch, seals, internal valve contaminants, pneumatic actuator, and ensuring correct operation and regular maintenance, you can effectively resolve the issue of a pneumatic ball valve not closing properly. Only in this way can the pneumatic ball valve function as intended in industrial production, ensuring smooth production processes and safe equipment operation.

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Isaac
Isaac