How to Troubleshoot a Stuck Air Actuated Valve?
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Air Actuated Valve is a very common actuator in modern industrial automation control and is widely used in petroleum, chemical industry, water treatment, pharmaceutical and other industries. It uses compressed air as the power source and controls the opening and closing of the valve through a air actuated actuator, thereby regulating the circulation state of the medium in the pipeline. However, during long-term operation, air actuated valves may become stuck, causing process interruption or equipment failure. This article will systematically explain how to troubleshoot and solve air actuated valve stuck problems from multiple perspectives.
The driving force of the air actuated valve comes entirely from compressed air. Therefore, whether the pressure of the air source is sufficient is the first step to troubleshoot the problem. If the air source pressure is too low, the actuator will not be able to provide enough thrust to drive the valve to open and close. On the contrary, if the air pressure fluctuates greatly, it may also lead to discontinuous or incomplete valve action. Check the output pressure of the air pressure system to confirm whether it is within the required working pressure range of the air actuated valve. At the same time, check whether there are air leaks, air supply interruptions, filter clogging and other problems, which will directly affect the stability of the air source.
Check whether the solenoid valve is working properly
As the control element of the air actuated valve, the solenoid valve is used to control the passage of compressed air into or out of the actuator. If the solenoid valve coil is burned out, stuck, or the control signal is abnormal, the air actuated valve will not operate. At this time, the test should be carried out by manually operating the solenoid valve or replacing the coil to observe whether the valve body has the action of opening and closing the air. In addition, check whether the control signal output by the PLC or control system is accurate to prevent the solenoid valve from receiving correct instructions due to logic errors or program abnormalities.
Check Whether There Is Any Mechanical Jamming Inside The Actuator
Air actuated actuators usually contain multiple moving parts such as pistons, springs, and sealing rings. During long-term use, poor movement or mechanical jamming may occur due to poor lubrication, entry of impurities, aging seals, etc. Especially for reciprocating actuators, if there is foreign matter blocking between the piston and the cylinder, the piston will not be able to complete its stroke, which will cause the valve to get stuck. At this time, the actuator should be disassembled for cleaning, aging seals should be inspected and replaced, and moving parts should be relubricated to ensure smooth operation.
Check Whether There Is Any Foreign Matter Between The Valve Core And Valve Seat
The connection between the valve core and the valve seat is the key contact part for air actuated valve execution. If the medium contains impurities, sediments or corrosion products, it is easy to cause the valve core to get stuck or act slowly. This type of stuck often manifests itself as the valve can only be partially opened or closed, or requires external force to assist the action. At this time, the valve body should be disassembled to check whether the inside of the flow channel is clean, and foreign matter or rust layers should be removed promptly. At the same time, consider adding a filter to the air inlet pipeline or performing regular flushing and maintenance to reduce the probability of contaminants entering the valve cavity.
Check Whether The Positioner And Feedback System Respond Accurately
Many air actuated valves are equipped with valve positioners to improve adjustment accuracy. If the positioner signal is abnormal or the feedback device responds slowly, it will also cause the control system to misjudge the valve position, causing the illusion of stuckness. For example, the actual valve has moved but the feedback signal is not updated in time, or the positioner itself has output lag. When troubleshooting such problems, you should use a multimeter or manual testing tool to check whether the input and output of the positioner are normal, and verify the real-time response capability of the feedback device. Re-calibrate the zero position and stroke if necessary.
Check whether ambient temperature or humidity is causing freezing or corrosion
In some low-temperature or high-humidity environments, untreated moisture in the compressed air will condense inside the air actuated pipeline or actuator, thereby freezing and blocking moving parts. Especially air actuated valves installed outdoors in winter are more prone to such problems. At this time, it can be solved by installing an air dryer, insulation cotton or heating belt. In addition, metal parts in humid environments are prone to rust or oxidation, which may also cause malfunction.
Check whether the installation location is correct
If the air actuated valve is not operated strictly in accordance with the requirements during the installation process, such as poor alignment between the actuator and the valve body, the impact of pipeline vibration, or improper installation angle, it may lead to eccentric wear or jamming during operation. When stuck but the valve body itself is not faulty, check whether its installation position is firm and whether its alignment is accurate, and reinstall it if necessary.
