Working principle and fault analysis of pneumatic valves


Publish Time:

2021-12-22

A pneumatic valve uses a pneumatic cylinder as its actuator and compressed air as its power source to control the opening and closing of the valve. When the control system sends a control signal to the regulating pipeline, it adjusts relevant parameters such as temperature, pressure, and flow rate. In general, pneumatic valves are characterized by their reliability, fast response, and simple control. During operation, when a signal pressure of 0.02-0.10 MPa is input to the regulating chamber, the diaphragm generates a thrust. As the thrust plate moves downward, the spring is compressed, thereby actuating the valve stem, push rod, and valve core to move downward, achieving the purpose of regulating the valve.

1 Pneumatic Valve Working Principle
A pneumatic valve specifically refers to a valve that uses a cylinder as an actuator and compressed air as a power source to control the opening and closing of the valve. When the control pipeline receives a control signal from the automated control system, it adjusts relevant parameters such as temperature, pressure, and flow rate. In general, pneumatic valves are characterized by their reliability, fast response, and simple control. During operation, after inputting a signal pressure of 0.02-0.10 MPa into the regulating chamber, the diaphragm generates thrust. As the thrust plate moves downward, the spring is compressed, thereby actuating the valve stem, push rod, and valve core to move downward, achieving the purpose of regulating the valve.


2 Common Malfunctions and Troubleshooting Methods for Pneumatic Valves
Through the research and analysis of the failure status of pneumatic valves, we have learned that possible malfunctions include valve blockage, valve malfunction, valve leakage, and impact. Therefore, it is necessary to develop countermeasures based on the actual malfunction to achieve stable system operation and create higher efficiency for the company.


2.1 Pneumatic Valve Seizure
If the valve stem movement is slow, it indicates that there may be a lot of viscous substances in the valve body, and the blockage of the pneumatic valve mainly occurs in the initial stage of system operation. In this case, the valve or auxiliary pipeline should be quickly opened and closed to flush away the medium that blocks the valve. At the same time, the valve stem can be clamped with pipe pliers, and signal pressure can be applied to rotate the valve stem reaction force. If the above problems still cannot be solved, the driving power can be increased to repeatedly move up and down. It should be noted that because the above operations are highly professional, when solving and handling this fault, it needs to be completed with the help of professionals.


2.2 Valve Malfunction
For this type of malfunction, first determine whether the air source pressure is normal, and then check for air source malfunctions. When the air source pressure in the valve is normal, it is necessary to determine whether the amplifier of the electro-pneumatic converter has an output. If there is no output, there may be two situations: first, the water in the air is compressed and placed at the power amplifier ball valve; second, the constant current hole of the amplifier is blocked. For this, it is necessary to implement various methods such as cleaning the air source, removing debris, and clearing the constant hole. If the valve still does not move after the above processing, the valve needs to be disassembled for a comprehensive inspection.

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