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The working principle of pneumatic valves and fault analysis

2023-01-03 14:13

The so-called pneumatic valves specifically refer to the use of cylinders as actuators and compressed air as the power source to achieve the actuation of the valves in order to achieve the adjustment of the switches. When the control signal is received by the control system, the temperature, pressure, flow and other relevant parameters are adjusted. In general, pneumatic valves are characterised by their reliability, rapid response and simple control. In the specific operation process, the regulating air chamber will be input 0.02-0.10MPa signal pressure, the film will appear thrust, in the process of thrust disc downward movement will be compressed spring, to achieve the valve stem, push rod and spool downward movement, to achieve the purpose of the valve regulation.

2 Pneumatic valve common faults and handling methods
Through the study and analysis of the fault state of pneumatic valves, it is understood that the possible faults are valve jamming, valve inaction, valve leakage and vibration, etc. Therefore, it is necessary to develop countermeasures according to the actual faults in order to achieve smooth operation of the system and create higher benefits.

2.1 Pneumatic valve jamming
If the action of the valve stem is sluggish, this means that there may be a viscous substance in the valve body and that the pneumatic valve is blocked, mainly at the beginning of the system's operation. In this case, the valve or sub-line should be opened and closed quickly to flush out the blocked medium. At the same time, the valve stem can also be clamped in a pipe vise and the signal pressure applied to rotate the stem against the force. If the above problem is still not solved, then repeated up and down movements can be made by increasing the drive power. It is important to note that the above operations are highly specialised and therefore need to be carried out with the help of specialist personnel when solving and dealing with this fault.

2.2 Valve does not move
For this fault, the first step is to determine whether the pressure of the gas source is normal, and on this basis to find the fault of the gas source. When the pressure of the gas source in the valve is normal, it is necessary to determine whether the amplifier of the electric/gas converter has an output. If there is no output, there are two possible scenarios: firstly, moisture in the air is compressed and placed at the amplifier ball valve; secondly, the amplifier's constant throttle is blocked. In this case, it is necessary to clean the air supply, remove debris and unclog the constant throttle orifice. If the valve still does not operate after these treatments, the valve needs to be removed and a full inspection carried out.