Pneumatic valve failure
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A double-acting valve controlled by two five-way solenoid valves will not open properly. The fault symptom is that the valve opens to less than 10%, and a large amount of air flows out when the exhaust port is closed. To relieve process pressure, the gas source is directly connected to the cylinder to open the valve; once the gas supply is restored, the valve can close properly. A malfunction in the solenoid valve was suspected; after it was replaced, the problem persisted for less than two days, with the same issues as before. Upon inspection, the command signal voltage is 19.9 VDC; there is no backflow in the cylinders, and there are no leaks in the air circuits. Moreover, after issuing the open command, when the valve is in a faulty state, the air supply is turned off; once the sound of airflow decreases slightly, the air supply is turned back on, and the valve can open properly. But after the valve is closed and reopened, it still cannot be opened; the fault remains the same as before. Please help! **Give me some solution!
Based on the description, it is caused by a large amount of water in the process gas or air leakage from the solenoid valve. It is impossible to determine due to the lack of key information provided in the description. 1. Valve type? Gas path configuration? Photos, etc. 2. Brand and model of the solenoid valve, photos of the pressure reducing valve, etc. Check it out using this approach first. I’ll tell you the reason after confirmation.
1. Air leakage in the air circuit of the solenoid valve base (mostly due to aging/damage of the sealing ring)； 2. Silencer filter is dirty/clogged ； 3. Water/oil in the air supply ； 4. The cylinder is scratched
Is it because the cylinder of this valve is very large?
Unified reply: Thank you all for your help and reminders! The fault has now been resolved; another unused valve cylinder on site was replaced in its entirety. Currently, two five-way solenoid valves are used to control the inlet and outlet air control valves, with the output from these valves feeding into the cylinders. It remains to be seen what the actual effects will be; for now, switching the valve on and off multiple times has worked normally.