Based on the diagram, let’s discuss the working principle of this pneumatic retaining valve.

This air circuit is really quite complicated

Did it sink? No one to give some guidance?

This post was last edited by Still Wu on 2017-10-6 at 14:28. I took another close look at the air circuit and will explain it in detail. In terms of the air circuit of this valve, the key components in situations of power loss or air supply failure are the double-acting locking valve and the double-acting retaining valve. When there is no air supply, the double-acting retaining valve comes into play; thanks to the spring force, it prevents air from entering or exiting the cylinder, thus maintaining its position. When there is no power supply, that is, when the solenoid valve and the actuator lose power, the air circuit of the double-acting locking valve is as shown in the diagram: out11 is connected to in12, out21 is connected to in22, and in22 is connected to the air reservoir. Air supply opens the valve. That’s basically how it works. The other components are quite common, so I think everyone understands them. I really haven’t seen any similar components before; I’m still learning

I now understand the double-acting position maintaining valve as well; it is driven by air pressure. When air flows in from above, it becomes conductive, and it can be considered like a tube that allows normal air intake and exhaust. Once there is a problem with the supply of instrument air and no air flows in from above, the spring takes over, the air supply is cut off, and the air inside the cylinder can no longer escape – thus the valve maintains its position

I took another close look at the air circuit and tried to explain it: in terms of the valve’s operation in situations of power loss or lack of air supply, the key components are the double-acting locking valve and the double-acting retaining valve. When there is no air available, the double-acting retaining valve comes into play; thanks to its spring mechanism, it prevents air from entering or exiting the cylinder, thus maintaining its position. In cases of power loss, that is, when the solenoid valves and positioners lose power, the air circuit for the double-acting locking valve is as shown in the diagram – out11 is connected to in12, out21 is connected to in22, and in22 is connected to the air reservoir. Air supply opens the valve. That’s basically how it works. The other components are quite common, so I think everyone understands them. I really haven’t seen any similar components before; I’m still learning about this