Analysis of valve connections in gas circuits

There isn’t much difference between the first and third ones; the third one simply has an additional solenoid valve. The air circuit in the second one hasn’t been fully restored, so it’s not possible to see everything clearly

Your gas supply pipeline is too complicated; it’s not necessary

The second one can also not be said to be incomplete; the part that isn’t connected is the middle section, which I have already connected using egg-yellow thread. (Because the air path connection of the valve was incorrect at that time, it was decided to connect the egg-yellow-colored pipeline, and then everything worked fine.) But I didn’t understand; it was handled by an experienced worker.)

The last edit to this post was made by ssln123 on 2018-9-14 at 11:41. The valves are quite high-quality – ASCO flameproof solenoid valves, along with Fisher positioners. It seems to be a large state-owned enterprise: lol. There’s an interesting question here: it appears that the air storage tank isn’t meant to keep the control valve operating for a while in case of a problem with the instrument air, but rather to enable the valve to act quickly (the valve stem moving downward) in order to open or close it when there’s a problem with the air supply.

I think the second image is clearer, so I’ll share my personal interpretation of the second image: First, let’s discuss the air path in order from left to right. The air path coming from the air supply main is divided into two branches: one branch connects to the inlet of the pressure regulator ①, while the other branch connects to the inlet for the amplifier drive air supply ③. The outlet of the pressure regulator ② is also divided into two branches, one of which connects to the inlet of the amplifier ④, and the other connects to the inlet of the pneumatic directional valve⑾ ； The amplifier output ⑤ is divided into two paths again. One path is connected to the drive air supply inlet ⑧ of the position maintenance valve, while the other path is connected to the solenoid valve inlet⑥ ； The outlet of the solenoid valve ⑦ is connected to the inlet ⒁ of the cylinder air intake tee connector B. The outlet of the pneumatic directional control valve splits into two paths, which are used to control the opening and closing of the valve. Among them, outlet ⑿ is connected to the inlet ⑩ of the hold valve, and the outlet ⑨ of the hold valve is connected to the air inlet tee connector A on the left side of the cylinder. The other outlet ⒀ of the pneumatic directional control valve is connected to the inlet ⒂ of the air intake tee joint B on the right side of the cylinder. Next, let’s discuss the working principle of the air circuit: when the overall air supply pressure is normal, the pressure holding valve does not function, and ⑨ and ⑩ are connected. The pneumatic directional valves ⑾ and ⑿ are connected, while ⑾ and ⒀ are disconnected. The air source enters the cylinder through tee connector A to drive the valve and maintain its current position. Assuming that pneumatic directional valves ⑾ and ⑿ are connected under the premise that ⒁ is pressurized, then the inlet ⑥ and outlet ⑦ of the solenoid valve must be in a connected state. After the solenoid valve switches between the powered and power-off states, the air path between inlet ⑥ and outlet ⑦ is disconnected. The air path of the pneumatic directional valve changes from ⑾→⑿ to ⑾→⒀; at this point, the air inlet ⑩ of the safety valve is under the pressure from the air reservoir, which is lower than the pressure at the control air inlet ⑧ of the safety valve, resulting in a disconnection between ⑨ and ⑩. The air in the left cylinder is discharged through the emergency exhaust port of cylinder tee connector A. The outlet ⒀ of the pneumatic directional control valve is connected to the inlet ⒂ of the cylinder’s three-way connector B, allowing air to be supplied to the right half of the cylinder and thereby causing the valve position to change. When there is no air supply, the inlet ⑧ of the retention valve is free of air; at this time, the pressure of the air source from the air reservoir is higher than the pressure at inlet ⑧, which keeps connections ⑨ and ⑩ open. Air then enters the left half of the cylinder through the tee connector A, thereby maintaining the valve’s position before the air supply is cut off. Once the air in the reservoir is exhausted, the retention valve takes effect. Here are the accompanying explanatory images:

Thank you so much! ! ! Thank you, thank you! ! ! Very detailed! I need some time to process this

Well, I can only say that this valve does indeed have a function for rapid operation. It seems to be as you said; I was really confused at the time, as it was my first time seeing some of those components. Your guess is very likely correct

Look at this mess; the piping isn’t organized either, and the management is inadequate.

The only difference between the first and third ones is that the first one doesn’t have a solenoid valve; all other accessories are identical in model