Help check the air circuit of this valve

The gas cylinder should keep the control valve open or closed in case of a gas supply failure. The air circuit of the pneumatic directional control valve seems a bit off.

Is this valve a pneumatic diaphragm actuator?

The interlock action of UC-60002 needs to be understood; the gas tank is not necessarily provided for the operation of double-acting cylinders in the event of a gas supply failure – it’s also possible that the fault position of the valve does not match the interlock position

Both solenoids become energized or de-energized simultaneously.

This design is intended to ensure that an interlock action and a gas supply failure result in the same outcome. Under normal operation, the valve remains open; when an interlock action occurs, the solenoid valve loses power, causing the operating air supply for the directional control valve to be depleted. As the pressure of this operating air supply drops, the directional control valve connects the air supply to the diaphragm valve, allowing air to enter and close the valve. The air storage tank is used to prevent the situation where, during an interlock action, there is a failure in the air supply, resulting in the valves not being able to close.

Generally, this type of air circuit design is used in dual-cylinder valves. It’s a bit strange to see a pneumatic diaphragm actuator used in this case; if that’s the case, the reaction force from the actuator could be utilized directly, eliminating the need for such a complex air circuit. I am not familiar with this type of operating condition, so I’m not clear about the actual purpose of such a design.

It’s probably for backup; the valve is normally closed.

The pneumatic directional valve should be a air-actuated shut-off valve to cut off the source of LV60003 in emergency situations.

To correct that, first understand the functions of several components. 1. Pneumatic directional control valve? No, this is a pneumatically controlled valve; it uses a small air source (usually the air circuit of a solenoid valve) to control the main air source (the power air circuit for the valve). It functions like a small pneumatic on/off valve. I’ve explained before why this design is used: large-diameter solenoid valves are relatively expensive. 2. Dual solenoid valves. It is generally a redundant design, ensuring that the valve can still function in case of a fault or jamming in one of the solenoid valves’ circuits. For example, in the case above, when the AB solenoid is powered, air flows to the left and right; at this time, air passes through solenoid A. When the solenoid is de-energized, air flows to the lower left, and no air flows at this point. When solenoid valve A fails and gets stuck in the de-energized position (i.e., allowing flow from the lower left), valve B becomes energized, allowing flow in both directions; thus, the air supply can still pass through B and then to A ； Conversely, if card B is at a power-off potential, A can still allow the gas supply to pass through. 3. Air storage tank. This is simple – there’s no difference between an accident tank and a buffer tank. If there is a check valve in front of the tank, it is an emergency tank; if there is something on the tank used to regulate pressure (such as an automatic pressure relief device or something similar), then it is a buffer tank. It can also be both. I’m completely exhausted after all this; figuring out the air circuits is the most mentally demanding task. When I first graduated, issues that could keep people in an office arguing for a whole day were related to valves and air circuits.