Dear experts, what type of valve is the one in this picture?

I posted a similar post a few years ago; the drawing method was exactly the same as yours, and there were no legend explanations either. Could it be that we encountered the same unprofessional manufacturer? (It’s not a drawing produced by a design institute; it’s a drawing provided by the manufacturer of the complete set of equipment.) HaiChuan’s response also does not provide a clear answer – some say that A/S refers to AIR SUPPLY, meaning the air source, and the line with two diagonal lines represents the air supply line ； There is also a saying that A/S stands for Analog/SWITCH conversion. Specifically, in this diagram of yours, the valve indicated by the circle is normally an electromagnetic three-way valve. If the A/S at the valve’s inlet is a gas supply line, then the two outlets of the valve correspond to the gas supply lines of the pneumatic shut-off valve XV88104A ； The other empty one there isn’t clear what it’s used for.

Two three-way solenoid valves; S refers to the solenoid coil, while A/S denotes the instrument air. These solenoid valves are used to control the opening or closing of XV88104A.

This post was last edited by stone_HOTO on 2019-11-13 at 11:00. The valve inside the circle is a three-way valve; S refers to the electromagnetic actuator and solenoid valve, while A/S stands for AIR SUPPLY, meaning the air source. The line with two slashes indicates the air supply line, and the blue line with an arrow shows the flow direction when the solenoid valve is not powered. Considering the fault condition of the valve, it should operate electrically, returning to its faulty state when power is lost

What does it mean when the valve returns to a fault state due to power loss?

The three-way solenoid valve – undoubtedly, they don’t know what A/S means; the double slashes indeed indicate the air supply source.

Solenoid Valve AIR SOURCE