Who knows about multi-stage pressure reduction control valves?
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Could you explain how to distinguish between gas on and gas off?
Pneumatic ball valves (also known as on-off valves or switch valves) can be divided into air-open valves and air-close valves. As the name implies, a pneumatic actuator refers to a valve that opens when instrument air is used to pressurize the actuator ； The valve closes when the actuator releases the instrument air inside it. The gas shut-off valve is the opposite. These two types of operation modes exist because the process system may experience gas supply failures. In such situations, depending on the requirements of the process flow, some valves need to be opened (such as cut-off valves) while others need to be closed (such as vent valves). Therefore, designers choose between air-operated open valves and air-operated closed valves based on the needs during the process design.
Air enters from below, the spring is on top; the valve seat still needs to be considered
It’s usually a valve in a formal design; from what I can see, this valve seems to be a Foß air-operated valve
It’s indicated on the nameplate: is it an air-open valve or an air-close valve?
Can someone who is a moderator do something like blocking messages?
Friend, multiple pressure reduction valves have nothing to do with whether the valve operates on air activation or air shutdown. Multiple pressure reduction levels refer to the design of the valve core, while air activation/air shutdown refers to the actuator. Additionally, as can be seen from the picture, you’re using a double-acting cylinder; as for the specific cause of the malfunction, it depends on how the air circuit components are configured. OP, what’s the point of having everything completely hidden? Everyone should take a look – the question raised is really odd. . .
First close the root valve, then shut off the air supply to the control valve; when the valve opens, it operates in air-shut mode； A closed valve means it is air-operated.
The nameplate of a standard control valve usually indicates whether it is air-operated open or air-operated closed. I don’t know the structure of the cylinder; it’s impossible to determine it from its appearance. It can also be confirmed by checking the instrument specification sheet issued by the design institute.
What’s going on? Why can’t I see it?
I can’t see anything, and I have no idea what you’re saying!!! It’s only possible to get a rough idea of the appearance of the valves; generally, the valve for air intake at the top is an air-shut valve, while the one for air intake at the bottom is an air-open valve. But it’s not accurate to say that. You can look at the label; FO stands for Fault Open Valve, which can be understood as a gas-shut valve ； FC stands for fail-closed valve, which can be understood as a gas-open valve. There are also FL valves that maintain the fault state. FC and FO can be achieved through positioners, gas cylinders, and gas circuit valves.