Pneumatic control valve
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When a pneumatic control valve loses air pressure, does it remain in its current state or does it take action after that? For example, what is the state of a diaphragm control valve with a spring when it loses air pressure, and what is the state of a control valve without a spring in such a situation? There are also two-position solenoid valves with only on/off states; what is the state of the solenoid valve when there is no air pressure? Thank you!
Pneumatic control valves come in air-open and air-close types; the air-open type closes when air supply is lost； The valve opens when the air supply is cut off. The simplest way to determine this is to check the state of the valve when there is no air in it....
As mentioned on the 2nd floor, when selecting valves, there are those that open under gas pressure and those that close under gas pressure, depending on the process requirements. On the PID diagram, there are F.C (air-open) and F.O (air-close)
Control valves are divided into FC and FO; they are the same whether there is a spring or not. FC means the air release valve is closed, and FO is the opposite. A two-coil solenoid valve with only on/off status should control a two-cylinder on/off valve, and when the air supply to the two-cylinder on/off valve is cut off, the valve remains in its original position.
Valves generally have fault closed, fault open, and fault hold modes. By \"fault\", it is meant the state of the valve in the event of a power or gas supply interruption, which is also a safe state
Valves generally have fault closed, fault open, and fault hold modes. By \"fault\", it is meant the state of the valve in the event of a power or gas supply interruption, which is also a safe state
For control valves, it depends on whether they are normally open or normally closed: those that are normally open will return to the open state when the air supply is cut off, while those that are normally closed will return to the closed state under the same conditions. For solenoids with dual control, the presence or absence of air does not affect their operation; when the power is cut off, the solenoid remains in the state it was in before the power was disconnected. This is also why dual-control solenoids are chosen
It is the process that determines whether to use a gas-open valve or a gas-close valve; in particular, it is the actions that the valve needs to perform under specific conditions that determine the type of pneumatic valve to be used. If one understands the process thoroughly and is familiar with the interlocks, it becomes clear naturally which type of valve is required for each application.
It depends on whether the valve is a gas-open or gas-close valve! It is mainly about considering safety aspects in the event of a failure
It depends on your choice. Air open valve, air close valve, and hold-in valve.
In other words, it is a matter of choosing the forward/reverse action of the control valve as well as whether to use single or double solenoid valves. This depends on the process and safety requirements. In fault condition, is it on, off, or held in place? Once the process steps and control requirements are clearly understood, this problem will naturally be solved.