We invite instrument technicians to help understand the function of the solenoid valve in pneumatic cut-off valves
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As shown in the picture, I am in the process engineering field. On site, while checking the exhaust vent SIS system isolation valve with colleagues, it was found that three solenoid valves controlled it together. The valve nameplate indicated that a faulty open state corresponded to the FO type; the SIS system required the valve to open for venting in the event of a power loss to the solenoid valves or a sudden loss of compressed air.
That’s why three solenoid valves are used for control? They are all two-position three-way
The part that is rusted in the middle at the bottom of the white rectangular solenoid valve is the one that leads to the cylinder
There are only 2 solenoid valves here; the one located near the air source is just a pneumatic switching valve. The one on top is the position feedback switch. When two solenoid valves operate in series, both must lose power for the valve to move, in order to meet the requirements of the corresponding SIL level design.
The role of solenoid valves in valve control systems indicates that they are part of the actuator. Its function is to control the on/off of the control valve for the air supply to the cylinder by applying or removing power. The control of power on and off can be performed automatically or manually. The cylinder is powered by a pneumatic source controlled by a solenoid valve, which enables the cylinder piston to move in both directions and thus operate the valve. This is the basic principle, and it is something that must be understood when working with manufacturing processes. It should also be a required course. The on-site equipment is severely corroded; with such management, it’s likely that this valve will fail someday. Aren’t you guys afraid?:lol
High-security wiring method; the schematic is available in the standards
Is the white one the solenoid valve? I couldn’t see the wiring.
These are two solenoid valves connected in series; the diagram on floor 6 shows the correct configuration, with the white component in the middle being a pneumatic switching valve. There should be one connection to DCS and one to SIS; SIS is fail-safe, meaning it resets in the safe state in the event of a power loss ； As part of normal operation, the DCS controls the opening and closing of valves. It can be understood by combining the 4th and 6th floors.
I’ve learned it. Thank you to those on floor 4 and floor 6
These two solenoid valves are connected in parallel. The exhaust port of one solenoid valve is connected to the silencer port of another solenoid valve.
Yes, I just viewed this material yesterday