Control valve with solenoid valve

Used in SIS systems to open or close valves.

It seems to be used for quick cutting; it might also be used for opening, depending on the process requirements

Solenoid valves are installed to quickly open or close valves; of course, the actual position is determined by the type of fault present in the valve itself. The solenoid valve serves merely to allow the gas to be discharged rapidly, thereby returning the valve to its original safe position

A control valve with interlock; the solenoid valve is used to issue commands for the higher-level valve to operate, taking precedence over the positioner. Another function is to enable the emergency reset of control valves; it is generally installed between the positioner and the cylinder or diaphragm head.

Over-designing is a waste. 1. Is it necessary to equip a control valve with a solenoid valve? The specifications for selecting instruments provide guidance on this (both HG and SH have relevant guidelines). 2. Can a control valve be used as the final element in a SIS system? GB50770 also addresses this issue. 3. What are the requirements for using a control valve as a final actuator? The SH selection specifications outline these requirements. 4. If a control valve is to be used as a final actuator, what signals are needed? HG20511 provides information on this. Recommendations: 1. It is not recommended to use control valves as SIS valves; if they must be used, their number should be kept as low as possible. 2. If a control valve is indeed used as a SIS valve, that is, within an IPL system, it must be equipped with a solenoid valve, as well as feedback for the locked position. The leakage level should be at least V (in line with the requirements for shut-off valves). 3. If the pipeline connected to the control valve has an XV device, then for SIL1 and lower levels, an XV device is sufficient. For SIL2 levels, it is recommended to use two XV devices, or, according to the specifications, an XV device combined with a CV device (it is preferable to avoid using a CV device when an XV device already meets the requirements). The diagram shows feedback for the valve’s open position, closed position, and valve position transmission – which represents excessive redundancy. Let’s do a quick calculation: an ASCO solenoid valve costs between 3,500 and 5,000; a DI+ cable plus installation costs no less than 2,500; circuit testing costs at least 300. The total cost is therefore no less than 7,000.

Also, the position feedback signal and the transmission signal do not need to go into the SIS. With Z, it is the SIS signal

One more thing... Under normal circumstances, it is not recommended to use a bypass; instead, a handwheel should be used directly (valves that are part of the SIS must not have handwheels or bypasses). There are piping specifications for choosing between handwheels and bypasses, as well as specifications for instrument selection.

If there is a need for quick opening or closing, pneumatic relays or similar devices are usually used. At this point, the process discipline requires a shutdown time, but the operating time of the existing valve equipment does not meet this requirement.