DCS interlock
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I currently have a heating furnace temperature control valve that requires interlocking; is it possible to achieve this without using a solenoid valve through the program? Which regulation specifies that a solenoid valve is required? Thank you!
Without using a solenoid valve, it is also possible to provide the actuator with a 100% closed output signal through the program; it just takes a little longer. Solenoid valves can respond quickly.
That’s exactly what I’m doing right now. I wonder if this approach is compliant, as I’m worried that it might cause problems during safety inspections. Are there any regulations that require the use of solenoid valves?
There are no regulations requiring that interlocks must use solenoid valves.
For interlock shutdown, the required response time varies depending on the different SIL levels. It is definitely possible to use a locator to close it, just slower. If the risk is high, it is necessary to assess whether it could lead to a major accident
If you want to interconnect with a control valve, it is necessary to understand the tightness of that control valve. Generally, the tightness requirements for control valves are not high; only the tightness of shut-off valves can be used for interlocking purposes in order to completely cut off the fuel supply.
Firstly, control valves can be used as shut-off valves; both SHT3005 and GBT50770 have corresponding regulations and requirements (please pay attention to these requirements). As for whether it should be controlled via a solenoid valve, HGT20507 and SHT3005 also have relevant specifications. If the process does not require low leakage from the valve, or if it is not part of a safety interlock system, there are no requirements regarding response time, or if there is a shut-off valve in place, then it may be unnecessary to use an electromagnetic valve.
The big shots explained it very clearly, and I also learned* a bit from it
Whether to include a solenoid valve depends on the structure and working principle of the temperature control valve.
If this is a safety interlock, a control valve won’t work; adding a solenoid valve is also not appropriate – use a shut-off valve instead. If it’s not a safety interlock, then it’s fine.