How should the isolation valves for SIS and DCS be configured?

“Can a cut-off valve with two solenoids be used? Taken from SIS and DCS respectively; does this constitute redundancy or sharing? ”Why are two solenoid valves needed for SIL1 level? You can send a signal from DCS to SIS, and then from SIS to the on-site shut-off valve; this also ensures that the SIS takes precedence in operation.

Looking at the standards, with such an ambiguous explanation, still don’t you understand? I won’t go into details about sil1. As for sil2, it means it’s acceptable to separate them or not; I believe that in most design firms they aren’t separated, after all, an additional valve comes at a cost. Regarding sil3, it means two valves must be installed. The common approach here is to use other methods to reduce the required level, so as to avoid having valves of type sil3. If nothing else works, installing two valves as a safety measure is the only option left

Judging by the standards, such an ambiguous explanation

Three levels, represented by three characters: ke, yi, ying

Yes, but the solenoid valves should be selected in accordance with SIS standards

We share the valve body and cylinder, with 2 two-position three-way solenoid valves connected in series in the gas circuit

This post was last edited by zhongjun0110 on 2018-3-13 09:27. It is a shut-off valve using two solenoid valves; one solenoid valve receives signals from the DCS and is used for automatic shutdown under normal conditions. Another solenoid valve is connected to the SIS signal for automatic shutdown in emergency situations. Solenoids used for DCS control do not require SIL rating certification, but solenoids used for SIS do need SIL rating certification.

As the original poster mentioned regarding classification, a decision should be made based on the actual conditions and level of importance; in most cases, one solenoid valve is sufficient. The interlock signal can be sent directly to the SIS or DCS, and by communicating it to another system, control can be achieved. . . .

This post was last edited by 1111111 on 2018-3-14 at 16:44. Brother has a vague feeling that SIS’s level certification system is some kind of nonsense For measuring elements and power control elements, to determine whether they are safe or not, which electrical or mechanical performance indicator can be used to describe this? Who knows, come give a lecture. . . Does installing more instruments and more valves truly increase the safety of the system? The instruments are connected in parallel, with a three-out-of-two voting system; this is said to enhance the reliability of measurements and reduce the likelihood of false alarms. There’s more to it as well: when valves are connected in series, any failure in either valve can cause the entire system to fail. In my opinion, this doesn’t increase safety at all – on the contrary, it reduces it. It seems like adding an extra control valve is just a way to create more points of failure in the system. Just as wearing 2 pairs of underwear or 3 pairs of underwear doesn’t necessarily make your private parts safer, right? If the crotch area is too tight, it can cause itching and heat rashes in your testicles; if the crotch area is too thick, it can lead to skin irritation when you urinate, right?

Yes. A shut-off valve for dual solenoid valves, with one solenoid receiving a signal from the DCS, used for automatic shutdown under normal conditions. Another solenoid valve is connected to the SIS signal for automatic shutdown in emergency situations. Solenoids used for DCS control do not require SIL rating certification, but solenoids used for SIS do need SIL rating certification.