Seeking help with valve operation issues in the SIS system
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Seeking help: Is there any issue with using the DCS system to control the opening and closing of valves in the SIS system? Thank you!
It shouldn’t work, right? The SIS system and the DCS system need to be separate.
The reset switch valve works fine after interlock activation.
Sure, no problem. The interlock in the SIS system has not been triggered, so the DCS can perform any operations； The SIS system is activated, and the DCS cannot perform any operations
In accordance with Article 13, Paragraph 3 of the regulations issued by the Safety Supervision Bureau regarding major hazard sources (Order No. 40 of the Safety Supervision Bureau), emergency shutoff devices must be installed for key facilities among those related to major hazard sources, such as toxic gases, highly toxic liquids, and flammable gases； For facilities handling toxic gases, emergency devices for dealing with leaks must be installed. For major hazard sources of level 1 or 2 involving toxic gases, liquefied gases, or highly toxic liquids, an independent Safety Instrumented System (SIS) must be installed ； This requires independence, meaning that the meters and the entire system must be independent of each other
Sis, if you love it that much, then die. Haha, what’s the point of adding extra stuff? Just die already. Bro, I support it
It is possible if it is a control valve, but it cannot be achieved if it is a shut-off valve. The SIS system interlock has not been triggered, allowing the DCS to perform any operations ； The SIS system is activated, and the DCS cannot perform any operations.
The SIS system is an independent system with the highest security level; in other words, it can control a valve together with the DCS, but it cannot control the same solenoid valve as the DCS, and its control level is higher. For example, there is a valve that is controlled by both the DCS and the SIS. The DCS can open and close it, but once the SIS triggers an interlock, the interlock settings of the SIS take precedence; if the SIS commands that the valve be closed, then the DCS cannot open it. Therefore, in this case, the solenoid valves controlled by SIS are usually placed on the main air circuit, while the valve accessories controlled by DCS (including solenoid valves, positioners, etc.) are placed later.
We encountered such problems during the renovation at the beginning of this year. First of all, if the design is done properly, then the valves of the DCS and those of the SIS should be separated – each system handles its own valves. For example, for feed into a tank area, it is best to have two valves. It is said that the SIS system for the tank farm should be independent; therefore, the tank farm interlock logic from the ESD was separated out and a separate SIS was installed. However, our tank area does not consist of storage and transportation tanks; it is used to store products produced continuously. When the process is not in operation, the valves need to be opened and closed, and this needs to be controlled by the DCS. It can be achieved through communication; we achieve it through hardwired connections. Nonsense
As long as the process permits it, there’s no problem. As long as it is ensured that DCS operations do not affect the valve control function of the SIS system, that is sufficient.
This post was last edited by 1111111 on 2017-12-30 07:28. SIS, DCS – controlling small valves and pumps: isn’t that equivalent to connecting two switches in series? Did you guess right? . .