Questions regarding DCS and SIS systems
Thread Content
Hello, teachers! Large and medium-sized chemical manufacturing enterprises now all have DCS systems, but some smaller enterprises still do not. I would like to ask whether there are any specifications or regulations specifying which types of installations must be equipped with control systems such as DCS, SIS, or PLC. Thank you!
SIS requirements seem to require both Class A and Class B
Whether a DCS or PLC is needed depends on the number of monitoring and control points in the system; generally, a PLC is required when there are dozens of such points, while a DCS or PLC should be considered when there are over 100 points. For SIS, a safety assessment is required to determine whether it is necessary to implement it, as well as to identify which SIL level—1, 2, or 3—it should correspond to.
This post was last edited by zhengpeichun on 2017-12-12 at 17:05. There is a general need to increase the level of automation in devices, which means that control systems are essentially necessary. **The Work Safety Supervision Bureau previously issued Document No. 40; this document can be referred to in order to determine whether it is necessary to implement an SIS system.
The SIL level requires a HAZOP analysis, which depends on the risk level of your project. SIS is merely a safety instrument system; you can take a look at similar posts at https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1562781 and https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1296476
For DCS, it depends on the scale of the control points; in the case of SIS, two critical points and one major point require installation. Otherwise, if a risk analysis indicates that an independent protection layer is needed, then it should be installed; otherwise, it isn’t necessary.
DCS (PLC) and SIS are two separate systems: the former is a process control system that is now standard in industrial plants, and its use can be determined based on the specific requirements of each plant; the latter is a safety interlock system that is required to be installed by law. Selection can be made with reference to a series of documents issued by the Safety Supervision Bureau (such as SIS for 18 types of hazardous processes).
For petrochemical plants, any instrument designated for interlock functionality must be integrated into a SIS, DCS, or PLC – the choice depending on the number of instrument points and investment considerations