DCS and SIS experts check whether the DCS and SIS alarm and interlock value settings are set to the same value?
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Experts currently have two opinions on the settings of DCS and SIS alarm and interlock values.: 1. It is considered safer to set the alarm and interlock values of DCS and SIS to the same value. 2. The DCS and SIS alarm and interlock value settings are different. The SIS interlock value setting is higher than the DCS setting value. Please check the specifications and how your company sets it? Thanks
Anyone who can propose the first type is a pseudo-expert
The SIS is "stationary" under normal circumstances. It does not need to alarm but is directly interlocked when conditions are met. The SIS workstation is not placed in the operation room, but in the instrument engineer's room. Is this alarm going to the instrument? So I think SIS’s call to the police is nonsense.
DCS action should precede SIS. SIS should be the protective layer after DCS action fails.
This post was last edited by zhuirvine on 2021-5-24 08:49. . . . Doesn't your SIS have an auxiliary console? Are there no alarm signals and emergency stop buttons on the auxiliary console? Isn't the auxiliary console placed in the operating room? Doesn’t the alarm on the auxiliary console have a buzzer?
This depends on whether your process alarm needs high and high alarms. You can use the value of high and high alarms as the interlocking value of SIS. In this way, the operator will have to react when the report is high. Generally, DCS will have two alarms: high alarm and high alarm. SIS is an interlocking reaction made after the high alarm is still uncontrollable and reaches the upper limit of safety requirements. This may result in a full or partial stop. From the perspective of process safety and confirmation of laws and regulations, experts are just opinions. As long as there is an SIS, it will be good. If there are legal provisions that clarify that SIS must be higher than or equal to the set value of DCS, you can follow the laws and regulations.
How dare this expert mention it! The interlocking protection of DCS can be seen as a protective layer. It is necessary to correctly understand the role of SIS. Study hard * Let’s look at 2.1.7 of the provisions of 50770
DCS alarm reminds the operator that there is an abnormal situation. SIS is a safety interlock. Generally, the DCS alarm range is narrower and smaller than the interlock value, so that there is room for adjustment when abnormality occurs.
This post was last edited by ssln123 on 2021-5-25 08:16 There is an auxiliary console, but the buzzer is no longer called an alarm, but reminds us that an interlock has occurred. It is different from the DCS alarm expression. To be precise, it is called an interlock reminder.
There is still something wrong with the settings. It stands to reason that the first-level alarm value is higher than the SIS chain value, so that it can serve as an early warning.
This post was last edited by ssln123 on 2021-5-25 11:01 Experts said that interlocking is the last line of protection. DCS reports high and high reports before interlocking takes place. Therefore, the company's SIS is interlocked as soon as the alarm is reported. :D If it were the other way around and they were all interlocked, there might not necessarily be a level one alarm.