Discussion on whether gas detectors require SIL certification

Give it a push – does that mean electrical fires and fire alarms are both required?

According to Document No. 116, GDS should use systems with SIL certification, but it is worth questioning whether such one-size-fits-all regulations are reasonable.

It is supposed to reach a certain SIL level, with reliability meeting the standards. But this is the IEC’s wishful thinking – it wants to bring everything under its control. For example, systems such as BMS systems must have a SIL rating. In fact, it is not necessary; it is only required to meet each NFPA85 standard. The fire gas alarm system also needs to meet the corresponding NFPA standards

Independent GDS units do not require SIL certification, but the toxic gas detector controllers that are integrated into the FGS system need to have SIL certification, as clearly stated in the new specifications (draft version).

This post was last edited by 1111111 on 2019-7-22 at 13:02. A few days ago, another explosion occurred at the gasification plant in Sanmenxia – and it’s yet another benchmark enterprise involved. SIS, does it work? What’s the use of it anyway? ! Hehehe, I really feel that SIS is nothing but something that pretends to be something else, relies on bluffing and showing off, is overconfident yet lacks actual ability, weak on the inside, easily defeated, and utterly useless. My brain isn’t working well. I love eating dumplings. I like looking at girls. Is there anyone who doesn’t want to agree? If you disagree, argue then; let me take on you and have some fun......... {:2_42:}

From a scientific perspective, SIS interlocks require a corresponding SIL level, fire protection interlocks need fire certification, while others do not.

As required by safety regulations, I need to convert all the gas detectors in the factory into an independent system. They were previously connected to the DCS system. I plan to add a PLC system, but I’m not sure what standards the gas detection system needs to meet – is 3CF required? SIL? I’d appreciate some advice from those who are more experienced; I’m worried that after going through all the effort, it might not meet this or that requirement.

Your point makes sense; it’s just that I’m not familiar with the safety inspection standards

SIL is a trend, but it’s difficult to implement. When everyone does it in a “mechanical, perfunctory” manner, things sometimes go awry. We still need to return to the principles of being strict and honest, and staying true to our original aspirations: we must continuously seek ways to optimize the industry in order to ensure the reliability of the test points!

Flammable and toxic gas detectors operate in natural environments, detecting the concentrations of such gases in that environment. Due to limitations in detection technology, detector manufacturing, and natural environmental conditions, flammable gas detectors experience more false alarms and missed detections than other process monitoring instruments used for measuring temperature, pressure, flow, etc. Even when regularly calibrated, adverse weather conditions such as rain, snow, high temperatures, strong winds, and dust storms can affect the detectors, leading to false alarms and missed detections [7]. Furthermore, leaks of flammable and toxic gases are mostly random events that cannot be predicted in advance. It is impossible to arrange the detectors in the most optimal locations, and their installation sites are influenced by factors such as the geographical environment and the distribution of equipment, all of which lead to inaccurate detection and result in missed detections by the flammable and toxic gas detectors. There are many causes of leaks of flammable and toxic gases. When a leak occurs, the methods used to stop it or eliminate the cause vary depending on the location of the leak and its underlying reason; thus, it is not possible to handle such leaks entirely in accordance with pre-established plans. Detection and alarm systems merely issue alerts, but they lack actuators and defined procedures for handling the situation. Therefore, GDSS is not a fail-safe instrumented system, nor does it possess the fail-safe characteristics of a SIS. In summary, due to the different uses, functions, and working principles of GDSS and SIS, GDSS cannot fulfill the role of SIS in preventing or reducing the occurrence of hazardous events or maintaining a safe state of the process. GDSS also does not possess the characteristics of SIS; it is unable to reduce the probability of process risks occurring. Moreover, the accuracy of GDSS alarms is greatly influenced by the detection environment and the distribution of detectors. Therefore, it is meaningless to use SIL ratings to evaluate GDSS. Therefore, GDs do not fall under the category of SIS, and there is no need to consider SIL levels when setting up GDs. “Discussion on the Installation of Flammable and Toxic Gas Detection and Alarm Systems in Large Integrated Chemical Plants” by Liu Ziyun (Shenhua Engineering & Technology Co., Ltd., Beijing 100011). Personally, I find this paper to be quite clear and easy to understand!