Application of Safety Relay in Safety Instrumented System

In response to the frequent occurrence of production safety accidents, Article 13 of the Document No. 3 [2014] No. 116 of the Safety Supervision Administration stated that starting from January 1, 2020, not only chemical plants and hazardous chemical storage facilities involving 'two key points and one major' are required At the same time, it is required that the safety instrumented systems of other new chemical plants and hazardous chemical storage facilities should implement the requirements of relevant standards for functional safety, and design safety instrumented systems that meet the requirements. How to apply the safety relay to correctly implement the standard requirements and design a safety instrumented system that meets the requirements is imminent. According to the different functions of the safety instrumented system, the safety instrumented system (hereinafter referred to as the SIS system) can be divided into safety interlocking system, emergency stop system, fire and gas detection system, etc. SIS system can realize one or more safety instrumented functions (hereinafter referred to as SIF). At the same time, it is stipulated that the use of experience requires corresponding evidence to prove that these components and subsystems are suitable for the SIS system. The applicability of the evidence should include: 1. The manufacturer has a complete quality control and management system; 2. The component or subsystem has appropriate 3. Good performance in similar process operation state and independent environment; The above content needs to be sorted and summarized into documents for safekeeping. In principle, the empirically used assessment is not applicable to SIL3 systems. However, according to the status quo investigation, ordinary relays have not undergone a systematic safety assessment, so it is impossible to summarize the λ class and related parameters used to calculate the safety integrity level; ordinary relay manufacturers have not tracked their products in specific process operating states and conditions. Performance in an independent environment does not provide valid evidence that its products are performing well. However, safety relay products with SIL certification are quite different. This type of product: 1. From the beginning of design, fail-safe guidance is considered; 2. Enhanced testing standards higher than ordinary products are adopted; 3. Corresponding documents are provided to clarify complete installation, operation, and maintenance instructions and requirements; 4. Manufacturers have regular quality control and management system audits; 5. Document management covers the entire life cycle of the product. Therefore, under the background of the continuous occurrence of chemical accidents and the strict inspection of Document No. 116, the use of safety relays with SIL certification is more in line with normative requirements and reduces the risk of use.