功能安全在所有过程工厂中都起着关键作用，化工行业在对人和环境的保护方面有着特别高的要求。如何设计一个符合标准的安全回路至关重要。要实现这一点，最佳的方法是采用谨慎的设计原则和可用于计算的可靠 SIL 数据。我们很乐意在风险评估过程中为您提供指导，并通过我们久经考验的元件和冗余系统来支持您的安全方案实施。
SIL 分类基于两个国际标准：IEC 61508 和 IEC 61511。
IEC 61508（“电气/电子/可编程电子安全系统的功能安全”）为基本标准。它描述了如何评估风险以及要设计合适的安全功能所需的措施。因此，它还包括对安全回路各个元件的要求。这些元件包括传感器（如压力传感器、温度传感器和液位计）或电子信号值比较和输出单元以及自动过程阀。
IEC 61511（“过程行业安全仪表系统的功能安全”）专门适用于过程自动化。它主要针对要求较低的低需求应用场合，即为标准实践。其中，IEC 61511 包含传感器和驱动器的选择标准，例如以操作可靠性为考量点。
如果您是工厂的安装人员或操作员，且您的工厂存在危及员工、居民或环境安全的可能性，那么您必须尽可能降低风险。IEC 61508 和 61511 标准为此规定了四个关键步骤：
1. 风险定义和评估：首先要确定传感器、控制器和驱动器等所有元件在工厂整个使用寿命中出现故障的概率。
2. 措施的定义和实施：定义并实施适当的措施来最小化剩余风险。
3. 使用合适的设备：工厂能成功进行 SIL 回路测试的先决条件是元件和元件组均适合各自的等级，必要时需经过认证。
4. 重复测试：操作员以规定的时间间隔监控安全功能的合规性。
我的工厂存在哪些潜在危险？化工行业中过程工厂的每个工程师都必须思考这个问题。一张风险图可以帮助您解答这个问题，它依据 IEC 61508 和 61511 标准结合四个定义的参数形成了一个决策树：
1. 损害的严重程度 (S)：可预见的后果有多严重？
2. 频率和接触时间 (F)：人员多久一次进入危险区？人员会在危险区停留多久？
3. 避免/缓释危险 (P)：我能预防或控制事件吗？
4. 发生的可能性 (W)：预计多久会出现一次事故？
实践经验表明，与安全相关的风险通常存在于细节中，并且通常只有在运行过程中才会暴露出来。系统分析已经可以在规划过程中识别出这些弱点。在 Festo，我们将根据您的需求提供符合规定的风险评估和功能安全解决方案，无论是完整的系统解决方案、精心规划的自动化技术还是单个元件。在此阶段，请随时咨询我们。
The systematic risk assessment of your system also reveals which factors drive up SIL requirements. Some of these are fixed, for example the production location. Others are factors that you can alter.
The first thing to look at is the probability of failure. You can significantly increase availability and reliability by focusing first and foremost on fault-tolerant components and redundant systems. Depending on the process, even solutions that enable individual components to be tested and replaced during operation can be useful.
The structural safety measures, for example pressure relief systems, always depend on the individual, specific production scenario. In general, you should consider how the processes can be made as low risk as possible. Your considerations should include structural measures and precautions, for example exhaust, overfill protection (for instance for acid tanks) or concrete casing (in the case of an explosion hazard).
Choosing devices and components with a proven performance which will guarantee a long and reliable service life for the system is also recommended. This includes temperature-resistant, acid-resistant and corrosion-protected materials. In addition, we have developed standard-compliant solutions for almost all individual processes which have proven their worth in the chemical and electrochemical industries, from valve terminals with integrated switch-off to the highly reliable 2oo3 control.
When determining the safety integrity level, the design of the SIL circuit in all individual parts must also reach this level. This means that, as an engineer, you need devices and components with a suitable SIL level. You need to be able to prove this using:
You can find all SIL certificates and manufacturer’s declarations for our products by entering the product type or part number in the search box at the top of the page and on the product detail page in the ‘Product Support' section.
The safety functions of your system must be checked at regular intervals. This is required by the statutory provisions of the German Ordinance on Industrial Health and Safety or accident prevention regulations. Under certain circumstances, local legal requirements also apply. The primary purpose of the recurring SIL tests is to prevent personal injury, damage to property and the environment, but it is also intended to ensure system reliability by preventing unplanned downtime and, last but not least, to ensure that the engineers have legal security. In the event of damage, these tests can prove that the malfunction was not caused by device or design defects.
The test intervals are set by the operator. The risk assessment is based on the safety characteristics of the individual SIL components, as well as other factors. From a design perspective, it can be very beneficial to have durable solutions that, if necessary, can be exchanged without interrupting operations. We would be happy to provide you with recommendations for our products.