Beckman L
HIMA-Americas, Inc., Houston, TX 77043, USA.
ISA Trans. 2000;39(3):357-61. doi: 10.1016/s0019-0578(00)00022-7.
The ANSI/ISA S84.01 standard was released in 1996. The companion technical report TR84.02 is in the process of being completed. The latter document is intended to provide the methodology to implement the safety performance requirements of the standard for the safety system. In this document, three techniques are presented; these being Simplified Equations, Fault Tree Analysis and Markov Modeling. Of the three, only the Simplified Equations approach would reasonably be utilized in the field by plant personnel. The Simplified Equations provided as part of TR84.02 comprehend common cause failures, systematic failures, and second failure prior to repair scenarios. They do not however comprehend the use of redundant field devices which are dissimilar, and as such have different failure rates. This situation is quite common in practice, and simple to manage using enhanced equations for the computation of PFDavg. A set of these equations for typical redundant architectures in the field, and several examples of their applications in safety loop analysis are derived and presented in this paper.
ANSI/ISA S84.01标准于1996年发布。配套技术报告TR84.02正在编制过程中。后一份文件旨在提供实施安全系统标准安全性能要求的方法。本文介绍了三种技术，即简化方程、故障树分析和马尔可夫建模。在这三种技术中，只有简化方程方法可能会被工厂人员在现场合理使用。作为TR84.02一部分提供的简化方程涵盖了共因故障、系统故障以及修复前的二次故障情况。然而，它们没有涵盖不同类型冗余现场设备的使用情况，因此这些设备具有不同的故障率。这种情况在实际中很常见，并且使用增强方程来计算PFDavg很容易管理。本文推导并给出了一组用于现场典型冗余架构的此类方程，以及它们在安全回路分析中的几个应用示例。
