Abstract: ANSI/ISA-S84.01-1996 and IEC 61508 require the establishment of a safety integrity level for any safety instrumented system
or safety related system used to mitigate risk. Each stage of design, operation, maintenance, and testing is judged against this safety integrity level.
Quantitative techniques can be used to verify whether the safety integrity level is met. ISA-dTR84.0.02 is a technical report
under development by ISA, which discusses how to apply quantitative analysis techniques to safety instrumented systems. This paper discusses two of those techniques: (1) Simplified equations and (2) Fault tree analysis.