ISA TR84.00.02-Part 5-2002

Scope
1.1 ISA-TR84.00.02-2002 – Part 5 is informative and does not contain any mandatory requirements.
ISA-TR84.00.02-2002 – Part 5 is intended to be used only with a thorough understanding of ISATR84.00.02-
2002 – Part 1 which defines the overall scope.

1.2 ISA-TR84.00.02-2002 – Part 5 provides:

a) guidance in PFD analysis of logic solvers;
NOTE The term "logic solver" will be used throughout Part 5 to indicate the SIS logic solver. The logic solver technology may be any E/E/PES.
b) a method to determine the PFD of logic solvers;
c) failure rates and failure modes of logic solvers;
d) the impact of diagnostics, diagnostic coverage, covert faults, test intervals, common cause,
systematic failures, redundancy of logic solvers on the PFD of the logic solver; and
e) a method for the verification of PFD of logic solvers.

1.3 The procedures and examples outlined in ISA-TR84.00.02-2002 – Part 5 provide the engineer with
Markov modeling steps to be followed in determining a mathematical value for the PFD for typical
configurations of SIS logic solvers designed according to ANSI/ISA-84.01-1996.

1.4 Persons using ISA-TR84.00.02-2002 – Part 5 require a basic knowledge of Markov Analysis.

1.5 See ISA-TR84.00.02-2002 – Part 1 (Introduction), Part 2 (Simplified Equations), Part 3 (Fault Tree
Analysis), and Part 4 (Markov Analysis) if it is necessary to mathematically evaluate the SIL of the safety
instrumented function (SIF).