ISA TR84.00.02 PART 1
Safety Instrumented Functions (SIF) - Safety Integrity Level (SIL) Evaluation Techniques Part 1: Introduction
|Publication Date:||17 June 2002|
ISA-TR84.00.02-2002 - Part 1 is informative and does not contain any mandatory clauses. ISA-TR84.00.02-2002 is intended to be used only with a thorough understanding of ANSI/ISA-84.01-1996 (see Figure I.1). Prior to proceeding with use of ISA-TR84.00.02-2002 in a safety application, the Hazards and Risk Analysis must have been completed and the following information provided
a) It is determined that a SIS is required.
b) Each safety instrumented function to be carried out by the SIS(s) is defined.
c) The SIL for each safety instrumented function is defined.
ISA-TR84.00.02-2002 - Part 1 provides
a) guidance in Safety Integrity Level analysis;
b) methods to implement Safety Instrumented Functions (SIF) to achieve a specified SIL;
c) discussion of failure rates and failure modes (Annex D) of SIS and their components;
d) discussion of diagnostic coverage, covert faults, common cause, systematic failures, redundancy of SIF;
e) tool(s) for verification of SIL; and
f) discussion of the effect of functional test interval.
The objective of ISA-TR84.00.02-2002 - Part 1 is to introduce the reader to the performance based approach for evaluating the reliability of SIF and to present system reliability methodologies that can be used to evaluate the system performance parameters, namely, the probability that the SIF fails to respond to a demand and the probability that the SIF creates a nuisance trip. ISA-TR84.00.02-2002 - Part 1 serves as an introduction for all other parts.