SIL Safety Lifecycle & Management 4

Question 1

What is the primary distinction between a Safety Instrumented System (SIS) and a Basic Process Control System (BPCS)?

Accepted Answer

The SIS is a dedicated independent protective layer while BPCS maintains normal operations

Answer

The SIS is an independent protection layer designed to bring the process to a safe state, separate from the BPCS that handles normal control.

Question 2

In the context of functional safety management, what is a 'Safety Case'?

Accepted Answer

A structured argument supported by evidence that a system is safe for its intended operation

Answer

A Safety Case is a documented argument with supporting evidence demonstrating that a system meets its safety requirements for a defined operational context.

Question 3

What is 'beta factor' in the context of SIL calculations for redundant systems?

Accepted Answer

A measure of the fraction of failures that are due to common cause

Answer

The beta factor represents the proportion of failures in a redundant system that are caused by a common shared cause, reducing the benefit of redundancy.

Question 4

Which IEC 61511 requirement addresses the need to assess the suitability of existing (prior use) equipment for use in a SIS?

Accepted Answer

Prior use justification

Answer

IEC 61511 allows equipment without third-party SIL certification if prior use evidence demonstrates adequate field performance in similar applications.

Question 5

What does 'spurious trip rate' measure in a Safety Instrumented System?

Accepted Answer

How often the SIS activates when there is no actual process hazard

Answer

Spurious trip rate measures how often the SIS unnecessarily brings the process to a safe state, which can impact process availability and safety culture.

(SIL) Safety Integrity Level Certified Practice Test

(SIL) Safety Integrity Level Certified Practice Test

SIL Safety Lifecycle & Management 4