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SIL Determination & Verification: LOPA, PFDavg & CHAZOP
11 students
SIL Determination & Verification: LOPA, PFDavg & CHAZOP
IEC 61511 practitioner skills — LOPA, PFDavg by hand, CHAZOP, writing an SRS & functional safety assessment
Last updated 11/2026
English
What you'll learn
- Determine the required SIL with LOPA using initiating events, independent protection layers and the risk gap
- Conduct a CHAZOP alongside a process HAZOP to find control system failures a HAZOP misses
- Write a safety requirements specification that links the hazard study to the SIS design
- Select a voting architecture such as 1oo2 or 2oo3 to balance safety against spurious trips
- Apply hardware fault tolerance and safe failure fraction to check architectural constraints
- Calculate PFDavg by hand and verify a safety instrumented function against its target SIL
- Plan proof test intervals and procedures and control bypasses so the SIL is maintained
- Scope a functional safety assessment across the lifecycle phases
Explore related topics
Course content
6 sections • 13 lectures • 2h 33m total length
Requirements
- No prior functional safety experience is required, the lifecycle and terms are built up from the start
- Any engineering, process or technical background is enough
- Helpful but not essential: familiarity with P&IDs and control loops
- A calculator is all you need, no SIL verification software is used
Description
This course contains the use of artificial intelligence.
A safety instrumented system may sit unused for years and then has to work the first time it is asked.
Plenty of training describes the IEC 61511 lifecycle. Far less shows how to produce the deliverables inside it: the LOPA, the safety requirements specification and the PFDavg calculation an assessor will challenge.
This course works through those deliverables by hand, and includes CHAZOP, a study that is rarely taught anywhere.
In this course you will learn how to determine, specify and verify the SIL of a safety instrumented function.
WHAT YOU WILL LEARN TO DO
By the end of this course you will be able to:
Run a LOPA and set the target SIL from the risk gap
Take part in a HAZOP and lead a CHAZOP
Write a safety requirements specification
Choose a voting architecture and check hardware fault tolerance
Calculate PFDavg by hand and verify it against the target
Plan proof testing and manage bypasses
Scope a functional safety assessment
HOW THE COURSE IS TAUGHT
Every calculation worked by hand, so you know what verification software is doing
A full worked example takes one hazard from LOPA to a verified SIF
Follows the IEC 61511 lifecycle in order
Section quizzes with explained answers
WHAT IS COVERED
Process safety, the bow-tie and where the SIS sits
IEC 61508 and IEC 61511 compared
HAZOP for SIS and CHAZOP
LOPA and SIL determination
The safety requirements specification
SIS architecture, redundancy, hardware fault tolerance and safe failure fraction
SIL verification and PFDavg calculation
Sensor, logic solver and final element selection
Operation, proof testing and bypass management
Functional safety assessment and TÜV FS Eng exam preparation
70 PRACTICE QUESTIONS
Every section ends with a quiz built around realistic scenarios, so you test your understanding as you go and reinforce what you have learned. Each answer comes with a short explanation.
Enrol today and learn to produce SIS deliverables that stand up to assessment.
Who this course is for:
- C&I and control engineers who specify, design or verify safety instrumented systems
- Functional safety engineers running SIL determination and verification
- Process and mechanical engineers who sit in LOPA studies or review an SRS
- Commissioning and maintenance staff responsible for proof testing and bypasses
- System integrators designing SIS logic solvers and final elements
- Engineers preparing for a functional safety certification such as TÜV FS Eng