Functional Safety Training - Should you do it?

By: Nathan Chapman, Electrical, Control and Instrumentation @ Richard Alan Engineering.

As an EC&I design engineer I work with different areas of design and regulatory standards day to day, one of those areas is functional safety – which is a hugely interesting subject area.

I was recently successful in becoming a certified Functional Safety Engineer through TUV SUD in the field of process industry – Safety Instrumented Systems.

I would 100% recommend the course to other engineers who want to further their knowledge in the area of functional safety in the process sector, below are a few snippets of information about Risk and standards.

Risk & Functional Safety

In a perfect world there would be no risk involved in our process or machine operation etc., but the reality is in nearly all cases, there will be an element of risk involved in parts of a process or a machines operation, it’s up to us as engineers to manage and control those risk(s) to achieve, as a minimum, a level that is tolerable.

What is Tolerable Risk?

A risk level that society (a person(s) company or organisation) is willing to accept and work with. The purpose of a Safety Instrument System, containing Safety Instrumented Function(s), is to help a process reduce risk to this level – as a minimum. If possible, it should always be our aim to reduce risk to a residual or negligible level. You could think and consider tolerable risk as the middle ground, between Intolerable and Residual.

What is a qualitative approach to Risk?

It’s descriptive and focuses on subject expertise and the experience of people in industry/workplace, a HAZOP (Hazard and Operability Study) is a qualitative risk assessment method, so is a Risk Matrix. The aim of these assessments is to assess the likelihood of occurrence & severity of hazards, so we can define our safety requirements for the system or project.

What is a quantitative approach to Risk?

It’s numerical and statistic based, fault and event trees are examples of quantitative risk assessments.

Functional Safety Standards

Unfortunately, it’s fairly easy to be bamboozled by BS EN, IEC standard numbers and descriptions when it comes to functional safety, I think a fairly good Analogy here is to remember that in the UK, BS EN 61508 - Functional safety of electrical/electronic/programmable electronic safety related systems is the king, and the king has a couple of well known princes (or princesses!) BS EN 61511: process industry and BS EN 62061: machinery.

So in a nutshell, BS EN 61508 is the main ‘go to’ reference standard that sets out good practices for all sectors of industry and both BS EN 61511 & BS EN 62061 take those practices and elaborate on them to be industry specific.