Safety Integrity Level (SIL) Assessments

Helping business confirm their SIL ratings

Safety Integrity Level (SIL) Assessments

Industry performs Safety Integrity Level (SIL) assessments on systems designed to prevent catastrophic events. Examples being aircraft control systems, train signals, automatic car braking systems etc. 

The SIL ratings range from the lowest being SIL 1 to the highest being SIL 4. A range of factors influence the overall SIL rating of a whole system including the SIL rating of the individual components such as valves, measurement devices and controllers.  Additionally the layers of protection also influence the SIL rating.

Only a Functional Safety Engineer should assess SIL ratings as they apply the requirements of IEC 61508 for Safety Instrumented Systems.

Do I Need a SIL Rated System?

Some people think that having a SIL rated system will ensure no injuries in a workplace.  Whilst SIL rated systems have a very low risk profile, for the majority of workplace processes, they are not necessary.

However, some individual systems in an overall process may benefit from a high SIL rating. For example an industry may use a large boiler to produce heated water or steam for the factory.  Due to the potential catastrophic effect of a boiler explosion, having a SIL rated boiler would be beneficial. However, the whole factory process does not necessarily need to be SIL rated.

Safety Resources Australia can assist your business to determine if you need a complete SIL rated system or just parts of it.

Component SIL Ratings 

When designing a process or control system that claims a SIL rating, the designer must use individual components that are also SIL rated. Furthermore the maximum SIL rating that an overall system can achieve is the lowest level SIL rating of any used components.

For example if a process system uses a control valve that has a SIL rating of 3 then the maximum SIL rating that the system can get is also 3, no matter how many layers of protection are present.

SIL 4 is highest rating

Unfortunately there are people in this world who will try to convince you that they have a better system than what anyone else has.  They may even try to claim that they have a product or system that has a SIL rating greater than 4.

If they claim this then they have no idea what they are talking about. This is due to the very high integrity rating that a SIL 4 system achieves.  As such, SIL 5 and above is almost technically impossible.  Like all things in the world beware of scammers.

Qualified Functional Safety Engineer

Only qualified Functional Safety Engineers should perform SIL level assessments. This is because they have undergone formal training and assessment in Safety Instrumented Systems to IEC 61508.

Safety Resources Australia has qualified Functional Safety Engineers who can assess process systems. We can assess any equipment or system that claims to operate at a certain SIL level.

Let us help you

Are you confused about Safety Integrity Level (SIL) Assessments?  If so, don’t panic, Safety Resources Australia can help.

That help, maybe to assess if you really need a SIL rated system. Alternatively to conduct an independent assessment on a system that claims to have a SIL rating.

Please contact us today and discuss you needs with us, as we are here to help.

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