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Safety Integrity Level (SIL): What Really Counts when It Comes to Assessments, Certificates and Manuals


The basis for the Safety Integrity Level (SIL) classification is the international standard IEC/EN 61508
The basis for the Safety Integrity Level (SIL) classification is the international standard IEC/EN 61508

Assessments, certificates, manuals: whenever safety facilities are planned, a set of documents is offered which varies between the different manufacturers of solutions and components. But what are the essential requirements that are relevant for your specific loop calculation? The international standard holds an answer to this question.

The basis for the Safety Integrity Level (SIL) classification is the international standard IEC/EN 61508. When a product is to be used in loops with a SIL level, the standard demands the fulfillment of prerequisites. In order to ensure that the respective products match a certain level of quality for use inside a SIL loop, the necessary processes need to be established within the manufacturing company.

This is generally reached by an assesment of the product and the processes, but not by only creating a certificate for a specific product. “Certification” means a formal confirmation of the assessment. This is neither more trustworthy than an assessment nor does it contain more information. Furthermore, the certification is not mandatory according to IEC/EN 61508.

Other important aspects:

  • An assessment can be carried out either as a self-assessment or by a third party. Note that an assessment by an external organization gives a customer the certainty of an independent and trustworthy assessment.
  • Several external organizations offer detailed, high quality assessments. Pepperl+Fuchs works with exida, TÜV Nord, TÜV Süd, TÜV Rheinland, and UL. By doing so, we ensure that we are absolutely independent from a specific external organization.

Functional Safety Management System is of vital importance

Functional Safety Management (FSM) is the set of methods that helps to prevent systematic errors in the design of products. The objectives comprise amongst other aspects of FSM planning, safety requirement management and hardware architecture design, as well as change and modification management.

The Functional Safety Management System of Pepperl+Fuchs has been successfully evaluated. exida confirmed that all relevant requirements of IEC 61508:2010 (SIL 3 capability) have been met. Most of the calculations are done by exida, which is more convincing for customers than making their own calculations.

Safety manuals are useful for your daily business

In order to implement a SIL rated safety loop, all parts of the loop need to be considered. This needs more than a SIL rating on a product. A safety manual is indispensable. It contains planning information such as details about the safety function and characteristic safety values, as well as safety recommendations and proof test procedures. Safety manuals are available for nearly all Pepperl+Fuchs SIL rated products.