Click here to read Part 1

Now that you know the step-by-step process of product certification, now let’s take a look at the actual information on the certificate. 

In the left panel (gray background) you will find an exida certification logo.  The logo contains information on the standard used for certification as well as the SIL Capabiliy.  The left panel also includes the FMEDA and assessment reports.  You want to reference these report numbers when requesting them from the manufacturer.  You can find the assessment report on the exida website however you’ll have to request the FMEDA report from the manufacturer.  I’ll get into why you need to request the FMEDA report when we turn to page 2 of the certificate. 

Certification is valid for three years, with the expiration date noted in the left panel.

The center panel contains the company name, address, as well as product information and a brief description of the safety function.

Also in the center panel is the SIL Capability Rating.  Just what does this mean?  SIL Capability is the measure of the manufacturer’s capability to eliminate systematic product failures.  This has to do with the manufacturer’s quality management system and development process.  Systematic failures are failures that can only be fixed by a change in design or procedure, as opposed to random failures, which cannot be fixed by a design or procedure change.  SIL 3 Capable means that the product can be used in a Safety Instrumented Function up to SIL 3.  One still has to determine the safety integrity of the SIF by calculating the PFDavg and Safe Failure Fraction for each element in the SIF. 
Signatures of the evaluating assessor and certifying assessor can be found at the bottom of the center panel.

Page 2 of the certificate includes the critical information, represented as a table containing the failure rates per IEC 61508 for the product.  The table is extracted from the FMEDA analysis. A word of caution here: these tables typically do not contain all the failure information need to determine the safety integrity of a SIF. You should request a copy of the FMEDA report from the manufacturer.  The report will give you information that may not be represented in the certificate including assumptions that were made during the analysis as well as the proof test coverage and description.  These are all needed to determine the safety integrity of a SIF. 

Tagged as:     steve close     sil capability     SIL     safety integrity level     safe failure fraction     product certification     PFDavg     iec 61508 certification     IEC 61508     fmeda  

Other Blog Posts By Steve Close