White Papers

Criteria for the Application of IEC 61508:2010 Route 2H

This paper explains how exida applies the requirements of IEC61508:2010 Route 2H to its process of certifying devices for use in safety applications. 

Rather than having specific designs and a long list of specific rules that become obsolete, the IEC 61508 standard allows any safety instrumented function (SIF) design to be implemented. The standard allows the design to use old products or new technology. The standard allows innovation and good engineering. However, any SIF design must be verified with documented performance metrics which must match risk reduction requirements in the form of safety integrity levels (SIL). In order to verify that a design meets the needed risk reduction, the designer must check three performance criteria.

This paper is devoted to one of those performance criteria, viz., minimal architectural constraints which, per IEC 61508, may be met in one of two ways, i.e., via Route 1H or Route 2H. Furthermore, this paper deals exclusively with Route 2H because, for practical purposes, Route 2H produces a realistic SIL level for a given design and does not impose artificial redundancy.

This paper

  • Describes the requirements of IEC 61508:2010 Route 2H,
  • Discusses how exida’s component failure rate and failure modes databases meet or exceed the data requirements of IEC 61508:2010 Route 2H,
  • Delineates the criteria exida uses in applying Route 2H to certify devices in a given environment,
  • Discusses the common situation of needing to certify a device, with a significant operational history that was previously certified in one environment, which will now be deployed in a new environment, and delineates the criteria exida uses to accomplish this certification. 

Download PDF