Development of SILSafeData DU Failure Rate Ranges | exida

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Development of SILSafeData DU Failure Rate Ranges is a website which provides credible failure rate ranges for dangerous undetected (DU) failures on generic devices. These devices include various sensors, logic solvers, and final elements by device category and types within a device category. For example, there are 10 separate types of level transmitters just in the category “level transmitter." There are 11 types of actuators in the device category “actuator.” There are 7 types of valves in the device category “valve.” Each of these valve types is further distinguished by the application. provides a way to check published failure rates for a specific device (manufacturer and model/series). For instance, if a user wants to perform safety calculations based on those published failure rates, before doing that the user can utilize to determine how realistic and credible those published failure rates are. This paper establishes the credibility of the DU failure rate ranges available at, by showing how those failure rate ranges were developed and how they are updated.

The paper is structured as follows. 

  • Overview of how DU failure rate ranges are calculated
  • Development of exida’s Component Reliability Database (CRD) for electrical/electronic and
  • mechanical components and how it is updated
  • FMEDA vs Calibrated FMEDA and when Calibrated FMEDAs are updated
  • How the CRD component data and Calibrated FMEDA predicted failure rates are validated
  • Statistical analysis of Calibrated FMEDA and how they are updated
  • What makes DU failure rate ranges credible
  • Summary and Conclusions

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