SIL Module

For evaluating Safety Instrumented Systems
in compliance with IEC 61 508 & 61 511 standards

This new module in the GRIF workshop enables instrumentation technicians in charge of designing Safety Instrumented System (SIS) architectures to evaluate the Safety Integrity Level (SIL) in compliance with IEC 61508 & 61511 standards.

Modeling and main computations

The user defines the SIS architecture to be evaluated by interactively selecting the components of the Safety Instrumented Function (sensors, solver, actuators, KooN voting logic). S/he then characterizes each component of the safety loop specifying:

Reliability parameters (failure rate, diagnostic coverage, common modes, etc.)

Maintenance parameters (test frequency and duration, time to repair, etc.).

The SIL module involves transcribing the SIS architecture into fault trees to run the SIL computations for PFD Average (Probability of Failure on Demand) and PFH (Probability of Failure per Hour).

Specificities and strengths

SIL allows evaluation of the temporal indicators for each part (sensors, solver and actuators) of the Safety Instrumented Function (SIF). The calculations are run using the computation engine ALBIZIA and to assess the PFD or PFH.

The computation technique that is used produces accurate results, which are the instantaneous values, average values and maximum values over the period and the percentage of time spent in each SIL.

The SIFs created can be reused as safety barriers with an event tree

Use of computation data and results

  • Creation and management of generic component models (sensors, actuators)
  • Synthesis of input data in the form of tables that makes it easier to control the quality of an entry.
  • Possibility of automating calculations (batch run)
  • Results stored in the same document and exportable in different formats (csv, XML, Excel, etc.).
  • Visualization of results as curves, pie charts or histograms.
  • Vector printing of graphic elements and curves in PDF format which maintains optimum quality, even in A3 or A2 format.
  • Interaction with the operating system: option to copy/paste curves, systems or results to word processing software, spreadsheets or presentation tools.
  • Possible connection to MySQL, Access and Excel databases to recover the values to be used for the settings.

Last improvements

Excel Export of data and results,

  • Handling architectural constraints taking into account A/B type of components,
  • Adding pie-chart displaying each part contributions,
  • SIF can be duplicated in a document,
  • Test periods of every component can be modified at once,
  • Advanced partial stroking test configuration,
  • Spurious Trip computation,
  • Multi-Loop systems,
  • Handling of 16 sensor channels containing up to 24 components,
  • Handling of 24 actuator channels.

Example of a report

GRaphical Interface for reliability Forecasting