Functional Safety (SIS / SIL) / Safety Instrumented Systems

Functional Safety / Safety Instrumented Systems (SIS) / SIL Assessments

The safety life cycle of safety instrumented systems  (more commonly known as Trips and Alarms) commences with the specification of the performance requirements (Safety Integrity Level) using SIL assessments, Risk Graphs, Fault Tree Analysis, Hazard Analysis and/or Layer of Protection Analysis (LOPA) techniques. The life cycle continues with reliability & availability analysis to demonstrate the required safety integrity levels, as defined in BS EN 61511, can be met over the life cycle of the SIS.

Engenda Group Ltd (t/a Clark Eriksson)  have TUV (Rheinland) Functional Safety Program Certified - TUV Functional Safety Engineers

We can provide a variety of expertise in the field of reliability analysis to ensure that the hardware safety integrity requirements, as defined in BS EN 61508 / 61511, are achieved for any Safety Instrumented System. The analysis includes:

  • Safety Requirements Specifications
  • SIL Assessments
  • Failure Modes, Effects and Criticality Analysis
  • Common Cause Failure Analysis
  • Reliability Block Diagrams
  • Fault Tree and Event Tree Analysis
  • Hardware Fault Tolerance Analysis

The full range of services are available from the initial planning of the functional safety through to the testing and commissioning and Clark Eriksson can even develop periodic test procedures for clients to maintain the Safety Instrumented Systems (SISs) and, if requested, can carry out these tests on that basis.

These services include:
• The chairing of HAZOPs and HAZIDs meetings by an experienced process engineer
• Undertake hazard and risk assessments to determine target Safety Integrity Levels (SILs) for Safety Instrumented Functions (SIFs)
• E&I engineers will specify the trips required to carry out the safety functions
• Specify and design, in-house, the logic solver, be it relay based or Safety PLC
• Factory test the software
• Installation and commissioning of the (SISs)
• Confirm that the target SIL operates as specified
• Verification that the design and installation of the SIS Meets the target SIL

If you require to speak to us about anything to do with Functional Safety/Alarm & Trips then please contact:

Scott McMartin on 01324 611294 or email me


Stuart Williamson on 01324 611294 or email me