Functional Safety and SIL
Process and Machinery safety is often achieved by the use of Safety Instrumented Systems (SIS) to provide safe control functions for processes; this would include functions such as emergency shutdown, gas or fire detection, explosion mitigation and dangerous level/pressure control.
ExVeritas can help you determine the level of Safety Required (SIL) by analyzing frequencies, demand rates and consequences. We specialize in fire and explosion consequences, but can evaluate most hazards for most industry types. We can determine the nature of the hazards, the appropriate detection and mitigation measures, design or procure suitable systems and complete the safety case to the requirements of IEC 61508.
SIL and the Machinery Directive
BS EN 62061 is a sector standard to the seven-part standard IEC 61508, ‘ Functional safety of electrical/electronic/programmable electronic safety-related systems ‘, written specifically for the machinery sector.
It takes a quantitative risk-based approach similar to that found in IEC 61508, which requires rather more work than the qualitative ‘risk graph’ that was in the former Standard EN 954-1.
SIL and the ATEX Directive
BS EN 50495:2010 ‘Safety devices required for the safe functioning of equipment with respect to explosion risks’ covers safety related devices such as purge controllers and Ex e motor circuit breakers. It is applied by Notified Bodies under the ATEX Directive. Under DSEAR (ATEX 137) safety devices or systems that have been added to prevent the formation of an explosive atmosphere (ventilation, dilution, gas monitoring) or mitigation of an explosion will probably require a functional safety assessment.
Click here to read our paper on SIL and Safety Systems: An Introduction to SIL
The assignment of Target SILs must involve people with relevant expertise and experience in the systems, processes and hazards under consideration. IEC 61508 specifically states,
“All persons involved in any overall safety life cycle activity, including management activities, should have the appropriate training, technical knowledge, experience and qualifications relevant to the specific duties they have to perform.”
ExVeritas have the technical knowledge and experience to support or lead your project.
ExVeritas use industry standard software and failure rate databases for failure rate determination and fault tree analysis.
Software used by ExVeritas:
- FARADIP 3
FREE On-Line SIL Calculator
Our free on line calculator will help determine your target SIL in line with the requirements of IEC 61508. Simply click here to go to our SIL Calculator.