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 analysing 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.