UNE-EN 61511-2:2006 Functional safety - Safety instrumented systems for the process industry sector -- Part 2: Guidelines for the application of IEC 61511-1
2017UNE-EN 61511-2:2017 Functional safety - Safety instrumented systems for the process industry sector - Part 2: Guidelines for the application of IEC 61511-1 (Endorsed by Asociación Española de Normalización in June of 2017.)
2006UNE-EN 61511-2:2006 Functional safety - Safety instrumented systems for the process industry sector -- Part 2: Guidelines for the application of IEC 61511-1