Prior Use & Proven In Use

IEC 61511 requires devices that make up a Safety Instrumented Function (SIF) to be either, assessed against the requirements of IEC 61508 or against the requirements of “Prior-Use”. Many facilities utilise equipment that is used in both Safety and Control functions and the operator has gained experience and confidence in these devices. In these circumstances, Prior Use may be considered a more suitable (and logical) alternative to replacing these devices for IEC 61508 assessed items of which the operator has no experience.


ES are a globally renowned providers of Functional Safety services having over 50 years of combined experience. ES can carry out Safety Instrumented System (SIS) conceptual designs, selecting appropriate equipment based on integrity and functional requirements. For more information, or to discuss your Functional Safety needs, please contact us using the form below or email [email protected].