Method Functional Safety was commissioned to conduct a Prior Use Assessment, according to IEC 61511, on a pilot burner flame detector, to determine if the component was suitable for use in a SIL 1 Safety Instrumented Function.
This assessment method is appropriate for end-users with installed (and legacy) systems, where evidence is available to prove a long term history of safety.
The Prior Use Assessment was based =Method's "Guideline for Prior Use Assessment", which is derived from relevant clauses of IEC 61511 Edition 2 and CDOIF's "Demonstrating prior use of elements of a safety instrumented function". The project involved interviewing engineers and obtaining and analysing over a decade of data in relation to performance and failure rates.
The report identified:
- that the historical performance indicated that the detector was capable of achieving compliance with IEC 61511 as a sub-system in a Safety Instrumented Function suitable for use at Safety Integrity Level 1
- the dangerous undetected failure rate for the device was low enough to allow for practical applications with other typical loop components
- a small number of observations and recommendations for procedural improvements for consideration by the client