What are the process plant requirements for Emerson Process Management devices used in SIS loops when IEC 61508 is applied?
When a plant implements IEC 61511 they will be required to use specific methodologies to document that the loop design meets the intended SIL level 1-4. These methodologies are quantitative and require specific data on each device per IEC 61508. The specific data required to determine Device SIL 1, 2, and 3 are documented in IEC61508 as follows: • Safe Failure Fraction (SFF) (Diagnostic Coverage Factors) • Safe Detected • Safe Undetected • Dangerous Detected • Dangerous Undetected • Mean time to repair • Frequency of Functional Check Requirements Rosemount publishes the required IEC 61508 data for their devices so that customers can calculate the SIS instrument loop value.
