Generalizing PFD formulas of IEC 61508 for KooN configurations

Jahanian, Hamid

doi:10.1016/j.isatra.2014.07.011

Cited by 29 publications

(13 citation statements)

References 8 publications

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“…The results obtained by means of the presented methods, Markov models and analytical equations are very similar. The greatest values of the PFD are obtained according to Equation (13). The PFD values according to generalized Equation (13) and values for the steady state according to the Markov model are nearly identical.…”

Section: Data and Calculation Resultsmentioning

confidence: 82%

“…The greatest values of the PFD are obtained according to Equation (13). The PFD values according to generalized Equation (13) and values for the steady state according to the Markov model are nearly identical. The average probability PFD Akoon values determined on the basis of unavailability changes (1-A(t)) in the proposed Markov model have slightly lower values.…”

Section: Data and Calculation Resultsmentioning

confidence: 82%

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Extending the Possibilities of Quantitative Determination of SIL - a Procedure Based on IEC 61508 and the Markov Model with Common Cause Failures

Pilch

2016

Qual. Reliab. Engng. Int.

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Generalized equations for calculating the probability of failure on demand (PFD) in accordance with the IEC 61508 standard and a model based on Markov processes, taking into account common cause failures, are proposed in this paper. The solutions presented in the standard and in many references concentrate on simple k‐out‐of‐n architectures. The equations proposed in the standard concern cases for n ≤ 3. In safety‐related systems applied in industry, architectures of a number of elements n larger than three often occur. For this reason, a generalized equation for calculating PFD was proposed. For cases presented in the standard, the proposed equation provides identical results. The presented simplified Markov model allows the determination of the system availability (A(t)) and unavailability (1–A(t)) as well as their values in the steady state (A and 1–A). This model can be an alternative method of PDF calculations for various k‐out‐of‐n architectures with self‐diagnostic elements. Calculations performed according to the proposed models provide very similar results. The developed models are suitable for practical implementations in calculations of the safety integrity level. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Data and Calculation Resultsmentioning

confidence: 82%

Section: Data and Calculation Resultsmentioning

confidence: 82%

Extending the Possibilities of Quantitative Determination of SIL - a Procedure Based on IEC 61508 and the Markov Model with Common Cause Failures

Pilch

2016

Qual. Reliab. Engng. Int.

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“…The calculation of target PFD avg is done in accordance with the IEC61508/61511 standards in the process industry (IEC, 2011c;Jahanian, 2015). Ideally, if all the requirements of these standards are fulfilled by the plant owner and system suppliers, one can assume that the actual probability of SIF failure on demand is not worse than the initial target PFD avg that is set for the SIF in the SIL determination process.…”

Section: Utility-based Sil Determinationmentioning

confidence: 99%

SIL determination as a utility-based decision process

Jahanian

Mahboob

2016

Process Safety and Environmental Protection

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“…In most literatures about SIL verification, redundant channels in a voting group are assumed to be statistically independent and identical [10][11][12][13]. However, in many practical applications, not all channels in a voting group can be treated as identical because they have different failure rates and diagnostic coverages, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…In this system degradation based method, CCF part of PFD G is quantified by using the multi-β factor model [22] introduced in PDS method [23] by SINTEF, new information are the quantification method for independent part of PFD G and two sets of general formulae to determine PFD G of any MooN(D) voting group with diverse redundancy, which are the new contributions of this paper. Some other generalized formulae for identical redundancy can be found in [2][3][4]13,24,25].…”

Section: Introductionmentioning

confidence: 99%