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Concepts that apply to prevention safety layers such as safety instrumented systems do not necessarily apply to mitigation safety layers such as fire & gas systems. Unlike safety instrumented system hardware, claiming any integrity level for fire & gas hardware alone is misleading. That information alone does not allow one to determine whether that the overall system will meet the desired level of risk reduction.

Budhi, Swastioko (Singgar Mulia)

PakWaskita,

Terima kasih atas infonya. Benar-benar menarik sekali tulisan yang dibuat oleh Paul Gruhn ini, mengkaitkan kemampuan Detektor F&G dengan SIL rating. Susah juga yah mendapatkan SIL 2 untuk F&G System kalau begitu. Saya forward dokumen kiriman anda ke milis.

Concepts that apply to prevention safety layers such as safety instrumented systems do not necessarily apply to mitigation safety layers such as fire & gas systems. Unlike safety instrumented system hardware, claiming any integrity level for fire & gas hardware alone is misleading. That information alone does not allow one to determine whether that the overall system will meet the desired level of risk reduction.

A chain is only as strong as its weakest link. Focusing on the performance of the fire & gas hardware alone and not accounting for the detector coverage and mitigation effectiveness is just as misleading as focusing only on the logic solver in a safety instrumented system. The impact of field devices (sensors and final elements) typically has a dominating impact on safety instrumented system performance. Similarly, detector coverage and mitigation effectiveness have a dominating impact on fire & gas system performance and may prevent most systems from ever meeting SIL 1 performance levels.

However, it is possible to apply performance based concepts to fire and gas systems. It is possible to assign risk reduction targets for fire and gas systems and apply quantitative techniques in system verification. Work is proceeding within the ISA 84 committee on ways to account for detector coverage, mitigation effectiveness and other factors, thus allowing a quantitative, performance based approach to fire and gas system design. Once the detector coverage and mitigation effectiveness limitations are better understood and addressed, then focusing on the SIL rating of the hardware will be more meaningful.

Attachment : SIL Rating For F&G System Hardware.pdf

Pembahasan selengkapnya dari Rangkuman Diskusi Mailing List Migas Indonesia pembahasan bulan Maret 2007

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