SIS Life Cycle

SIS Life Cycle – IEC 61511 The image shows the main phases of the SIS Life Cycle (Life Cycle of Safety Instrumented System), as well as the technical disciplines that lead each part. Analysis Phase In this phase, a rigorous analysis of the hazards of the process is carried out, comparing the probability that a …

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Key Parameters

Key Parameters As previously seen, to design the SIS (“Safety Instrumented System”) according to IEC 61511, several requirements must be met throughout its life cycle. Compliance with the SIL level assigned to each SIF (“Safety Instrumented Function”) is one of these requirements, and is performed by calculating the Average Probability of Failure on demand (PFDavg …

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Architectures

Most used Architectures In the following table we show the most used architectures when designing Safety Instrumented Functions (SIF). Logic Channels HFT (S) HFT (A) Objetives Used for 1oo1 1 0 0   sensor, actuator 1oo2 2 1 0 More Safety sensor, actuator 2oo2 2 0 1 More Availability sensor, actuator 2oo3 3 1 1 …

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Safety Standards

Safety Standards International Standards such as IEC 61508 and IEC 61511 are prepared by committees of experts from different fields and functions, and are not mandatory in the design or manufacturing, unless the end user or local legislation specifies their direct or indirect compliance. As an example, we will say that OSHA in USA and …

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Safety Instrumented Function

Safety Instrumented Function The Safety Instrumented Function, whose abbreviation is SIF, is a protection layer whose objective is to achieve or maintain a safe state of the process when a specific dangerous event occurs. The SIF is implemented in the SIS (Safety Instrumented System) which is normally composed of several Safety Functions. Each Safety Instrumented …

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