How to Calculate Sil
The complexities of the digital economy have introduced new safety issues. Correspondingly, a new sub-field of industrial science has emerged around these new concerns. Novel safety methods are being developed that seek to reduce risk while increasing productivity and efficiency, utilizing electronic control technologoies that were previously unavailable. Safety Integrity Level, or SIL, establishes safety standards and measures the risk of a given safety procedure.
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Instructions
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Understand how risk is computed. In this context, the total risk equals the quantity of error multiplied by gravity of error.
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Determine Safety Instrumented Function, which is a component of SIL. An SIF's sensors, logic solver, and final elements work together within the context of SIL to detect risks and go through a process safely.
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Assign the target SIL. Various methodologies are employed for such assignment, but require the involvement of personnel with sufficient experience and expertise. Once the methodology is established, compute the "PFDavg," or "Probability of Failure on Demand," which refers to a safety process' failure to respond to an action taken when a risk is detected.
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Calculate SIL according to the following. A PFDavg between .001 and .0001 yields an SIL level of 4, or greater than 99.99% (potential for fatalities in the community). A PFDavg between .001 and .01 yields an SIL level of 3, or 99.9% (potential for multiple fatalities). A PDDavg between .01 and .1 yields an SIL level of 2, or 90% to 99% (potential for major injuries or one fatality).
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