Using agreed tolerable risk criteria and a SIL determination procedure, eFunctionalSafety can lead your SIL study team sessions with one of our highly experienced and senior facilitators. We can support selection by Rish Graph or Risk Matrix, Safety Layer Matrix or Layer of Protection Analysis - LoPA
A solid safety requirements specification is the backbone of any safety system. We have proven templates and checklists which have been tested on multiple industry projects. Our service can be as little as checking your requirements are complete, or providing support to author the full requirements specification.
eFunctionalSafety has access to the know-how, software tools and equipment failure rate data that can model the hardware performance of even the most complex Safety Instrumented Function (SIF) designs. We also check for equipment systematic capability, hardware fault tolerance and calculate the PFDavg or PFH according to application requirements.
We provided SIL verification support for an entire package of turbomachinery safety functions for a well-known gas turbine supplier.
We reviewed the SIL target assessment, supported the authoring of the system and functional safety requirements specification, and provided the probability of failure calculations for every function within the gas turbine (GT).
Our comprehensive report has enabled the GT supplier to demonstrate that the required SIL targets could be met by the hardware design.
A SIl study can mean multiple things, depending on who is asking the question. For any project or system involving SIL-rated functions, the study process must begin with SIL target assessment, also known as a SIL analysis or SIL determination. This procedure sets a target level of safety integrity for one or more safety functions.
A multi-discipline team uses one of a number of techniques to set the SIL target to match the required risk reduction or safety performance of the safety functions. Techniques include risk graphs, risk matrices and layers of protection analysis.
In some companies, the "SIL study" term may also include the requirement for verifying the target SIL can be met. In other companies this is a separate activity, and is also known as SIL Verification.
A SIL target is the main measure of integrity used for defining the required safety performance of safety functions. In hardware terms, one performance requirement is defined as a probabilty of failure on demand (PFD / PFD average) when the frequency of demands on the safety function is lower than once per year. If the frequency of demand is higher, an assessment of probability of failure per hour (PFH) is required.
SIl targets range from SIL 1 (lowest integrity) to SIL 4 (the highest integrity).
A SIL study is generally started after hazard identification has been completed. There needs to be a clear understanding of the potential conseuences and frequencies of events before SIL targets can be estimated.
For a SIL verification to be completed, there needs to be a clear safety requirements specification and ultimately the equipment that will be used in the end system must be selected.
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