Functional Safety is governed by the IEC standards 61508 and 61511. Both standards are based on two fundamental concepts:

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• Safety Lifecycles

• Safety Integrity Levels (SIL)

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IEC61508 is more focused on manufacturers supplying safety equipment and instrumentation, IEC61511 is used by end users 

and projects to design, install and operate a SIS in the process industry.

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The safety lifecycle is a useful tool as represents all the stages from project conception,  risk assessment, specification, design, installation, commissioning, operation, maintenance, modification and de-commissioning.

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The safety lifecycle plan (SLP) is often embedded in a Functional Safety Management Plan (FSMP) which details and demonstrates compliance with the requirements of  IEC61511, identifying for each safety lifecycle phase:

 

• The purpose of the phases

• The responsible persons

• The deliverables

• The procedures used

• The techniques used