What is SIL?

Industrial safety in pre-digital eras centered mainly around safe work practices, hazardous materials control, and the protective “armoring” of personnel and equipment. Today, safety penetrates far deeper into more complex manufacturing infrastructures, extending its protective influence all the way to a company’s bottom line. Contemporary safety systems reduce risk with operational advancements that frequently improve reliability, productivity and profitability as well. Nothing is more important than safety to the process control industries.

High temperature and pressure, flammable and toxic materials are just some of the issues faced on a daily basis. Reliability is a key component of safety; the more reliable the device, the safer the critical process. After years of work by the ISA SP84 committee, IEC 61508 and IEC 61511 have recently come together to yield a safety standard that the world is embracing. IEC 61511 is particularly important as it is written specifically for the Process Industries.

This standard quantifies safety issues as never before. Although the safety issues addressed are critical to users with installations like Emergency Shutdown Systems (ESD), the reliability defined in this specification is being used by all users to separate great products from good ones. SIL (Safety Integrity Level) and SFF (Safe Failure Fraction) are two of the key values that customers can use as an objective comparison of instrument reliability from various suppliers.


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