The International Society of Automation (ISA) is the US-based professional society and standards body for the automation world. It started in 1945 as the Instrument Society of America and took its current name in 2008. For functional safety, what matters is its ISA 84 committee, which wrote the original US standard for safety instrumented systems (SIS) and now publishes IEC 61511 for US use as ANSI/ISA-61511. If you design SIS in the US, the standard on your desk is very likely an ISA document.
Key Points
- The ISA 84 committee produced ANSI/ISA-S84.01-1996, the first US process-sector SIS standard, years before the IEC version existed.
- The Occupational Safety and Health Administration (OSHA) recognized ISA 84 as good engineering practice in a 2000 letter, which is how a voluntary standard picked up real regulatory weight in the US.
- Other ISA documents come up constantly in SIS work, including the TR84 technical reports, ISA-18.2 for alarm management, and ISA/IEC 62443 for cybersecurity.
Example
A US client’s design basis says the SIS is designed “per ISA 84.” The ANSI/ISA-84.00.01 designation was retired in 2018, so in practice that means ANSI/ISA-61511, the word-for-word US adoption of the IEC standard. Same requirements, different cover.
See Also: NAMUR, OSHA, CDOIF, EI
Cited Sources