With the goal of publishing this year, Working Group 7 of the ISA 84 committee continues to make progress on the first revision to the ISA-TR84.00.07-2010 Guidance on the Evaluation of Fire, Combustible Gas, and Toxic Gas System Effectiveness.
The technical report (TR) provides guidance on application of the principles of ANSI/ISA 84 to the subject of Fire & Gas system design.
The key distinction is a Fire & Gas System typically benefits by mitigating the severity of a hazard instead of preventing the hazard, as is the case in Safety Instrumented System (SIS) design.
The working group decided to make a focused revision of the TR by incorporating practical learned applications from users who are conducting performance-based fire & gas system design. Some of the changes coming in the revised document include:
• Changes to Fire & Gas Safety Lifecycle to address full range of engineering activities, not just hazard and risk analysis
• Illustration of fully quantitative and semi-quantitative techniques for selecting performance targets
• Information on how the User’s chosen mitigation philosophy will impact the fire & gas system design, with practical guidance on hazards that form the basis of FGS design
• Guidance on Conceptual FGS design and the impact on detector coverage
• Considerations on Effectiveness of FGS Mitigation actions and how they impact performance
• Additional worked examples, including toxic gas example and use of semi-quantitative hazard analysis to define FGS performance targets
In addition, the committee will describe how a user can invoke and apply the requirements of the ANSI/ISA 84 standard for Safety Instrumented Systems, if it is determined there is a need based on user-selected risk reduction requirements of SIL 1 (risk reduction in excess of 10) or higher.
The committee has a goal of publishing the revised Technical Report in 2015.