Working Group 7 of the ISA 84 committee continues to make progress on the 1st revision to the ISA-TR84.00.07-2010 Guidance on the Evaluation of Fire, Combustible Gas, and Toxic Gas System Effectiveness. The TR provides informative guidance on application of the principles of ANSI/ISA 84 to the subject of Fire & Gas system design. The key distinction is that 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 has decided to make a focused revision of the Technical Report by incorporating practical learnings by users who are conducting performance-based fire & gas system design. Some of the changes that you should expect 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 both 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 had several productive meetings, and has a goal of publishing the revised Technical Report in 2015. In order to learn more, note that ISA currently offers training on the subject in class EC56 Performance-Based Fire & Gas. Kenexis continues to expend significant effort in developing the guidance contained in the TR. If you have questions about performance-based fire & gas system design in general, please contact Kenexis.