The following methodology conforms to ISA-TR84.00.07 Guidance on the Evaluation of Fire, Flammable Gas and Toxic Gas System Effectiveness and can be applied to sites adhering to Shell DEP 32.30.20.11-Gen.
The steps are:
- Identify Fire & Gas Hazards for Major Equipment.
- Hazard Grading.
- Performance Requirements.
- Development of Design-Basis Hazards
- Detector Coverage Mapping and Optimization.
A principal objective of F&G system design is to reliably detect, alarm, and, if necessary, take automatic action to mitigate a fire hazard, flammable gas hazard, or toxic hazard. The ability of system to perform its intended safety actions in a demand condition is dependent on number of factors associated with design, installation, site-specific operating conditions, and maintenance. Most failures of F&G systems to function properly under a demand condition are related to inadequate coverage, i.e. failure to detect a defined type and magnitude of hazard due to inappropriate sensor type, inadequate number, and/or incorrect location.