Definition:
The NFPA Hazard Ratings, commonly called the NFPA Fire Diamond, are a standardized system developed by the National Fire Protection Association (NFPA) to quickly communicate the health, flammability, reactivity, and special hazards of chemicals. The system is defined in NFPA 704 and is widely used in the United States for emergency response, firefighting, and facility hazard communication.
This system is not part of the functional safety standards, but it is often present in facility documentation and labeling. As such, it is useful for functional safety practitioners to understand its purpose.
The ranking involves four colors (red/blue/yellow/white) and five levels (0 through 4). See here for a breakdown of the colors and numbers.
Confusingly there is another similar chemical marking standard per the United Nations involving colors and triangles. The US DOT has adopted that (US/DOT) as have most countries. Just remember these are distinct rules from NFPA’s and can cause confusion.
Key Points:
- Hazard ratings per NFPA 704 primarily used in the United States
- The system provides a quick qualitative, high-level indication of hazards
- NFPA ratings are commonly found on chemical containers, storage areas, and facility drawings.
- In the US, generally enforced at local levels
Example:
A functional safety engineer performs a facility walkdown to prepare for a HAZOP. This engineer notes the fire diamond labels on chemical storage tanks indicating high flammability and reactivity. This information will feed into the HAZOP and LOPA.
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