NFPA diamond (National Fire Protection Association) is a standard system used for the identification of the hazards of materials for emergency response. It is used mainly by emergency personnel to quickly and easily identify the risks posed by hazardous materials. This also helped determine what, if any, special equipment should be used, procedures followed, or precautions taken during the initial stages of an emergency response.
The NFPA diamond provided a quick visual representation of the health hazard, flammability, reactivity, and special hazards that a chemical may pose during a fire.
The GHS (Global harmonized system) labeling is what is generally in use now.
NFPA diamond hazard rating system
This NFPA hazard rating system includes three color codes and five intensity levels.
Each color code (blue, red, and yellow) of the hazard rating system corresponds to a hazard: health, fire, and instability (denotation or chemical change).
Within each colored section, a numerical rating is given to the hazard. The ratings range from 0 to 4. A rating of 4 is the highest. If a 4 is in the red section of the hazard rating system, then the material should be considered highly flammable and therefore dangerous.
Within the NFPA hazard rating system, there is also a white colored section. This section is often left blank, but if a hazardous material presents a special hazard, such as a material that reacts explosively to water, then this section would be used.
There are only two symbols that are officially part of the NFPA hazard rating system for use in the special hazard section, with one additional symbol for simple asphyxiant gases that is recognized. Other additional symbols can be added by the end-user, and placed outside the NFPA diamond.