What does the NFPA diamond mean?

The NFPA (National Fire Protection Association) diamond is meant to give general hazard information on the chemical that is being labeled.

There are 4 squared sections within the diamond, each with its own color: red, blue, yellow and white.

These colors correspond to specific hazards:

Red- Flammability Hazard

Blue- Health Hazard

Yellow- Instability Hazard

White- Special Hazard


The red, blue and yellow sections each have a corresponding number ranging from 0 to 4. The white section is left blank and used only to denote fire fighting measures and hazards.

0- Minimal Hazard

1- Slight Hazard

2- Moderate Hazard

3- Serious Hazard

4- Severe Hazard

For each different color, the numbers have varying meaning.

For example, the blue box represents health hazards, so a 4 would mean that the substance can be highly toxic, sometimes even lethal. But, a red box rated a 4 would mean the substance is highly flammable.

The white section is reserved for special notations mainly in the form of symbols. These special notations could be used to indicate the substance is corrosive (COR) or acidic (ACID) or not to be used with water ( W).

Let’s go over an example.

Oxygen gas is colorless and tasteless. It supports everyday life and although it supports the burning of combustible materials, pure Oxygen is nonflammable. Therefore, the NFPA diamond would be labeled as follows:

Red- 0, this is because Oxygen itself is not flammable

Blue- 3, this is because 100% Oxygen can cause serious or permanent injury. Specifically when inhaled, it can cause nausea, dizziness, irritation of the lungs and possible pneumonia.

Yellow- 0, this is because Oxygen is stable, even under fire conditions.

White- OX, this is because Oxygen possesses oxidizing properties especially when combined with other substances.


The NFPA diamond is meant to provide a simple, easily understood system for identifying specific hazards and their severity that might occur during an emergency response. They are typically labeled outside of buildings, on doors, on tanks and visible to emergency personnel in the event of a fire or spill.

The NFPA diamond is different from both the Department of Transportation (DOT) placard and the OSHA HazCom/GHS Standard. Each of the three hazard identification systems are to be used in a specific transport, storage, handling or information purpose.





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