You've probably seen the National Fire Protection Agency's (NFPA) Fire Diamond, even if you didn't know its name. It's a multi-dimensional code that offers people a quick label or diagram of the potential hazards and dangers of a substance. It's used to tag, label, mark, identify, and notify workers about the severity of a substance.

Give the role it plays, it's important to understand the code and how to read it properly. Here is an overview of the four quadrants of the NFPA's Fire Diamond.

Red Quadrant

The information in the red quadrant indicates the substance's level of flammability. It is scored on a scale of 0 - 4, with 0 representing the least concern and four representing an extremely flammable substance. Water, for example, scores a 0 while gasoline scores a 3. Other considerations within this section include flash point values, which indicates at what temperature a substance can spontaneously ignite.

Blue Quadrant

This color indicates the level of health risks, also scored on a scale of 0 - 4. Ether falls in the middle, at a 2, because it can cause temporary incapacitation and residual injury. Sarin gas and carbon monoxide, on the other hand, are both on the extreme end of the scale, both scoring a 4. Exposure to these substances can cause death or serious injury within a very short period of time (learn more about Carbon Monoxide: The Silent Killer).

Yellow Quadrant

The diamond's yellow quadrant indicates the level of chemical reactivity, scored again on a scale of 0 - 4. Substances, such as helium, that do not react with water score a zero. A more reactive element like potassium, which undergoes a violent reaction when mixed with water, scores a 2. Nitro glycerin, which is capable of explosions at a normal temperature and pressure, is an example of a substance that scores a 4.

White Quadrant

This color is reserved for special codes that may be particular to a specific substance. These codes range between different jurisdictions, but, generally, may be classified by the following acronyms:

COR, ACID, ALK: Strong Acid or Base

These tags are usually supplemented by a larger identifying tag like a radioactive or biohazard sign, and is often clearly marked.


It's never a good idea to assume that a material will be clearly marked, so it's important to become familiar with the NFPA's Fire Diamond and each of its quadrants. Know what the dangerous goods are in your workplace and make sure employees have the right qualifications before handling them. Crack the code of the Fire Diamond's four colors and you will always see green when it comes to safety.