Understanding the NFPA Diamond [NFPA 704 Standard]

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NFPA 704 container labels

The “NFPA 704: Standard System for the Identification of the Hazards of Materials for Emergency Response” is a standard developed and maintained by the
National Fire Protection Association. The standard is a system consisting of a label with a “fire diamond” or “safety square” that communicates with both workers and emergency personnel on the severity and other components on nearly any type of
chemical container. Paramedics, police officers, and firemen are usually trained to read and understand these labels quickly to execute the appropriate response in case of a spill. The diamond used in the NFPA standard is broken into four smaller
diamonds: a red diamond at the top, a white diamond at the bottom, a yellow diamond to the right, and a red diamond on the left. In each of these is a number or symbol indicating severity and characteristics of the material, or the precautions that
must be taken when handling the material.

In this post we will look at each diamond separately, and what it indicates. Ensure all hazardous chemicals in the workplace are labeled with the NFPA 704, and workers are trained on the meaning.

Left diamond (Blue)

Example of an NFPA diamond

This section of the diamond will indicate the health hazard that is posed from the chemical. There will be a number in the diamond with a corresponding level, ranging from zero to four.

  • Zero: Pose no health hazard and no precautions are necessary. Water, entirely safe chemicals, etcetera.
  • Level One: Used for any chemical that can only cause a mild reaction or injury due to exposure. The only PPE that is necessary for this level is a pair of safety
    gloves    .
  • Level Two: Chemicals that can cause temporary incapacitation or residual injury, but only in the circumstances of intense or prolonged exposure to the chemical.
  • Level Three: Used for chemicals that cause either a temporary or a moderate residual injury even in the event of a short exposure period.
  • Level Four: Chemicals in this level can cause serious injury or death with even brief or limited exposure. Extreme precaution is necessary. PPE should always be donned before working with this chemical or even the container
    that holds it; especially during an emergency such like a chemical spill.

Top diamond (Red)

This portion of the diamond depicts the level of the chemical’s or liquid’s flammability, also rated on a scale from zero to four.

  • Zero: Means the material in the diamond will not burn, even in typical fire conditions. Standard specifies this is for materials that will not burn while in the air and exposed to a temperature of 1500ºF for five minutes.
  • Level One: Used for any material or chemical that will burn (only when heated significantly) and has a flash point of 200ºF or higher.
  • Level Two: Meant to signify a material or chemical that will ignite when exposed to a “relatively” high temperature before it will ignite. Any material with a flash point between 100º and 200ºF is in this level.
  • Level Three: Use level three for any material or chemical that can ignite under most ambient temperatures and has a flash point below 73ºF and a boiling point of at least 100ºF.
  • Level Four: Items in this category will readily burn and have a flash point that is below normal room temperatures of 73ºF. These materials are the most dangerous (i.e. acetylene and propane)

Right diamond (Yellow)

This part of the diamond relates to the stability of the compound. In this case, stability refers to how easily the chemical can change or have a reaction (dangerous or not). Stability is, like the previous two diamonds, measured on a scale from zero
to four.

  • Zero: any chemical that is normally very stable and won’t react even under conditions such as fire or immersion in water.
  • Level One: For chemicals and materials that are mostly stable but can become unstable if temperatures or pressures are elevated significantly.
  • Level Two: materials and chemicals that can have a violent chemical change when exposed to elevated pressures or temperatures. And may have a serious reaction when exposed to water.
  • Level Three: Any chemical that can explode or detonate after an initiation or when exposed to heat. May also have a serious reaction to water or shock.
  • Level Four: These materials can react or detonate even at normal pressures and temperatures. Need to be kept in a very well-regulated environment at all times to ensure a dangerous reaction doesn’t occur.

Bottom diamond (White)

This section of the diamond indicates any special precautions that must be taken before handling the chemical. Unlike the other sections of the diamond, it does not use a numerical rating, but rather a symbol conveying the precaution. Examples of
this include the following three approved symbols:

  • W: Means the chemical being labeled has a strong reaction to water. Think of chemicals like potassium, magnesium, rubidium, and cesium that will explode burn, or give off dangerous gases when exposed to water. Important to
    warn emergency responders, namely firefighters to not use water around the chemical.
  • OX: Used for materials to indicate the chemical will have a violent reaction if exposed to oxygen. Think of things like ammonium nitrate, ketone peroxides, bromates, and chromates.
  • SA: The symbol for simple asphyxiate gases. These gases reduce or displace the oxygen in the area, creating an extreme danger for nearby people, which could result in suffocation/ these chemicals include nitrogen, helium

Additional Resources

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