NFPA’s Hazard Diamond

NFPA’s Hazard Diamond

Ron Parker STS, CHST

The National Fire Prevention Association (NFPA) developed a rating system to identify and rank the hazards of a material, their “hazard diamond”.  If you have previously worked in construction you’ve probably seen the colorful labels used to explain these hazards.  The NFPA’s hazard rating is diamond-shaped, made up of four smaller diamonds.  The NFPA symbol colors are blue, red, yellow and white.  Inside the colored smaller diamonds are numbers or symbols loaded with a wealth of knowledge.

nfpa hazard rating diamond, flammable, health, reactivity

Many people take one look at these labels and assume either it is too complicated for them to understand or they assume it is not important.  Both assumptions are wrong.  So what do these colors mean?  Let’s go through the meanings.

Symbol Meanings

The blue diamond, appearing on the left side of the label, conveys HEALTH HAZARD information for persons exposed to the material.  A number from 0 to 4 is written in the blue diamond.  Remember, the higher the number inside the diamond, the higher the hazard, as follows:

  • 0 – No hazard
  • 1 – Can cause irritation if not treated
  • 2 – Can cause injury.  Requires prompt treatment
  • 3 – Can cause serious injury despite medical treatment
  • 4 – Can cause death or major injury despite medical treatment

The red diamond, appearing at the top of the label, conveys FLAMMABILITY HAZARD information.  Again, the numbers 0 to 4 are used to rate the flammability hazard, as follows:

  • 0 – Will not burn
  • 1 – Ignites after considerable pre-heating
  • 2 – Ignites if moderately heated
  • 3 – Can be ignited at all normal temperatures
  • 4 – Very flammable gases or volatile flammable liquids

The yellow diamond, appearing at the right side of the label, conveys REACTIVITY ( or stability ) information.  Again the o to 4 numbers are used to rank reactivity hazards, as follows:

  • 0 – Normally stable.  Not reactive with water
  • 1 – Normally stable.  Unstable at high temperature and pressure.  Reacts with water
  • 2 – Normally unstable but will not detonate
  • 3 – Can detonate or explode, but requires strong initiating force or heating under confinement
  • 4 – Readily detonates or explodes

The white diamond, appearing at the bottom of the label, conveys SPECIAL HAZARD information.  This information is conveyed by use of symbols that represent the special hazard..  Two of the most common symbols are as follows:

  • W – Denotes the material is water reactive
  • OX – Denotes an oxidizing agent

What if a Material doesn’t fall into these Categories?

To determine the NFPA hazard rating for a material that does not have the label affixed on the hazard diamond, check the safety data sheet (formerly called material safety data sheet prior to the globally harmonized system being initiated).

Follow the warnings on the NFPA label or any label affixed to a container or material. Your safety and the safety of others working around you may depend on your knowledge of the NFPA hazard diamond label.

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