This document was last updated on 04/11/2013 using NFPA 704 2012 Edition

Why should the NFPA 704 Rating System be used?

Understanding the NFPA 704 sign?

U-channel Post Mounting

NFPA 704 Sign Configuration

NFPA 704 Signs

Hazard Category: HEALTH (Blue)

The degree of hazard shall indicate to fire-fighting and emergency response personnel one of the following:

  1. They can work safely in the area only with specialized protective equipment.
  2. They can work safely in the area with suitable respiratory protective equipment.
  3. They can work safely in the area with ordinary clothing.

Degrees of Hazard. The degrees of health hazard shall be ranked according to the probable severity of the effects of exposure to emergency response personnel.

Hazard Category: FLAMMABILITY (Red)

Because many materials will burn under one set of conditions but will not burn under others, the form or condition of the material shall be considered, along with its inherent properties

Degrees of Hazard: The degrees of flammability hazard shall be ranked according to the susceptibility of materials to burning.

Hazard Category: INSTABILITY (Yellow)

The degree of instability hazard shall indicate to firefighting and emergency personnel whether the area shall be evacuated, whether a fire shall be fought from a protected location, whether caution shall be used in approaching a spill or fire to apply extinguishing agents, or whether a fire can be fought using normal procedures.

Degrees of Hazard: The degrees of hazard shall be ranked according to ease, rate, and quantity of energy release of the material in pure or commercial form.

Hazard Category: SPECIAL HAZARDS (White)

Only W with a line thru (water reactivity), OX (oxidizers) and SA (simple asphyxiant gases) are officially part of the NFPA 704 2012 standard.

8.2 Symbols. Special hazards shall be represented by a spatial arrangement denoted by symbols always at the six o'clock position.

8.2.1* Materials that react violently or explosively with water (i.e., water reactivity rating 2 or 3) shall be identified by the letter "W" with a horizontal line through the center ( W ).

8.2.2* Materials that possess oxidizing properties shall be identified by the letters "OX"

8.2.3* For chemicals requiring both "special hazard" symbols (i.e., W and OX), the W shall be displayed inside the special hazards quadrant, and the OX shall be displayed directly below or adjacent to the special hazards quadrant.

8.2.4* Materials that are simple asphyxiant gases shall be permitted to be identified with the letters "SA" and shall be limited to the following gases: nitrogen, helium, neon, argon, krypton, and xenon.

Official Recognized NFPA 704 Symbols

Optional Symbol

Non-Standard Symbols

User-defined symbols or markings below must be placed outside the NFPA "diamond". Appropriate training and communication addressing these other markings are essential. Other special hazard symbols (beyond OX and W ) should not be considered to be part of the NFPA 704 hazard rating system. In many cases, the hazards represented by these symbols are already considered in the health, flammability, or instability rating categories. In addition, because these additional symbols are not defined by the standard, emergency responders might not recognize their significance.