NFPA 704 Signage

NFPA 704 Standard System for the Identification of the Hazards of Materials for Emergency Response is intended to standardize basic hazardous material signage into a simple, easily understood, and recognizable system.  Commonly referred to as “NFPA 704 diamonds”, these signs communicate four hazard categories: health hazard (blue), flammability (red), instability (yellow), and special hazard (white).

The degree of hazard for health, flammability, and instability hazards is on a scale of 0 – 4, with 4 assigned to materials that are the most hazardous, and 0 to materials that are the least hazardous. Recognized special hazards are represented by unique symbols in the special hazard quadrant and address water reactive materials (“W” with a horizontal line through it), oxidizers (“OX”), and simple asphyxiant gases (“SA”).

There may also be additional jurisdiction requirements for NFPA 704, so it is important to work closely with the local Fire Department in developing a coordinated and consistent signage package.  As an example, for new and existing laboratories, the Boston Fire Prevention Code specifies a slightly modified version of the NFPA 704 Diamond including a “G” designation for categories where hazardous compressed gases are included.

Detailed information and definitions pertaining to each of the hazard rankings is provided in NFPA 704 including primarily NFPA 704 Table 5.2 (health hazards), Table 6.2 (flammability hazards), and Table 7.2 (instability hazards).  However, the simple numerical system on the NFPA 704 diamonds allows Emergency Responders to quickly identify the relative hazards of a given material or space, and the potential severity thereof, prior to entering the space.  Understanding the hazards present helps inform the safest course of action to take during an emergency event.

Required locations of signage can be found in 527 CMR 1.00 Massachusetts Comprehensive Fire Safety Code, NFPA 704, as well as based on local jurisdiction requirements.  Refer to the Code Red Consultants blog post, Laboratory Emergency Signage, for more information on the types of laboratory signage.

If there is more than one chemical present in a specific area, or the building, there are three methods to indicate the hazard ratings applicable to the space:

  • Composite Method – If multiple chemicals are present, a single sign can be used to represent the maximum rating contributed by a material in each category. If there are special hazards, those would be listed as well on the sign.
  • Individual Method – If only a few chemicals are present, signs for each of the individual chemicals can be posted with the chemical name written on the sign.
  • Composite-Individual Combined Method – This method would employ the composite method for some spaces and the individual method for other spaces, depending on the number of chemicals within each area.

If you have any questions or would like assistance with fire and life safety code compliance relative to laboratories, please do not hesitate to contact us at


Application of any information provided, for any use, is at the reader’s risk and without liability to Code Red Consultants. Code Red Consultants does not warrant the accuracy of any information contained in this blog as applicable codes and standards change over time. The application, enforcement and interpretation of codes and standards may vary between Authorities Having Jurisdiction and for this reason, registered design professionals should be consulted to determine the appropriate application of codes and standards to a specific scope of work.