The National Fire Protection Association (NFPA) 704 diamond is a warning sign posted to indicate a potential hazard from chemicals. The familiar diamond shape is composed of four colored diamonds that refer to different types of hazards. Each colored diamond contains a number indicating the severity of the hazard.
Colors
According to the NFPA, the colors on the sign are blue, red, yellow and white. The blue diamond indicates health hazards, the red flammability, and the yellow indicates unstable chemicals.
Special Warning
The white diamond shape at the bottom of the sign is reserved for special warnings. The letters W or Ox will appear in this space to indicate that water should not be used to put out a fire or that the substance oxidizes.
Numbers
Each chemical substance the sign or label is posted on has a number from 0 to 4 in the three top diamond shapes. The number 0 indicates that the risk is minimal, while number 4 indicates a severe hazard level.
Tags: diamond shape, number indicates