NFPA 704

NFPA 704: Standard System for the Identification of the Hazards of Materials for Emergency Response, or NFPA 704 for short is the fire diamond things. They are typically placed on a door or a container and it gives warnings about what is inside of the container or behind the door. There are three colors and they each have a number 0 through 4 (0 being not present and 4 being extremely). Red indicates flammability/combustibility (A material with a 4 will likely combust under normal atmospheric temperatures/pressures) (Propane has a flammability rating of 4) . Blue indicates health hazards (a material with a 4 can cause death or serious harm upon exposure). (Hydrogen cyanide has a health rating of 4). Yellow indicates reactivity/stability (a material with a 4 can detonate under normal temperatures) (nitroglycerin has a reactivity rating of 4) The white section doesn't have a number and instead serves as a place for special warnings. Examples of which include but are not limited to: OX: indicates the substance is an oxidizer SA: indicates the substance is a asphyxiant gas BIO: indicates the substance carries a biological hazard (used for things such as viruses) RA/RAD: indicates the substance is radioactive ACID/ALK: indicates the substance is Acid or Alkaline respectively