Hazard Classes

• The shipper is responsible for identifying the hazardous material. The carrier uses the shipper's information to place the appropriate placard on the transport vehicle or container. The U.S. DOT requires the carrier to mount a placard that communicates the hazard classification. The U.S. DOT recognizes the following hazardous response classes: 1 - explosives, 2 - gases, 3 - flammable and combustible liquids, 4 - flammable solids, such as spontaneously combustible materials and dangerous when wet materials, 5 - oxidizers and organic peroxides, 6 - toxic material and infectious substances, 7 - radioactive materials, 8 - corrosive materials and 9 - miscellaneous dangerous goods.
  
  

Divisions and Identification Numbers

• Some hazard classes include subdivisions. Subdivisions allow the grouping of hazardous materials within the same class. Gases are Hazard Class 2. The division identifier for a flammable gas is 2.1, and the division identifier for a poisonous gas is 2.3. If the shipper identifies a hazardous material that fits into one of the subdivisions, the carrier will use a placard with the appropriate division identifier. For some hazardous materials, the U.S. DOT regulations require the posting of a four-digit identification number. The identification number is displayed on the hazardous material placard or on an accompanying orange sign with black lettering.
  
  

Placard Requirements

• Hazardous material placards are square signs that are printed and positioned to stand on-point. The 49 CFR 172 Subpart F contains the U.S. DOT placard regulations. Sections 172.521 through 172.560 provide detailed guidelines for each hazard class or division. The detailed guidelines contain instructions on the proper placement, background color, text and coding. Secton 172.504(e) contains two placarding tables that list the hazard classes according to general handling instructions. Table 1 hazards require a placard when transporting any amount of the listed materials. The materials that are listed in Table 2 require a placard if the amount exceeds 1,001 lbs.
  
  

Placarding Exceptions

• Section 172.504 includes exceptions to the general requirements. Section 172.504(c) does not require a highway or rail carrier to placard a non-bulk Table 2 hazardous material shipment if the weight is less than 1001 lbs. Section 172.504(d) allows the carrier to disregard placarding requirements for containers that may only contain the residue of a non-bulk Table 2 hazardous material. Section 172.504(f) allows the carrier to use the lowest Class 1 division number placard when transporting multiple divisions of an explosive material.