how to read hazmat placards

If you’ve been on the road long enough, you are sure to have noticed the diamond-shaped labels on the back and sides of semi-trucks and trailers. These helpful signs are called hazmat placards and they are used to communicate what kind of hazardous materials trucks are hauling. The US Department of Transportation requires vehicles hauling over 1,000 pounds of hazmat to display them on all sides of their vehicle letting everyone know, including first responders, what’s inside so they know how to handle it safely.

The signs not only tell if something is flammable, explosive, radioactive, poisonous, biohazardous, or corrosive but also give details about what specific chemicals make up the material, and the dangers it poses. The color of the sign is the most noticeable detail from far away and communicates the basics about what kind of threat the cargo on board can pose. Here are some of the placard colors and the characteristics they convey:

• Red - flammable
• Green - non-flammable
• Yellow - oxidizer
• Blue - dangerous when wet
• White - inhalation hazard and/or poison
• Black and white - corrosive
• Red and white - flammable solid or spontaneously combustible
• White and yellow - radioactive
• Orange - explosive

Hazard class
As you get closer to the hazmat placards you can make out symbols (that are self-explanatory) and class numbers in the bottom corner of the diamond. Each class number indicates a specific characteristic of the material and can go further with subclasses (e.g. 1.1, 1.2, etc.) to explain how that material might react.

• Class 1 - Explosives
• Class 2 - Gases (flammable, nonflammable, oxygen, inhalation hazard, poison)
• Class 3 - Liquids (flammable and combustible liquids)
• Class 4 - Flammable solids, spontaneously combustible, or dangerous when wet
• Class 5 - Oxidizers and organic peroxides
• Class 6 - Poison/toxic solids and liquids, or infectious materials
• Class 7 - Radioactive materials
• Class 8 - Corrosives (acids and bases)
• Class 9 – Miscellaneous

UN/NA Numbers
Knowing what type of material you are dealing with and how it might react is vital in hazmat transportation, however, hazmat placards have an additional detail that specifies even more about what’s inside called the United Nations ID (UN ID) number. This four-digit number, ranging from 0004-3534, is another way to communicate hazard and will often specify what exact chemical is being hauled. To give some examples UN 1202 means diesel fuel, UN 1072 means compressed oxygen, and UN 3066 indicates paint or paint related material. Unlike color, symbols and class numbers, you might need a reference to know what the number means but they can be very useful to understand how to handle it properly or to contain the substance if something were to go wrong.
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Some hazmat doesn’t have a UN ID number and is assigned North American (NA) numbers by the US DOT. UN/NA numbers can be found in the middle of a hazmat placard.

Before booking a shipment
At Dillon Logistics, we believe all accidents and injuries are preventable. Our commitment is a ZERO accident rate. If you are booking a hazmat shipment with Dillon, it’s important to let us know what exactly is being hauled, any special requirements it may have in being moved, assembled or disassembled, and its hazard class (as detailed above). The safety of drivers, first responders, terminal staff, and even the general public depends on properly labeling hazmat.

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