DOT Hazmat Placard Chart: Classes, Thresholds, and Placement

The DOT hazmat placard chart, set out in 49 CFR 172.504, pairs each of the nine hazard classes with a specific diamond-shaped sign and tells you when that sign has to go on the vehicle.¹ The chart is built on two tables. Table 1 materials require a placard in any quantity. Table 2 materials only require a placard once the aggregate gross weight of hazardous cargo on the vehicle reaches 454 kg (1,001 pounds) or more. Reading the chart correctly is a matter of knowing which table your material lands in, then matching its class or division to the right placard.

Table 1: Placard in Any Quantity

Table 1 covers the highest-risk categories. If even a single package is on board, the corresponding placard must be displayed before the vehicle moves. Check Table 1 first, because these rules override the weight thresholds that apply elsewhere.¹

Divisions 1.1, 1.2, and 1.3: explosives with mass explosion, projection, or predominant fire hazards
Division 2.3: poisonous gas (POISON GAS placard)
Division 4.3: dangerous-when-wet materials
Division 5.2: organic peroxides that are temperature-controlled (Type B, liquid or solid)
Division 6.1: materials poisonous by inhalation (POISON INHALATION HAZARD placard)
Class 7: radioactive materials shipped under a Yellow III label, under exclusive use, or as unpackaged low-specific-activity material

A Poison Inhalation Hazard notation on the shipping paper is the kind of flag that pulls a material into Table 1 no matter how little of it is loaded. Miss the notation, and the wrong placard goes on the truck.

Table 2: The 1,001-Pound Threshold

Table 2 covers the more commonly hauled hazardous materials. These require placarding only when the total weight of Table 2 hazardous materials on the vehicle reaches 1,001 pounds or more.

Divisions 1.4, 1.5, and 1.6: lower-risk explosives
Divisions 2.1 and 2.2: flammable and non-flammable gases
Class 3: flammable liquids, plus combustible liquids (separate placard)
Divisions 4.1 and 4.2: flammable solids and spontaneously combustible materials
Division 5.1: oxidizers
Division 5.2: organic peroxides not covered by Table 1
Division 6.1: poisonous materials other than inhalation hazards
Class 8: corrosives
Class 9: miscellaneous (not required for domestic transport)

When a vehicle carries materials from multiple Table 2 classes and none of them individually hits 1,001 pounds but the combined weight does, a single DANGEROUS placard can replace the individual class placards. That option is limited to non-bulk packages. And if 2,205 pounds (1,000 kg) or more of any single Table 2 category is loaded at one facility, the specific placard for that category must go on the vehicle, even if the rest of the load is riding under the DANGEROUS placard.¹

Residue in an empty non-bulk package of a Table 2 material does not count toward the 1,001-pound calculation.

The Nine Hazard Classes and Their Placards

Federal regulations sort every hazardous material into one of nine classes, and most classes are broken into divisions based on the specific danger involved. The class or division number appears at the bottom of the placard, and each class has its own standardized background color so responders can identify the general hazard from a distance.²

Class 1, Explosives: six divisions from 1.1 (mass explosion hazard) through 1.6 (extremely insensitive detonating substances). Division 1.4 covers explosives with no significant blast hazard.
Class 2, Gases: flammable gas (2.1), non-flammable compressed gas (2.2), and poisonous gas (2.3).
Class 3, Flammable and Combustible Liquids: gasoline, acetone, and similar liquids. Combustible liquids get their own placard.
Class 4, Flammable Solids: flammable solids (4.1), spontaneously combustible materials (4.2), and dangerous-when-wet materials (4.3).
Class 5, Oxidizers and Organic Peroxides: oxidizers (5.1) and organic peroxides (5.2).
Class 6, Toxic and Infectious Substances: poisonous materials (6.1) and infectious substances (6.2).
Class 7, Radioactive Materials: the RADIOACTIVE placard applies when the shipment meets specific label or shipment criteria.
Class 8, Corrosives: materials that cause visible destruction or irreversible damage to skin, or corrode steel or aluminum.
Class 9, Miscellaneous: a catch-all for hazardous materials that don’t fit Classes 1 through 8. Class 9 placards are not required for domestic transportation.

For certain shipments, the four-digit UN or NA identification number is displayed either directly across the center of the placard on a white background, or on a separate orange panel measuring 160 mm by 400 mm. An ID number may only appear on a placard that matches the material’s primary hazard class.³

Bulk Packaging Ignores the Weight Rule

The 1,001-pound threshold does not apply to bulk packaging. Any bulk package holding any quantity of hazardous material must be placarded on each side and each end, regardless of weight.¹ A half-empty cargo tank of a Table 2 flammable liquid still needs its FLAMMABLE placard. The DANGEROUS placard is not an option for bulk packaging either.

Exceptions That Change Which Placard You Use

A handful of exceptions come up regularly and can trim the number of placards required, or swap one for another.¹

When a vehicle carries explosives from more than one Class 1 division, only the placard for the lowest-numbered division needs to be displayed.
A FLAMMABLE placard can substitute for a COMBUSTIBLE placard on cargo tanks and portable tanks.
A vehicle carrying both flammable gas and non-flammable gas does not need the NON-FLAMMABLE GAS placard if the FLAMMABLE GAS placard is already displayed.
Explosives classified as Division 1.4, Compatibility Group S that aren’t required to be labeled 1.4S don’t need the EXPLOSIVES 1.4 placard.

The rules run in the other direction too. Displaying a placard when no hazardous material is on board, or displaying one that doesn’t match the actual hazard, is itself a violation. You also cannot affix any sign or device to a vehicle that could be confused with a DOT placard by its color, shape, or design.⁴ Drivers need to remove or cover placards after offloading hazardous cargo.

Where the Placards Go on the Vehicle

Placards must appear on all four sides of the vehicle: front, rear, and both sides, each visible from the direction it faces. On a truck-tractor combination, the front placard can go on the tractor rather than the cargo body.⁵ Each placard must be:

Securely attached to the vehicle or placed in a placard holder
At least 3 inches away from any advertising, logo, or other marking that could reduce its visibility
Clear of equipment such as ladders, pipes, doors, and tarpaulins
Positioned to avoid road spray from wheels, so far as practicable
Oriented with text reading horizontally from left to right
Set against a contrasting background, or bordered with a contrasting outline

The carrier has to keep every placard legible for the whole trip. Dirt, snow, road grime, or weather damage that substantially reduces color, format, or visibility puts the vehicle out of compliance, and inspectors at weigh stations check placard condition as a matter of course.

Penalties for Getting It Wrong

A knowing violation of federal hazardous materials transportation law carries a civil penalty of up to $102,348 per violation, with each day of a continuing violation counted separately. If a violation results in death, serious injury, or substantial destruction of property, the maximum rises to $238,809.⁶

A vehicle can also be placed out of service at a roadside inspection for placarding deficiencies. Missing placards for multiple divisions within the same hazard class is specifically flagged as an out-of-service condition. The vehicle stays parked until the violation is corrected, which means delayed deliveries and possible contract penalties on top of the regulatory fine.