2.2 Placards, Labels, and GHS Pictograms
Key Takeaways
- DOT placards mark transport vehicles and bulk packagings (minimum 250 mm / 9.84 in on a side); DOT labels mark non-bulk packages (minimum 100 mm / 3.9 in) under 49 CFR 172.
- The four-digit identification number is displayed on the placard itself or on a rectangular orange panel next to the placard — not guessed from color.
- The current PHMSA marking, labeling, and placarding chart is the official visual; Chart 17 replaced Chart 16 and dropped the ORM-D marking.
- OSHA GHS pictograms (29 CFR 1910.1200) are workplace hazard-communication symbols on a white diamond with a red border; they overlap DOT hazards but are not the same system.
- The GHS environment pictogram (dead fish and tree) is not a DOT hazard class; DOT uses a separate marine-pollutant mark when that transport requirement applies.
Once you can name Classes 1–9, you still have to know where the communication is supposed to appear and which system you are looking at. A technician who treats a four-inch GHS pictogram on a drum as a highway placard, or who treats a red GHS flame as proof of DOT Class 3, will mis-size the problem. 49 CFR Part 172 governs DOT labels, markings, and placards. OSHA 29 CFR 1910.1200 (Hazard Communication, aligned to GHS) governs workplace container labels and SDS pictograms. They overlap. They are not interchangeable.
Vehicle placards versus package labels
DOT labels go on non-bulk packages — drums, boxes, cylinders, and similar packagings. Under 49 CFR 172.407, a standard hazard label is a square-on-point at least 100 mm (3.9 inches) on each side, with the class or division number in the lower corner.
DOT placards go on transport vehicles, bulk packagings, and freight containers. Under 49 CFR 172.519, a placard is a square-on-point at least 250 mm (9.84 inches) on each side (the common printed placard is about 273 mm / 10.8 inches). You placard all four sides of a motor vehicle when placarding is required. A label that is legal on a 55-gallon drum is not a legal vehicle placard, and a vehicle placard taped to a fiberboard box is not a package label.
Use this rule of thumb on scene: if it is on the truck, trailer, rail car, or cargo tank, you are looking for placards. If it is on the box, drum, or cylinder, you are looking for labels. Bulk cargo tanks and tank cars also carry identification numbers, specification plates, and often orange panels — those are markings, not a third hazard class.
Four-digit ID number on the placard or orange panel
The class diamond tells you the hazard class. The four-digit identification number tells you which material entry you are dealing with (UN1203 gasoline versus some other Class 3). Display methods under 49 CFR 172.332 / 172.336:
- White numerals on the placard itself, or
- Black numerals on a rectangular orange panel mounted adjacent to the placard.
Either display is an identification number, not a second class. Technicians who ignore the orange panel because it is not a colored diamond miss the fastest path into the ERG yellow pages (next chapter). If you see both a Class 3 red diamond and 1203 on the orange panel, you have class and identity for gasoline — still confirm with shipping papers when you can, because the panel can be wrong, missing, or leftover from a prior load.
When placards are required (Table 1 versus Table 2)
49 CFR 172.504 splits placarding into two tables. You do not need to recite every row, but you must know the logic:
- Table 1 — specified severe hazards require a placard for any quantity. Core Table 1 examples technicians are tested on include explosives 1.1, 1.2, and 1.3; 2.3 poison gas; 4.3 dangerous when wet; specified 5.2 organic peroxides; 6.1 PG I inhalation hazard; and Class 7 when Yellow-III labels are required.
- Table 2 — remaining classes (including 1.4, 2.1, 2.2, Class 3, 4.1, 4.2, 5.1, 6.1 other than PG I inhalation, Class 8, Class 9 in specified cases) generally require placards when the aggregate gross weight on the vehicle reaches 454 kg (1,001 pounds).
A DANGEROUS mixed-load placard may be used in limited Table 2 mixed-load situations. It does not hide a Table 1 material. Infectious substances, limited quantities, and certain combustible liquids in non-bulk packages have placarding exceptions — absence of a placard is not proof of a non-hazardous load.
The current PHMSA chart (the official visual)
PHMSA publishes a full-color marking, labeling, and placarding chart that reproduces the diamonds, panels, and marks specified in 49 CFR 172. Older training packets still say DOT Chart 16. PHMSA later issued Chart 17, including removal of the ORM-D marking after the 2020 phase-out. Do not memorize a chart edition number as if it were a regulation. Use the current PHMSA DOT chart as the visual, and use 49 CFR 172 as the rule. If your department still has a Chart 16 poster on the wall, check it against current PHMSA art before you teach from the ORM-D square.
GHS pictograms versus DOT diamonds
OSHA Hazard Communication (1910.1200) requires GHS pictograms on shipped-container labels and they appear in SDS Section 2. A GHS pictogram is a black symbol on a white background inside a red square-on-point. That red border is not a DOT Class 3 red diamond.
Overlap is real and is the exam trap:
| Hazard idea | DOT transport diamond | GHS workplace pictogram |
|---|---|---|
| Flame / flammable | Colored background by class (often solid red for 2.1 and 3) | Flame on white with red border |
| Oxidizer | Class 5.1 yellow, flame over circle | Flame over circle on white, red border |
| Explosion | Class 1 orange, bursting ball | Exploding bomb on white, red border |
| Gas under pressure | Class 2 cylinder on green (2.2) or other Class 2 colors | Gas cylinder on white, red border |
| Corrosive | Class 8 white over black, test tubes on hand and metal | Corrosion pictogram on white, red border |
| Acute toxicity | 2.3 or 6.1 white, skull | Skull and crossbones on white, red border |
| Chronic health | Not a DOT class diamond | Health-hazard silhouette (chest burst) |
| Irritant / warning | Not a DOT class diamond | Exclamation mark |
| Environment | Not a DOT class; separate marine-pollutant mark | Dead fish and tree (GHS; not an OSHA-mandatory pictogram in the U.S.) |
Environment is GHS, not a DOT class. DOT Class 9 can include environmentally hazardous substances, and DOT/IMDG require a marine pollutant mark (also a dead fish and tree) when that transport criterion is met. That mark is a marking, not Class 10, and not an NFPA 704 special hazard.
A single drum in commerce may legally wear both: DOT labels for the shipment and a GHS/OSHA product label for the workplace. Read each system with its own rules. GHS does not assign UN numbers, packing groups, or vehicle placards.
Other marks technicians must not skip
These are markings (and a few labels) that ride along with the class diamond:
- Marine pollutant — fish-and-tree mark for materials that meet the marine-pollutant definition, especially in water mode and when required by 49 CFR 172.322.
- Inhalation hazard — additional INHALATION HAZARD marking for specified 2.3 and 6.1 PIH materials (49 CFR 172.313). The skull diamond alone may not communicate the inhalation route.
- Fumigant — warning marking on a transport unit that has been fumigated (49 CFR 173.9). The cargo may not be a DOT-placarded load, but the atmosphere in the box can still kill you.
- Elevated temperature — triangle with a thermometer, or the word HOT, for materials offered at elevated temperature (49 CFR 172.325). Molten product is a burn and a container-failure problem even when the class looks familiar.
- Cargo aircraft only — CARGO AIRCRAFT ONLY label: the package is forbidden on passenger aircraft. That is a mode restriction, not a ninth-and-a-half hazard class.
Limited-quantity marks, orientation arrows, and fumigant / HOT marks are easy to dismiss as shipping clutter. They are identification. A HOT mark on a Class 9 molten-sulfur load changes your approach just as surely as a 2.3 skull.
Comparison table: placard vs label vs GHS
| Feature | DOT placard | DOT label | GHS pictogram |
|---|---|---|---|
| Typical use | Vehicle, rail car, bulk packaging | Non-bulk package | Workplace container and SDS |
| Size | ≥ 250 mm (9.84 in) | ≥ 100 mm (3.9 in) | No DOT size rule; red-bordered square-on-point |
| Background | Class color (orange, red, green, yellow, white, blue, striped) | Same class art as the placard, smaller | White with red border |
| Number in corner | Class or division number | Class or division number | No DOT class number |
| ID number | May include the 4-digit ID, or sit next to an orange panel | Package also marked with UN/NA number | Does not replace the UN/NA mark |
| Legal basis | 49 CFR 172 Subpart F | 49 CFR 172 Subpart E | OSHA 1910.1200 |
| Environment symbol | Not a class placard; marine-pollutant mark is separate | Same | GHS environment pictogram (not OSHA-mandatory) |
On a technician exam, if the stem shows a white diamond with a red border and a black flame, it is a GHS flame, not a DOT Class 3 placard. If the stem shows a 10-inch solid red diamond on a trailer with 1203 in white, it is a DOT placard plus identification number.
Put the systems in order on scene: container and vehicle type, placards and labels, four-digit number, then shipping papers and SDS. GHS pictograms help when you are in a fixed facility or looking at a product drum, but they do not drive ERG yellow-page lookup.
Which statement correctly distinguishes DOT placards from DOT labels?
A workplace drum shows a white diamond with a red border and a black dead-fish-and-tree symbol. What is that mark?
On a placarded cargo tank, where may the four-digit identification number be displayed?