Hazmat placards
A hazmat placard is the diamond on the side of a tank car or freight car. It is hazard communication for that trip. It is not a reporting mark, and it is not the tank's specification stencil. The reporting mark says who the equipment is registered to. The placard says what kind of hazard is in the shipment.
Read the diamond in two places. The number in the bottom corner is the hazard class, from 1 through 9. A four-digit number in the middle of the diamond, or on a separate orange panel, is the UN or NA identification number for the material. Class 3 with 1203 is a different statement from class 3 with 1993. One names gasoline. The other names a flammable liquid that the shipper has to describe more fully on the papers.
Color is a memory aid and it weathers. The class number and the identification number are what you write down. A faded red diamond with no readable number is a poor identification. Get a cleaner angle before you decide you know the car.
This guide is for recognition. It is not an emergency response manual, and it is not permission to approach a car. If something is leaking, smoking, or involved in a wreck, leave the area and call the local emergency number. Responders use the Emergency Response Guidebook and the shipping papers. A railfan website is not a substitute for either.
Hazard classes
- CLASS 1Class 1 — explosivesClass 1 placards mark explosives. The division number matters more than the word alone.
- CLASS 2Class 2 — gasesClass 2 covers gases: flammable, non-flammable, and toxic. The division is the real label.
- CLASS 3Class 3 — flammable liquidsClass 3 is flammable liquids such as gasoline, crude oil, and diesel fuel.
- CLASS 4Class 4 — flammable solidsClass 4 covers flammable solids, spontaneous combustibles, and substances dangerous when wet.
- CLASS 5Class 5 — oxidizers and organic peroxidesClass 5.1 is oxidizers. Class 5.2 is organic peroxides. They feed a fire rather than behaving like ordinary freight.
- CLASS 6Class 6 — toxic and infectious substancesClass 6.1 is toxic substances. Class 6.2 is infectious substances.
- CLASS 7Class 7 — radioactiveClass 7 marks radioactive material. The placard is uncommon and unmistakable when you can read it.
- CLASS 8Class 8 — corrosivesClass 8 is corrosive materials, including common acid and caustic tank-car loads.
- CLASS 9Class 9 — miscellaneousClass 9 is the miscellaneous hazard class, used when the risk doesn't fit classes 1 through 8.
Numbers you will actually see
A short set of UN numbers that show up on North American tank cars. Each page is an identification note, not a response guide.
- UN 1005anhydrous ammoniaUN 1005 is anhydrous ammonia, a toxic gas, typically placarded class 2.3.
- UN 1017chlorineUN 1017 is chlorine, a toxic gas, placarded class 2.3.
- UN 1075petroleum gases, liquefiedUN 1075 is liquefied petroleum gas, placarded as a class 2.1 flammable gas.
- UN 1202diesel fuelUN 1202 is gas oil, diesel fuel, or heating oil, placarded class 3.
- UN 1203gasolineUN 1203 is gasoline, including motor spirit, placarded class 3.
- UN 1267petroleum crude oilUN 1267 is petroleum crude oil, placarded class 3.
- UN 1789hydrochloric acidUN 1789 is hydrochloric acid, placarded class 8.
- UN 1824sodium hydroxide solutionUN 1824 is sodium hydroxide solution, a class 8 corrosive, and it is a base rather than an acid.
- UN 1830sulfuric acidUN 1830 is sulfuric acid with more than 51 percent acid, placarded class 8.
- UN 1993flammable liquid, n.o.s.UN 1993 is a flammable liquid not otherwise specified. The placard names the hazard, not the exact chemical.