Placards
Class 1 Explosives Placards Explained (Divisions 1.1 to 1.6)
What the orange Class 1 explosives placard means, the six divisions from 1.1 to 1.6, compatibility groups, and which ones must be placarded in any amount.
Lawrence Arya··6 min
Placards
Class 2 Gas Placards Explained (Divisions 2.1, 2.2, 2.3)
Class 2 gases come in three colors for three divisions: red flammable gas, green non-flammable gas, and white toxic gas. Here is how to tell them apart.
Lawrence Arya··6 min
Placards
Class 3 Flammable Liquid Placards Explained (the Red Diamond)
The red Class 3 placard is the one drivers see most. Here is what it means, the common materials behind it, and the UN numbers worth recognizing.
Lawrence Arya··5 min
Placards
Class 4 Flammable Solids Placards Explained (4.1, 4.2, 4.3)
Class 4 has three very different divisions: flammable solids, spontaneously combustible materials, and dangerous-when-wet. Here is how to tell the placards apart.
Lawrence Arya··6 min
Placards
Class 5 Placards: Oxidizer vs Organic Peroxide (5.1, 5.2)
Class 5 has two yellow-leaning divisions that students mix up. Here is how oxidizers (5.1) and organic peroxides (5.2) differ and how to read each placard.
Lawrence Arya··6 min
Placards
Class 6 Placards Explained: Toxic and Infectious (6.1, 6.2)
Class 6 covers toxic substances and infectious substances. Here is what the skull-and-crossbones and biohazard placards mean, plus the inhalation-hazard rule.
Lawrence Arya··6 min
Placards
Class 7 Radioactive Placards Explained for CDL Students
What the yellow-over-white Class 7 radioactive placard means, the trefoil symbol, the label categories, and when the radioactive placard is required.
Lawrence Arya··5 min
Placards
Class 8 Corrosive Placards Explained for CDL Students
What the white-over-black Class 8 corrosive placard means, the dripping-liquid symbol, common examples, and how to avoid confusing it with toxic placards.
Lawrence Arya··5 min
Placards
Class 9 Miscellaneous Placards Explained (Lithium Batteries)
What the black-and-white striped Class 9 placard means, why lithium batteries and dry ice fall here, and the quirky domestic placarding rules.
Lawrence Arya··6 min
Placards
Compatibility Groups for Explosives Explained (the Letter Codes)
What the letter on a Class 1 explosives placard means, how compatibility groups decide what can travel together, and why 1.1D looks the way it does.
Lawrence Arya··5 min
Placards
Dangerous When Wet Placard Explained (Division 4.3)
What the blue dangerous-when-wet placard means, why it is the only blue diamond, which materials carry it, and why it must be placarded in any amount.
Lawrence Arya··5 min
Placards
Flammable vs Combustible Liquid: The Difference (Class 3)
Flammable and combustible liquids are both Class 3 but split on flash point. Here is the dividing line, the placards, and why diesel sits near the edge.
Lawrence Arya··5 min
Placards
Hazardous Materials Hazard Classes Explained (1 to 9)
A plain-English breakdown of the nine DOT hazard classes, what each one covers, the placard color and symbol that signal it, and how to memorize them.
Lawrence Arya··6 min
Placards
Hazmat Placard Symbols Explained (Every Diamond Icon)
A guide to every hazmat placard symbol: the flame, skull, trefoil, exploding bomb, dripping corrosive, and more, plus what each one tells you instantly.
Lawrence Arya··6 min
Study tips
How to Memorize the 9 Hazard Classes (Fast and for Good)
Mnemonics, chunking, and active-recall techniques to memorize the nine DOT hazard classes in order, plus how to anchor each one to its placard.
Lawrence Arya··5 min
Placards
Lithium Battery Transport Rules Explained (Class 9)
Why lithium batteries are regulated, the UN numbers and marking that identify them, and the special rules around fire risk and damaged batteries.
Lawrence Arya··5 min
Placards
Most Confused Hazmat Placards: Look-Alikes Decoded
The placard pairs that trip up CDL students most, from red gas versus red liquid to yellow oxidizer versus organic peroxide, and the one detail that tells each apart.
Lawrence Arya··6 min
Placards
US vs International Hazard Placards (UN, ADR, TDG, IMDG)
Why hazmat placards look almost the same worldwide, how the US system relates to the UN model, and the main differences across ADR, TDG, IMDG, and IATA.
Lawrence Arya··5 min
Placards
What Is a Hazardous Material? The DOT Definition
How the U.S. Department of Transportation defines a hazardous material, how materials are classified, who decides, and how it relates to dangerous goods.
Lawrence Arya··5 min
Placards
How to Read a Hazmat Placard: A Simple Step-by-Step Guide
A clear, step-by-step way to read any Hazmat placard: color, symbol, class number, and ID number, in that order.
Lawrence Arya··5 min
Placards
Hazmat Placard Colors Explained for CDL Students
What each Hazmat placard color signals, why color is the fastest first clue, and where color alone is not enough.
Lawrence Arya··6 min