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Endorsements - 9 min read

HazMat Endorsement Study Guide: Key Topics and Practice Tips

Everything you need to pass the HazMat knowledge test, from hazard classes to placarding rules and shipping paper requirements.

The Hazardous Materials (HazMat) endorsement is the most valuable addition to your CDL, but the knowledge test is one of the hardest. Here's what you need to study.

The 9 Hazard Classes

You must know all 9 DOT hazard classes and their divisions:

  1. Class 1 — Explosives: Divisions 1.1 (mass explosion), 1.2 (projection), 1.3 (fire), 1.4 (minor), 1.5 (insensitive), 1.6 (extremely insensitive)
  2. Class 2 — Gases: 2.1 (flammable), 2.2 (non-flammable/non-poisonous), 2.3 (poisonous/toxic)
  3. Class 3 — Flammable Liquids: Flash point below 140°F (gasoline, diesel, alcohol)
  4. Class 4 — Flammable Solids: 4.1 (flammable solid), 4.2 (spontaneously combustible), 4.3 (dangerous when wet)
  5. Class 5 — Oxidizers/Organic Peroxides: 5.1 (oxidizers), 5.2 (organic peroxides)
  6. Class 6 — Poisons/Infectious Substances: 6.1 (poison), 6.2 (infectious)
  7. Class 7 — Radioactive Materials
  8. Class 8 — Corrosives: Acids, batteries, caustic substances
  9. Class 9 — Miscellaneous: Hazardous substances that don't fit other classes

Placarding Rules

  • Placards are required on all four sides of the vehicle
  • Placards must be readable from 50 feet away
  • Any amount of Table 1 materials requires placarding (Classes 1.1-1.3, 2.3, 4.3, 5.2, 6.1, 7)
  • Table 2 materials require placarding at 1,001+ lbs aggregate weight
  • "DANGEROUS" placard can replace individual placards when carrying 1,001+ lbs of two or more Table 2 materials

Shipping Papers

Every HazMat shipment requires shipping papers with:

  • Proper shipping name (from 49 CFR HazMat table)
  • Hazard class and division number
  • UN/NA identification number
  • Packing group (I = great danger, II = medium, III = minor)
  • Total quantity and weight

Papers must be within reach while driving and on the driver's seat or door pocket when you leave the cab.

Loading and Unloading Rules

  • Never smoke within 25 feet of a HazMat vehicle
  • Set parking brake and chock wheels before loading/unloading
  • Never open packages of HazMat
  • Use the required emergency equipment (fire extinguisher, spill kit)
  • Some materials cannot be loaded together (check compatibility chart)

TSA Background Check

Unlike other endorsements, HazMat requires a Transportation Security Administration background check. You'll need to:

  • Complete an application at a TSA enrollment center
  • Provide fingerprints
  • Pay the fee (~$86)
  • Wait 30-60 days for approval

Apply for the TSA check early — you can't get your endorsement until it clears.