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Colorado CDL Hazmat study materials
Colorado CDL Hazmat study resources

Colorado CDL Hazmat: Loading and unloading hazardous materials

Colorado CDL Hazmat · Work through your exam, one topic at a time.

All guide sections

Loading and unloading hazardous materials

This domain tests the physical handling of hazmat packages: preparing the vehicle, supervising the load, preventing ignition, protecting packages, and keeping incompatible materials apart. The core highway rules are in 49 CFR 177.834 and related sections.

Before loading

  • Set the parking brake, place the transmission in gear or park, and chock the wheels before loading or unloading.
  • Turn off the engine during loading or unloading of flammable materials unless necessary for operation.
  • No smoking or open flame within 25 feet of a vehicle containing flammable or combustible materials.
  • Inspect packages for leaks, damage, and labels; reject damaged packages.
  • Keep unauthorized people away and stay in attendance.

Compatibility and handling

  • Do not load cyanides or cyanide mixtures with acids; a leak can create deadly hydrogen cyanide gas (177.848(d)).
  • Keep oxidizers away from flammable liquids and combustible materials; the segregation table may require separation or prohibit mixed loading.
  • Load packages so they cannot shift, fall, or be crushed. Do not drop, drag, or roll drums carelessly.
  • For Class 1 explosives, follow the specific loading rules and never load detonators with other explosives unless authorized.

Worked example

A driver loads 500 pounds of UN1789, Hydrochloric acid, Class 8, PG II, and 1,200 pounds of UN1263, Paint, Class 3, PG II. The acid and paint are not a prohibited cyanide/acid pair, but the driver still checks the segregation table. Placarding: Class 8 and Class 3 are both Table 2. The aggregate gross weight of Table 2 materials is 1,700 pounds, over 1,001 pounds, so the vehicle needs CORROSIVE and FLAMMABLE placards on both sides and both ends. If the acid were only 500 pounds by itself, no CORROSIVE placard would be required. The driver must set the brake, chock wheels, and secure both loads against movement.

Traps

Leaving the vehicle unattended during loading, failing to chock wheels, and smoking near the vehicle are frequent errors. Do not assume small quantity means no placard for Table 1 materials. Do not load incompatible materials just because they are in separate packages. Do not overlook damaged packages or missing labels.