Loading, Unloading, and Segregation of Hazardous Materials
What this domain tests
This domain tests loading, unloading, and segregation: keeping incompatible materials apart, securing packages, and controlling the scene while cargo is handled. The key federal rule is the segregation table in 49 CFR 177.848, which uses X, O, and star entries.
Core rules
- X means the materials may not be loaded together in the same vehicle or transport vehicle.
- O means they may be loaded together only if separated by a barrier, such as a tank truck bulkhead or an approved portable tank.
- A star means separation is required unless the materials are separated by a barrier or the table note allows otherwise.
- Never load acids with cyanides or other materials that can generate toxic gas. Keep oxidizers away from flammable liquids and combustible materials. Keep poisons away from foodstuffs.
- Secure packages against movement; check labels and placards; set brakes, chock wheels, and shut off the engine before unloading. No smoking in or near the vehicle.
Worked example
A shipper wants to load sulfuric acid (Class 8) and sodium cyanide (Division 6.1) in one van. The segregation table gives an X for this combination, and mixing an acid with a cyanide can release hydrogen cyanide gas. The correct answer is to refuse the mixed load, not to add absorbent or separate them with a single sheet of cardboard. The load must be segregated or shipped separately.
Traps
Do not assume materials in the same hazard class are compatible. Do not treat O as no restriction; it requires a barrier. Do not overlook foodstuffs and poisons. A load that is legal on paper can still be unsafe if packages are crushed, leaking, or unsecured.