CDL Hazardous Materials Endorsement (HME)Loading and Unloading Hazardous MaterialsMedium
A driver is transporting a shipment that includes both Class 4.3 (Dangerous When Wet) materials and Class 2.1 (Flammable Gas) cylinders. Which of the following segregation requirements applies?
- AThey can be loaded together if separated by a distance of 3 feet.
- BThey must not be loaded together in the same transport vehicle.
- CThey must be segregated unless the dangerous when wet material is in a closed transport vehicle.
- DThey must be segregated if the flammable gas is in a portable tank.
Show answer & explanationAnswer & explanation
Correct answer: B. They must not be loaded together in the same transport vehicle.
Class 4.3 (Dangerous When Wet) materials are incompatible with Class 2.1 (Flammable Gas) because contact with water can produce flammable gases, which would be extremely dangerous in the presence of existing flammable gases. The segregation table (49 CFR 177.848) prohibits loading these two classes together in the same transport vehicle.
Why the other options are wrong
- A. A 3-foot separation is insufficient and does not address the fundamental incompatibility; they are forbidden.
- C. Enclosed vehicles do not negate the chemical incompatibility between these two classes.
- D. The form of the flammable gas packaging does not change the core incompatibility.
Segregation: Dangerous When Wet & Flammable Gas
A specific segregation requirement prohibiting the transportation of Class 4.3 (Dangerous When Wet) materials and Class 2.1 (Flammable Gas) in the same transport vehicle due to their severe incompatibility.
- Class 4.3 reacts with water to produce flammable gases.
- Class 2.1 is already a flammable gas.
- Loading together is strictly forbidden by regulations.
Memory trick: Wet danger, gas flare, never together, beware!