The DOT’s HMR (49 CFR Parts 100-185) regulate the transportation of hazardous materials, including refrigerant cylinders. The HMR specify requirements for cylinder design, testing, and certification, as well as packaging, labeling, and marking of cylinders for transportation. They also outline training requirements for employees involved in the transportation of refrigerant cylinders and provide guidelines for emergency response planning. Compliance with HMR ensures that refrigerant cylinders are transported safely and in accordance with federal regulations.