Anhydrous ammonia is regulated by the USDOT under CFR Title 49
Anhydrous Ammonia is regulated by the United States Department of Transportation (USDOT) as a hazardous material, and its classification, description, hazard communications requirements, and packaging for transportation are governed by the Federal Hazardous Materials Transportation Regulations (HMR) in Title 49 of the Code of Federal Regulations.
The HMR regulate anhydrous ammonia as a Division 2.3 toxic gas for international shipments, and provide an exception classifying it as a Division 2.2 non-flammable gas for domestic transportation. Both entries in the hazardous materials table require ammonia to be identified as an inhalation hazard on shipping papers and hazard marking on packaging.
The USDOT regulates anhydrous ammonia as a Hazard Zone D inhalation hazard (49 CFR 173.116 (a)). Hazard Zone D materials have a lethal concentration (LC 50 ) greater than 3000 parts per million and less than or equal to 5000 parts per million.
Bulk and non-bulk packaging of ammonia must be marked Inhalation Hazard as a warning of ammonia toxicity.
Authorized packaging for anhydrous ammonia transportation is referenced in 49 CFR 173.304 for non-bulk packaging, §173.314 for railroad cars, and §173.315 for cargo tanks and portable tanks moved by highway. No person can transport anhydrous ammonia in commerce unless it is packaged as authorized in these regulations.
Additionally, Minnesota Statutes 18C.201 make it illegal to place or transport anhydrous ammonia in any container not designed, constructed, maintained or authorized for that purpose.
USDOT Emergency Response Guidebook
Anhydrous ammonia entries in the 2020 Emergency Response Guidebook (ERG) note both its toxic and corrosive properties. Anhydrous ammonia is a highlighted material in both the yellow and blue pages of the ERG meaning it is included in the green boarded pages of the Table of Initial Isolation and Protective Action Distances. This table predicts the size of downwind areas which could be affected by a cloud of toxic gas. People in this area should be evacuated and/or sheltered in place in buildings in the event of a release or threatened release. The ERG identification number and guide number for anhydrous ammonia is 1005 and 125, respectively.
The most common road trailer used to transport anhydrous ammonia is the MC 331 high pressure tank. It has a capacity of 11,500 gallons and can also transport propane, butane, and LPG. The operating pressure of the vessel is 300 pounds per square inch (psi). Tank valving will be under the tank toward the rear.
Anhydrous ammonia will be transported by rail in a DOT 105J series insulated tank car. This tank car has a capacity of 33,500 gallons. The tank will have a pressure relief valve set to open at an internal tank pressure of 225 psi. All valving will be on top of the rail car.
Information concerning nurse tanks can be found by visiting: Nurse Tank Anatomy