Hazardous Materials Regulations and the Hazardous Materials Table
What the exam tests
This domain tests your ability to work within the Hazardous Materials Regulations in 49 CFR Parts 171-173, 177, and 397, with special attention to the 172.101 Hazardous Materials Table (HMT). You must understand how the table is organized, how to choose a proper shipping name (PSN), and how that choice drives packaging, marking, labeling, and shipping-paper entries. Questions are usually applied: given a material and a table row, decide the correct description and the rules that follow.
Structure of the HMT
The HMT has 14 columns. Column 1 contains symbols; column 2 is the PSN; column 3 is the hazard class or division; column 4 is the UN or NA identification number; column 5 is the packing group (PG); column 6 lists label codes; column 7 contains special provisions; columns 8-10 cover packaging exceptions, non-bulk packaging, and bulk packaging; columns 11-12 give quantity limits for passenger and cargo aircraft; columns 13-14 give vessel stowage. A plus sign (+) means the PSN must be supplemented with a technical name in parentheses on the shipping paper. A "D" symbol identifies an entry authorized for domestic transportation only. Special provisions can add, remove, or modify requirements, so read the row before assuming a generic rule applies.
Selecting the entry
Start with the material's hazard class and physical state, then find the most specific PSN listed. Trade names and common names are not PSNs unless the table lists them. When only a generic n.o.s. entry fits, the technical name of the hazardous constituent generally must follow in parentheses, particularly when the entry carries a plus sign. Once you choose the PSN, use the same row to confirm the identification number, PG, label codes, and packaging. Do not combine columns from different rows.
Worked example
A shipper has a flammable liquid with a flash point of 20°C, PG II, containing methanol and toluene, and no more specific listed PSN applies. The correct entry is "Flammable liquid, n.o.s., 3, UN1993, PG II." Because the entry requires a technical name, the shipping description reads "Flammable liquid, n.o.s. (methanol, toluene), 3, UN1993, PG II." The reasoning: the class is 3, the identification number must match the n.o.s. entry, PG II is shown in that row, and the technical name identifies the generic entry. Omitting the technical name is a communication violation even when the class and identification number are correct.
Traps
Using a common name instead of the table's PSN; carrying a domestic-only "D" entry into cross-border service; forgetting the technical name for a plus-sign entry; treating the hazard class as a PSN; assuming every material has a PG; and ignoring special provisions that add or relax requirements.