3.2 The Hazardous Materials Table

Section 3.2: The Hazardous Materials Table

Why This Topic Matters for the Exam

The Hazardous Materials Table (HMT), found in Title 49 of the Code of Federal Regulations (49 CFR § 172.101), is the central reference document for transporting hazardous materials. For any driver seeking a Texas CDL Hazardous Materials Endorsement (HME), understanding how to read and interpret this table is a core competency tested on the exam. When you arrive at a shipper's facility, you cannot simply take their word that the load is safe. You must check the shipping papers against the entries in the HMT to verify that the proper shipping name, hazard class, identification number, and packaging requirements are correct. During roadside inspections by the Texas Department of Public Safety (DPS), any discrepancy between your shipping papers and the HMT will lead to immediate citations and your vehicle being placed out of service. Furthermore, in an emergency, first responders use the identification number listed in the table to cross-reference the Emergency Response Guidebook (ERG) and save lives.

The Ten Columns of the Hazardous Materials Table

The HMT is organized into ten columns. To pass the CDL exam and operate safely, you must know the function of each column:

Column 1: Symbols

This column contains codes that indicate special regulatory conditions or shipping rules:

• No Symbol: The material is regulated under all modes of transport (highway, rail, air, and vessel).
• + (Plus Sign): Fixes the proper shipping name, hazard class, and packing group for that entry, regardless of whether the material meets the chemical defining criteria.
• A: Identifies a material that is subject to the Hazardous Materials Regulations (HMR) only when transported by aircraft.
• D: Identifies proper shipping names that are appropriate for domestic transportation within the U.S.
• G: Identifies generic entries (such as "Flammable Liquids, n.o.s.") that require the shipper to write the technical chemical name in parentheses on the shipping paper.
• I: Identifies proper shipping names appropriate for international transportation.
• W: Identifies a material that is subject to regulations only when transported by vessel (waterway).

Column 2: Hazardous Materials Descriptions and Proper Shipping Names

This column lists the official proper shipping names (PSN) in roman type. Shippers must use these exact names on all shipping papers and package markings. Any text in italics is for descriptive purposes and is not part of the official shipping name.

Column 3: Hazard Class or Division

This column lists the primary hazard class or division number of the material. If a material is too dangerous to transport, the word Forbidden will appear here, and you must refuse to load it.

Column 4: Identification Numbers

Lists the four-digit identification number assigned to each chemical. These numbers are prefixed with UN (United Nations, for international shipments) or NA (North American, for domestic or Canadian shipments). This number must match the placards or orange panels on your truck when transporting bulk loads.

Column 5: Packing Group

Indicates the packing group (PG I, PG II, or PG III) in Roman numerals, reflecting the severity of the hazard. PG I represents great danger, PG II represents medium danger, and PG III represents minor danger.

Column 6: Label Codes

Specifies the hazard warning labels that the shipper must apply to the packages. The first code listed represents the primary hazard; any subsequent codes represent subsidiary hazard labels. Unlike placards, labels are applied directly to the individual packages, not the transport vehicle.

Column 7: Special Provisions

Contains alphanumeric codes that refer to specific rules in 49 CFR § 172.102. These codes outline special requirements for packaging materials, temperature controls, or chemical stabilization. For example, specific codes indicate if a material is a Poison Inhalation Hazard (PIH).

Column 8: Packaging Authorizations

This column points to the specific sections in 49 CFR Part 173 that govern how the material must be packaged. It is divided into three sub-columns:

• 8A (Exceptions): Details packaging exceptions (like limited quantities) that allow shippers to bypass some requirements.
• 8B (Non-bulk): Governs standard packaging, such as drums, boxes, and cylinders.
• 8C (Bulk): Governs bulk packaging, including cargo tanks, portable tanks, and railcars.

Column 9: Quantity Limitations

Specifies the maximum net quantity that can be transported in a single package on passenger aircraft/rail (Column 9A) or cargo-only aircraft (Column 9B).

Column 10: Vessel Stowage Requirements

Specifies location requirements for cargo transported on ships. Column 10A lists the authorized stowage category, and Column 10B lists specific handling and stowage codes.

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HMT Column Reference Summary

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Real-World Driving Scenarios and Exam Traps

• The "N.O.S." Technical Name Trap: Many drivers fail roadside inspections because they accept a shipping paper for a generic description like "Flammable Liquids, n.o.s." without checking for the technical names. Under Column 1, generic entries are marked with a "G." This means the shipper must include the technical chemical names in parentheses next to the shipping name (e.g., "Flammable Liquids, n.o.s. (contains Acetone and Methanol)"). If the technical names are missing, the paperwork is incomplete, and you can be placed out of service.
• The Bulk Packaging Definition: Drivers often get confused about when non-bulk rules transition to bulk rules. A bulk packaging is defined as a container with a capacity greater than 119 gallons (450 liters) for liquids, 882 pounds (400 kg) for solids, or a water capacity greater than 1,000 pounds (454 kg) for gases. If your cargo exceeds these limits, you must refer to Column 8C (Bulk Packaging) of the HMT to ensure your cargo tank or portable tank is authorized for that material.