Exceptions, limited quantities and materials of trade

Applying every requirement of the HMR to a single can of spray paint or a propane cylinder for a torch would bury small shippers in paperwork without making anyone safer. So the HMR contain exceptions that relieve small or low-risk shipments from some requirements when strict conditions are met. Exceptions are used every day by contractors, retailers, couriers, farmers and maintenance crews. They are also a common source of mistakes, because people remember the relief and forget the conditions. An exception is never a blanket release: it lists exactly which requirements no longer apply and which conditions must be met.

Excepted quantities

The smallest amounts of many hazardous materials can travel as excepted quantities under 49 CFR 173.4a. A code from E0 (not permitted) to E5, shown in the Hazardous Materials Table special provisions or packaging columns, sets the maximum amount per inner packaging (as little as 1 g or 1 mL for the most hazardous materials) and per outer package. Excepted quantity packages need strong combination packaging, absorbent material for liquids and the excepted quantity marking, a square with red hatched edges showing the class number. Laboratory samples and small reagents often travel this way. Section 173.4 has a separate small quantities exception for highway and rail.

Limited quantities

Limited quantities are small inner packagings, below the limits set in the packaging sections of Part 173 (for example 173.150 for class 3), packed in a strong outer package generally not exceeding 30 kg (66 pounds) gross weight. They cover a huge share of consumer and retail products: aerosols, paints, cleaners, adhesives, lighter fluid and fuel in small containers. Limited quantities by highway or rail do not need shipping papers (unless they are a hazardous substance, hazardous waste or marine pollutant), hazard labels, placards or specification packaging. In return, each package must carry the limited quantity marking; the August 2026 rules allow a reduced 25 mm marking in some cases. Air limited quantities have their own lower limits and a Y version of the marking. The old ORM-D consumer commodity marking ended on 31 December 2020.

Materials of trade

Materials of trade, defined in 49 CFR 173.6, are hazardous materials carried on a motor vehicle to protect the health and safety of the driver or passengers, to support the operation or maintenance of the vehicle, or by a private motor carrier in direct support of a principal business that is not transportation, such as a contractor, landscaper, exterminator or utility. Typical examples are propane and acetylene cylinders for torches, gasoline for small engines, paints, pesticides and batteries.

Quantities are limited. For most classes, packing group II and III materials and class 9 are limited to 30 kg (66 pounds) or 30 L (8 gallons) per package, packing group I materials to 0.5 kg or 0.5 L, and division 2.1 and 2.2 cylinders to 100 kg (220 pounds) gross weight each. The total aggregate gross weight of all materials of trade on one vehicle must not exceed 200 kg (440 pounds), with some exceptions such as some cylinders and diluted mixtures. Packagings must be leak-tight, securely closed, secured against movement and protected from damage; gasoline must be in a metal or plastic can meeting set standards; cylinders must meet DOT specifications and be marked and labeled. Packages must be marked with a common name or proper shipping name, and the operator must be informed of the presence of the material and of the materials of trade requirements.

What materials of trade relieve

Shipments meeting all the materials of trade conditions do not need shipping papers, emergency response information, placards or formal training under 172.704, and do not need to meet the hazmat registration requirements for those materials. However, the vehicle must still meet the materials of trade conditions at all times, the driver must know what is on board, and incident reporting may still be required. Materials of trade cannot be used for materials that require placards in any quantity, self-reactive materials, poison-inhalation-hazard materials or hazardous waste. The August 2026 rules expanded materials of trade to allow equipment containing more lithium batteries, a change aimed at contractors who carry battery-powered tools, taking effect by December 2026.

Materials of trade work well for service vans and contractors' pickups, but they are not available to for-hire carriers delivering goods to customers. A plumbing company carrying its own cylinders qualifies; a gas supplier delivering cylinders to that plumbing company does not, and must follow the full rules or the limited quantity rules.

# Does a contractor's pickup qualify as materials of trade? (simplified; conditions abridged)
truck = [  # (item, class, packing group, gross weight lb, number)
    ("propane cylinder 20 lb", "2.1", None, 37, 2),
    ("acetylene cylinder", "2.1", None, 70, 1),
    ("gasoline can 5 gal", "3", "II", 37, 2),
    ("aerosol case", "2.1", None, 18, 3),
    ("battery pack", "9", None, 9, 2),
]
total = sum(w * n for _, _, _, w, n in truck)
problems = []
for item, cls, pg, w, n in truck:
    if cls.startswith("2") and w > 220:
        problems.append(f"{item}: cylinder over 220 lb")
    if not cls.startswith("2") and pg == "I" and w > 1.1:
        problems.append(f"{item}: PG I package too large")
    if not cls.startswith("2") and pg in ("II", "III", None) and w > 66:
        problems.append(f"{item}: package over 66 lb")
print(f"aggregate gross weight: {total} lb (limit 440 lb)")
if total > 440:
    problems.append("aggregate over 440 lb")
print("materials of trade:", "conditions met" if not problems else "; ".join(problems))

aggregate gross weight: 290 lb (limit 440 lb)
materials of trade: conditions met

The pickup's 290 pounds of materials is under the 440-pound aggregate limit, so it qualifies as materials of trade: no shipping papers, placards or formal training, but every package must be secured and leak-tight, the cylinders marked and labeled and the driver informed. Another 151 pounds, such as four more propane cylinders and a second acetylene cylinder, would push it over the limit, and the full rules, or another exception, would apply.

Lithium batteries and other special cases

Lithium batteries have their own section, 49 CFR 173.185, which sets out when cells and batteries packed with or contained in equipment are excepted from most requirements, how small batteries must be protected against short circuits and damage, and when the lithium battery mark is needed. Lithium-ion batteries shipped alone by air must generally be at a state of charge not exceeding 30 %, and many are forbidden on passenger aircraft. Damaged, defective or recalled batteries are excluded from most exceptions and need special packaging. Batteries carried by passengers for personal use follow separate airline rules.

Other exceptions cover agricultural operations (173.5), the fuel in a vehicle's own tanks, hazmat in use for vehicle operation, empty packagings that have been cleaned or purged, residue, and shipments by federal and state agencies in some circumstances. Special permits, issued by PHMSA under Part 107, allow specific shippers to depart from the regulations when they show an equivalent level of safety; the August 2026 rules wrote several commonly used special permits into the regulations so they are available to everyone.

Exemption mistakes in the field

Inspectors and incident investigators see the same exemption errors repeatedly. A contractor's truck claims an exemption but carries one container larger than the per-container limit. A van claims to be under the total limit, but nobody counted the aerosols and limited quantity products in the back. A shipper uses the limited quantity rules for a product whose list entry shows that limited quantities are not permitted. A battery shipment uses the small-battery exception for batteries that are above the watt-hour limit or have been damaged. Each of these turns an exempt shipment into a non-compliant one, often with no placards, documents or emergency information to warn responders.

The safest habit is to write down which exception a regular load relies on and check it against a short list of conditions: aggregate weight, per-package limits, excluded materials, packaging condition, marking and who has been informed. Many companies print the checklist on a card kept in each vehicle.