UN Number on Hazmat
What is a UN number on hazmat?
A UN number is the identification number given to each proper shipping name for a hazardous material in transport. In the US Hazardous Materials Table (49 CFR 172.101), Column 4 "lists the identification number assigned to each proper shipping name." Numbers starting with "UN" belong to shipping names "considered appropriate for international transportation as well as domestic transportation" (49 CFR 172.101(e), 10-1-24 edition).
What the number points to: Each number is tied to one entry in the Table. That entry also sets the hazard class, the packing group, the labels and the packaging rules. Acetone is an example: its entry is UN1090, hazard class 3, packing group II, label 3, with its own special provisions, packaging references and quantity limits [1]. Packing groups I, II and III mean the danger is "great, medium, or minor" (172.101(f)).
Other prefixes in the US Table (172.101(e)):
| Prefix | Meaning |
|---|---|
| UN | Recognised for international and domestic transport |
| NA | Shipping names "not recognized for transportation outside of the United States" |
| NA9000 series | Names not properly covered by international dangerous goods standards, or by their emergency response information, except for transport within the US |
| ID | Shipping names recognised by the ICAO Technical Instructions (air transport) |
Where it appears: The UN number is part of the shipping description, which also includes the proper shipping name, the hazard class and the packing group (for example, Acetone / 3 / UN1090 / II). It is also shown on package markings and placards.
Approach: I checked the US DOT/PHMSA Hazardous Materials Table and read 49 CFR 172.101 in the official govinfo edition. UNECE's UN Model Regulations, where UN numbers are first assigned, and PHMSA's guidance pages wouldn't open this time, so the definition here comes from the US rule only.
How do I look up the UN number for a chemical?
You look up a UN number by finding the chemical's proper shipping name in the dangerous goods list for your transport mode. The UN number is printed on that entry. In the US that list is the Hazardous Materials Table in 49 CFR 172.101. If you only have a CAS number, the ILO/WHO International Chemical Safety Card for the substance gives the UN number too. Here is how it works for acetone (CAS 67-64-1).
1. Search the Hazardous Materials Table by name
- Searching "Acetone" returns the entry Acetone / class 3 / UN1090 / packing group II [1].
- Pick the exact name, not one that only looks similar. The same search also returns "Acetone oils" (UN1091) [2] and "Acetone cyanohydrin, stabilized" (UN1541, class 6.1, packing group I) [3]. These are different entries with different numbers.
- Some entries have no UN number because the material is Forbidden for transport. One example is "Acetyl acetone peroxide with more than 9 percent by mass active oxygen" [4].
2. Cross-check by CAS number
- ICSC 0087 (Acetone, revised April 2024) lists CAS 67-64-1, UN 1090, UN hazard class 3 and packing group II [5]. That matches the US Table.
3. If the chemical has no named entry, use a generic "n.o.s." entry
- Choose the generic entry that fits the hazard class. For a flammable liquid that is "Flammable liquids, n.o.s.", UN1993.
- Under UN1993 the Table has separate lines for packing groups I, II and III, and each line has its own provisions and quantity limits [6][7][8]. So you need the hazard class and packing group before you can choose the right line.
Practical points
- The UN number goes with the whole entry: name, class, packing group and form (for example "stabilized"). It is not tied to the CAS number alone. A mixture or solution may fall under a different entry from the pure substance.
- Use the list for the regime you are shipping under. The US Table governs US transport. For other modes or regions, take the number from that mode's own dangerous goods list, not from a supply (GHS/CLP) classification.
Approach: I searched the US DOT/PHMSA Hazardous Materials Table (49 CFR 172.101) and the WHO/ILO International Chemical Safety Cards, using acetone as the example. I found no acetone entry in New Zealand's EPA chemical classification database (CCID). I did not check the ADR, IMDG Code or IATA dangerous goods lists here.
If you give me your chemical's name or CAS number and how you ship it, I can look up its entry.
What's the UN number for gasoline and diesel?
Gasoline is UN1203 and diesel fuel is UN1202. Both are hazard class 3 (flammable liquid). Gasoline is packing group II and diesel is packing group III. In US domestic transport only, diesel can also be shipped as NA1993.
Gasoline (49 CFR 172.101 Hazardous Materials Table)
- The entry is "Gasoline includes gasoline mixed with ethyl alcohol, with not more than 10% alcohol": class 3, UN1203, packing group II, label 3, special provisions 144, 177, B1, B33, IB2 and T4, with limits of 5 L on passenger aircraft and 60 L on cargo aircraft [9].
- "Petrol", "Motor spirit" and "Casinghead gasoline" all point to the Gasoline entry, so the same number applies [10][11][12].
- Blends with more than 10% ethanol (for example E15 and E85) have their own entry, "Ethanol and gasoline mixture", which is UN3475, class 3, packing group II [13].
Diesel fuel: the Table has two entries
| Column 1 symbol | Entry | ID no. | Class / PG | Label |
|---|---|---|---|---|
| I | Diesel fuel | UN1202 | 3 / III | 3 |
| D | Diesel fuel | NA1993 | 3 / III | None |
In 172.101(b), "I" marks names that are "appropriate for describing materials in international transportation". "D" marks names for domestic transportation that "may be inappropriate for international transportation" (49 CFR 172.101(b)(3), (b)(5), 10-1-24 edition). In practice:
- Use UN1202 for any shipment that leaves the US, or if you want one description that works everywhere.
- NA1993 is for US domestic use only.
Related fuels you may need to tell apart
- Gas oil: UN1202, class 3, PG III [16]
- Heating oil, light: UN1202, class 3, PG III [17]
- Fuel oil (No. 1, 2, 4, 5, or 6): NA1993, class 3, PG III, a domestic "D" entry [18]
- Jet fuel is listed under "Fuel, aviation, turbine engine": UN1863, with separate lines for packing groups I, II and III [19]
Approach: I searched the US DOT/PHMSA Hazardous Materials Table and read the Column 1 symbol rules in the official govinfo text of 49 CFR 172.101. I did not check the ADR, IMDG Code or IATA dangerous goods lists, so the numbers and packing groups above are confirmed only for US transport.
What about UN 3082 and UN 2014?
UN3082 is "Environmentally hazardous substance, liquid, n.o.s.", in Class 9, packing group III. UN2014 covers hydrogen peroxide aqueous solutions with 20% to 60% hydrogen peroxide, in Division 5.1 (oxidizer) with a Class 8 (corrosive) subsidiary label, packing group II. Under 20% or over 60% hydrogen peroxide takes a different UN number.
UN3082: Environmentally hazardous substance, liquid, n.o.s.
- Class 9, packing group III, label 9. The entry is marked "G", so a technical name must be added in brackets after the shipping name. Special provisions are 8, 146, 173, 335, 441, IB3, T4, TP1 and TP29. There is no quantity limit on passenger or cargo aircraft, and vessel stowage is A [20].
- This is a generic catch-all entry. "Marine pollutants, liquid or solid, n.o.s." and "Hazardous substances, liquid or solid, n.o.s." both send you to it [21][22].
- The solid version is UN3077, "Environmentally hazardous substance, solid, n.o.s.", also Class 9, packing group III [23].
- For US domestic transport only, there are two NA3082 entries: "Hazardous waste, liquid, n.o.s." and "Other regulated substances, liquid, n.o.s." Both are Class 9, packing group III, marked "D" [24][25].
UN2014: Hydrogen peroxide, aqueous solutions (stabilized as necessary)
The Table has two lines under UN2014, and they differ mainly on air transport:
| Concentration | Class / PG | Labels | Special provisions | Passenger air / Cargo air | Vessel |
|---|---|---|---|---|---|
| 20% to 40% | 5.1 / II | 5.1, 8 | A2, A3, B53, IB2, IP5, T7, TP2, TP6, TP24, TP37 | 1 L / 5 L | D; 25, 66, 75 |
| Over 40% to 60% | 5.1 / II | 5.1, 8 | 12, A60, B53, B80, B81, B85, IB2, IP5, T7, TP2, TP6, TP24, TP37 | Forbidden / Forbidden | D; 25, 66, 75 |
Other hydrogen peroxide concentrations use different numbers:
- 8% to under 20%: UN2984, Division 5.1, packing group III, label 5.1 only [28].
- Over 60% (stabilized): UN2015, Division 5.1, packing group I, labels 5.1 and 8. It is forbidden on both passenger and cargo aircraft [29].
Approach: I searched the US DOT/PHMSA Hazardous Materials Table (49 CFR 172.101). I did not check the ADR, IMDG Code or IATA dangerous goods lists, so these entries are confirmed for US transport only.