14.1 UN Number
The UN number is a four-digit code used worldwide to identify hazardous materials during transport. This section explains what UN numbers are, how to find them, and why they are important for safety and compliance.
What is a UN Number?
A UN number (United Nations number) is a four-digit number that identifies hazardous materials, dangerous goods, and articles (such as explosives, flammable liquids, toxic substances, etc.) during international transport.
Think of a UN number as a universal "ID code" for dangerous materials. Just like every person has a unique ID number, each hazardous substance or group of similar hazardous substances has its own UN number.
For example:
- UN 1203 is the UN number for gasoline/petrol
- UN 1830 is the UN number for sulfuric acid with more than 51% acid
- UN 1170 is the UN number for ethanol (ethyl alcohol)
Important to know: The absence of a UN number on a Safety Data Sheet (SDS) means either:
- The material is not classified as dangerous for transport, or
- The SDS is incomplete and not compliant with regulations
Always verify this information if you are responsible for shipping or transporting chemicals.
Why Are UN Numbers Important?
UN numbers serve several critical purposes:
1. Universal Identification
They provide a standardized way to identify dangerous goods worldwide, regardless of language barriers.
2. Emergency Response
Emergency responders can quickly identify the substance and take appropriate action in case of accidents.
3. Regulatory Compliance
Proper UN number assignment ensures compliance with international transport regulations.
4. Proper Handling
They help ensure proper packaging, labeling, and transport conditions for hazardous materials.
How UN Numbers Are Assigned
UN numbers are assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods. They range from UN 0001 to about UN 3600, with new numbers being added as needed.
UN numbers are organized into ranges:
- UN 0001-0999: Explosives
- UN 1000-1999: Gases, flammable liquids, flammable solids, substances liable to spontaneous combustion, substances which emit flammable gases in contact with water
- UN 2000-2999: Oxidizing substances, toxic substances, infectious substances, corrosive substances
- UN 3000-3999: Miscellaneous dangerous substances and articles, environmentally hazardous substances
- UN 4000+: Reserved for future assignments
How to Read a UN Number on Packaging
UN numbers appear on shipping papers, containers, and packages in several formats:
On Boxes
"UN 1263" directly printed or on a label
On Placards
On orange panels with the hazard class
On Drums
Usually near the top with other markings
On IBCs
Intermediate Bulk Containers with UN marking
Common Mistakes with UN Numbers:
- Confusing the UN number with other codes (CAS numbers, EC numbers)
- Using an incorrect UN number for a mixture
- Failing to update the UN number when a formula changes
- Not specifying a UN number for dangerous goods
- Using the same UN number for a substance in different conditions (solid vs. solution)
UN Numbers vs. Other Identification Systems
| Identification System | Purpose | Format | Example |
|---|---|---|---|
| UN Number | Transport classification | 4-digit number | UN 1203 (Gasoline) |
| CAS Number | Chemical identification | Hyphenated numbers | 64-17-5 (Ethanol) |
| EC Number | European regulatory identification | XXX-XXX-X format | 200-578-6 (Ethanol) |
| NFPA Diamond | Hazard communication for emergency response | Four-colored diamond | 3-0-0 (Gasoline) |
How to Find the Correct UN Number
To find the correct UN number for a substance or mixture:
- Check the supplier's Safety Data Sheet (Section 14.1)
- Consult the dangerous goods list in transport regulations:
- ADR/RID for road/rail transport (Europe)
- IMDG Code for maritime transport
- IATA DGR for air transport
- 49 CFR for US transportation
- Use online databases of dangerous goods
- Consult a dangerous goods safety advisor or consultant
- Contact regulatory authorities
Common UN Numbers Reference
Special Cases and Considerations
Mixtures
For mixtures, the UN number is assigned based on:
- The most hazardous component
- The overall hazard of the mixture
- Special provisions in transport regulations
N.O.S. Entries (Not Otherwise Specified)
When a substance doesn't have a specific UN number, it may be assigned to a generic "N.O.S." entry based on its hazard properties.
Example: "UN 1993, FLAMMABLE LIQUID, N.O.S. (contains ethanol and isopropanol)"
Limited Quantities
Small amounts of certain dangerous goods may qualify for "limited quantity" exceptions, but the UN number is still required on documentation.
Remember: The UN number is just one part of the transport classification. It must be used together with the proper shipping name, hazard class, packing group, and any special provisions to ensure safe and compliant transportation.