Differences between un number and hazchem action code app memory game
A UN number is a four-digit code that identifies the specific substance, like 1203 for gasoline. A Hazchem code (an Emergency Action Code) is a short code used in some countries that tells responders how to fight the incident: what firefighting media to use, whether to contain or dilute, what protection to wear, and whether to evacuate. One names the material; the other directs the response.
Two codes, two purposes
Both can appear on an orange panel, which is why they get confused, but they answer different questions. The UN number answers what is it. The Hazchem code answers what do we do about it right now. Knowing which is which keeps you from reading a response instruction as a substance and the reverse.
The UN number
The UN number is a four-digit identification number assigned to a specific material or group of materials. Gasoline is 1203, for example. Responders look the number up in a guide like the Emergency Response Guidebook to find the material and its general hazards. It is purely an identifier.
The Hazchem (Emergency Action Code)
The Hazchem code packs response guidance into a few characters:
| UN number | Hazchem / EAC | |
|---|---|---|
| Form | Four digits | A number plus letters |
| Tells you | Which substance | How to respond |
| Covers | Material identity | Firefighting media, containment, PPE, evacuation |
| Where used | International and US | UK, Australia, and others |
The UN number identifies; the Hazchem code instructs. Confirm against the official materials for the system in use.
How to keep them straight in memory
Anchor each code to its question. UN number, all digits, equals identity. Hazchem code, a digit followed by letters, equals action. A memory game that pairs each code with its one job, name the substance versus run the response, fixes the difference faster than trying to memorize the code systems themselves. Because Hazchem is a non-US convention with its own lookup rules, verify the details against the official materials for the country and system you are studying.
Frequently asked questions
- What is the difference between a UN number and a Hazchem code?
- A UN number is four digits identifying the specific substance (like 1203 gasoline). A Hazchem (Emergency Action Code) tells responders how to fight the incident: media, containment, protection, and evacuation. Verify in the official materials.
- Is the Hazchem code used in the US?
- Hazchem / Emergency Action Codes are mainly used in the UK, Australia, and some other countries. The US relies on UN numbers and the Emergency Response Guidebook. Check the system that applies to you.
- What does a UN number tell you?
- It identifies the exact material so responders can look it up. It does not tell you how to respond; that is what the Hazchem code or a response guide provides.