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DG Class 2.1 vs 2.2 — Flammable vs Non-Flammable Gas
Last updated: 6 Jul 2026Reviewed by Ms. Rubab Nizami, Lead AVSEC Faculty
In short
Class 2.1 is flammable gas and carries a RED diamond label (butane, propane). Class 2.2 is non-flammable, non-toxic gas and carries a GREEN diamond label (nitrogen, carbon dioxide, oxygen). The colour is the fastest way to tell them apart.
Class 2.1 vs Class 2.2 — side by side
| Class 2.1 | Class 2.2 | |
|---|---|---|
| Hazard | Catches fire | Neither flammable nor toxic |
| Label colour | Red | Green |
| Examples | Butane, propane, hydrogen | Nitrogen, CO₂, compressed oxygen |
Which should you use?
Red diamond = flammable gas (2.1). Green diamond = non-flammable gas (2.2). Never confuse the two colours.
Quick answers
What colour is a flammable gas label?
Red. A non-flammable, non-toxic gas label is green.