Understanding Dangerous Goods Classes 1 to 9

Understanding Dangerous Goods Classes 1 to 9 and What They Mean

🧭 Why Dangerous Goods Classes Matter

Dangerous Goods (DG) class numbers exist to identify the type of hazard a substance presents during storage or transport. Under the Land Transport Rule (2005) and HSNO Regulations, every vehicle, tank, and storage area holding hazardous materials must display the correct placard for quick recognition by emergency services.

The colour, symbol, and class number instantly tell responders what they’re dealing with — from explosives to corrosives. If the wrong sign is missing or obscured, response time and safety both take a hit.

🔢 Overview of the Nine Dangerous Goods Classes

Class Hazard Type Placard Colour / Symbol Common Examples Typical Signage Location
1 – Explosives Explosive risk from shock or heat. Orange with exploding bomb symbol. Fireworks, ammunition, detonators. Magazine stores, firework storage, transport vehicles.
2 – Gases Compressed, liquefied, or dissolved gases. Class 2.1 (Flammable Gas – Red Flame) Class 2.2 (Non-Flammable – Green Cylinder) Class 2.3 (Toxic – White Skull). LPG, oxygen, chlorine. Cylinders, tankers, laboratories.
3 – Flammable Liquids Liquids that ignite easily. Red with flame symbol. Petrol, ethanol, diesel. Fuel stations, tanks, vehicles.
4 – Flammable Solids Solids that ignite by friction or moisture. 4.1 (Striped Red/White) 4.2 (White/Red half) 4.3 (Blue). Matches, metal powders, sodium. Chemical stores, laboratories.
5 – Oxidising Substances & Organic Peroxides Supply oxygen and intensify fires. 5.1 (Yellow flame over circle) 5.2 (Red/Yellow). Pool chlorine, hydrogen peroxide. Pool areas, industrial plants.
6 – Toxic & Infectious Substances Poisonous or infectious materials. White with skull or biohazard symbol. Pesticides, medical samples. Laboratories, agricultural sheds.
7 – Radioactive Materials Emit ionising radiation. Yellow upper / white lower with radiation trefoil. Radioactive gauges, X-ray equipment. Hospitals, construction labs, transit containers.
8 – Corrosive Substances Destroy living tissue & metals. Black and white hands and bar symbol. Acids, alkalis, battery fluids. Chemical stores, treatment plants.
9 – Miscellaneous Dangerous Goods Environmentally hazardous or other risks. Black and white stripes. Dry ice, lithium batteries, UN 3082 liquids. Freight depots, battery storage, containers.

🧱 Placards vs Labels – What’s the Difference?

  • Placards: Large format signs (250 – 800 mm) used for vehicles, tanks, and site entrances.

  • Labels: Smaller stickers (50 – 150 mm) used on packages and chemical drums.

  • Both must display the same class number, UN code, and pictogram for consistency.

✅ Available Sizes & Recommended Use

For compliance with AS/NZS 1319 and NZTA transport requirements:

  • 120 × 120 mm – For small containers, drums, or inner packaging where space is limited.
    Ideal for labelling cartons or chemical containers.

  • 250 × 250 mm – Most common size for transport packages and crates.
    Required for short-distance visibility during handling and storage.

  • 400 × 400 mm – Standard vehicle placard size under NZTA’s Land Transport Rule (Dangerous Goods 2005).
    Must be displayed on the front, rear, and both sides of vehicles carrying DGs.

  • 800 × 800 mm – Required for bulk containers, tankers, or site entrances where long-range visibility is essential.
    Suitable for permanent outdoor mounting or reflective ACM panels.

All Dangerous Goods and HAZCHEM signs on hazard-signs.nz are printed on long-term laminated vinyl, mounted on Corflute, PVC, Magnetic or ACM, and compliant with AS/NZS 1319:1994 and WorkSafe NZ requirements.

🧩 How Classes Relate to HAZCHEM Codes

Each class has matching HAZCHEM codes (letters and numbers) that further describe the response needed in an emergency.

For example:

  • 3YE Diesel – Flammable liquid, foam extinguishant, evacuate area.

  • 2WE Ethanol – Moderately flammable, use water fog, contain spillage.

  • 4X Solid oxidiser – Dry agent only, avoid contact with water.

👉 Read more in our related blog: What HAZCHEM Codes Mean

🧠 Common Compliance Tips

✅ Display placards on every side of vehicles or storage areas.
✅ Ensure the UN number matches the substance being stored or transported.
✅ Replace faded or damaged signs immediately.
✅ Check visibility from the standard viewing distance (see size chart above).

🧭 External References

🔗 Related Links on Hazard-Signs.nz

🧩 Conclusion

Every class 1–9 sign plays a critical role in helping emergency crews respond safely and fast. Displaying the right placard is not only a legal requirement — it can prevent a minor spill from becoming a major incident.

All Dangerous Goods signs from Hazard Signs NZ are NZ/AU compliant, laminated, and weatherproof for the toughest conditions.
Need help choosing the right set for your site? Contact our team and we’ll sort you out before the inspectors do.

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