Hazard Pictograms & Dangerous Goods Class Diamonds Explained

If your site stores fuel, solvents, pool chemicals or gas cylinders, two separate labelling systems apply to them — and most workplaces mix the two up. Hazard pictograms come from the GHS and appear on chemical containers. Dangerous goods class diamonds come from the transport code and go on packages, storage areas and site entrances. This guide explains what each system covers, which Australian Standard sets the design, and where the signs actually have to go. It builds on our broader guide to chemical and hazardous substance signs, and you can browse the full dangerous goods diamonds range to see the class labels.

What are hazard pictograms and dangerous goods class diamonds?

A hazard pictogram is the red-bordered white diamond printed on a chemical container — a flame, a skull and crossbones, a corrosion symbol. It comes from the Globally Harmonised System of Classification and Labelling of Chemicals (GHS), and it tells a worker what that chemical does to people, property or the environment.

A dangerous goods class diamond is the solid-coloured diamond used in transport and storage — orange for explosives, red for flammable liquids, black-and-white for corrosives. It comes from the Australian Dangerous Goods (ADG) Code, and it tells emergency services what they are about to walk into.

The two systems overlap but are not interchangeable. A drum of solvent can carry a GHS flame pictogram on its product label while sitting inside a store placarded with a Class 3 flammable liquid diamond. One is chemical hazard communication aimed at workers; the other is class identification aimed at transport, storage and emergency response. Sites that run only one of the two usually have a gap.

What is AS 1216?

AS 1216-2006 Class labels for dangerous goods is the Australian Standard that sets the design of dangerous goods class labels. It specifies the colours, symbols, proportions and class numbering for every class, division and subsidiary risk listed in the ADG Code — which is why a Class 3 diamond looks identical on every compliant sign in the country.

Hazard pictograms sit under a different rule set. Under the model WHS Regulations, hazardous chemicals must be classified and labelled using GHS Revision 7, which has been the required version since 1 January 2023 (31 March 2023 in Western Australia).

Placarding is handled separately again. Schedule 11 of the model WHS Regulations sets the threshold quantities that trigger placards, and Schedule 13 sets what those placards must look like. The practical effect: buying signage made to AS 1216 means the diamond itself is right. Whether you need it, and where it goes, is decided by the quantities you hold and the regulator in your state or territory.

The nine dangerous goods classes

Class diamonds are numbered 1 to 9, with several split into divisions. The colour and symbol do the work at a distance; the number confirms it up close.

• Class 1 — Explosives. Orange, exploding bomb symbol.
• Class 2 — Gases. Red for flammable gas (2.1), green for non-flammable non-toxic gas (2.2), white for toxic gas (2.3).
• Class 3 — Flammable liquids. Red with a flame. The most common class on Australian sites — petrol, diesel blends, solvents, thinners.
• Class 4 — Flammable solids. Red-and-white stripes (4.1), red-and-white halves for spontaneously combustible (4.2), blue for dangerous when wet (4.3).
• Class 5 — Oxidisers. Yellow with a flame over a circle for oxidising agents (5.1); red-and-yellow for organic peroxides (5.2).
• Class 6 — Toxic and infectious substances. White with a skull and crossbones (6.1) or a biohazard symbol (6.2).
• Class 7 — Radioactive. Yellow-and-white with a trefoil.
• Class 8 — Corrosive. Black-and-white, with liquid burning a hand and a surface.
• Class 9 — Miscellaneous dangerous goods. Black-and-white vertical stripes over white.

Australia also uses a C1 combustible liquid placard, which is not a UN class but is widely required for diesel and heating oil storage. Marine pollutant and elevated temperature placards cover further transport cases.

There are nine GHS pictograms as well — flame, flame over circle, exploding bomb, gas cylinder, corrosion, skull and crossbones, exclamation mark, health hazard and environment. A quick way to tell the systems apart on site: solid colour with a class number at the bottom is a dangerous goods diamond; red border with a white centre and no number is a GHS pictogram.

Where dangerous goods signs have to go

Placarding works in three layers, from the front gate inwards.

1. The site entrance

Where holdings exceed the Schedule 11 thresholds, a HAZCHEM outer warning sign goes at each entrance emergency services may use. It is a set format — the word HAZCHEM in red letters on a white or silver background, 600 mm wide by 120 mm high, with 100 mm letters — so a responding crew reads it from the truck without slowing down.

2. The storage area

Individual stores, cabinets, cages and bulk tanks carry the class diamonds for what is actually inside them, so a crew arriving at the gate can be directed to the right shed. Keep the diamonds current when stock changes — an out-of-date placard is worse than none, because it sends responders in with the wrong plan.

3. Packages and containers

Individual containers carry GHS labels with the pictogram, signal word and hazard statements. Packages consigned for transport carry class labels to AS 1216.

Placards belong outdoors, so specify metal or UV-stable polypropylene rather than self-adhesive vinyl on anything weather-exposed. Round the layout out with the supporting signage the store needs anyway: no smoking and no naked flame prohibition signs, fire equipment location signs, and AS 1319 warning signs on the approach. Where chemicals move around the site in pipework, pipe marker signs to AS 1345 identify the contents and flow direction.

Dangerous goods signage checklist