Dangerous Goods Classification & Storage Compliance Guide

The nine classes of dangerous goods group hazardous materials by their primary hazard: explosives, gases, flammable liquids, flammable solids, oxidising substances, toxic and infectious substances, radioactive material, corrosives, and miscellaneous dangerous goods. This is the structure behind dangerous goods classification, and it comes from the United Nations Recommendations on the Transport of Dangerous Goods. Australia adopts that system through the ADG Code for transport and the GHS within the Work Health and Safety Regulations for the workplace. Storage then sits under a class-specific Australian Standard plus the state DG or WHS regulator. Each class can carry divisions and packing groups that refine the hazard, where packing group I is the highest danger and group III the lowest. Knowing the class and packing group of a substance is the first decision in specifying compliant storage, because it sets which standard applies and what containment the goods need.

Class 1 explosives and Class 7 radioactive material sit under their own regulatory regimes and fall outside relocatable container storage. The classes most often held in an outdoor DG store are 3, 5, 6, and 8, plus mixed inventories that combine them.

Class 5: Oxidising Substances and Organic Peroxides

Class 5 dangerous goods are oxidising agents and organic peroxides, substances that release oxygen and intensify a fire even without an external ignition source. Division 5.1 covers oxidising agents such as pool chlorine, ammonium nitrate, and hydrogen peroxide solutions, and class 5.1 dangerous goods are stored under AS 4326. Division 5.2 covers organic peroxides, which need temperature control and are governed by AS 2714. Both divisions have to be kept clear of flammable and combustible material, because an oxidiser feeds a fire that a Class 3 liquid starts. A bunded container with the right segregation and ventilation isolates oxidisers from incompatible classes and contains any liquid oxidiser that leaks.

Class 6: Toxic and Infectious Substances

Class 6 dangerous goods are toxic and infectious substances. Division 6.1 covers toxic substances, materials that cause death or injury if swallowed, inhaled, or absorbed through skin, and class 6.1 dangerous goods are stored to AS/NZS 4452 and the WHS hazardous-chemicals provisions, with containment that stops a spill reaching people, drains, or soil. Division 6.2 covers infectious substances, which fall under biosafety controls rather than general DG storage. For 6.1 toxics held outdoors, a sealed bunded floor and a lockable, ventilated container keeps the goods isolated and the spill captured. Toxic substances are often stored alongside corrosives or flammables, so segregation under AS 3833:2024 matters when classes are mixed.

AS 1940:2017 is the controlling Australian standard for storing and handling flammable and combustible liquids, the goods classified as Class 3. It sets the rules for bund sizing, ventilation, ignition control, separation distances, and the signage a store must display. AS 1940:2017 draws a line between flammable liquids, which give off vapour that ignites at lower temperatures, and combustible liquids, which need more heat, and it scales the controls to the quantity and packing group on site.

For containerised storage, the AS 1940 bunding requirements are the part procurement teams ask about most. The standard sizes secondary containment to the largest single container stored inside the compound, not the total inventory. That single rule sets the largest drum or IBC a compliant store can hold. Ventilation has to clear vapour so it cannot build to an ignitable concentration, which is why a Class 3 store uses passive high and low vents rather than a sealed box. Ignition control means no unprotected electrical fittings or hot work inside the separation zone.

Separation distances keep a flammable store clear of site boundaries, occupied buildings, and ignition sources, with the distance set by the quantity held. For a site, that means the store's location is part of compliance, not just its build. SCS builds flammable liquid storage containers to AS 1940, with the bund volume confirmed against the largest container before manufacture. Class 3 is the most common DG class stored in a relocatable container, because fuels, solvents, and thinners move with the job and need containment at the work front.

AS 3780:2023 is the controlling Australian standard for storing Class 8 corrosive substances: acids, alkalis, and other materials that attack metal, skin, and building fabric. AS 3780:2023 sets a tighter build than AS 1940, because a corrosive leak damages the store itself. It calls for a sump at least 150 mm deep holding at least 25% of the aggregate stored volume, self-closing and self-latching multi-point doors that cannot swing inward, venting fitted with flash arrestors, a chemical-resistant internal finish, and a safety shower located between 2 and 10 metres from the store. The 2008 edition has been superseded, so a compliant build references the 2023 edition.

Class 8 dangerous goods carry packing groups I to III, and the packing group drives the lining specification and the separation from incompatible classes. A strong acid in packing group I needs a more resistant lining than a dilute solution in packing group III. Corrosives also segregate from Class 5 oxidisers and many Class 3 flammables, so a single-class corrosive store is often a cleaner compliance answer than a mixed box.

For quality engineers, the AS 3780 sump and door clauses are the items most often checked on audit, because they are the difference between a box that captures a corrosive spill and one that lets it run to ground. SCS builds corrosive storage containers to AS 3780, with the lining and sump specified against the substance and packing group at order. The chemical-resistant finish is selected for the corrosive held, not applied as a generic coating, because the wrong lining fails as fast as bare steel.

AS 4332 governs the storage and handling of gases in cylinders, the goods classified as Class 2. It covers cylinder restraint, separation of incompatible gases, ventilation, and the handling rules that stop a cylinder becoming a projectile or a leak source. AS 4332 sits alongside AS/NZS 1596 for LP Gas, which is Division 2.1, the flammable gas division. Searches for AS4332 usually come from sites holding oxygen, acetylene, LPG, or industrial gas packs that need a compliant store.

Class 2 splits into three divisions: 2.1 flammable gases, 2.2 non-flammable non-toxic gases such as nitrogen and argon, and 2.3 toxic gases. Flammable and toxic gases segregate from each other and from oxidising gases, so a gas store is laid out by division as much as by quantity. Ventilation is critical, because a gas leak in a sealed space builds to an explosive or asphyxiant concentration faster than a liquid spill does.

A relocatable container suits gas cylinder storage where a site needs a ventilated, secured cage that can move between work fronts. The container is fitted with cylinder restraint and high and low ventilation, and gases are grouped by division to meet the separation rules in the standard.

Chemical bunding is the secondary containment that captures a leak or spill before it reaches drains, soil, or waterways. It is the core control for any liquid dangerous goods store, and it is what separates a compliant outdoor store from a plain steel box. Bunding for chemicals works as a sealed compound, usually a welded steel sump built into the floor, sized to hold a defined proportion of the liquid stored above it.

The chemical storage bunding requirements come from the controlling storage standard for the class. Under AS 1940, the bund is sized to the greater of 100% of the largest single container or 25% of the aggregate stored volume. State EPA guidance commonly cites 110% of the largest container for outdoor storage, so the controlling figure depends on whether the storage standard or the environmental regulator sets the higher bar for the site. Either way, the principle is the same: the compound has to hold a credible worst-case spill without overflowing.

Integrated bunding, built into the container floor frame at the factory, performs differently from an aftermarket tray dropped onto a flat floor. A welded structural bund ties into the floor cross-members, so the containment is part of the box and stays leak-tight under load and movement, where an aftermarket liner can lift, tear, or leak at the seams. A compliant bund also needs a controlled drain point: a lockable stainless steel drain valve lets a site release clean rainwater but keeps a spill contained until it is dealt with, and it cannot be opened by mistake. The valve material matters as much as the bund, because 316L stainless steel resists the chlorides and mild acids that pit a lesser fitting.

For when bunding is required and when an unbunded store is acceptable, see our bunded vs unbunded storage explained comparison, and for substance-specific containment, our bunded chemical storage range. Safe Work Australia sets the model work health and safety duties for storing hazardous chemicals that sit alongside the bunding standard.

Knowing how to store dangerous goods starts with the goods themselves, not the container. The decision runs in four steps, and getting them in order is what keeps a site compliant and the specification right the first time.

AS 3833:2024 is the standard to read when a single store holds mixed classes, because it sets the segregation and separation that stop incompatible goods reacting. The placard and manifest thresholds come from the model Work Health and Safety Regulations as each state adopts them. SCS engineers run this pathway on every DG enquiry and flag any gap in the class, quantity, or compatibility data before quoting, because a missed subsidiary risk changes the build.

DG signage tells anyone approaching a store what is inside and how to respond in an emergency. Placarding becomes mandatory once a site holds dangerous goods above the placard quantity, and it has to be visible, durable, and correct for the goods actually stored. The signage is read by site workers, visiting contractors, and, in an incident, by emergency services who set their approach from the placards before they get close.

A compliant store displays the class diamond for each class held, the HAZCHEM placard that tells emergency services how to fight a fire and contain a spill, the UN number and packing group for the substances, and emergency contact information. Outdated or missing placards are one of the most common findings on a DG audit, because inventory changes and the signage is not updated to match.

What information can a dangerous goods sign contain?

A dangerous goods sign can contain the class diamond showing the hazard class, the HAZCHEM code that directs the emergency response, the UN number identifying the substance, the packing group indicating the degree of danger, and the emergency contact details for the site. Safe Work Australia and the relevant state regulator set what a placard must show and when it is required.

What is the purpose of the classification of dangerous goods?

The purpose of the classification of dangerous goods is to group hazardous materials by the danger they present, so that transport, handling, and storage controls match the hazard. Classification sets the packaging, labelling, segregation, and storage standard for each substance, which is what makes consistent safety and compliance possible across sites and borders.

What are the nine classes of dangerous goods?

The nine classes of dangerous goods are explosives (1), gases (2), flammable liquids (3), flammable solids (4), oxidising substances (5), toxic and infectious substances (6), radioactive material (7), corrosives (8), and miscellaneous dangerous goods (9). Dangerous goods classification places every regulated substance into one of these classes, and in practice that means a known set of storage and handling rules for each.

What is the difference between AS 1940 and AS 3780?

AS 1940 is the storage standard for Class 3 flammable and combustible liquids, while AS 3780 is the storage standard for Class 8 corrosive substances. AS 1940 focuses on bund sizing, ventilation, and ignition control. AS 3780 adds a graded sump, a corrosion-resistant lining, flash-arrestor venting, and a nearby safety shower for the goods it covers.