DG Class 3: Flammable Liquids – ADG Code, Chapter 2.3

Published: September 5, 2025| Last Updated: September 5, 2025

There are 9 dangerous goods classes in total, as set by the Australian Dangerous Goods Code, which is developed and maintained by the National Transport Commission (NTC). This article covers the 3rd dangerous goods class, referred to as Dangerous Goods (DG) Class 3.

The information from this article was obtained from Chapter 2.3 – Flammable Liquids on the latest version of the ADG Code. This guide provides up-to-date, helpful information on DG Class 3, but is not a replacement for the official documentation, which can be accessed from the National Transport Commission’s (NTC’s) website at the following address: https://www.ntc.gov.au/codes-and-guidelines/australian-dangerous-goods-code

Dangerous Goods (DG) Class 3 includes liquids that can produce a flammable vapour, posing a significant fire risk during transport. The classification hinges on a liquid’s “flash point”—the lowest temperature at which it gives off enough vapour to ignite. This class covers a vast range of common industrial and commercial products, from fuels and solvents to paints and adhesives. Here’s what logistics providers, shipping professionals, and SMEs need to know about properly classifying DG Class 3: Flammable Liquids.

Overview of DG Class 3 Materials

At a glance, Class 3 is not just one type of substance. The category covers several distinct groups:

Flammable Liquids: The primary group, consisting of liquids or mixtures of liquids (like paints or lacquers) that have a flash point of not more than 60°C.
Liquid Desensitised Explosives: These are explosive substances dissolved or suspended in a liquid to suppress their explosive properties, making them safe enough to be treated as flammable liquids. Examples include UN 1204 (NITROGLYCERIN SOLUTION IN ALCOHOL).
Elevated Temperature Materials: Liquids that are transported at or above their flash point, or substances transported hot which give off a flammable vapour at or below the maximum transport temperature.

Detailed Breakdown: Packing Groups I, II, & III

The ADG Code divides Class 3 liquids into three Packing Groups (PG) based on their flash point and initial boiling point. This determines the level of danger and the required packaging standards.

Packing Group I (High Danger)

These liquids are highly volatile and present the greatest flammability risk.

Classification Criteria: Substances with an initial boiling point of 35°C or less.
Common Examples:
- UN 1155: DIETHYL ETHER (ETHYL ETHER)
- UN 1131: CARBON DISULPHIDE
- UN 1280: PETROLEUM ETHER

Packing Group II (Medium Danger)

This is a very common category for many industrial solvents and fuels.

Classification Criteria: Substances with a flash point of less than 23°C and an initial boiling point of more than 35°C.
Common Examples:
- UN 1203: PETROL / GASOLINE
- UN 1090: ACETONE
- UN 1170: ETHANOL SOLUTION (ETHYL ALCOHOL SOLUTION)
- UN 1219: ISOPROPANOL (ISOPROPYL ALCOHOL)

Packing Group III (Minor Danger)

This group includes less volatile flammable liquids like diesel and other combustible liquids.

Classification Criteria: Substances with a flash point from 23°C up to 60°C and an initial boiling point of more than 35°C.
Key Compliance Note: Liquids transported at elevated temperatures are also assigned to PG III.
Common Examples:
- UN 1202: DIESEL FUEL
- UN 1223: KEROSENE
- UN 1263: PAINT or PAINT RELATED MATERIAL
- UN 1993: FLAMMABLE LIQUID, N.O.S. (Not Otherwise Specified)

Special Provisions & Exemptions for Viscous Liquids

The ADG Code includes important rules for viscous substances like paints, varnishes, enamels, and adhesives, which can change their classification.

Reassignment to Packing Group III: Viscous liquids with a flash point below 23°C (which would normally be PG II) can be reassigned to the less restrictive PG III if they meet specific criteria for viscosity, solvent separation, packaging size (≤ 450L), and do not have a subsidiary risk of Class 6.1 (Toxic) or 8 (Corrosive).
Exemption from the ADG Code: Some viscous liquids with a flash point between 23°C and 60°C are not subject to the code at all if they are packed in receptacles of ≤ 450L, have very low solvent separation, and pass a stringent viscosity test (e.g., a flow time of ≥ 60 seconds from a 6mm jet).

Practical Takeaways for Your Business

Classification is Your Responsibility: The consignor must ensure the correct classification. Since impurities can alter a flash point, you cannot rely on a generic product name; experimental testing is often required.
Flash Point and Boiling Point Are Key: The entire hazard classification for a flammable liquid depends on two numbers: its flash point and initial boiling point. Accurate data is essential.
Check for Special Provisions: The rules for viscous liquids can significantly reduce compliance burdens by allowing a lower packing group or even a full exemption. Always check if your product qualifies.
Use Certified Testing Methods: When in doubt, the flash point must be determined experimentally. The ADG code lists approved international (ISO) and national (ASTM, AS) standards for this testing.
When in Doubt, Refer to the Code: This guide is a summary. The official ADG Code is the ultimate source for detailed compliance requirements and should always be consulted. It is available from the NTC at: https://www.ntc.gov.au/codes-and-guidelines/australian-dangerous-goods-code.

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