Dangerous Goods Classification UK: 9 Classes & UN Numbers

Dangerous goods classification is the legal system used in the UK to identify what a substance or article is, what hazards it presents, and how it must be moved safely. Each item is assigned a UN number and a proper shipping name, based on hazard criteria in ADR (for road and rail), with aligned rules in IMDG (sea) and IATA (air). Getting the classification right is not optional: it dictates packaging, marking, labelling, documentation, emergency response information and any exemptions you can use.

This article gives you a practical, UK‑focused overview. You’ll see the nine UN classes and key divisions at a glance, learn how ADR Part 2 classification works, and how to select the correct proper shipping name and UN number using Tables A and B. We’ll cover packing groups, subsidiary hazards, transport categories, tunnel codes, mixtures and N.O.S. entries, environmental hazards (UN 3077/3082), wastes and samples, limited and excepted quantities, mode differences, and a step‑by‑step workflow from SDS to compliant shipment. Let’s start with the classes.

The 9 classes and divisions at a glance

ADR groups all dangerous goods into nine UN classes. Use this quick reference to orient your dangerous goods classification in the UK before you apply the detailed criteria and naming rules.

How dangerous goods are classified in the UK (ADR part 2)

In the UK, dangerous goods classification follows ADR Part 2. The consignor must identify all relevant hazards, test against the class/division criteria, and apply ADR’s hierarchy of classification to decide the primary class and any subsidiary hazards. Part 2 provides the detailed definitions and thresholds for each class, and this step is the precursor to everything else.

Many substances are already classified; otherwise mixtures, solutions and articles are classified from first principles. Where applicable, a Packing Group is assigned by severity, and environmental hazards are assessed under ADR 2.1.3.8/2.2.9.1.10. For unknown samples, ADR 2.1.4 permits conservative over‑classification. The output is a defensible class/division, subsidiary hazards and (if relevant) Packing Group.

Choosing the proper shipping name and UN number (using ADR tables A and B)

With your class, any subsidiary hazards and (if relevant) packing group determined, the next task is to select the proper shipping name and UN number. Use ADR Table A (3.2.1) together with the alphabetical index in Table B, applying ADR 3.1.2 naming rules.

1. Find candidate entries: Search Table B by name or group; cross‑check in Table A.
2. Choose the most appropriate entry: Prefer specific over generic per ADR 3.1.2.
3. Apply name qualifiers: Add terms like “SOLUTION”, “LIQUID”, “SOLID”, “MOLTEN”, “STABILIZED” as required (ADR 3.1.2.3–3.1.2.7).
4. Handle N.O.S. entries: Where indicated, add technical name(s) per Special Provision 274.
5. Confirm all columns: In Table A verify PG, labels, special provisions, packing/IBC/tank instructions, transport category and tunnel code.

Packing groups, subsidiary hazards and precedence rules

Packing groups (PG) express severity within a class. Once you’ve classified in ADR Part 2, assign PG I–III using the criteria, then confirm in Table A column 4. Some goods have no PG (notably gases and explosives). Identify all subsidiary hazards, then apply ADR’s precedence of hazards (2.1.3.5.3) to fix the primary class and the extra labels/provisions. These decisions feed directly into packaging performance levels, labels and documentation.

Transport categories and tunnel restriction codes (ADR road)

ADR road adds two planning flags that complete dangerous goods classification in the UK: transport category and tunnel restriction code. In Table A, the transport category (0–4) sets the small/‘limited load’ thresholds for ADR 1.1.3.6 exemptions. The tunnel restriction code indicates which tunnel categories (A–E) are prohibited for that UN entry. Always verify both for your chosen UN number, packing/quantity and route.

Mixtures, solutions and N.O.S. entries (including the predominant substance rule)

Most mixtures and solutions aren’t listed individually. Classify against Part 2, then apply 2.1.3.3 (predominant substance): name by the component driving the hazards, ignoring impurities unless an exception applies. If no specific or generic entry fits, use an N.O.S. name with the technical name(s) per SP 274. Add “SOLUTION” where required and set PG from mixture properties.

Environmental hazards and marine pollutants (UN 3077/UN 3082)

Under ADR, assess environmental hazards using ADR 2.1.3.8 and 2.2.9.1.10. If criteria are met, the goods are “environmentally hazardous” and must display the dead fish and tree mark (ADR 5.2.1.8/5.3.6), even when another primary class applies. Where no other hazard governs, use UN 3077 for solids or UN 3082 for liquids. At sea, IMDG treats these as marine pollutants; methods can differ but the outcome is the same: liquids to UN 3082, solids to UN 3077.

Wastes and samples: special classification and descriptions

Wastes follow the same ADR Part 2 process as other substances: identify hazards and select the correct UN entry. For generic/N.O.S. names, Special Provision 274 may require naming the constituent(s) that create the hazard. Add the word “WASTE” before the proper shipping name in the transport description (ADR 5.4.1.1.3). If full classification isn’t practicable for samples, ADR 2.1.4 allows conservative over‑classification. Note: clinical waste has specific provisions.

Limited quantities and excepted quantities

Your dangerous goods classification in the UK also determines access to small-quantity reliefs. Limited quantities (LQ) and excepted quantities (EQ) are packaging-based concessions shown against each UN entry in ADR’s lists. If permitted, you may use small inner packagings within combination packs and apply the specific LQ or EQ mark, with many full ADR provisions not applying. These are not the same as “limited loads” under ADR 1.1.3.6. Always check the UN entry to confirm eligibility, limits and any exclusions before relying on LQ or EQ.

Mode differences: air (IATA), sea (IMDG), road/rail (ADR/RID)

Dangerous goods classification in the UK starts from the same UN criteria, but the modal rules you apply differ. The UK uses ADR/RID for road and rail, IMDG for sea and IATA DGR for air. All are harmonised with the UN Model Regulations, but each adds mode‑specific provisions you must verify for your chosen UN entry.

• ADR/RID: Check Table A for transport category and tunnel restriction code for exemptions and routing.
• IMDG: Marine pollutant treatment can differ in method, but outcomes align (e.g., UN 3077 solids, UN 3082 liquids).
• IATA: Uses aligned UN classes and names; consult IATA DGR for air carriage specifics before packing and booking.

How classification drives packaging, marking, labelling and documentation

Your dangerous goods classification in the UK is the switch that turns on every downstream requirement. The chosen UN number, proper shipping name, class/divisions, subsidiary hazards and (if applicable) packing group map via ADR Table A to the correct packing instructions, performance level, marks/labels/placards and what must appear on the transport document. If the substance is environmentally hazardous under ADR 2.1.3.8/2.2.9.1.10, the dead fish and tree mark is required even when another primary class applies.

• Packaging: Select UN performance-tested packaging to the assigned PG (I–III) and follow the stated packing/IBC/tank instructions in Table A; note some entries (e.g., gases, explosives) have no PG.
• Marking and labelling: Apply the UN number and proper shipping name, primary and subsidiary hazard labels, and the environmental mark where required; use LQ/EQ marks only when permitted for that UN entry.
• Documentation: Show the UN number and proper shipping name (with qualifiers like “WASTE”, “SOLUTION”, “MOLTEN”, “STABILIZED” as applicable), the class and PG (if assigned), and include technical names for N.O.S. entries per Special Provision 274.

Common examples by class in UK transport

Seeing real-world items helps bring dangerous goods classification in the UK to life. Use these as familiar touchpoints, but always confirm the exact UN number, name and conditions in ADR Tables A and B before shipping.

• Class 2.1 (flammable gas): Butane cylinders
• Class 3 (flammable liquids): Paints and many solvents
• Class 5.1 (oxidising substances): Oxidising agents
• Class 6.2 (infectious substances): Infectious materials
• Class 8 (corrosives): Sulphuric acid solutions (PG II/PG III depending on concentration)
• Class 9 (miscellaneous): Lithium batteries, asbestos, automotive airbags

Practical classification workflow (from SDS to UN number)

Use this fast, defensible workflow to turn product data into a compliant dangerous goods classification in the UK, ready for packing and paperwork. It keeps you aligned with ADR Part 2 and the naming rules in Tables A and B.

1. Gather data: Composition and key properties from the SDS/supplier.
2. Assess hazards: Classify per ADR Part 2; set subsidiary hazards and PG (if any).
3. Check environment: Apply ADR 2.1.3.8/2.2.9.1.10 for environmental hazards.
4. Select name/UN: Use Table B then confirm in Table A; follow ADR 3.1.2 hierarchy.
5. Qualify the name: Add “SOLUTION”, “LIQUID”, “SOLID”, “MOLTEN”, “STABILIZED” as required.
6. N.O.S. rules: If used, add technical name(s) per SP 274.
7. Verify all columns: Labels, special provisions, packing/IBC/tank, transport category, tunnel code.
8. Edge cases: Mark “WASTE” where applicable; for unknown samples, over‑classify under ADR 2.1.4.

When classification triggers other duties (DGSA, training, packaging approvals)

Once you confirm an item is dangerous goods, further obligations follow. In the UK this can trigger the need to appoint a Dangerous Goods Safety Adviser (DGSA) under ADR, ensure role‑appropriate dangerous goods training for all staff involved (per mode), and use UN performance‑tested packaging with any required approvals and periodic revalidation as indicated by the packing instruction in Table A. Classification therefore drives resourcing, training and packaging approvals.

Frequent mistakes and how to avoid them

Common pitfalls that derail dangerous goods classification in the UK include: treating GHS/CHIP supply classifications as transport classification; picking an N.O.S. name but omitting the required technical name(s) (SP 274); missing subsidiary hazards and precedence; mixing up LQ/EQ with ADR 1.1.3.6 “limited loads”; forgetting qualifiers or the word WASTE; overlooking environmental hazard marking; and ignoring transport category/tunnel codes. Always verify against ADR Part 2 and Table A/B.

Key takeaways

Classification is the foundation of compliance. Use ADR Part 2 to determine class, divisions and any subsidiary hazards, then choose the proper shipping name and UN number via Tables A and B. Assign the correct packing group (if applicable), check environmental hazard rules, and verify every Table A column so packaging, marking, labelling, documentation, transport category and tunnel codes are right the first time.

• Start in ADR Part 2: Determine primary class and subsidiary hazards.
• Select the name/UN: Apply ADR 3.1.2 and qualifiers.
• Assign PG: Where relevant, set I–III from criteria.
• Apply environment rules: Mark if hazardous; use UN 3077/3082 where appropriate.
• Name accurately: Add “WASTE” and required technical names for N.O.S.
• Confirm exemptions: LQ/EQ, 1.1.3.6 and routing via transport category/tunnel code.

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