UK ADR module revision

ADR Class 2 Gases Study Guide

Understand gas divisions, containment systems and cylinder handling, including pressure, cryogenic injury, asphyxiation, fire and BLEVE hazards.

Practise Class 2: Gases in the app Read the Class 2: Gases guide

120 app questions4 practice topics

Module overview

What is the Class 2: Gases module?

ADR Class 2 covers gases carried in several physical forms, including compressed, liquefied, dissolved, refrigerated liquefied and adsorbed gases, as well as articles and chemicals under pressure. Unlike many other classes, gases are not assigned packing groups. Drivers instead use the Class 2 divisions, labels and additional hazardous properties to recognise whether the load is flammable, non-flammable and non-toxic, or toxic.

The module links those classifications to cylinders and other containment systems, correct handling, storage, segregation and protection from heat. A release can create more than one danger: fire or explosion, toxicity, corrosivity, oxidation, oxygen displacement and asphyxiation, rapid vapour expansion or cryogenic injury. BLEVE awareness, flammability limits, liquid-to-vapour expansion and suitable PPE help drivers understand why distance, ventilation and early emergency communication matter.

Syllabus coverage

What you study in Class 2: Gases

These themes group the official learning objectives into practical revision areas. Open the topic map below for the exact question-bank structure used by ADR Driver Pro.

Divisions, marks and labels

The three Class 2 divisions, how hazardous properties influence the classification, why packing groups are not used and how labels communicate primary and subsidiary hazards.

Gas states and containment

Compressed, liquefied, dissolved, refrigerated and adsorbed gases, chemicals and articles under pressure, and the special packaging or containment systems used for them.

Pressure, fire and cryogenic hazards

Toxicity, flammability, oxidation, corrosion, asphyxiation, low-temperature injury, BLEVE, flammability limits and the large volume change when a liquefied gas becomes vapour.

Cylinders and safe handling

Correct lifting, securing, storage and transport of cylinders, avoiding overheating, protecting valves and preventing damage during the journey.

Segregation, escape and PPE

Keeping incompatible loads apart, recognising an escape, protecting people, selecting PPE or RPE and knowing when withdrawal and specialist assistance are required.

Practice-topic map

Question-bank coverage

The app total counts unique questions in each canonical practice topic. The free column is the separate TopicsLite.plist subset available on this website.

Practice topic	In app	Free online
Divisions, Classification, Marks & Labels	25	—
Gas States, Containment & Cryogenic Risks	30	—
Gas Hazards, Escape, BLEVE & Flammability	35	—
Cylinders, Handling, Segregation & PPE	30	—
Module total	120	—

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Qualification context

How this module fits an ADR route

Class 2 belongs to Group A with Classes 3, 6 and 8. A general route combines Core and Packages and/or Tanks with either the relevant individual class modules or the Common Characteristics and Group A selection.

The class module explains shared gas hazards, but actual precautions depend on the substance, containment, quantity and transport documents. Always use product-specific and employer information for operational decisions.

Revision plan

How to study Class 2: Gases

1Start by identifying the physical form and division before deciding which gas hazard dominates a scenario.
2Compare pressure hazards, toxic exposure, asphyxiation and cryogenic contact so they do not blur into one generic “gas risk”.
3Practise cylinder checks and restraint using realistic loading and journey examples.
4Link BLEVE and liquid-to-vapour expansion to heat exposure, evacuation and the need for emergency-service control.

Common questions

Class 2: Gases FAQs

What are the ADR Class 2 divisions?

Class 2 is divided into flammable gases, non-flammable non-toxic gases and toxic gases. Other properties such as corrosivity or oxidation may appear as subsidiary hazards.

Why do Class 2 gases not use packing groups?

ADR indicates the level and type of danger for gases through their Class 2 classification codes, divisions and labels rather than assigning packing groups.

What is a BLEVE in ADR gas training?

A boiling liquid expanding vapour explosion can occur when a vessel containing liquefied gas is heated, loses strength and fails. Driver training focuses on recognising the hazard, keeping away and alerting emergency services.

Revise Class 2: Gases in ADR Driver Pro

Continue with all 120 Class 2: Gases questions, flash cards, bookmarks and saved practice history in the app.