Dangerous goods quick reference - Class 4: Flammable substances

Class 4 dangerous goods include flammable solids and substances that can ignite spontaneously or emit flammable gases when in contact with water. These pose risks such as property damage, cargo damage, injury, environmental harm, insurance invalidation, and potential criminal prosecution.

Classification & Examples:

4.1 Flammable Solids: Self-reactive, polymerising substances, and solid desensitised explosives.
Examples: Aluminium powder, matches, sulphur, fire lighters, activated charcoal.
4.2 Spontaneously Combustible Substances: Liable to ignite without external ignition.
Examples: Phosphorus, sodium sulphide, fishmeal, carbon, oily cotton waste.
4.3 Dangerous When Wet: Emit flammable gases when in contact with water.
Examples: Calcium carbide, sodium, potassium.

Key Handling Guidelines:

• Packing: Use only approved packaging; airtight for 4.2, watertight for 4.3; never repackage without expert advice.
• Storing: Store in well-ventilated, temperature-controlled areas; away from heat, ignition sources, and (for 4.3) water; inspect regularly; train staff in emergency response; alert DG competent person if issues arise.
• Transporting: Keep risk assessments updated; secure cargo; use temperature-controlled units for self-reactive substances; comply with CTU Code; never allow ignition sources near cargo.

Handling:

Never expose to extreme temperatures; never throw, drop, or drag cargo; maintain emergency response plans; communicate clearly across the supply chain.