Class 4 Flammable Solids Explained | NZ Dangerous Goods Guide

What Are Class 4 Flammable Solids?

Class 4 dangerous goods include substances that can easily catch fire, self-heat or produce flammable gas when in contact with water.

These materials present significant fire and ignition risks during handling, storage, and transport, and are regulated under dangerous goods transport rules in New Zealand and internationally.

Class 4 is divided into three divisions, depending on how the fire risk occurs.

Class 4.1: Flammable Solids

Class 4.1 includes solid substances that:

Ignite easily
Can cause or spread fire through friction
May undergo strong heat-producing reactions

These substances can burn rapidly and may intensify fires once ignited.

Common examples:

Matches
Certain hand wipes
Sulphur Metal powders (some types)

Class 4.2: Substances Liable to Spontaneous Combustion

Class 4.2 includes substances that:

Can self-heat under normal transport conditions or Heat when exposed to air and ignite without an external flame.

These materials may begin burning on their own without any ignition source.

Common examples:

Charcoal Fish meal
Some metal powders
Oily rags (under certain conditions)

Class 4.3: Substances That Emit Flammable Gas

When in Contact with Water Class 4.3 includes substances that:

React with water and produce flammable gases or may ignite spontaneously when exposed to moisture.

These substances must be kept completely dry during storage and transport.

Common examples:

Calcium carbide
Sodium metal
Potassium metal
Lithium metal

We are an online training platform that helps shippers and professionals understand and comply with dangerous goods requirements.

Class 4 Flammable Solids Explained | NZ Dangerous Goods Guide

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