Dangerous Goods Class 4: Flammable Solids

The descriptions for Dangerous Goods Class 4 Flammable Solids cover solid materials that combust or ignite under the standard situation when the ignition source is present. This definition doesn’t apply if it involves accelerants or deliberate variable changes (i.e. density or pressure). Flammable solids also cover materials that combust when in contact with water, or spontaneously combust.

Dangerous Goods Class 4 consist of three divisions based on the characteristics of the materials.

Dangerous Goods Class 4 Division 4.1

Division 4.1 consists of solid materials that can ignite or combust based when certain treatments are applied to them, outside water. They consist of four types of materials, such as:

·       Self-Reactive Materials

Self-reactive materials have unstable thermal conditions. They can undergo independent chemical reactions that happen without oxygen or other ignition sources.

·       Desensitized Explosives

Explosives are classified as Dangerous Goods Class 1, but explosives suppressed with water, alcohol, or other substances are called desensitized explosives. When in this condition, they are grouped into flammable solids.

·       Readily Combustible Solids

Readily combustible solids are materials that can ignite with just frictions, such as matches. They also consist of metal powder that can react (or be ignited) in less than 10 minutes.

·       Generic Types

Generic types are combustible materials that are not included in the previous three definitions.

The placard for these materials bears a black flame on striped red and white background, with number “4” and a text “Flammable Solid”.

Dangerous Goods Class 4 (Flammable Solids) Division 4.2

Division 4.2 consists of materials that can spontaneously combust, which include pyrophoric and self-heating materials.

Pyrophoric materials can spontaneously ignite without any external sources. Some materials combust after five minutes of contact with air, while others combust in the air temperature of 54 degrees Celsius (129 degrees Fahrenheit). Common examples are powdered or sliced iron sulfide, uranium, and plutonium.

Self-heating materials are a little different. They can generate heat independently without external factors or ignitions, which can result in combustion. These materials require special storage that can prevent heat reactions.

The placard for these materials bears a black flame on a white and red background, with number “4” and a text “Spontaneously Combustible”.

Dangerous Goods Class 4 (Flammable Solids) Division 4.3

Unlike the common combustible or flammable solids, Dangerous Goods Class 4 Division 4.3 are dangerous when wet. These materials emit a flammable gas when they experience contact with water. Other similar materials can also spontaneously combust when they are wet or soaked.

Some of the most common examples are pure alkali metals, which consist of the elements of sodium, lithium, caesium, rubidium, and francium. The placard for these materials bears a white flame on a blue background and number “4”, with the text “Dangerous When Wet”.

How to Transport Flammable Solids

Transporting flammable solids like resins, matches, metal powders, alkali metals, adhesives, lighters, sodium batteries, and aluminum phosphide requires special handling. Most flammable solids must be kept in a refrigerated container, kept under the normal temperature (around 8 to 25 degrees Celsius). All containers must be labelled and marked clearly following the regulations. During transportation, the containers must be stabilized to avoid frictions or shakes. All handlers and drivers must possess a HAZMAT training background. The drivers transporting flammable solids must also be physically and mentally healthy. They also possess a valid driver’s license and is regularly tested for health problems and drugs.