Class 4.1 - Flammable Solids, Self-Reactive Substances, Solid Desensitized Explosives, & Polymerizing Substances

Under the first of these divisions, Class 4.1, there are three sets of substances described.

The first set of flammable solids in Class 4.1 are those that under normal transport conditions may either burn easily or contribute to or cause fires through friction. This group includes materials that can easily start a rapidly spreading fire if in brief contact with an ignition source (such as a burning match). In some cases, the fire can release toxic fumes or be very difficult to extinguish. Packing groups are assigned on the basis of testing and depend upon the reaction time and burning time.

The second set of flammable solids grouped under Class 4.1 is referred to as self-reactive substances. These are substances that are likely to undergo a heat-producing change even when oxygen is not present. These "self-reactive substances" are classified into seven types according to the degree of danger they present and how they must be packaged to be safe. These classifications are designated by the upper-case letters A through G.

The third division of Class 4.1 is referred to as "solid desensitized explosives." These are explosive substances that are wetted with water or alcohols, or diluted with other substances, to create a solid mixture with suppressed explosive properties.

The fourth and final division of Class 4.1 is referred to as "polymerizing substances." These are substances likely to undergo a chemical reaction that releases energy by light or heat.

To learn more about IMDG visit our International Maritime Dangerous Goods Code Online Training web page.