IMO Classes

Gases in liquid, compressed, or refrigerated form. Depending on their properties, these goods are classified as either asphyxiant, oxidizing, flammable, or toxic gases. Based on the reactions they cause, these gases are divided into three subclasses:

• Subclass 2.1. Flammable gases. This is any type of gas that is ignitable when it comes in contact with a heat source, such as propylene, ethane, or butane. The label must contain a symbol with a black or white flame on a red background, with the number “2” at the bottom.
• Subclass 2.2. Non-flammable, non-toxic gases. These are gases that displace oxygen, causing asphyxiation; one example of these gases is helium. The label contains an image of a black or white bottle of gas on a green background, with the number “2” at the bottom.
• Subclass 2.3. Toxic gases. These are gases that can cause serious injury or death when inhaled. They can be flammable, corrosive, or oxidizing, such as chlorine. The label contains an image of a black skull over black crossbones. The background is white and it contains the number “2” at the bottom.

This classification includes flammable liquids and insensitive liquid explosives. Examples include turpentine, gasoline, paints, and varnishes. The label contains a symbol with a black or white flame on a red background (like the label for gases in Class 2.1). The label for Class 3 is different in that it has a number “3” at the bottom.

This class is divided into the following subcategories based on the properties of the solids:

• Subclass 4.1. Flammable solids, self-reactive substances, and desensitized explosives. These solids are liable to spontaneous combustion. The label contains a black flame on a white background with seven vertical red stripes and the number “4” at the bottom.
• Subclass 4.2. These are spontaneously flammable substances. This means that they could suddenly ignite when they come in contact with the air or during transport. Examples include coal, ferrous metal shavings, wet cotton, etc. The label contains a black flame on a background that is white on top and red on the bottom, with the number “4”.
• Subclass 4.3. Substances that emit flammable gases when they come in contact with water. Some of the most common materials in this subclass include sodium, potassium, and calcium carbide. The label contains a black or white flame on a blue background with the number “4” at the bottom.

This class is divided into the following subcategories based on the properties of the solids:

• Subclass 5.1. Oxidizing substances. Liquids or solids that can cause combustion or create a flammable environment. One example is ammonium nitrate. The label contains a black flame on top of a circle, with a yellow background and the number “5.1” at the bottom.
• Subclass 5.2. Organic peroxides. These substances are derived from hydrogen peroxide. They are highly dangerous and may only be transported in certain quantities in special cargo units. The label contains a black or white flame with a background that is red on top and yellow on the bottom. It also contains the number “5.2” at the bottom.

This class is divided into the following subcategories based on the properties of the substance:

• Subclass 6.1. Toxic substances. These are substances that may cause death by inhalation, cutaneous absorption, or ingestion. Examples include methanol and dichloromethane. The label for this subclass contains a black skull and crossbones over a white background (like the label for Class 2.3, toxic gases) but is distinguished by the number “6” at the bottom.
• Subclass 6.2. Infectious substances. These substances contain pathogens (microorganisms) that could cause disease. Some examples include diagnostic specimens, material for preparing vaccines, secretions, blood, excrement, lab cultures, etc. The label for this subclass may contain the words “Infectious substances” or “In case of damage, flood, or fire, alert the health authorities immediately” at the bottom. The label includes a symbol made up of three black crescent moons on top of a circle, with a white background and the number “6” at the bottom.

Materials that contain radionuclides, such as uranium, plutonium, and thorium. The labels for this substance are determined as follows:

• Category I. Packages with a maximum surface radiation level of 0.5 mrem/hr or containers that do not contain packages with higher categories. The label for this category is white with a black trefoil shape; below this is the word “Radioactive”, followed by a small red vertical line. The label also contains the words “Contents,” “Quantity,” and “Activity,” as well as the number “7” at the bottom.
• Category II. Packages with a surface radiation level greater than 0.5 mrem/hr, but no more than 50 mrem/hr . The transport index must not exceed 1.0; this can also apply to containers with a transport index not exceeding 1.0 with no Category III packages visible.
• Category III. Packages with a maximum surface radiation level of 200 mrem/hr, or containers whose transport index is less than or equal to 1.0 and which are transporting visible Category III packages.

The label for Categories II and III is yellow with a border on top and white on the bottom. It includes an image of a black trefoil and should always include the word “Radioactive” followed by two or three small vertical lines, depending on the category. It must also contain the words “”Contents” and “Activity,” along with a box outlined in black that says “Transport Index”. It also contains the number “7” at the bottom of the label.

• Category IV. Fissionable materials. This label is white and must contain the word “FISSIONABLE” in black at the top. At the bottom is a box that says “Critical Care Index” and the number “7”.

These substances have a destructive effect when they come in contact with other substances, meaning that they are damaging to skin tissue. Some examples of corrosive substances are sulfuric acid and sodium hypochlorite. The label must contain a symbol with two test tubes pouring liquid over a hand and a piece of metal; the background of the top portion is white and the bottom is black with the number “8”.

This category includes dangerous substances not included in the other classes, such as dioxins, lithium batteries, dry ice, etc. The label is white with seven vertical black lines on the top half and the number “‘9”, underlined, in the bottom half.