When fully regulated, you know your inventory will be properly classified under the Department of Transportation’s (DOT) Hazardous Materials Regulations (HMR). But what does this mean? What are these hazardous materials classes and how many are there? This article will discuss these hazard classes and answer this question for fully regulated shippers by providing an overview of each hazard class, including the materials that fall within it.
How Many Hazard Classes Are There For Fully Regulated Items?
There are 9 hazard classes for fully regulated items; they are –
1. Explosives
Explosives meet the hazardous materials classification (Class 1) because they can produce hazardous amounts of heat, sound, smoke, gas, or light. Through a chemical reaction, they are also capable of producing gases at speeds, temperatures, and pressures that can cause disastrous damage.
These include dynamite, fireworks, blasting caps, and detonating cords.
2. Gases
Gases include compressed, liquefied, dissolved, refrigerated liquefied, aerosols, and other gases. They are defined by the hazardous materials classification (Class 2) as “substances that have a vapor pressure of 300 kPa or greater at 50°c or are completely gaseous at 20°c at standard atmospheric pressure.” Gases are considered dangerous because they pose an imminent threat as a potential asphyxiate and because they are often extremely flammable.
3. Flammable Liquid and Combustible Liquid
Flammable liquids or combustible liquids are volatile, and can often give off a flammable vapor. They are defined by the hazardous materials classification (Class 3) as “liquids, mixtures of liquids or liquids containing solids in solution or suspension which give off a flammable vapor, and have a flash point at temperatures not more than 60.5°C or 141°F.” Flammable liquids are capable of posing serious threats because of their volatility, and the potential to cause severe conflagrations and combustibility.
4. Flammable Solid, Spontaneously Combustible and Dangerous When Wet
Flammable solids fit within the hazardous materials classification (Class 4) because they are highly combustible, are capable of posing serious hazards due to their volatility, combustibility, potential to cause or propagate severe conflagrations, and can even cause fire through friction.
READ: GHS Label (Globally Harmonized System Label)
Flammable solids are defined as “materials under conditions encountered in transport, are combustible or may cause or contribute to fire through friction, self-reactive substances which are liable to undergo a strongly exothermic reaction or solid desensitized explosives.”
5. Oxidizer and Organic Peroxide
Oxidizers are substances that can produce oxygen. They are within the hazardous materials classification (Class 5) because the right circumstances they can contribute to the combustion of other hazardous substances, though they are not always combustible themselves. Oxidizers can be defined as “substances that can cause or contribute to combustion, typically by producing oxygen as a result of a redox chemical reaction.” Organic peroxides are considered dangerous goods because they are thermally unstable and can exude heat while undergoing exothermic auto-catalytic decomposition. These materials can also undergo explosive decomposition, burn rapidly, be sensitive to friction, or react dangerously with other substances.
6. Poison (Toxic) and Poison Inhalation Hazard
Toxic materials fall under the hazardous materials classification (Class 6) because of the ability to cause serious injury or death if swallowed, inhaled, or in contact with skin. Infectious substances are also classified as dangerous and good for containing pathogens, which include bacteria, viruses, parasites, and/or other agents that can cause disease to humans or animals when contact is made. Dangerous goods regulations define pathogens as “microorganisms, such as bacteria, viruses, rickets, parasites, and fungi, or other agents which can cause disease in humans or animals.”
7. Radioactive
Radioactive materials are defined by hazardous materials classification as “any material containing radionuclides where both the activity concentration and the total activity exceeds certain pre-defined values.” While undergoing radioactive decay, radioactive materials can emit harmful ionizing radiation.
8. Corrosive
Corrosive are substances that degrade or disintegrate other materials upon contact through a chemical reaction if leakage or damage occurs to the surrounding materials. It is capable of destroying materials, such as living tissues. The Department of Transportation considers an acid with a pH <2 or greater than 12.5 to be corrosive.
9. Miscellaneous, and the general Dangerous placard
As the name implies, miscellaneous hazardous materials classification (Class 9) are substances that present an imminent threat that is not covered within the definitions of the other 8 classes. Class 9 miscellaneous dangerous goods present a wide variety of potentially hazardous threats to human health and safety, infrastructure, and/or their means of transport.
Moreover, miscellaneous hazards are present at every worksite and workers need to take appropriate prevention measures against them. Hence, courses like OSHA 30-hour dispense general knowledge about every type of hazard.
These hazards are defined as but not limited to “environmentally hazardous substances, substances that are transported at elevated temperatures, miscellaneous articles and substances, genetically modified organisms and micro-organisms and magnetized materials and aviation regulated substances.”
READ: What Is COSHH? Everything You Need To Know
Dangerous substances are very widely defined, but some, for example, most medicines and cosmetics, do not have the hazardous properties that would bring them within the scope of the requirements, and those that do are usually carried in very small receptacles, allowing least partial exemption from the requirements (either limited quantities or limited loads – see Main Exemptions)
Consignors must identify the hazards of the goods they intend to transport. There are nine classes, some with divisions, as follows.
| UN Class | Dangerous Goods | Division(s) | Classification |
| 1 | Explosives | 1.1 – 1.6 | Explosive |
| 2 | Gases | 2.1 | Flammable gas |
| 2.2 | Non-flammable, non-toxic gas | ||
| 2.3 | Toxic gas | ||
| 3 | Flammable liquid | Flammable liquid | |
| 4 | Flammable solids | 4.1 | Flammable solid |
| 4.2 | Spontaneously combustible substance | ||
| 4.3 | The substance which in contact with water emits flammable gas | ||
| 5 | Oxidising substances | 5.1 | Oxidising substance |
| 5.2 | Organic peroxide | ||
| 6 | Toxic substances | 6.1 | Toxic substance |
| 6.2 | Infectious substance | ||
| 7 | Radioactive material | Radioactive material | |
| 8 | Corrosive substances | Corrosive substance | |
| 9 | Miscellaneous dangerous goods | Miscellaneous dangerous goods |
READ: What Is Hazmat Test
Part 2 of ADR works through the categories in a logical sequence. It sets out descriptions and criteria in some detail. The consignor must assign a “proper shipping name” and UN Number to the substance.
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