Hazard Classification System

The Department of Transportation (DOT) lists hazardous chemicals within nine classes in the Emergency Response Guidebook put out by the Pipeline Hazardous Materials Safety Administration (PHMSA). OSHA follows this codified system when dealing with chemical hazards within confined spaces. As a competent person entry supervisor, you must be knowledgeable of these hazards.

The nine hazard classes are:

• Class 1 - Explosives
• Class 2 - Gases
• Class 3 - Flammable liquids
• Class 4 - Flammable solids; substances liable to spontaneous combustion; substances which, in contact with water, emit flammable gases
• Class 5 - Oxidizing substances and organic peroxides
• Class 6 - Toxic and infectious substances
• Class 7 - Radioactive material
• Class 8 - Corrosives
• Class 9 - Miscellaneous dangerous goods

Please note that the class numbers are for convenience only; they DO NOT indicate a relative degree of danger. Let us now take a closer look at each class.

To learn more about Confined Spaces Competent Person/Supervisor visit our Confined Spaces Competent Person/Supervisor Online Training web page.