On Tuesday we covered the first three classes of hazardous waste classes including explosives, gasses, and flammable liquids. Today, we are going to cover the remaining 6 classes as well as the ORM (other regulated materials) definitions. To refresh your memory, a hazard class is the category of hazard assigned to a hazardous material under the definitional criteria of 49 CFR Part 173 and the provisions of the HMT at §172.101. A material may meet the defining criteria for more than one hazard class but is assigned to only one hazard class. That said, read on for the definitional criteria of classes 4-9.

Class 4  

  • Division 4.1 – Flammable Solid – Explosives wetted with sufficient water, alcohol, or plasticizer to explosive properties that when dry are Class 1 explosives and self-reactive explosives that are liable to undergo at normal or elevated temperatures a strongly exothermal decomposition caused by high transport temperatures or by contamination. Also included in this definition are readily combustible solids that may cause a fire through friction, have a burning rate faster than 2.2 mm (0.087 inches) per second, or any ignitable metal powders. Ref. 173.124(a).
  • Division 4.2 – Spontaneously combustible materials – Includes pyrophoric material, which is a liquid or solid that even in small quantities and without an external ignition source can ignite within five minutes after coming into contact with air; and self-heating material, which is liable to self-heat when it comes into contact with air even without an energy source. Ref. 173.124(b).
  • Division 4.3 – Dangerous when wet materials – A material that by contact with water is liable to become spontaneously flammable or to give off flammable or toxic gas at a rate greater than one liter per kilogram of the material per hour. Ref. 173.124(c).

Class 5  

  • Division 5.1 – Oxidizer – A material that may by yielding oxygen cause or enhance the combustion of other materials. Ref. 173.127(a).
  • Division 5.2 – Organic peroxide – Any organic compound containing oxygen in the bivalent -O-O structure and which may be considered a derivative of hydrogen peroxide where one or more of the hydrogen atoms have been replaced by organic radicals, must be classed as an organic peroxide unless: it classifies as an explosive; the predominant hazard of the material is other than from an organic peroxide; the material is forbidden for transport; or the material will not pose a hazard in transport. Ref. 173.128(a).

Class 6  

  • Division 6.1 – Poisonous materials – A material, other than a gas, which is known to be so toxic to humans as to afford a hazard to health during transportation; or the material is presumed to be toxic because there is evidence of oral, dermal, and/or inhalation toxicity in laboratory animals. Ref. 173.132(a).
  • Division 6.2 – Infectious substance or etiologic agent – A viable microorganism, or its toxin, which causes or may cause disease in humans or animals. Ref. 173.134(a).

Class 7  

  • Radioactive Material – Any material, or combination of materials, that spontaneously emits ionizing radiation, and having a specific activity greater than 0.002 microcuries per gram. Ref. 173.403.

Class 8  

  • Corrosive Material – A liquid or solid that causes visible destruction or irreversible alterations in human skin tissue at the site of contact, or a liquid that has a severe corrosion rate on steel or aluminum. Ref. 173.136(a).

Class 9  

  • Miscellaneous hazardous material – A material that presents a hazard during transport but is not included in any other hazard class. Ref. 173.140(a) and (b).

ORM – Other Regulated Materials – A material such as a consumer commodity that, though otherwise subject to DOT regulations, presents a limited hazard during transportation due to its form, quantity and packaging. Ref. 173.144.

In our RCRA training programs, we provide information about the different hazard classes and their divisions, each division has a specific definition of what constitutes that type of material. A hazard class is the category of hazard assigned to a hazardous material under the definitional criteria of 49 CFR Part 173 and the provisions of the HMT at §172.101. A material may meet the defining criteria for more than one hazard class but is assigned to only one hazard class. The nine (9) hazard classes, numbered 1-9, are defined at 49 CFR Part 173. Of these nine classes, some are further broken down into divisions. For your reference, we will be defining these classes and divisions this week. Classes 1-3 are defined below, look for 4-8 on Thursday!

Class 1 – Explosives – Any substance, article, or device, which is designed to function by explosion, i.e., an extremely rapid release of gas and heat, or by chemical reaction within itself is able to function in a similar manner even if not designed to function by explosion, unless such substance or article is otherwise specifically classified.

  • Division 1.1 – Consists of explosives that have a mass explosion hazard. A mass explosion is one which affects almost the entire load instantaneously. (Formerly Class A explosives prior to Jan. 1, 1991). Ref. 173.50(b)(1).
  • Division 1.2 – Consists of explosives that have a projection hazard but not a mass explosion hazard. (Formerly Class A or Class B explosives). Ref. 173.50(b)(2).
  • Division 1.3 – Consists of explosives that have a fire hazard and either a minor blast hazard or minor projection hazard or both, but not a mass explosion hazard. (Formerly Class B explosives). Ref. 173.50(b)(3).
  • Division 1.4 – Consists of explosive devices that present a minor explosion hazard. No device in this division may contain more than 25 g (0.9 ounces) of a detonating material. (Formerly Class C explosives.) Ref. 173.50(b)(4).
  • Division 1.5 – Consists of very insensitive explosives. This division comprises substances which have a mass explosion hazard but are so insensitive that there is very little probability of initiation or of transition from burning to detonation under normal conditions of transport. (Formerly Blasting Agents.) Ref. 173.50(b)(5).
  • Division 1.6 – Consists of extremely insensitive articles which do not have a mass explosive hazard. This division comprises articles which contain only extremely insensitive detonating materials with negligible probability of accidental initiation or propagation. (No previous applicable hazard class.) Ref. 173.50(b)(6).

Class 2 

  • Division 2.1 – Flammable Gas – Material that is a gas at 20°C (68°F) or less and 101.3kPa (14.7 psi) of pressure or a material which has a boiling point of 20°C or less at 101.3 kPa, which is ignitable at 101.3 kPa of pressure when in a mixture of 13 percent or less by volume of air; or has a flammable range at 101.3 kPa with air of at least 12 percent regardless of the lower limit. Ref. 173.115(a).
  • Division 2.2 – Non-flammable, non-poisonous compressed gas – including compressed gas, liquefied gas, pressurized cryogenic gas, and compressed gas in solution. Any material which exerts pressure of 280 kPa (41 psi) at 20°C and does not meet the definition of Division 2.1 or 2.3. Ref. 173.115(b).
  • Division 2.3 – Poisonous Gas – A material which is a gas at 20°C or less and a pressure of 101.3 kPa and which is a material known to be toxic to humans or is presumed to be toxic to laboratory animals and therefore poses a hazard to health during transportation. Ref. 173.115(c).

Class 3

  • Flammable Liquid – Any liquid having a flashpoint of not more than 60°C (140°F), with certain exceptions. Ref. 173.120(a).
  • Combustible Liquid – Any liquid that has a flashpoint above 60°C (140°F) and below 93°C (200°F) and does not meet the definition of any other hazard class. Ref. 173.120(b).