TDG – Unit 3
How are Dangerous Goods Classified?
Classification matters for dangerous goods are dealt with in Part 2 of the TDG regulations. Persons who manufacture dangerous goods or products containing dangerous goods cannot offer them for transport unless they have been properly classified. Each dangerous good falls within one of the nine designated "classes" of dangerous goods found in the Regulations. Each of these classes is further broken down into sections to give us more specific information on a dangerous good.
Under the "Clear Language" Regulations the system of classification has been simplified. For example, the old regulations used a number of different schedules to aid in classification.
The Classification Schedules
The classification schedules are found in the TDG Regulations and are designed to provide the user with the immediate information they need to know regarding the classification and transportation of dangerous goods. There are three schedules.
SCHEDULE 1
Schedule 1 lists all dangerous goods sorted by UN Number. You can also find the classification of a dangerous good by Class (1 through 9). Schedule 1 also includes information on things like quantity exemptions and limitations, special provisions for handling, and emergency response assistance plan (ERAP) index numbers
UN Number
The UN Number of a dangerous good is a designation for identification purposes which has been established as an international standard by the United Nations international codes.
Schedule 1
Schedule 1 provides 10 columns of information:
Column 1 - The UN Number of a Dangerous Good
Column 2 - The Shipping Name and Description of a Dangerous Good
Column 3 - The Class of a Dangerous Good (1 to 9)
Column 4 - Packing Group/ Risk Group
Column 5 - Special Provisions for Handling
Column 6 – Explosives Limit and Limited quantity Index
Column 7 – Emergency Response Assistance Plan Index
Column 8 – Passenger Carrying Ship Index
Column 9 – Passenger Carrying Road Vehicle or Passenger Carrying Railway Vehicle Index
Column 10 – Marine Pollutant - designated by the use of the letter "P" (marine pollutant) or the letters "PP" (severe marine pollutant).
Schedule 1
Schedule 1 should be referred to first when classifying a dangerous good. If a material is not listed in Schedule 1, then Part 2 in the regulations should be referred to for the detailed classification criteria and diagnostic tests that need to be used to determine each class of dangerous goods.
SCHEDULE 2
Schedule 2 contains special provisions that apply to dangerous goods. The numbers of the special provisions in this Schedule correspond to the numbers in column 5 of Schedule 1. Each UN number that has the special provision against it is also found in italics at the end of each special provision.
SCHEDULE 3
Schedule 3 is a cross-reference index that is intended to supplement Schedule 1. Schedule 3 lists each shipping name and description in alphabetical order, followed by the corresponding primary class and UN number. The first two columns deal with the alphabetical listing dependant on which version you use (French or English). For example, if you are using the French version the English listing would be found in column 2.
This Schedule also includes dangerous goods that are forbidden for transport, and includes goods that do not have a UN number. Schedule 1 also forbids some dangerous goods from being transported when the word "forbidden" is shown in column 3 (class).
Schedule 3
Schedule 3 provides 5 columns of information:
- Column 1 - Alphabetical listing (English)
- Column 2 - Alphabetical Listing (Corresponding Number in French)
- Column 3 – Description (name)
- Column 4 – Primary Class (1-9, if applicable) and forbidden goods
- Column 5 – UN Number
Example - Schedule 3
SCHEDULE 3 (Example of the first 5 listings – English version)
Classification of Dangerous Goods
To aid in identification, dangerous goods are separated into distinct classes according to the dangers they represent. There are nine classes of dangerous goods and most of these classes are further divided into "divisions". The classes and divisions of dangerous goods will be examined in detail at the end of this section.
Material Class and Division
The "division" is a more precise identification of the danger associated with a particular good within the class. For example, the division may relate to the flashpoint of flammable liquids, or the sensitivity of explosives, or the danger associated with compressed gasses. To determine the division of a particular dangerous good you need to consult the schedule.
Material Class and Division
Each Each class and division of a dangerous good is represented by two numerals that are separated by a decimal point. The division number follows the class number. To illustrate this decimal system we will look at sulphur dioxide as an example. Sulphur dioxide is a gas which under TDG is classified as a Class 2 material. Sulphur dioxide is further classified as a poison which is denoted as a Division 3 material. Therefore, under the TDG classification system sulphur dioxide is classified as 2.3.
Material Class and Division
Many dangerous goods present more than one type of danger. When this is the case the more serious or "primary" classification is listed first on the shipping document, followed by the less serious classification(s) in brackets.
Material Class and Division
For example, Battery fluid acid is classified as a corrosive but carries a second less serious hazard of being environmentally hazardous. On the shipping document it would be listed as "BATTERY FLUID ACID - Class 8 (9)." In this circumstance class 8 represents the corrosive properties and class 9 represents the "less serious" environmental hazard. Each class and division of dangerous goods will be examined in detail later in this section.
Packing Groups
Another method used to aid in the identification of dangerous goods for transport is the assignment of "Packing Groups". A packing group is intended to provide the degree of danger associated with a material. Packing groups are designated with roman numerals.
Packing Groups - Types
There are three types of "Packing Groups" found in the TDG Regulations and Schedules. For more detailed information on the criteria and standards used to establish packing groups for each class of material you should consult Part 2 of the Regulations.
Packing Group I - Great Danger
Packing Group II - Moderate Danger
Packing Group III - Minor Danger
Responsibility for Classifying - Consigner
It is the consignor’s responsibility to classify a substance, product or organism to determine if it is a dangerous good. A "consignor" is defined as "the person who is named in a shipping document as the consignor, or imports dangerous goods into Canada; or if this is not applicable, has possession of a dangerous good immediately before they are in transport." A person may be both a consignor and a carrier of the same consignment, for example, a manufacturer who also transports the dangerous goods they produce.
A consignor must do all the prep work, or hire someone to do it, before a carrier can take possession of a dangerous good. Preparing the dangerous goods for transport includes:
- classifying the dangerous goods,
- completing the appropriate documentation,
- affixing the dangerous goods safety marks on the means of containment,
- selecting a means of containment, etc.
When importing dangerous goods into Canada, the consignor must ensure that they have the correct classification before the dangerous goods are transported.
Responsibility for Classifying Dangerous Goods
Classification is normally done by, or in consultation with, a person capable of understanding the nature of the dangerous goods such as a manufacturer, a person who formulates, blends, or prepares mixtures or solutions of goods. In the case of infectious substances, a doctor, scientist, veterinarian, epidemiologist, genetic engineer, microbiologist, pathologist, nurse, coroner or laboratory technologist or technician is involved.
Classifying dangerous goods involves determining the shipping name, UN number, primary class, and as applicable, the subsidiary class(es), compatibility group letter, packing group and risk group.
Responsibility for Classifying Dangerous Goods
The consignor may use a classification that was determined by the Department of Natural Resources for Class 1 explosives. A consignor may also use a classification determined by Health Canada or the Canadian Food Inspection Agency for Class 6.2 infectious substances. The classification of a previous consignor or manufacturer may be used for any class of dangerous goods.
Classification of Dangerous Goods – Mode of Transport
Dangerous goods are often transported by more than one mode of transport. In the old TDG Regulations, each mode of transportation had its own set of rules. This made it difficult to determine how to properly prepare dangerous goods for transport, for example, by truck to a train, then by train to a ship and then by ship to a destination.
These rules, often based on international modal requirements, have been converging due to harmonization efforts and this is recognized where possible in the Clear Language Regulations. This serves to allow a consignor to more easily prepare dangerous goods for multi-modal transportation
Classification of Dangerous Goods – Mode of Transport
Depending on the mode of transport required, classification of dangerous goods is done in accordance with the International Civil Aviation Organization (ICAO) Technical Instructions, the International Maritime Dangerous Goods (IMDG) Code. The United Nations (UN) Recommendations may be used within Canada by road vehicle, railway vehicle or by ship on a domestic voyage.
The ICAO Technical Instructions and Part 12 (Air), of the TDG Regulations must be consulted for all shipments by air. For international transport by ship, the IMDG Code must be consulted, as well as, Part 11 (Marine), of the regulations.
Responsibility for Classifying Dangerous Goods
For transport from the United States into Canada by road vehicle or railway vehicle, the shipping name used must be one that is recognized in Schedule 1, Classes 1 to 9, of the Regulations or in the UN Recommendations.
Errors in Classification
If an error in classification is noticed or if there are reasonable grounds to suspect an error in classification, the consignor must not allow a carrier to take possession of the dangerous goods for transport until the classification has been verified or corrected.
If a carrier notices or suspects an error in classification while the dangerous goods are in transport they must advise the consignor and immediately stop transporting the dangerous goods until the consignor verifies or corrects the classification. The consignor must immediately verify or correct the classification and ensure that the carrier is provided with the proper information.
We will now take a look at each of the Classes and Divisions involved with the TDG system.
The Nine Classes of Dangerous Goods
Class 1 – Explosives:
This class includes explosives within the meaning of the Explosives Act. Explosives are included in Packing Group II.
Class 1 materials are further divided into six divisions.
Class 1 – Explosives (cont)
Division 1.1– This division of Class 1 materials consist of explosives that have a mass explosion hazard.
Division 1.2 - These materials consist of explosives that present a projection hazard (shrapnel). Fireworks are an example of this class of material.
Class 1 – Explosives (cont)
Division 1.3 – These materials consist of explosives that present an "incendiary" fire hazard and may also have a minor blast and/or projection hazard.
Division 1.4 – These materials consist of explosives which present a minor blast hazard.
Class 1 – Explosives (cont)
Division 1.5 – These materials consist of "insensitive" explosives. Insensitive means that these materials present little risk of initiation.
Division 1.6 - These materials consist of extremely "insensitive" detonating devices. These materials present a very low risk of initiation.
Class 1 - Explosives: Compatibility Groups
Explosives are also assigned a letter for "Compatibility Groups". These letters provide guidance in identifying materials that can be transported together without significant increase of hazard. The "compatibility groups" are identified by 13 letters - A through H, J, K, L, N and S. More information on the compatibility groups for explosives can be found in the Appendix 2 of the Clear Language Regulations.
Class 2 – Gases
This class of materials includes gases that are compressed, deep refrigerated, liquefied or dissolved under pressure. A substance is included in Class 2, Gases, if it is a gas, a mixture of gases, a mixture of one or more gases with one or more vapours of substances included in other classes, an article charged with a gas, tellurium hexafluoride, or an aerosol. There are no packing groups for Class 2, Gases.
Class 2 – Gases (cont):
Division 2.1 – This division of Class 2 consists of gases that are flammable. Propane is a common example of this type of material.
Division 2.2 – These materials consist of non-flammable compressed gases. Oxygen is an example of this class of material.
Division 2.3 – These materials consist of gases that are poisonous or toxic. Sulphur dioxide is an example of this class of material.
Class 3 - Flammable Liquids
Flammable liquids have a "flash point" of not more than 60 degree Celsius. A combustible liquid has a flash point above 60.5 degrees Celsius and below 93 degrees Celsius. The flash point of a material refers to the minimum temperature at which a liquid gives off enough vapour to ignite in test circumstances. When you find a material with a low flashpoint it means that the material presents a higher hazard of catching fire or exploding. Flammable liquids, depending on their physical properties and tendencies, can fall into any one of the three packing groups.
Class 4 - Flammable Solids/ Spontaneously Combustive Material / Water-Reactive Substances
Division 4.1: This division consists of solid materials that are flammable. An example of this would be matches or lighters.
Division 4.2: This division consists of substances which present a hazard of spontaneous combustion.
Division 4.3: These materials consist of water-reactive substances which when wet will react to emit hazardous gases. Calcium carbide is an example of this type of material.
Class 5 - Oxidizing Materials/ Organic Peroxides
Division 5.1: This division of class 5 consists of materials which are oxidizers. Ammonium Nitrate, commonly used as a fertilizer, is an example of an oxidizing substance.
Division 5.2: This division of class 5 consists of organic peroxides. Organic peroxides exhibit a variety of dangerous characteristics, for example explosive decomposition, rapid burning, sensitivity to impact or friction, react dangerously with other substances, or , can cause damage to human tissue or eyes.
Class 6
Class 6 – Toxic and Infectious Substances:
Substances are included in Class 6 if they are liable to cause death or serious injury or harm to human health if swallowed or inhaled or come into contact with human skin; or infectious substances.
Division 6.1: This division of class 6 consists of poisonous solids and liquids. These materials are poisonous by ingestion, inhalation, or skin absorption. Arsenic is an example of this division of material.
Division 6.2: This division consists of substances which are considered "infectious" based on their ability to spread infection or disease in humans or animals. Infectious substances are further classified into "risk groups" from I (low risk) to 4 (high risk).
LC50 and LD50
When handling Toxic and Infectious substances it is important to understand the following terms:
LC 50– The "LC" stands for lethal concentration. This measurement is designed to tell you the level of hazard to your health associated with a dangerous good. In scientific terms, the LC 50 is the lowest concentration of gas , vapour , mist or dust that, when administered by continuous inhalation to both male and female young adult albino rats for one hour, results in the death within 14 days of one half of the animals.
LD 50 – The "LD" stands for lethal dose. This measurement is the lowest amount of a substance that, when administered by continuous contact with the bare skin of both male and female young adult albino rabbits for 24 hours, results in the death within 14 days of one half of the animals.
These terms provide an indicator of the level of danger associated with a good.
Class 7
Class 7 - Radioactive Materials: This class of materials contains any radioactive material being transported that has a specific radioactivity greater than 0.002 micro curies per gram. These materials may also appear as "Nuclear Substances" in the schedules in accordance with other regulations. Nuclear substances, such as uranium, fall into this category.
There are no divisions or packing groups for Class 7.
Class 8
Class 8 - Corrosive Materials: These materials consist of liquid or solid substances that can cause the decomposition of other materials (e.g. metals) or damage human tissue. Hydrochloric and Sulphuric Acid are examples of corrosive materials.
Class 9
Class 9 – Miscellaneous Products, Substances or Organisms:
A substance is included in Class 9, if it:
1) Is listed in column 3(Class designation) of Schedule 1 of the Regulations; or
2) Does not meet the criteria for inclusion in any of Classes 1 to 8, and:
contains a genetically modified micro-organism that would endanger public safety if accidentally released during transport,
is a marine pollutant intended for marine transport,
with the exception of asphalt or tar, is offered for transport or transported at a temperature greater than or equal to 100°C if it is in a liquid state, or, at a temperature greater than or equal to 240°C if it is in a solid state,
is intended for disposal, and is in a form that can release toxic substances through leaching,
is intended for disposal and is a mixture that includes an environmentally hazardous substance listed in the regulations at or above the concentration listed for that substance.
There are no divisions for Class 9. Substances included in Class 9 are included in Packing Group III unless they are included in a different packing group in column 4 of Schedule 1 of the Regulations.
Summary of changes to the Regulations Respecting Classification
Persons who are familiar with the old regulations will note a number of changes with respect to classification in the Clear Language Regulations. Briefly, the changes in classification can be summarized as follows:
- The old schedules have been incorporated into a single Schedule 1, which includes all classes of dangerous goods. The schedule is arranged by UN Number in accordance with International Standards. The new schedule 3 provides a UN Number/Shipping Name cross reference. The content and structure of schedule 1 varies significantly.
- There is no longer a Class 2.4 (Oxidizing Gases)
- Class 9 Divisions have been eliminated
- The word waste is no longer a part of the shipping name
- The "NA" (not applicable) prefix will no longer be used in the schedules
- Class 3 Flammable Liquids have been expanded to include liquids which are transported at temperatures greater than their flashpoint.
- A consignor may classify substances as Class 9. Previously this was done only by Transport Canada.
- Environmentally Hazardous substances, the old Class 9.2, are regulated only if they are intended for disposal and they are listed in Appendix 5 of the regulations.
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