Chapter 2.1 General Provisions | Part II CLASSIFICATION AND COMPATIBILITY OF DG CLASSIFICATION | Code of Practice | Regulation of Dangerous Goods (2024)

Classes, Proper Shipping Name and Packing Groups

DG presenting a danger of a particular class is assigned to that class and packing group, if applicable. For the purpose of the Ordinance, DG are substances listed in the Schedule 2 of Cap. 295E and are specifically listed and identified by UN number(s) / HK number(s) and proper shipping names (PSN) with their appropriate classes, subsidiary hazard(s) and, when applicable, packing groups, etc.

Classes

Substances (including mixtures and solutions) subject to Cap. 295E are assigned to different classes according to the hazard or the most predominant of the hazards they present. Those classes are:

Class 2: Gases

- Class 2.1: Flammable gases

- Class 2.2: Non-flammable and non-toxic gases

- Class 2.3: Toxic gases

Class 3: Flammable liquids

Class 3A: Diesel, fuel oil and furnace oil, having flashpoints exceeding 60°C (closed-cup test)

Class 4: Flammable solids; substances liable to spontaneous combustion; substances which, in contact with water, emit flammable gases

- Class 4.1: Flammable solids, self-reactive substances, solid desensitized explosives and polymerizing substances

- Class 4.2: Substances liable to spontaneous combustion

- Class 4.3: Substances which in contact with water emit flammable gases

Class 5: Oxidizing substances and organic peroxides

- Class 5.1: Oxidizing substances

- Class 5.2: Organic peroxides

Class 6.1: Toxic substances

Class 8: Corrosive substances

Class 9: Miscellaneous dangerous substances or materials

Proper shipping names are of the following four types:

(a) Single entries for well-defined substances:

e.g. UN 1090 ACETONE

UN 1194 ETHYL NITRITE SOLUTION;

(b) Generic entries for well-defined group of substances:

e.g. UN 1133 ADHESIVES

UN 1266 PERFUMERY PRODUCT

UN 3101 ORGANIC PEROXIDE, TYPE B, LIQUID;

(c) Specific N.O.S. entries covering a group of substances of a particular chemical or technical nature:

e.g. UN 1477 NITRATES, INORGANIC, N.O.S.

UN 1987 ALCOHOLS, N.O.S.

(d) General N.O.S. entries covering a group of substances meeting the criteria of one or more hazard classes:

e.g. UN 1325 FLAMMABLE SOLID, ORGANIC, N.O.S.

UN 1993 FLAMMABLE LIQUID, N.O.S.

If test data showed that a substance listed by proper shipping name in the DG List does not meet the classification criteria for any hazard class or subsidiary hazard(s) identified in the DG List, the substance may be assigned:

Packing Groups

Most substances other than those of Classes 2, 3A, 5.2 and self-reactive substances of Class 4.1 are assigned to three packing groups, which are indicated in the corresponding packing group entries in the DG List, in accordance with the degree of danger they present:

Packing group I (PG I): Substances presenting high danger;

Packing group II (PG II): Substances presenting medium danger; and

Packing group III (PG III): Substances presenting low danger.

DG meeting the defining criteria of more than one hazard class and which are not listed by name in the DG List, are assigned to a class and subsidiary hazard(s) on the basis of the precedence of hazards prescribed in 2.1.2.

Precedence of Hazard Characteristics

The table below should be used to determine the class of a substance, mixture or solution having more than one hazard, when it is not named in the DG List. For substance having multiple hazards which are not specifically listed by name in the DG List, the most stringent packing group denoted to the respective hazards of the substance takes precedence over other packing groups, irrespective of the Table for Precedence of Hazards in this Chapter. The precedence of hazard characteristics of the following has not been dealt with in the Table for Precedence of Hazards in 2.1.2.3, as these primary characteristics always take precedence:

(a) Gases of Class 2;

(b) Liquid desensitised explosives of Class 3;

(c) Self-reactive substances and solid desensitised explosives of Class 4.1;

(d) Pyrophoric substances of Class 4.2;

(e) Substances of Class 5.2;

(f) Substances of Class 6.1 with a packing group I inhalation toxicity (Except for substances or preparations meeting the criteria of Class 8 having an inhalation toxicity of dust and mists (LC₅₀) in the range of packing group I, but toxicity through oral ingestion or dermal contact only in the range of packing group III or less, which shall be allocated to Class 8).

Table for Precedence of Hazards

Class and Packing Group

4.2

4.3

5.1, I

5.1, II

5.1, III

6.1, I

Dermal

6.1, I

Oral

6.1, II

6.1, III

8, I

Liquid

8, I

Solid

8, II

Liquid

8, II

Solid

8, III

Liquid

8, III

Solid

3

I^a

4.3

3

3

3

3

3

–

3

–

3

–

3

II^a

4.3

3

3

3

3

8

–

3

–

3

–

3

III^a

4.3

6.1

6.1

6.1

3

8

–

8

–

3

–

4.1

II^a

4.2

4.3

5.1

4.1

4.1

6.1

6.1

4.1

4.1

–

8

–

4.1

–

4.1

4.1

III^a

4.2

4.3

5.1

4.1

4.1

6.1

6.1

6.1

4.1

–

8

–

8

–

4.1

4.2

II

4.3

5.1

4.2

4.2

6.1

6.1

4.2

4.2

8

8

4.2

4.2

4.2

4.2

4.2

III

4.3

5.1

5.1

4.2

6.1

6.1

6.1

4.2

8

8

8

8

4.2

4.2

4.3

I

5.1

4.3

4.3

6.1

4.3

4.3

4.3

4.3

4.3

4.3

4.3

4.3

4.3

4.3

II

5.1

4.3

4.3

6.1

4.3

4.3

4.3

8

8

4.3

4.3

4.3

4.3

4.3

III

5.1

5.1

4.3

6.1

6.1

6.1

4.3

8

8

8

8

4.3

4.3

5.1

I

5.1

5.1

5.1

5.1

5.1

5.1

5.1

5.1

5.1

5.1

5.1

II

6.1

5.1

5.1

5.1

8

8

5.1

5.1

5.1

5.1

5.1

III

6.1

6.1

6.1

5.1

8

8

8

8

5.1

5.1

6.1

I Dermal

8

6.1

6.1

6.1

6.1

6.1

6.1

I Oral

8

6.1

6.1

6.1

6.1

6.1

6.1

II Inhalation

8

6.1

6.1

6.1

6.1

6.1

6.1

II Dermal

8

6.1

8

6.1

6.1

6.1

6.1

II Oral

8

8

8

6.1

6.1

6.1

6.1

III

8

8

8

8

8

8

Table notes:

^a Substances of Class 4.1 other than self-reactive substances and solid desensitised explosives and substances of Class 3 other than liquid desensitised explosives.

– Denotes an impossible combination.

For hazards not shown in this table, see 2.1.2.1.

Supplementary Notes

Supplementary notes (SN) of some DG are provided in column 6 of the DG List in Appendices 1 to 3. The meanings of those SN are listed in Appendix 4. The SN apply regardless of the quantity of that DG, unless otherwise specified.