PACKING GROUPS

Packing groups indicate the level of danger and thus assist in selecting correct type of package for Dangerous Goods

There are three packing groups assigned in IMDG Code as below

Packing group I:                substances presenting high danger;

Packing group II:               substances presenting medium danger; and

Packing group III:             substances presenting low danger

Classes 1, 2, 5.2, 6.2 and 7, and self-reactive substances of class 4.1 are not assigned with packing groups

Let us look at the criteria for assigning packing groups for each of the classes.

Class 1: Explosives

No Packing group assigned

Class 2: Gases

No Packing group assigned

Class 3: Flammable liquids

 Flammable liquids are grouped for packing purposes according to their flashpoint, their boiling

point, and their viscosity. Below table shows the relationship between flashpoint and boiling point

Packing Group

Flashpoint in °C closed cup (c.c.) Initial boiling point in °C

I

II

III

< 23

≥ 23 to ≤ 60

≤ 35

> 35

> 35

Viscous substances such as paints, enamels, lacquers, varnishes, adhesives and polishes having a flashpoint of less than 23 °C may be placed in packing group III in conformity with the procedures prescribed in part III, chapter 32.3, of the United Nations Manual of Tests and

Criteria on the basis of:

.1 the viscosity, expressed as the flowtime in seconds;

.2 the closed-cup flashpoint;

.3 a solvent separation test.

Viscous flammable liquids such as paints, enamels, varnishes, adhesives and polishes with a flashpoint of less than 23 °C are included in packing group III provided that:

.1 less than 3% of the clear solvent layer separates in the solvent separation test;

.2 the mixture or any separated solvent does not meet the criteria for class 6.1 or class 8.

.3 the viscosity and flashpoint are in accordance with the following table:

.4 the capacity of the receptacle used does not exceed 30 ℓ.

Substances classified as flammable liquids due to their being transported or offered for

transport at elevated temperatures are included in packing group III.

Class 4.1 Flammable solids

Substance

Packing Group

Criteria

Readily combustible solids (other than metal powders)

II

If the burning time is less than 45 s and the flame passes the wetted zone
Powders of metal or metal alloys

II

if the zone of reaction spreads over the whole length of the sample in five minutes or less
Readily combustible solids (other than metal powders)

III

If the burning time is less than 45 s and the wetted zone stops the flame propagation for at leastfour minutes
Powders of metal

III

if the reaction spreadsover the whole length of the sample in more than five minutes but not more than ten minutes
Solids which may cause fire through friction packing group shall be assigned by analogy with existing entries or in accordance with any appropriate special provision

Class 4.2 – Substances liable to spontaneous combustion

 Class 4.2 comprises Pyrophoric substances & Self-heating substances

Substance

Packing Group

Criteria

Pyrophoric solids and liquids

I

Always Packing group I
Self-heating substances

II

which give a positive result in atest using a 25 mm sample cube at 140 °C
Self-heating substances

III

A positive result is obtained in a test using a 100 mm cube sample at 140 °C and a negative result is obtained in a test using a 25 mm cube sample at 140 °C and thesubstance is to be transported in packages with a volume of more than 3 m3;A positive result is obtained in a test using a 100 mm cube sample at 140 °C and a negative result is obtained in a test using a 25 mm cube sample at 140 °C, a positive result is obtained in a test using a 100 mm cube sample at 120 °C and the substance is to be transported in packages with a volume of more than 450 ℓ;

A positive result is obtained in a test using a 100 mm cube sample at 140 °C and a negative result is obtained in a test using a 25 mm cube sample at 140 °C and a

positive result is obtained in a test using a 100 mm cube sample at 100 °C.

Class 4.3 – Substances which, in contact with water, emit flammable gases

 

Packing Group

Criteria

I

any substance which reacts vigorously with water atambient temperatures and demonstrates generally a tendency for the gas produced to ignite spontaneously, or which reacts readily with water at ambient temperatures such that the rate of evolution of flammable gas is equal to or greater than 10 litres per kilogram of substance over any one minute.

II

any substance which reacts readily with water at ambienttemperatures such that the maximum rate of evolution of flammable gas is equal to or greater than 20 litres per kilogram of substance per hour, and which does not meet the criteria for packing group I.

III

any substance which reacts slowly with water at ambienttemperatures such that the maximum rate of evolution of flammable gas is equal to or greater than 1 litre per kilogram of substance per hour, and which does not meet the criteria forpacking groups I or II.

Class 5.1 – Oxidizing substances

 

Packing Group

Criteria

I

any substance which, in the 1:1 mixture (by mass) of substance andcellulose tested, spontaneously ignites; or the mean pressure rise time of a 1:1 mixture (by mass) of substance and cellulose is less than that of a 1:1 mixture (by mass) of 50% perchloric acid and cellulose;

II

Packing group II: any substance which, in the 1:1 mixture (by mass) of substance and cellulose tested, exhibits a mean pressure rise time less than or equal to the mean pressure rise time of a 1:1 mixture (by mass) of 40% aqueous sodium chlorate solutionand cellulose; and the criteria for packing group I are not met;

III

any substance which, in the 1:1 mixture (by mass) of substance andcellulose tested, exhibits a mean pressure rise time less than or equal to the mean pressure rise time of a 1:1 mixture (by mass) of 65% aqueous nitric acid and cellulose; and the criteria for packing groups I and II are not met;

Not Classified as 5.1

any substance which, in the 1:1 mixture (by mass) ofsubstance and cellulose tested, exhibits a pressure rise of less than 2070 kPa gauge; or exhibits a mean pressure rise time greater than the mean pressure rise time of a 1:1 mixture (by mass) of 65% aqueous nitric acid and cellulose.

Class 5.2 – Organic peroxides

No Packing group assigned

 

Class 6.1 – Toxic substances

  Grouping criteria for administration through oral ingestion, dermal contact and inhalation of dusts and mists

Tear gas substances shall be included in packing group II even if their toxicity data

correspond to packing group III values.

Liquids having toxic vapours

Liquids having toxic vapours shall be assigned to the following packing groups, where “V” is

the saturated vapour concentration in mℓ/m3 air at 20 °C and standard atmospheric pressure:

Packing group I:                If V ≥ 10 LC50 and LC50 ≤ 1,000 mℓ/m3.

Packing group II:               If V ≥ LC50 and LC50 ≤ 3,000 mℓ/m3, and do not meet the criteria for

packing group I.

Packing group III:             If V ≥ 5/1 LC50 and LC50 ≤ 5,000 mℓ/m3, and do not meet the criteria

for packing groups I or II.

Tear gas substances shall be included in packing group II even if their toxicity data correspond to packing group III values.

Class 6.2 – Infectious substances

No Packing group assigned

 Class 7 – Radioactive material

No Packing group assigned


Class 8 – Corrosive substances

Packing Group

Criteria

I

substances that cause full thickness destruction of intactskin tissue within an observation period of up to 60 minutes starting after an exposure time of 3 minutes or less

II

substances that cause full thickness destruction of intactskin tissue within an observation period of up to 14 days starting after an exposure time of more than 3 but not more than 60 minutes.

III

cause full thickness destruction of intact skin tissue within an observation period of up to 14 days starting after an exposure time of more than 60 minutes but not more than 4 hours; orare judged not to cause full thickness destruction of intact skin tissue but which exhibit a corrosion rate on either steel or aluminium surfaces exceeding 6.25 mm a year at a test temperature of 55 °C when tested on both materials.

 

 Class 9 – Miscellaneous dangerous substances and articles and environmentally hazardous substances

Some are assigned to Packing Group II and some to III.

Test methods for determining packing groups for each class are published in United Nations Recommendations on the Transport of Dangerous Goods-Manual of Tests and Criteria, as amended

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