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Classification – in Vol 1, Ch
2.
Learning
objectives:
A basic knowledge of chemistry
so that you are able to understand
the terms used in the IMDG Code
A general knowledge of the
hazard associated with the DG you
are dealing with.
A knowledge to determine which
goods are dangerous and which are
not; a good knowledge of the nine
groups or classes the substances
are divided into.
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Basic Physics and Chemistry
When browsing the
IMDG Code you will
found a number of
terms:
Elements
Mixtures
Compounds
Materials
Substances
Articles
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Elements
Elements are the basics
building blocks from which
all chemical structures are
made. They cannot be
broken into simpler
substances and are
composed of identical
atoms, which are the
smallest particles of an
element that can chemically
exist.
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Mixture
If the elements iron and
sulphur are blended
together, then a mixture
is formed. The two
components retain their
individual chemical and
physical characteristics
and can be separated
from each other again.
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Compounds
If the mixture of iron and
sulphur powders is heated
together, their atoms combine
to form molecules of a new
substance called a chemical
compound, in this instance the
substances is called ferrous
sulphide.
The compounds can have
properties which may be
significantly different from the
substances from which they
have been formed.
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Materials
A material is defined as
having some general
properties but these may
vary depending upon
the composition.
For example: wood has
the same general
properties, but different
colours and textures.
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Substances
The IMDG Code refers to
the term SUBSTANCES,
which covers chemical
compositions that do not
vary significantly from one
sample to another. Many
substances are compounds
and some are elements.
Example of substances are:
SALT and CANE SUGAR.
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Articles
The IMDG Code also
refers to the term
ARTICLE. An article is
a device that contains a
dangerous substances or
mixture of substances.
Example: fireworks,
aerosols, lighters and
bombs.
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Physical state of MATTER
“Matter” exists in three states:
Solids
Liquids
Gases
The physical state of many substances will
vary depending upon the temperature and
pressure applied to them.
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Solids
Many solids, such as
common salt, have a
regular shape and are
crystalline. Some solids
take water from the air
and become damp. It is
difficult to compress
solids.
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Liquids
Liquids have definite
mass and volume but
not shape. The Code
recognises that
increasing viscosity can
reduce hazard and effect
packing. Liquids are
difficult to compress.
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Gases
Gases, like air has a definite
mass but no defined volume
and will expand to fill the
volume of the containment
vessel. Some gases, like
chorine are heavier than air,
others like hydrogen is
lighter. Gases are easily
compressed and are available
in pressure-resistant gas
cylinders.
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Chemistry - Physical Properties
Chemicals are identified and characterised by
their properties. Physical properties are used to
assist in the classification of substances and
articles within the Code and some important
physical properties are also specified in the Code
on individual schedules.
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Physical properties can be defined as follows:
Boiling point
Vapour pressure
Flashpoint
Auto-ignition point
Explosive limit
Melting point
Density
Solubility
Odour
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Boiling point
This is the temperature at
which a liquid boils and
begins to turn into vapour.
The boiling point will vary
depending upon the pressure
applied. Boiling point criteria
are used together with
flashpoint to allocate
flammable liquids into
packing groups.
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Vapour Pressure
All solids and liquids give off
vapour consisting of atoms or
molecules of the substance that
have evaporated from the surface.
The pressure, which the vapour
exerts under specified conditions,
is known as the vapour pressure.
Vapour pressure is an important
consideration in defining whether
a particular substance should be
classified as a gas and also in
determining the toxicity of
substances if inhaled.
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Flashpoint
Flash point is the lowest
temperature of a liquid at which
its vapour forms an ignitable
mixture with air. A flammable
liquid cannot be ignited so long
as its temperature remains
below the flashpoint.???
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Auto-ignition point
This is the temperature to
which a liquid must be raised
to cause a sustained fire or
explosion when touched by a
flame or hot object or by the
heat generated during the
reaction or by friction.
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Explosive limit
This is the percentage-by-
volume vapour / air
concentration of a substance,
which is ignitable.
Below the “lower explosive
limit” the mixture is too
“lean” to ignite and above the
upper explosive limit the
mixture is too “rich”.
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Melting point
The melting point is the
lowest temperature at which a
solid will change into a liquid
when heated, for example ice
turning to water.
Care must be exercised in the
section of packing materials
for solids, which have a
relative low melting point
(transport from northern areas
to a tropical climate).
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Density
The density of a sample of a substance is
determined by dividing its mass by the volume
it occupies.
The UN package performance test recognise,
that product relative density can effect
container performance, particularly impact
strength and therefore the drop height.
For example: the toxic gas arsine, which has a
relative vapour density of 2.8 compared to air,
would not be stowed below deck, where it
could not easily disperse.
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Solubility
When a solid or a gas dissolves
in a liquid, a homogeneous
mixture or solution is formed.
Eventually, as more solute is
added, the solution cannot
dissolve any more and is said to
be saturated.
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Odour
Many substances have a
characteristic smell, which
may be the first indication of
product escape. Any unusual
odour should be treated as a
warning and appropriate
emergency action taken.
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The purpose of Classification
The purpose of the
classification is to divide
hazardous goods into
broad groups having the
same properties, viz:
Reactivity
Flammability
Toxicity
Corrosiveness
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Classification of DG
There are nine classes defined. The class
numbers do not indicate the degree of
hazard but only the type of hazard.
The classification should be made by the
shipper/consignor or by the appropriate
competent authority where specified in
this Code.
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Dangerous Goods Classifications
Class 1 - Explosives (six divisions)
1.1 - mass explosion hazard
1.2 - projectile hazard
1.3 - minor blast/projectile/fire
1.4 - minor blast
1.5 - insensitive explosives
1.6 - very insensitive explosives
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Class 1: Explosives
Division 1.1: substances and articles
which have a mass explosion hazard
A cargo has a mass
explosion when the
explosion is
instantaneously released
in the total cargo.
For example:
NITROGLYCERINE;
BOMBS.
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Class 1: Explosives
Division 1.2: substances and articles
which have a projection hazard but not
a mass explosion hazard
Examples of substances
in this group are
PYROTECHNICS,
FIREWORKS and
certain types of SMALL
ARMS AMMUNITION.
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Class 1: Explosives
Division 1.3: substances and articles which
have a fire hazard and either a minor blast
hazard or a minor projection hazard or both,
but not a mass explosion hazard
This division comprises substances and
articles:
Which give rise to considerable radiant
heat, or
Which burns one after another, producing
minor blast or projection effects or both.
Examples of substances in this group are
certain types of GUNPOWDER.
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Class 1: Explosives
Division 1.4: substances and articles
which present no significant hazard
This division comprises substances
and articles, which present only a
small hazard in the event of ignition
or ignition during transport.
Example of substances in this group
are different types of FUSE,
SMOKE and LIGHT SIGNALS.
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Class 1: Explosives
Division 1.5: very insensitive
substances which have a mass
explosion hazard
This division comprises substances
and articles, 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.
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Class 1: Explosives
Division 1.6: extremely insensitive articles
which do not have a mass explosion
hazard
This division comprises substances and
articles, which contain only extremely
insensitive detonating substances and
which demonstrate a negligible
probability of accidental initiation or
propagation. The risk from article of
div 1.6 is limited to the explosion of a
single article.
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Class 2 – Gases
Class 2.1
This class is flammable gases
which at 20 deg C and standard
pressure of 101.3 kPa are
ignitable when in a mixture of
13% or less by volume with air.
Examples: BUTANE and
PROPANE.
Note: (Inflammable means the
same as flammable)
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Class 2 – Gases
Class 2.2
Non – flammable, non toxic
gases, which are transported at a
pressure not less than 280 kPa at
20 deg C, or as refrigerated
liquids.
Examples of substances in this
class are NITROGEN, CARBON
DIOXIDE and OXYGEN.
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Class 2 – Gases
Class 2.3
This class of 2.2 is a toxic gases
that are known to be so toxic or
corrosive to humans as to pose a
hazard to health. (poisonous has the
same meaning as toxic).
Examples: CHLORINE and
SULPHUR DIOXIDE.
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Dangerous Goods Classifications
Class 3 – Flammable liquids
Class 3 contains:
Liquids
Mixture of liquids
Solids in solution or suspension
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Dangerous Goods Classifications
Class 4 – Flammable solids
Class 4 comprises both inorganic and organic
substances and is divided into three sub-
classes:
Class 4.1 – Inflammable solids
Class 4.2 – Spontaneously combustible substances
Class 4.3 – Substances emitting inflammable
gases when wet.
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Class 4 - Flammable solids
Class 4.1 – Inflammable
solids group
These are solids possessing the
properties of being ignited by
external sources, such as sparks
or flame, and being readily
combustible.
Examples: MAGNESIUM
POWDER; MATCHES;
SULPHUR;JUTE.
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Class 4 - Flammable solids
Class 4.2 – Spontaneously
combustible substances
These are either liquids or solids,
which are liable to spontaneous
heating and then being liable to
catch fire.
Examples:
SODIUM SULPHIDES;
POTASSIUM SULPHIDES; WHITE
and YELLOW PHOSPHORUS.
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Class 4 - Flammable solids
Class 4.3 – Substances emitting
inflammable gases when wet
These are either liquids or solids,
which are liable to become
spontaneously flammable or to
give off flammable gases.
Examples: FERRO SILICON;
CARBIDE;ALUMINIUM SILICATE.
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Dangerous Goods Classifications
Class 5 – Oxidizing and Organic
Class 5 is divided into two groups:
Class 5.1 – Oxidizing substances
Class 5.2 – Organic peroxides
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Class 5 – Oxidizing and Organic
Class 5.1 – Oxidising substances
Substances of this class will, under
certain circumstances directly or
indirectly give off oxygen. For this
reason oxidizing substances increase
the risk and intensity of fire in
combustible material with which they
come into contact.
Examples:
HYDROGEN PEROXIDE;
SODIUM PEROXIDE.
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Class 5 – Oxidizing and Organic
Class 5.2 – Organic peroxides
Substances of this class are liable to
exothermic decomposition at normal or
elevated temperatures. The
decomposition can be initiated by heat,
contact with impurities, friction or
impact. Decomposition may result in
the evolution of harmful or flammable
gases or vapours.
Examples:
ORGANIC PEROXIDES CLASS B to F.
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Dangerous Goods Classifications
Class 6 – Toxic and Infections
Class 6 is divided into two groups:
Class 6.1 – Toxic substances
Class 6.2 – Infectious substances
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Class 6 – Toxic and Infectious
Class 6.1 – Toxic substances
Substances of this class posses the
common property of being liable to
cause death or serious injury or to harm
health if swallowed or inhaled, or by
skin contact.
Examples:
ARSENIC; HYDROCYANIC ACID;
MERCURY COMPOUND.
It is very important to keep toxic
substances far way from food!!!
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Class 6 – Toxic and Infectious
Class 6.2 – Infectious Substances
Substances of this class are those
known to contain pathogens.
Examples:
Bio MEDICAL WASTE; INFECTIOUS
SUBSTANCES affecting humans.
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Dangerous Goods Classifications
Class 7 - Radioactive
Class 7 is divided into the following Low
Specific Activity (LSA) materials:
LSA I
LSA II
LSA III
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Class 7 - Radioactive
Class 7 – Category I
Lowest hazard
Transport index: 0 (1)
Maximum radiation level at any point
on the external surface:
Not more than 5 m Sv/h 0.5 mrem/h
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Class 7 - Radioactive
Class 7 – Category II
Transport index: More than 0 but not
more than 1 (1)
Maximum radiation level at any point
on the external surface:
More than 5 m Sv/h (0.5 mrem/h), but
not more than 0=5 mSv/h (50 mrem/h)
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Class 7 - Radioactive
Class 7 – Category III
Highest hazard
Transport index: More than 1 but not
more than 10.
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Dangerous Goods Classifications
Class 8 - Corrosive
Examples:
Different types of ACIDS;
SODIUM HYDROXIDE
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Marine Pollutant
Marine pollutants means substances
which, because of their potential to
bioaccumulate in seafood or because of
their high toxicity to aquatic life, are
subject to the regulations in Annex III
of MARPOL 73/78.
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Hazard Classifications
Discussion Points
What are the characteristics of the 6
divisions of Class 1 explosives?
What are the characteristics of the 3
divisions of Class 2 gases?
What classes are explosives; poison?
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Hazard Classifications
Discussion Points
Without looking, describe the
placard for a 5.1 oxidizer?
What are some common examples of
each class of Dangerous goods?