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Lesson Objectives
Lesson 2
Classification of Physical
Hazards
• Learn what physical hazards are covered by
the GHS.
• Become familiar with the criteria for
evaluating the physical hazard potential of
substances and mixtures.
• Apply the criteria to example substances.
2
GHS Part 2. Physical Hazards
Physical Hazards Covered
2.1 Explosives
2.2 Flammable gases
(including chemically
unstable gases)
2.3 Aerosols
2.4 Oxidizing gases
2.5 Gases under pressure
2.6 Flammable liquids
2.7 Flammable solids
2.8 Self-reactive
Each Chapter contains:
• Definitions/General considerations
• Classification criteria
• Hazard communication
• Decision logic and guidance
2.9 Pyrophoric liquids
2.10 Pyrophoric solids
2.11 Self-heating
2.12 Emit flammable
gases in contact with
water
2.13 Oxidizing liquids
2.14 Oxidizing solids
2.15 Organic peroxides
2.16 Corrosive to metals
3
4
Physical Hazards
Hazard Class
Explosives
Flammable Gases (including
chemically unstable gases)
Aerosols
Oxidising Gases
Gases Under Pressure
Compressed Gases
Liquefied Gases
Refrigerated Liquefied
Gases
Dissolved Gases
Flammable Liquids
Flammable Solids
Self-reactive Substances
Pyrophoric Liquids
Pyrophoric Solids
Self-heating Substances and
Mixtures
Hazard Category
Unstable
Explosives
Div 1.1
1
1A
1B
1
1
1
2
3
1
1
2
2
Type
B
Type A
Div
1.2
Div
1.3
Div
1.4
2
2A
2B
Div
1.5
Div
1.6
3
4
Type
C
Type
D
Type
E
Type
F
Type
G
Type
D
Type
E
Type
F
Type
G
1
1
1
2
Substances and mixtures
which, in contact with water,
emit flammable gases
1
2
3
Oxidising Liquids
Oxidising Solids
1
1
2
2
Type
B
3
3
Type
C
Organic Peroxides
Type A
Corrosive to Metals
1
Physical Hazard Criteria
• Physical hazards are related to the physical and
chemical properties of the substance or mixture
involved.
• The physical hazard criteria are based on the
criteria of the UN Recommendations for the
Transport of Dangerous Goods (TDG).
• They refer to the results of tests performed in
accordance with the UN Recommendations on
the Transport of Dangerous Goods, Manual of
Tests and Criteria.
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Physical Hazard Criteria, cont.
• Since all substances or mixtures that are transported
have been classified under the UN Recommendations
for physical hazards, many suppliers will already have
considered the criteria definitions in the GHS as well.
• There are some differences—GHS sectors may cover
additional hazard categories (e.g., Category 4 of
flammable liquids).
• As a practical approach to classification, reviewing and
updating the existing transport classifications may help
to minimize the task of completing GHS classifications
for these hazard classes.
2.1 Explosives
• General considerations:
– The class of explosives comprises:
• (a) Explosive substances and mixtures;
• (b) Explosive articles, except devices containing explosive
substances or mixtures in such quantity or of such a
character that their inadvertent or accidental ignition or
initiation shall not cause any effect external to the device
either by projection, fire, smoke, heat or loud noise; and
• (c) Substances, mixtures and articles not mentioned under
(a) and (b) above which are manufactured with the view to
producing a practical, explosive or pyrotechnic effect
2.1 Explosives
• Definitions:
– An explosive substance (or mixture) is a solid or liquid substance
(or mixture of substances) which is in itself capable by chemical
reaction of producing gas at such a temperature and pressure
and at such a speed as to cause damage to the surroundings.
Pyrotechnic substances are included even when they do not
evolve gases.
– A pyrotechnic substance (or mixture) is a substance or mixture
of substances designed to produce an effect by heat, light,
sound, gas or smoke or a combination of these as the result of
non-detonative self-sustaining exothermic chemical reactions.
– An explosive article is an article containing one or more
explosive substances or mixtures.
– A pyrotechnic article is an article containing one or more
pyrotechnic substances or mixtures.
Explosive Hazard
• Explosive – solid or liquid substance or mixture
which reacts to detonate (produce gas at speed to damage surroundings)
• Includes
– Pyrotechnic substances or mixtures (heat, light, gas, smoke effects)
non-detonative
– Articles (with some exceptions)
• Indicators
– Explosion is a ‘fast fire’ – chemically most explosives contain
combustible plus oxidiser
– Require initiation energy
• Classification is the transport classification (see UNRTDG)
• Explosive class includes substances and articles designed for explosive
(including pyrotechnic) effect
10
Classification Criteria
• Classification in one of the six divisions is based on test series 2 through 8
in Part 1 of the TDG Test Manual:
Table 2.1.1: Criteria for explosives
Category
Unstablea explosives
or explosives of
Division 1.1 to 1.6
Criteria
For explosives of Divisions 1.1 to 1.6, the following are the core set of tests that
need to be performed:
Explosibility:
according to UN Test Series 2 (Section 12 of the
UN Recommendations on the Transport of Dangerous Goods,
Manual of Tests and Criteria). Intentional explosivesb are not
subject to UN Test Series 2.
Sensitiveness: according to UN Test Series 3 (Section 13 of the
UN Recommendations on the Transport of Dangerous Goods,
Manual of Tests and Criteria).
Thermal
stability:
according to UN Test 3(c) (Sub-section 13.6.1 of the
UN Recommendations on the Transport of Dangerous Goods,
Manual of Tests and Criteria).
Hazard Classes
• Division1.1: Mass explosion hazard
• Division 1.2: Projection hazard
• Division 1.3: Fire hazard plus minor blast or projection hazard (or both)
• Division 1.4: No significant hazard outside package in which contained
• Division 1.5: Mass explosion hazard – very insensitive
• Division 1.6: Extremely insensitive
Unstable explosives are those which are thermally unstable and/or too
sensitive for normal handling, transport, and use. Special precautions are
necessary.
Further tests are necessary to allocate the correct Division.
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•
•
Classification Procedure
Practical Classification Approach
Complex 3 step procedure
– Requires UNRTDG Tests and Criteria to complete
Steps
a) Determine if the substance or mixture has explosive effects (Test series 1)
b) Carry out procedure for acceptance within classification (Test series 2- 4)
c)
Assignment to hazard division (Test series 5-7)
• Substances presenting explosive hazards have
likely already been tested and classified.
• Obtain proper shipping name and UN Number.
• Determine classification from listing (Chapter
3 UNRTDG).
• If testing is required, employ a certified
specialist international laboratory familiar
with the explosive testing and classification
criteria.
Notes:
•
This procedure is from the UNRTDG, and the GHS is consistent
•
The classification step involves compatibility groupings designated by letters (A,
B, C, D, E, F, G, H, J, K, L, H, S)
•
Special case of ammonium nitrate emulsion
Hazard Communication for Explosives, Annex 1
Explosive Example Classifications
EXPLOSIVES
Unstable
explosives
Name
Division 1.1
Division 1.2
Division 1.3
Division 1.4
UN
Classification*
Number
Lead azide wetted with not less than 20%
water
0129
Sounding devices (explosive)
0204
1.2F
Signals distress ship
0195
1.3G
Black powder (Gunpowder) granular
0027
1.1D
Rockets with inert head
0183
1.3C
Trinitrotoluene (TNT) dry or wetted with less
than 30% water
0209
1.1D
Division 1.5
Division 1.6
No pictogram No pictogram
1.5 on orange 1.6 on orange
background background
1.1A
Danger
Danger
Danger
Danger
Warning
Danger
No signal word
Unstable
explosive
Explosive;
mass
explosion
hazard
Explosive;
severe
projection
hazard
Explosive;
fire, blast or
projection
hazard
Fire or
projection
hazard
May mass
explode
in fire
No hazard
statement
No pictogram
assigned in the
UN Model
Regulations
(Transport not
allowed)
* Compatibility letter (A-G) not part of the GHS
15
2.2 Flammable Gases
(including chemically unstable gases)
Criteria for Flammable Gases
• Definitions:
– A flammable gas is a gas having a flammable
range with air at 20 °C and a standard pressure
of 101.3 kPa.
– A chemically unstable gas is a flammable gas that
is able to react explosively even in the absence of
air or oxygen.
Table 2.2.1: Criteria for flammable gases
Category
Criteria
1
Gases, which at 20 °C and a standard pressure of 101.3 kPa:
(a) are ignitable when in a mixture of 13% or less by volume in air; or
(b) have a flammable range with air of at least 12 percentage points regardless of the
lower flammable limit.
2
Gases, other than those of Category 1, which, at 20 °C and a standard pressure
of 101.3 kPa, have a flammable range while mixed in air.
NOTE 1:
purposes.
Ammonia and methyl bromide may be regarded as special cases for some regulatory
NOTE 2:
Aerosols should not be classified as flammable gases. See Chapter 2.3.
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Criteria for Chemically Unstable Gases
• A flammable gas that is also chemically unstable will be additionally
classified in one of the following categories:
Flammable Gas: Mixture
• Calculation: ISO 10156:1996
𝒏
𝒊
Table 2.2.2: Criteria for chemically unstable gases
𝑽𝒊%
≥𝟏
𝑻𝒄𝒊
Vi%
Equivalent flammable gas content
A
Flammable gases which are chemically unstable at 20°C and a standard pressure of
101.3 kPa
Tci
Maximum concentration of the flammable gas in
nitrogen at which the mixture is not flammable in air
B
Flammable gases which are chemically unstable at a temperature greater than 20°C
and/or a pressure greater than 101.3 kPa
i
First component in mixture
n
nth component in mixture
Category
Criteria
NB: use of equivalency factors between other inert gases and nitrogen
20
Hazard Communication for Flammable Gases (Annex 1)
2.3 Aerosols
FLAMMABLE GASES (INCLUDING CHEMICALLY UNSTABLE GASES)
Flammable gases
Category 1
Chemically unstable gases
Category 2
No pictogram
Danger
Warning
Extremely
flammable gas
Flammable gas
Category A
Category B
Note
Under the UN
Recommendations
on the Transport of
Dangerous Goods,
Model Regulations,
the symbol,
number and border
No additional signal No additional signal line may be shown
word
word
in black instead of
white. The
May react
May react explosively background colour
explosively even in even in the absence of stays red in both
the absence of air
air at elevated
cases.
pressure and/or
temperature
No additional
pictogram
• Definition:
– Aerosols, this means aerosol dispensers, are any
non-refillable receptacles made of metal, glass or
plastics and containing a gas compressed,
liquefied or dissolved under pressure, with or
without a liquid, paste or powder, and fitted with
a release device allowing the contents to be
ejected as solid or liquid particles in suspension in
a gas, as a foam, paste or powder or in a liquid
state or in a gaseous state.
No additional
pictogram
Not required under the UN Model Regulations
Classification Criteria
Classification Criteria
•
• An aerosol should be considered for
classification as flammable if it contains a
component classified as one of the following:
•
– Flammable liquid
– Flammable gas
– Flammable solid
•
Classification basis
– Heat of combustion of contents
– Ignition distance test (spray type) - UNRTDG Tests & Criteria Section 31.4
– Foam test (foam type) – UNRTDG Tests & Criteria Section 31.6
Summary classification logic
a) Check ≤ 1% flammable components and heat of combustion ≤ 20kJ/g if so Do
not classify
b) Check ≥ 85% flammable and heat of combustion ≥ 30kJ/g if so classify
category 1
c) If not, classify (category 1 or2) using
• ignition distance test results
(spray aerosol)
• foam test results (foam aerosols)
Non-flammable aerosol. If the aerosol does not meet requirements for Category 1
or 2, it should be classified as Category 3 (non-flammable aerosol).
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Hazard Communication for Aerosols,
Annex 1
AEROSOLS
Category 1
Category 2
Danger
Warning
Extremely flammable
aerosol
Pressurized container:
may burst if heated
Flammable aerosol
Pressurized container:
may burst if heated
Category 3
Note
Under the UN
Recommendations on the
Transport of Dangerous
No pictogram
Goods, Model
Regulations, the symbol,
number and border line
may be shown in black
Warning
instead of white. The
background colour stays
red in the first two cases
and green in the third
Pressurized container:
case.
may burst if heated
2.4 Oxidizing Gases
• Definition:
An oxidizing gas is any gas which may,
generally by providing oxygen, cause or contribute
to the combustion of other material more than air
does.
NOTE: “Gases which cause or contribute to
the combustion of other material more than air
does” means pure gases or gas mixtures with an
oxidizing power greater than 23.5% as determined
by a method specified in ISO 10156:2010.
Guidance from ISO 10156: 2010
Classification Criteria
• To classify an oxidizing gas, tests or calculation methods as described in
ISO 10156:2010 “Gases and gas mixtures – Determination of fire potential
and oxidizing ability for the selection of cylinder valve outlets” should be
performed.
• The criteria for this class are basically the same as the definition of
oxidizing gases:
The classification method described in ISO 10156 uses the criterion that a gas mixture should be considered
as more oxidising than air if the oxidising power of the gas mixture is higher than 0.235 (23.5%).
The oxidizing power (OP) is calculated as follows:
n
x C
i
OP 
i
i 1
p
n
x  K
i
i 1
k Bk
k 1
Where:
xi
Table 2.4.1: Criteria for oxidizing gases
= molar fraction of the i:th oxidising gas in the mixture;
Ci = coefficient of oxygen equivalency of the i:th oxidising gas in the mixture;
Kk = coefficient of equivalency of the inert gas k compared to nitrogen;
Category
Criteria
1
Any gas which may, generally by providing oxygen, cause or contribute to the
combustion of other material more than air does.
Bk = molar fraction of the k:th inert gas in the mixture;
n
= total number of oxidising gases in the mixture;
p
= total number of inert gases in the mixture;
Example mixture:
9% (O2) + 16% (N2O) + 75% (He)
Hazard Communication for Oxidizing
Gases, Annex 1
Guidance, cont.
Calculation steps
OXIDIZING GASES
Step 1:
Ascertain the coefficient of oxygen equivalency (Ci) for the oxidising gases in the mixture and
the nitrogen equivalency factors (Kk) for the non-flammable, non-oxidising gases.
Category 1
-
-
-
Note
Ci (N2O) = 0.6 (nitrous oxide)
Ci (O2)
= 1 (oxygen)
Kk (He) = 0.9 (helium)
Danger
Step 2:
May cause or
intensify fire;
oxidizer
Calculate the oxidising power of the gas mixture
n
x C
i
OP 
Pictogram colours:
i
i 1
x  K
i
i 1

p
n
k Bk
0.09  1  0.16  0.6
 0.201
0.09  0.16  0.75  0.9
k 1
Therefore the mixture is not considered as an oxidising gas.
20.1 < 23.5
5.1
Symbol (flame over
circle): black;
Background:
yellow; Figure
“5.1” in bottom
corner: black.
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2.5 Gases Under Pressure
• Definition:
Gases under pressure are gases which are
contained in a receptacle at a pressure of 200 kPa
(gauge) or more at 20 °C, or which are liquefied or
liquefied and refrigerated.
• They are in one of the following physical states
when packaged:
–
–
–
–
compressed gases
liquefied gases
dissolved gases
refrigerated liquefied gases
Classification Criteria
Table 2.5.1: Criteria for gases under pressure
Group
Criteria
Compressed gas
A gas which when packaged under pressure is entirely gaseous at -50 °C; including
all gases with a critical temperature  -50 °C.
Liquefied gas
A gas which when packaged under pressure, is partially liquid at temperatures
above -50 °C. A distinction is made between:
(a) High pressure liquefied gas: a gas with a critical temperature between -50°C
and +65°C; and
(b) Low pressure liquefied gas: a gas with a critical temperature above +65°C.
Refrigerated
liquefied gas
A gas which when packaged is made partially liquid because of its low temperature.
Dissolved gas
A gas which when packaged under pressure is dissolved in a liquid phase solvent.
The critical temperature is the temperature above which a pure gas cannot be liquefied, regardless of the
degree of compression.
NOTE: Aerosols should not be classified as gases under pressure. See Chapter 2.3.
Examples/Gases Under Pressure
Guidance
Classification
• In order to classify substances or mixtures as
gases under pressure, the following information
will be needed:
– The vapor pressure at 50 °C
– The physical state at 20 °C at standard ambient
pressure
– The critical temperature
• Data can be found in literature, calculated, or
determined by testing. Most pure gases have
already been classified under the UNRTDG.
Hazard Communication for Gases Under Pressure, Annex 1
Gas
Critical temperature
Compressed gas
Argon, compressed [UN
1006]
-122.3 °C
High pressure liquefied gas
Xenon [UN 2036]
16.5°C
Low pressure liquefied gas
Propane [UN 1978]
96.6°C
Refrigerated gas
Ethylene, refrigerated liquid 9.5°C
[UN 1038]
Dissolved gas
Acetylene, dissolved [UN
1001] (e.g. in acetone)
35.1°C
2.6 Flammable Liquids
GASES UNDER PRESSURE
Compressed gas
Warning
Liquefied gas
Warning
Contains
Contains
gas under pressure; gas under pressure;
may explode if
may explode if
heated
heated
Refrigerated
liquefied gas
Warning
Contains
refrigerated gas;
may cause
cryogenic burns
or injury
Dissolved gas
Note
Under the UN
Recommendations
on the Transport of
Dangerous Goods,
Model Regulations,
pictogram
elements:
Warning
(1) Not required
for toxic or
Contains
flammable
gas under pressure;
gases.
may explode if
heated
(2) The symbol,
number and
border line
may be shown
in white
instead of
black. The
background
stays green in
both cases.
• Definition:
A flammable liquid means a liquid having a flash point of
not more than 93 °C.
• Guidance Note:
In order to classify a flammable liquid, data on its
flash point and initial boiling point are needed. Data
can be determined by testing, found in literature or
calculated.
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Flammable Liquids
Classification Criteria
• Combustion always in the vapour above the liquid
• Classifications are based on flashpoint – mixtures included
Table 2.6.1: Criteria for flammable liquids
• Depends on the definition of liquid used for all of the GHS
– Vapour pressure of ≤ 300 kPa (3 bar) at 500C and
– Not completely gaseous at 200C and 101.3 kPa and
– Melting point of ≤ 200C at pressure of 101.3 kPa
– Includes viscous substances where fluidity criteria of either
ASTM D 4359-90 or section 2.3.4 of Annex A of the European
Agreement concerning the International Carriage of Dangerous
Goods (ADR) are met
Note:
Category
Criteria
1
Flash point < 23 °C and initial boiling point  35 °C
2
Flash point < 23 °C and initial boiling point > 35 °C
3
Flash point  23 °C and  60 °C
4
Flash point > 60 °C and  93 °C
GHS includes some flammable liquids excluded from transport
classification
Examples/Flammable Liquids
Substance
Flash point
Initial boiling
point
Guidance
• The flammable liquid chapter provides some
additional guidance on determining the
flashpoint of mixtures of flammable
components using calculation methods.
• The guidance also provides a number of
international test methods that can be used to
provide flashpoints. Closed cup methods are
preferred, and open cup methods are only
permitted in special circumstances.
Classification
Diethyl ether
-450C
34.60C
Category 1
Methanol
120C
64.70C
Category 3
Ethanol
12.80C
78.40C
Category 3
Gasoline
-400C
23.60C - 1900C
Category 3
Diesel fuel
520C - 960C
1750C - 3450C
Category 4 (most)
Jet A fuel
380C - 660C
1600C - 3000C
Category 4
39
Hazard Communication for Flammable Liquids, Annex 1
FLAMMABLE LIQUIDS
Category 1
Category 2
Danger
Danger
Extremely
flammable liquid
and vapour
Highly
flammable liquid
and vapour
3
3
Category 3
Category 4
Note
Under the UN
Recommendations
on the Transport of
No pictogram
Dangerous Goods,
Model Regulations,
the symbol,
number and
Warning
Warning
border line may be
shown in black
Flammable liquid Combustible liquid instead of white.
and vapour
The background
colour stays red in
both cases.
Not required under
the UN
Recommendations
on the Transport of
3
Dangerous Goods
Model Regulations
2.7 Flammable Solids
• Definition:
– A flammable solid is a solid which is readily
combustible, or may cause or contribute to fire
through friction.
– Readily combustible solids are powdered, granular,
or pasty substances which are dangerous if they
can be easily ignited by brief contact with an
ignition source, such as a burning match, and if
the flame spreads rapidly.
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Classification Criteria
Classification Criteria, cont.
Table 2.7.1: Criteria for flammable solids
Category
Criteria
1
Burning rate test:
Substances or mixtures other than metal powders:
(a) wetted zone does not stop fire; and
(b) burning time < 45 s or burning rate > 2.2 mm/s
Metal powders: burning time  5 min
2
Burning rate test:
Substances or mixtures other than metal powders:
(a) wetted zone stops the fire for at least 4 min; and
(b) burning time < 45 s or burning rate > 2.2 mm/s
Metal powders: burning time > 5 min and  10 min
NOTE 1:
For classification tests on solid substances or mixtures, the tests should be performed on the
substance or mixture as presented. If for example, for the purposes of supply or transport, the same chemical
is to be presented in a physical form different from that which was tested and which is considered likely to
materially alter its performance in a classification test, the substance must also be tested in the new form.
NOTE 2:
• Classification is based on tests in the UNRTDG
Manual of Tests and Criteria, Part III, subsection 33.2.1.
• Solids which may cause fire through friction
will be classified by analogy with existing
entries (e.g., matches) until definitive criteria
are established.
Aerosols should not be classified as flammable solids. See Chapter 2.3.
Flammable solid – examples
Hazard Communication for Flammable Solids, Annex 1
FLAMMABLE SOLIDS
Category 2
Category 1
Substance
Classification
Aluminium powder
Category 1
Silicon powder
Category 2
Sulphur
Category 2
Matches (safety)
Category 2
Danger
Warning
Flammable solid
Flammable solid
4
4
-
-
Note
Colours for
pictogram
under the UN
Recommendations
on the Transport of
Dangerous Goods,
Model Regulations:
Symbol (flame):
black; Background:
white with seven
vertical red stripes;
Figure “4” in the
bottom corner:
black.
45
2.8 Self-Reactive Substances and
Mixtures
• Definition:
Self-reactive substances or mixtures are thermally
unstable liquid or solid substances or mixtures liable to
undergo a strongly exothermic decomposition even without
participation of oxygen (air). This definition excludes
substances and mixtures classified under the GHS as
explosives, organic peroxides or as oxidizing.
Classification Criteria (1)
• Sensitivity and effect threshold
– Heat of decomposition < 300 J/g OR
– Self-Accelerating Decomposition Temperature (SADT) >
750C (50 kg package)
• Summary classification ...
• A self-reactive substance or mixture is regarded as
possessing explosive properties when in laboratory testing
the formulation is liable to detonate, to deflagrate rapidly
or to show a violent effect when heated under
confinement.
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Classification Criteria (2)
• Summary classification, cont.
Practical Classification Method
Classification Method
• Classification method is outside the GHS.
• Complex test sequences as set out in
UNRTDG Tests and Criteria Part II.
• Requires specifically set up laboratory (e.g., some tests
require testing of in excess of 50kg in intended package).
• Overall logic
– test if substance or mixture propagates detonation
– test if substance or mixture propagates deflagration
– determine behaviour as packaged and under confinement
Note: Temperature-sensitive self-reactive substances (as
measured by SADT) require continuous temperature control.
Hazard Communication for Self-Reactive Substances and Mixtures, Annex 1
SELF-REACTIVE SUBSTANCES AND MIXTURES
Type A
• Obtain chemical name of substance or
components of mixture and information on
diluents used (if any).
• Obtain generic UN Number from Section 2.4.3.2.3
UNRTDG.
• Use generic number to determine classification.
• If testing is required, employ a certified specialist
international laboratory.
Type B
Types C and D
Types E and F
There are no label
elements allocated to
this hazard category
Danger
Danger
Heating may cause Heating may cause
an explosion
a fire or explosion
Same as for
explosives (follow
same symbol
selection process)
4
Danger
Warning
Heating may
cause a fire
Heating may
cause a fire
4
4
Note: List includes only substances permitted
for transport.
2.9 Pyrophoric Liquids
• Definition
Type G
Not
required
under the UN
Recommendations on
the Transport of
Dangerous Goods,
Model Regulations
Classification Criteria
• Classification is based on testing in Part III of the UNRTDG
Tests and Criteria Manual:
– A pyrophoric liquid is a liquid which, even in small
quantities, is liable to ignite within five minutes
after coming into contact with air.
Table 2.9.1: Criteria for pyrophoric liquids
Category
1
Criteria
The liquid ignites within 5 min when added to an inert carrier and exposed to air, or it
ignites or chars a filter paper on contact with air within 5 min.
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Example Chemicals Classified as
Pyrophoric Liquids
Guidance
• The classification procedure for pyrophoric
liquids need not be applied when experience
in production or handling shows that the
substance or mixture does not ignite
spontaneously on coming into contact with air
at normal temperatures (i.e., the substance is
known to be stable at room temperature for
prolonged periods of time (days)).
Hazard Communication for Pyrophoric
Liquids, Annex 1
PYROPHORIC LIQUIDS
Category 1
-
-
-
Danger
Note
Colours of UN
Recommendations
on the Transport of
Dangerous Goods,
Model Regulations,
pictogram:
Symbol (flame):
black;
Background: upper
half white, lower
half red; figure “4”
in bottom corner:
black.
Catches fire
spontaneously if
exposed to air
2.10 Pyrophoric Solids
• Definition
– A pyrophoric solid is a solid which, even in small
quantities, is liable to ignite within five minutes
after coming into contact with air.
4
Classification Criteria
• Classification is based on testing in Part III of the UNRTDG
Tests and Criteria Manual:
Table 2.10.1: Criteria for pyrophoric solids
Category
1
Criteria
The solid ignites within 5 min of coming into contact with air.
NOTE:
For classification tests on solid substances or mixtures, the tests should be performed on the
substance or mixture as presented. If for example, for the purposes of supply or transport, the same chemical
is to be presented in a physical form different from that which was tested and which is considered likely to
materially alter its performance in a classification test, the substance or mixture must also be tested in the
new form.
Guidance
• The classification procedure for pyrophoric
solids need not be applied when experience in
production or handling shows that the
substance or mixture does not ignite
spontaneously on coming into contact with air
at normal temperatures (i.e., the substance or
mixture is known to be stable at room
temperature for prolonged periods of time
(days)).
10
5/9/2012
Examples of Chemicals Classified as Pyrophoric Solids
Categor
y
Substance
1
Phosphorous, white or yellow, dry or underwater or in
solution
1
Iron powder
1
Magnesium powder (pyrophoric)
Hazard Communication for Pyrophoric
Solids, Annex 1
PYROPHORIC SOLIDS
Category 1
-
-
-
Note
Colours of UN
Recommendations
on the Transport of
Dangerous Goods,
Model Regulations,
pictogram:
Symbol (flame):
blac k;
Background: upper
half white, lower
half red; figure “4”
in bottom corner:
black.
Danger
Catches fire
spontaneously if
exposed to air
Remark: Mg or Mg alloys > 50% Mg in pellets, turnings
or ribbonsFlammable solid Cat 1
1
Sodium sulphide, anhydrous or with<30% water of
crystallisation
1
Wool waste, wet
4
2.11 Self-Heating Substances and
Mixtures
Classification Criteria
• Definition
Table 2.11.1: Criteria for se
– A self-heating substance or mixture is a solid or liquid
substance or mixture, other than a pyrophoric liquid or solid,
which, by reaction with air and without energy supply, is
liable to self-heat; this substance or mixture differs from a
pyrophoric liquid or solid in that it will ignite only when in
large amounts (kilograms) and after long periods of time
(hours or days).
• NOTE: Self-heating of a substance or mixtures is a process where
the gradual reaction of that substance or mixture with oxygen (in
air) generates heat. If the rate of heat production exceeds the rate
of heat loss, then the temperature of the substance or mixture will
rise which, after an induction time, may lead to self-ignition and
combustion.
Additional Factors
- Reaction of the substance or mixture with oxygen
(in the air), and the heat developed not being
conducted away rapidly enough.
- Rate of heat production exceeds the rate of heat
loss and the auto-ignition temperature is reached.
- Liquids normally not self-heating due to
insufficient surface for reaction with air.
Category
lf-heating substances and mixtures
Criteria
1
A positive result is obtained in a test using a 25 mm sample cube at 140
2
(a)
A positive result is obtained in a test using a 100 mm sample cube at 140
negative result is obtained in a t
est using a 25 mm cube sample at 140
substance or mixture is to be packed in packages with a volume of more than 3 m
°C
(b)
A positive result is obtained in a test using a 100 mm sample cube at 140
°C and a
negative result is obtained in a t
est 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 or
mixture is to be packed in packages with a volume of more than 450 litres; or
(c)
A positive result is obtained in
a test using a 100 mm sample cube 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.
°C and a
°C and the
3
; or
NOTE 1 :
For classification tests on solid substan
ces or mixtures, the tests should be performed on the
substance or mixture as presented. If for example, for the purposes of supply or transport, the same chemical
is to be presented in a physical form different from that which was tested and which is cons
idered likely to
materially alter its performance in a classification test, the substance or mixture must also be tested in the
new form.
NOTE 2 :
The criteria are based on the self
-ignition tempe rature of charcoal, which is 50
°C for a
sample cube of 27 m3. Substances and mixtures with a temperature of sponta
neous combustion higher than
50 °C for a volume of 27
m3 should not be assigned to this hazard class. Substances and mixtures with a
self igni tion temperature higher than 50
°C for a volume of 450
litre s should not be assigned to hazard
Category 1 of this hazard class.
Guidance
• The classification procedure for self-heating
substances or mixtures need not be applied if
the results of a screening test can be
adequately correlated with the classification
test and an appropriate safety margin is
applied.
• The GHS provides two types of screening tests
that could be applied.
11
5/9/2012
Examples of Chemicals Classified as
Self-Heating
Category
Chemical
UN TDG
1
Metal powder, self-heating N.O.S. (UN
3189)
Class 4.2
Packing Group II
1
Sodium hydrosulfide with < 25 % of water
of crystallization (UN 2318)
Class 4.2
Packing Group II
2
Alkaline Earth Metal, alcoholates, N.O.S.
(UN 3205)
Class 4.2
Packing Group III
2
Titanium disulfide (CAS 12039-13-3; UN
3174)
Class 4.2
Packing Group III
2
Charcoal (UN1361)
Class 4.2
Packing Group III
Hazard Communication for Self-Heating
Substances and Mixtures, Annex 1
SELF-HEATING SUBSTANCES AND MIXTURES
Category 1
Danger
Warning
Self-heating in
large quantities;
may catch fire
4
4
•
•
•
•
•
Chemical structure
Physical state/form (e.g., particle size)
Water solubility
Friability
Other hazardous properties (e.g.,
pyrophoric, toxic)
-
Note
Colours of UN
Recommendations
on the Transport of
Dangerous Goods,
Model Regulations,
pictogram:
Symbol (flame):
black;
Background:
upper half white,
lower half red;
figure “4” in
bottom corner:
black.
Classification Criteria
Table 2.12.1: Criteria for substances and mixtures which, in contact with water,
emit flammable gases
• Definition
Other Relevant Factors
-
Self-heating; may
catch fire
2.12 Emit Flammable Gases in Contact
with Water
– Substances or mixtures which, in contact with
water, emit flammable gases are solid or liquid
substances or mixtures which, by interaction with
water, are liable to become spontaneously
flammable or to give off flammable gases in
dangerous quantities.
Category 2
Category
Criteria
1
Any substance or mixture which reacts vigorously with water at ambient 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.
2
Any substance or mixture which reacts readily with water at ambient temperatures such that
the maximum rate of evolution of flammable gas is equal to or greater than20 litres per
kilogram of substance per hour, and which does not meet the criteria for Category1.
3
Any substance or mixture which reacts slowly with water at ambient temperatures 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 forCategories 1 and 2.
Guidance
• The classification procedure for this class need not be
applied if:
(a) The chemical structure of the substance or
mixture does not contain metals or metalloids;
(b) Experience in production or handling shows that
the substance or mixture does not react with water, e.g. the
substance is manufactured with water or washed with
water; or
(c) The substance or mixture is known to be soluble
in water to form a stable mixture.
12
5/9/2012
Examples of Chemicals Classified as Emit
Flammable Gases in Contact w/Water
Hazard Communication for Chemicals that Emit
Flammable Gases in Contact with Water, Annex 1
SUBSTANCES AND MIXTURES, WHICH IN CONTACT WITH WATER,
EMIT FLAMMABLE GASES
Category 1
Category 2
Category 3
Danger
Danger
Warning
In contact with
water releases
flammable gases
which may ignite
spontaneously
In contact with
water releases
flammable gases
In contact with
water releases
flammable gases
4
4
4
2.13 Oxidizing Liquids
-
Note
Under the UN
Recommendations
on the Transport of
Dangerous Goods,
Model Regulations,
the symbol,
number and border
line may be shown
in black instead of
white. The
background stays
blue in both cases.
Classification Criteria
• Definition
Table 2.13.1: Criteria for oxidizing liquids
– An oxidizing liquid is a liquid which, while in itself
not necessarily combustible, may, generally by
yielding oxygen, cause, or contribute to, the
combustion of other material.
Category
Criteria
1
Any substance or mixture which, in the 1:1 mixture, by mass, of substance (or mixture) and
cellulose 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;
2
Any substance or mixture which, in the 1:1 mixture, by mass, of substance (or mixture)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 solution and cellulose;
and the criteria for Category 1 are not met;
3
Any substance or mixture which, in the 1:1 mixture, by mass, of substance (or mixture) 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 65% aqueous nitric acid and cellulose; and the criteria
for Categories 1 and 2 are not met.
Guidance
Guidance, cont.
• Experience showing substances or mixtures to be
oxidizing may take precedence over test results.
• For organic substances or mixtures the
classification procedure for this class need not be
applied if:
• For inorganic substances or mixtures, the
classification procedure for this class need not
be applied if they do not contain oxygen or
halogen atoms.
– (a) The substance or mixture does not contain
oxygen, fluorine or chlorine; or
– (b) The substance or mixture contains oxygen,
fluorine or chlorine and these elements are chemically
bonded only to carbon or hydrogen.
13
5/9/2012
Examples of Chemicals Classified as
Oxidizing Liquids
Hazard Communication for Oxidizing
Liquids, Annex 1
OXIDIZING LIQUIDS
Category 1
• Definition
Category 3
Danger
Danger
Warning
May cause fire or
explosion; strong
oxidizer
May intensify
fire; oxidizer
May intensify
fire; oxidizer
5.1
2.14 Oxidizing Solids
Category 2
5.1
-
Note
Under the UN
Recommendations
on the Transport of
Dangerous Goods,
Model Regulations,
pictogram colours:
Symbol (flame
over circle): black;
Background:
yellow; Figure
“5.1” in bottom
corner: black.
5.1
Classification Criteria
Table 2.14.1: Criteria for oxidizing solids
– An oxidizing solid is a solid which, while in itself is
not necessarily combustible, may, generally by
yielding oxygen, cause, or contribute to, the
combustion of other material.
Guidance
• Experience showing substances or mixtures to be
oxidizing may take precedence over test results.
• The classification procedure for this class need not be
applied to organic substances or mixtures if:
– (a) The substance or mixture does not contain oxygen,
fluorine or chlorine; or
– (b) The substance or mixture contains oxygen, fluorine or
chlorine and these elements are chemically bonded only to
carbon or hydrogen.
• The classification procedure for this class need not be
applied to inorganic substances or mixtures if they do
not contain oxygen or halogen atoms.
Category
Criteria
Any substance or mixture which, in the 4:1 or 1:1 sample-to-cellulose ratio (by mass) tested,
1
exhibits a mean burning time less than the mean burning time of a 3:2 mixture, by mass, of
potassium bromate and cellulose.
Any substance or mixture which, in the 4:1 or 1:1 sample-to-cellulose ratio (by mass) tested,
2
exhibits a mean burning time equal to or less than the mean burning time of a 2:3 mixture (by
mass) of potassium bromate and cellulose and the criteria for Category 1 are not met.
Any substance or mixture which, in the 4:1 or 1:1 sample-to-cellulose ratio (by mass) tested,
3
exhibits a mean burning time equal to or less than the mean burning time of a 3:7 mixture (by
mass) of potassium bromate and cellulose and the criteria for Categories 1 and 2 are not met.
Guidance, cont.
Important Considerations:
• Physical form
• Particle size: the smaller the size, the higher
the capacity
• Other hazards besides combustion hazard
• Dilution: no linear decrease
14
5/9/2012
Examples of Chemicals Classified as
Oxidizing Solids
Hazard Communication for Oxidizing
Solids, Annex 1
OXIDIZING SOLIDS
Category 1
Category 2
Category 3
Danger
Danger
Warning
-
May cause fire
May intensify fire; May intensify fire;
or explosion; strong
oxidizer
oxidizer
oxidizer
5.1
2.15 Organic Peroxides
• Definition
– Organic peroxides are liquid or solid organic
substances which:
• contain the bivalent -O-O- structure and may be
considered derivatives of hydrogen peroxide, where
one or both of the hydrogen atoms have been replaced
by organic radicals.
– The term also includes organic peroxide formulations
(mixtures). Organic peroxides are thermally unstable
substances or mixtures, which may undergo
exothermic self-accelerating decomposition.
Classification Criteria
• Characteristics
– based on chemical structure {-O-O-}
– thermally unstable
– class includes substances and mixtures
• Hazardous effects (depending on type)
– explosive
– rapidly combustible (may be difficult to
extinguish)
– reactive with other substances => fire or explosion
5.1
Note
Under the UN
Recommendations
on the Transport of
Dangerous Goods,
Model Regulations,
pictogram colours:
Symbol (flame
over circle): black;
Background:
yellow; Figure
“5.1” in bottom
corner: black.
5.1
Organic Peroxides
• In addition, they may have one or more of the following
properties:
(a) be liable to explosive decomposition;
(b) burn rapidly;
(c) be sensitive to impact or friction;
(d) react dangerously with other substances.
• An organic peroxide is regarded as possessing explosive
properties when in laboratory testing the formulation is
liable to detonate, to deflagrate rapidly or to show a violent
effect when heated under confinement.
Organic Peroxides Classification (1)
{-O-O-} chemical structure
means substance or mixture
is included in the class
unless:
• ≤ 1% available oxygen
from organic peroxides
when containing ≤ 1%
hydrogen peroxide OR
𝑨𝒗𝒂𝒊𝒍𝒂𝒃𝒍𝒆 𝒐𝒙𝒚𝒈𝒆𝒏 𝒄𝒐𝒏𝒕𝒆𝒏𝒕 = 𝟏𝟔 ×
𝒏 𝒏𝒊 ×𝒄𝒊
𝒊 𝒎
𝒊
ni = number of peroxide groups per molecule of organic peroxide
ci = mass concentration (mass %) of organic peroxide
• ≤ 0.5% available oxygen
from organic peroxides
when containing
between 1% and 7%
hydrogen peroxide
mi = molecular mass of organic peroxide i
15
5/9/2012
Organic Peroxides Classification (2)
Organic Peroxides Classification (3)
Summary classification - seven categories
Category
• Summary Classification continued
Description
Type A
May detonate or deflagrate rapidly as packaged
Type B
Explosive properties: as packaged does not detonate or deflagrate but may undergo
thermal explosion
Type C
Explosive properties: when packaged cannot detonate or deflagrate or undergo
thermal explosion
Type D
•Detonates partially, does not deflagrate & shows no violent effect when heated under
confinement OR
•Does not detonate, deflagrates slowly & shows no violent effect when heated OR
• does not detonate or deflagrate and shows medium effect when heated under
confinement
• Note: Failure to meet any part of the Type G criteria requires
reassignment to Type F.
Classification Method
Practical Classification Method
• Classification method is outside the GHS.
• Complex test sequences as set out in UNRTDG Tests and Criteria Part II.
• Requires specifically set up laboratory (e.g., some tests require testing of
in excess of 50kg in intended package).
• Overall logic:
– test if substance or mixture propagates detonation
– test if substance or mixture propagates deflagration
– determine behavior as packaged and under confinement
Note: Temperature-sensitive organic peroxides (as measured by SADT)
require continuous temperature control.
Hazard Communication for Organic Peroxides, Annex 1
ORGANIC PEROXIDES
Type A
Type B
Types C and D
Types E and F
• Obtain chemical name of organic peroxide and
information on diluents used (if any).
• Obtain generic UN number from section 2.5.3.2.4
UNRTDG.
• Use generic number to determine classification.
• If testing is required, employ a certified specialist
international laboratory.
Note: List includes only substances permitted for
transport.
2.16 Corrosive to Metals
Type G
• Definition
There are no label
elements allocated
to this hazard
category
Danger
Danger
Heating may cause Heating may cause
an explosion
a fire or explosion
Same as for
explosives (follow
same symbol
5.2
selection process)
Danger
Warning
Heating may
cause a fire
Heating may
cause a fire
5.2
5.2
– A substance or a mixture which is corrosive to
metals is a substance or a mixture which by
chemical action will materially damage, or even
destroy, metals.
Not required under
the UN
Recommendations
on the Transport of
Dangerous Goods,
Model Regulations.
16
5/9/2012
Classification Criteria
Table 2.16.1: Criteria for substances and mixtures corrosive to metal
Category
Criteria
1
Corrosion rate on either steel or aluminium surfaces exceeding 6.25 mm per year
at a test temperature of 55 °C when tested on both materials.
Minimum Mass Loss
Equivalency to Criterion 6.5 mm/year
Exposure Time
[d]
Mass Loss
[%]
7
14
21
28
13.5
26.5
39.2
51.5
NOTE:
Where an initial test on either steel or aluminium indicates the substance or mixture being
tested is corrosive the follow-up test on the other metal is not required.
Examples of Chemicals Classified as
Corrosive to Metals
Hazard Communication for Corrosive
to Metals, Annex 1
CORROSIVE TO METALS
Category 1
-
-
-
Note
Under the UN
Recommendations
on the Transport of
Dangerous Goods,
Model Regulations,
pictogram colours:
Warning
May be corrosive
to metals
Symbol
(corrosion): black;
background: upper
half: white; lower
half: black with
white border;
Figure “8” in the
bottom corner:
white.
Physical Hazards Exercise
• Data regarding example chemicals will be
provided.
• Reference may be made to the Purple Book
criteria chapters.
• Classification of the example chemicals will be
completed based on the data provided.
• The instructor will describe the correct
solution, with the rationale.
17