ADR Class 4.2
Pyrophoric materials, both liquids and solids, which in contact with air ignite within five minutes.
Materials and objects that undergo spontaneous heating and can become hot when they come into contact with air. These materials can ignite in large quantities and after a long period of time.
Ranking
Substances and objects of Class 4.2 may be classified as follows:
- SC Substances that may experience spontaneous ignition, corrosives
- SC1 Organic, corrosive, liquid materials
- SC2 Organic, corrosive, solid materials
- SC3 Inorganic, corrosive, liquid materials
- SC4 Inorganic, corrosive, solid materials
- ST Substances that may experience spontaneous ignition, toxic
- ST1 Organic, toxic, liquid materials
- ST2 Organic, toxic, solid materials
- ST3 Inorganic, toxic, liquid materials
- ST4 Inorganic, toxic, solid matter
- S Substances which may spontaneously ignite in contact with air
- S1 Spontaneously flammable liquid organic matter
- S2 Solid organic matter
- S3 Liquid inorganic materials
- S4 Solid inorganic materials
- S5 Organo-metallic materials
- SW Substances that can spontaneously ignite releasing flammable gases when in contact with water.
- SO Substances which may undergo spontaneous ignition, oxidizers.
Properties
Spontaneous heating is caused by the contact of oxygen in the air with matter, generating heat that is not dissipated to the outside. This undissipated heat reaches the spontaneous ignition temperature.
Spontaneously flammable (pyrophoric) liquids:
- When ignited within five minutes after spillage on an inert substrate
- Either ignite or carbonate after five minutes on a dry filter paper support
Pyrophoric substances are considered packing group I.
Those materials in which a cubic sample of 10 cm of side, at 140ºC temperature, if in a period of 24 hours spontaneous inflammation or a temperature increase of more than 200ºC is observed will be classified in class 4.2. If the material to be treated is prepared in a cubic sample of 2.5 cm of side at a test temperature of 140ºC during 24 hours, spontaneous inflammation or heating of more than 200ºC should be observed, we assign packing group II. If this test does not bear fruit we apply a cubic sample of 10 cm of side at a test temperature of 140ºC for a period of 24 hours, we assign packing group III.
Substances transported in packages with a volume not exceeding 3 m3 shall not be considered as Class 4.2 if the test has been carried out on a cubic sample of 10 cm on each side at a temperature of 120ºC and does not show spontaneous ignition or temperature rise above 180ºC during 24 hours.
Materials transported in packages with a volume of less than 450m3 are not considered to be of class 4.2 if the test on a cubic sample of 10 cm of side at 100ºC does not experience spontaneous ignition or temperature increase at 160ºC during 24 hours.
Class 4.2 packing groups
The criteria to establish the packing groups as well as the criteria to establish if it belongs to a class are:
- Pyrophoric substances should be included in packing group I.
- Substances that undergo spontaneous heating on a cubic sample of 2.5 cm of side at 140ºC for 24 hours, if it shows spontaneous ignition or heating of more than 200ºC, are considered as packing group II.
- Materials that undergo spontaneous heating, if a temperature of 140ºC is applied to a cubic sample of 2.5 cm for 24 hours, spontaneous ignition or a temperature increase of 200ºC is not observed, but if the cubic sample passes to 10cm on a side if it is observed, it will be considered as packing group III.
