ADR Class 4.1
Flammable solids, desensitized explosive substances, polymerizing substances and self-reactive liquids or solids.
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Class 4.1 includes the following hazardous materials:
- Readily flammable materials and solid objects
- Liquid or solid self-reactive materials
- Desensitized solid explosive materials
- Subjects related to self-reactive materials
- Polymerizing materials
Classification of materials Class 4.1
Substances and articles of ADR Class 4.1 can be subdivided as follows:
- F
- F1 organic solids
- F2 Molten organic solids
- F3 Inorganic
- FO Solid flammable oxidizing materials
- FT Toxic flammable solids
- FCCorrosive flammable solids
- D Desensitized explosive substances without subsidiary risk
- DT Toxic desensitized explosive materials
- SR. Self-reactive matter:
- SR1 Not requiring temperature regulation
- SR2 Requiring temperature regulation
- PM. Polymerizing materials:
- PM1 Not requiring temperature regulation
- PM2 Who need temperature regulation
Flammable solids
Flammable solids are easily combustible solids and can cause friction fires.
Powdery, granular or pasty materials shall be classified as highly flammable when a slight contact with a source of ignition spreads rapidly, calculated burning time is less than 45 seconds at a distance of 100mm. Packing group II shall apply when the flame spreads beyond the wetted area. Packing group III will be applied when the wetted area stops the flame for at least four minutes.
Metal powders or metal alloy powders should be included in Class 4.1 when they ignite on contact with flame and the reaction propagates in less than 10 minutes. Packing group II when the reaction propagates over the length of the sample in less than five minutes. Packing group III when the reaction propagates over the length of the sample in more than five minutes.
Solid substances which can be ignited by rubbing are classified under 4.1 by the existing headings, and the packing group is assigned by analogy with the existing headings.
Ranking
The inclusion of organic and inorganic materials or objects not mentioned in Table A of Chapter 3.2 in this class shall be made on the basis of the tests carried out and described in the Manual of Tests and Criteria and the experience accumulated by such material or object.
The criteria will be as follows:
- Powdery, granular or pasty materials are of Class 4.1 when ignited by a slight contact with an ignition source, provided that the burning time is less than 45 seconds or the burning velocity reaches 2.2 mm/sec.
- Metal powders and/or metal alloy powders when in contact with flame combustion spreads in less than 10 minutes.
Solid materials that can be ignited by rubbing should be included in this class under an existing heading or by means of a special provision in Chapter 3.1.
The test procedures in the Manual of Tests and Criteria and the criteria established for this class 4.1 may determine that a matter expressly mentioned is not subject to the provisions of this class.
Desensitization
To avoid the decomposition of these materials and according to technological progress, diluents are introduced to mitigate the self-reactive properties.
Any diluent will be compatible and must be prevented from concentrating (evaporation) with respect to the self-reactive material. A good diluent is one that does not affect the thermal stability and hazardous properties of the self-reactive material.
Provisions regarding temperature regulation
Temperature regulation is understood as the maximum temperature at which a material can be transported together with its correct packaging.
Materials with a TDAA below 55ºC will be subject to temperature regulation during transport. A decrease in the regulation temperature will lead to the critical temperature where emergency procedures are applied to try to avoid irreversible AADT.
Desensitized solid explosive substances
Desensitized explosive solids are materials that have been moistened with water or alcohol or other diluents to eliminate their explosive properties.
Polymerizing materials
They are those materials that without stabilization are susceptible to undergo strong exothermic reactions that give rise to larger molecules or even polymers under normal transport conditions. Criteria for materials considered as susceptible to offer polymerization:
- Those whose temperature of self-accelerating polymerization (TPAA) is lower than 75ºC, with or without chemical stabilization, as presented for transport. CONTAINER/PACKAGING, IBC, or TANKER
- It has a heat of reaction greater than 300 J/gr.
- Do not meet any other criteria from classes 1 to 8
Polymerizing materials shall be subjected to temperature control during transport as long as their TPAA:
- To be transported in containers/packaging, IBC’s do not exceed 50ºC.
- To be transported in a tank, it should not exceed 45ºC.
Materials meeting the criteria for polymerizing materials, as well as for inclusion in Classes 1 to 8, are subject to the requirements of special provision 386 of Chapter 3.3.
The stability to avoid polymerization will be given by two possible types of stabilization: thermal or chemical, in the latter case it will be necessary to ensure whether at low temperatures and the concentration of the inhibitor is suitable to maintain the non-polymerization of the material or substance, because in case of proven ineffectiveness it will be necessary to resort to stable temperature regulation.
Packaging groups
The decomposition of the material can occur by heat, contact with heavy metals, acids, bases, etc. Some self-reactive materials may decompose and explode if the site is confined. Such decomposition can be mitigated by the use of suitable diluents and packaging according to P520 of 4.1.4.1 packaging instructions.
