2.2.4. Additional Classification Considerations
2.2.4.1. Flammability shall be determined by tests or, for mixtures where there are sufficient data available, by calculation in accordance with the methods adopted by ISO (see ISO 10156 as amended, ‘Gases and gas mixtures — Determination of fire potential and oxidising ability for the selection of cylinder valve outlets’ and, if using fundamental burning velocity for Category 1B, see ISO 817 as amended ‘Refrigerants-Designation and safety classification, Annex C:- Method of test for burning velocity measurement of flammable gases’). Instead of the test apparatus according to ISO 10156 as amended, the test apparatus for the tube method according to clause 4.2 of EN 1839 as amended (Determination of explosion limits of gases and vapours) may be used.
2.2.4.2. Pyrophoricity shall be determined at 54 °C in accordance with either IEC 60079-20-1 ed1.0 (2010-01) ‘Explosive atmospheres – Part 20-1: Material characteristics for gas and vapour classification – Test methods and data’ or DIN 51794 ‘Determining the ignition temperature of petroleum products’.
2.2.4.3. The classification procedure for pyrophoric gases need not be applied when experience in production or handling shows that the substance does not ignite spontaneously on coming into contact with air at a temperature of 54 °C or below. Flammable gas mixtures, which have not been tested for pyrophoricity and contain more than one percent pyrophoric components, shall be classified as a pyrophoric gas. Expert judgement on the properties and physical hazards of pyrophoric gases and their mixtures shall be used in assessing the need for classification of flammable gas mixtures containing one percent or less pyrophoric components. In this case, testing need only be considered if expert judgement indicates a need for additional data to support the classification process.
►M19 2.2.4.4. ◄ Chemical instability shall be determined in accordance with the method described in Part III of the UN RTDG, Manual of Tests and Criteria. If the calculations in accordance with ISO 10156 as amended show that a gas mixture is not flammable it is not necessary to carry out the tests for determining chemical instability for classification purposes.