User Guide to Thresholds and Classification - Environmental ...

63User Guide for Thresholds and Classificationsincreases with temperature and varies with the substance. Decomposition may result in the evolution of toxicgases and vapours, particularly if no ignition occurs.Some self-reactive substances may decompose explosively, particularly if confined. This characteristic maybe modified by the addition of diluents or by the use of appropriate packaging.Some self-reactive substances burn vigorously. For certain self-reactive substances, the temperature atwhich they are held must be controlled.Examples of self-reactive substances are compounds such as:aliphatic azo compounds (-C-N=N-C-);organic azides (-C-N3);diazonium salts (-CN2+Z-);N-nitroso compounds (-N-N=O); andaromatic sulphohydrazides (-SO2-NH-NH2).This list is not exhaustive and substances with other reactive groups and some mixtures of substances mayhave similar properties.Current New Zealand criteriaThe Dangerous Goods Act 1974 groups class 4.1 flammable solids into categories A, B, and C, and listsspecific substances. The entries in these categories in the Schedule to the Dangerous Goods Act do notreadily correlate with UN division 4.1(b) or the HSNO Act classification subclasses 4.1.1, 4.1.2, and 4.1.3.Example substancesTable 6.1: Example substances classified as self-reactive flammable solids in the UN Model RegulationsTypeAExamples of substances meeting the criteria for that typeNone currently assigned*2-diazo-1-naphthol-4-sulfochloride,B2-diazo-1-naphthol-5-sulfochlorideAzodicarbonamide formulation Type B, temperature controlledAzodicarbonamide formulation Type CC2,2‘ -azodi (isobutyronitrile)Tetramine palladium(II) nitrateAzodicarbonamide formulation Type DDBenzene sulfohydrazideDiphenyloxide-4,4‘-disulfohydrazide4-nitrosophenolEFDiethyleneglycol bis(allyl carbonate) + di-isopropylperoxydicarbonateNone currently assignedJanuary 2012 EPA0109