User Guide to Thresholds and Classification - Environmental ...

67User Guide for Thresholds and Classificationsdesensitised state, it still meets the criteria for a substance with explosive properties. Such substancesshould still be classified as explosive substances.When substances are diluted so as to exempt them from the explosives classification by failing Test Series6, but they have flammable properties, then they are classified as subclass 4.1.3, solid desensitisedexplosives.Current New Zealand criteriaThe Dangerous Goods Act 1974 grouped class 4.1, flammable solids, into categories A, B, and C, and listedspecific substances. Although overall these Dangerous Goods Act categories did not readily correlate withUN class 4.1 or the HSNO Act classification subclasses 4.1.1, 4.1.2, and 4.1.3, DG class 4.1 category B didlist substances now classified as HSNO Act subclass (UN division) 4.1.3, desensitised explosives.6.4. Spontaneously combustible flammable solids – subclass 4.26.4.1. Threshold criteria for subclass 4.2 substances liable to spontaneous combustionand pyrophoric and self-heating substances (equivalent to UN division 4.2)A substance is considered to be a subclass 4.2 substance (substances liable to spontaneous combustionand pyrophoric and self-heating substances), within the meaning of the HSNO Act, if, when tested asdescribed in para 33.3.1 of the UN Manual of Tests and Criteria, it meets one or more of the followingcriteria.a. It is a substance that is a solid in powder form and, when tested in accordance with Test N.2 (para33.3.1.4, UN Manual of Tests and Criteria), ignites in one of the tests (pyrophoric solids).b. It is a substance that is a liquid and, when tested in accordance with Test N.3 (para 33.3.1.5, UN Manualof Tests and Criteria), ignites in the first part of the test (para 33.3.1.5.3.1) or ignites or chars the filterpaper in the second part of the test (para 33.3.1.5.3.2) (pyrophoric liquids).c. It is a substance that is a solid and, when tested in accordance with Test N.4 (para 33.3.1.6, UN Manualof Tests and Criteria), gives a positive result in a test using a 100 mm sample cube at 140ºC(self-heatingsolids).6.4.2. Notes on the threshold for subclass 4.2The threshold criteria for HSNO Act subclass 4.2 are equivalent to those for division 4.2 as set out in the UNManual of Tests and Criteria.The EPA is not aware of any alternative comparable test methods recognised by any overseas nationalcompetent authority, so the methods described above from the UN Manual of Tests and Criteria have beenused to define the threshold.For any substance subjected to the threshold test methods described in (a) and (c) above (that is, testmethods N3 and N4), the result must be determined using either:January 2012 EPA0109