User Guide to Thresholds and Classification - Environmental ...

50User Guide for Thresholds and Classifications6. Flammable Solids, Self-Reactive Flammable Solids, SolidDesensitised Explosives, Spontaneously CombustibleFlammable Solids, and Substances Dangerous When Wet –Subclasses 4.1.1, 4.1.2, 4.1.3, 4.2, and 4.36.1. Flammable solids – subclass 4.1.1The Hazardous Substances and New Organisms Act 1996 (HSNO Act) classification system for solids withflammable properties provides for five subclasses, reflecting different manifestations of the flammableproperty. This generally mirrors the system under the UN Model Regulations (United Nations, 1999b) forclass 4 flammable solids, which provides for three divisions within the class, with one of these subdividedinto three types of substance.The HSNO Act subclasses for flammable solids are:subclass 4.1.1 – flammable solids, which includes solids that may cause fire through friction (see section6.1 above);subclass 4.1.2 – self-reactive substances (see section 6.2 below);subclass 4.1.3 – solid desensitised explosives (see section 6.3 below);subclass 4.2 – substances liable to spontaneous combustion and pyrophoric and self-heatingsubstances (see section 6.4 below); andsubclass 4.3 – substances that in contact with water emit flammable gases (see section 6.5 below).Key terms are defined in section 3.2 in chapter 3.6.1.1. Threshold criteria for flammable solids subclass 4.1.1 (equivalent to UN division4.1(a))This subclass covers substances that are readily combustible or may cause or contribute to fire throughfriction.a. The threshold criterion for substances considered easily ignitable and readily combustible is as follows.Any solid that meets the criteria of para 33.2.1.4.4 (test criteria and method of assessing results) of theUN Manual of Tests and Criteria (United Nations, 1999a), when tested in accordance with the burningrate test method for readily combustible solids set out in Test Series N.1 (para 33.2.1.4, UN Manual ofTests and Criteria).b. The threshold criterion for substances that may cause or contribute to fire through friction is as follows.Any solid listed in the Dangerous Goods List, chapter 3.2, of the UN Model Regulations, with the serialnumber: UN 1331, 1343, 1944, 1945, or 2254.For any substance subjected to the threshold test method in (a) above, the result must be determined using:the finest particle form in which that substance is reasonably capable of being used or rendered; orwhere it is likely or known that more than 10% of the mass of the substance will crumble into a finerparticle form, then that finer form.January 2012 EPA0109