User Guide to Thresholds and Classification - Environmental ...

48User Guide for Thresholds and Classificationsoctanol; anddiesel.5.2. Liquid desensitised explosives – subclass 3.2This subclass was recently introduced to the UN classification system in the 11th edition of class 3 of the UNModel Regulations).5.2.1. Threshold criteria for liquid desensitised explosivesLiquid desensitised explosives are explosive (class 1) substances that are dissolved or suspended in wateror other liquid substances to form an homogeneous liquid mixture to suppress their explosive properties,where the concentration of the explosive substance is at or above the minimum level deemed subject to theUN Model Regulations. This criterion is in para 2.3.1.4 of the UN Model Regulations.Current entries in the Dangerous Goods List in chapter 3.2 of the UN Model Regulations are UN 1204, 2059,3064, 3343, and 3357.5.2.2. Classification of liquid desensitised explosivesThere are three classification categories to subclass 3.2, liquid desensitised explosives. The criteria forinclusion in these categories are as follows.Category A (high hazard) – classification 3.2A (equivalent to UN PG I)a. Any substance that is listed in para 2.3.1.4 of the UN Model Regulations as a liquid desensitisedexplosive and is assigned UN PG I in the UN Dangerous Goods List in chapter 3.2 of the UN ModelRegulations (the only such substance currently listed is UN 2059, nitrocellulose solution, PG I).b. Any liquid desensitised explosive that is formed from an explosive by adding a desensitising agent toform a liquid substance that no longer meets a threshold for class 1, is not already listed in the UNModel Regulations, and has not been assigned a packing group in the UN Model Regulations.Category B (medium hazard) – classification 3.2B (equivalent to UN PG II)Any substance that is listed in para 2.3.1.4 of the UN Model Regulations as a liquid desensitisedexplosive and is assigned UN PG II in the UN Dangerous Goods List in chapter 3.2 of the UN ModelRegulations (such substances currently listed are UN 1204, 2059, 3064, and 3357).Category C (low hazard) – classification 3.2C (equivalent to UN PG III)Any substance that is listed in para 2.3.1.4 of the UN Model Regulations as a liquid desensitisedexplosive and is assigned UN PG III in the UN Dangerous Goods List in chapter 3.2 of the UN ModelRegulations (the only such substance currently listed is UN 2059, nitrocellulose solution, PG III).5.2.3. DiscussionDesensitised explosives are substances that have been assigned to class 1 (explosives) but which havebeen diluted to suppress their explosive properties to the extent that they are excluded from class 1 by UNTest Series 6, as listed in section 16 of the UN Manual of Tests and Criteria (United Nations, 1999a). TheyJanuary 2012 EPA0109