User Guide to Thresholds and Classification - Environmental ...

21User Guide for Thresholds and Classificationsdeflagration under confinement results in an increase in pressure, rate of reaction, and temperature,which may cause detonation.A substance designed to produce a pyrotechnic effect will, when initiated, produce a non-detonative,self-sustaining, exothermic chemical reaction, producing an effect of heat, light, sound, smoke, gas, ormotion, or a combination of these. Pyrotechnic effect refers to a display of fireworks or to the ignitionof a substance for technical or military purposes.b. External bonfire test for manufactured articlesThis is a test performed on explosive articles or packages of explosive articles to determine whetherthere is a mass explosion or a hazard from dangerous projections, radiant heat, and/or violent burning,or any other dangerous effect when the articles are involved in a fire. An article is above this thresholdif it produces some effect of projection of fragments, fire, smoke, heat, or loud noise external to thearticle when tested as a stack of articles in accordance with test type 6(c) in section 16.6 of the UNManual of Tests and Criteria (test criteria in para 16.6.1.4.7, pp 155–156).2.4. Classification criteria for explosive substances and articlesThe explosive property classification scheme groups explosive substances in terms of three effects. Theseeffects are the:degree of sensitiveness to stimuli;type of explosive effect; anddifferent levels at which those explosive effects might be displayed.The HSNO Act classification scheme uses the system in the UN Model Regulations. Thus, the classificationfor substances with an explosive property is based on:subclasses (UN divisions) for types and levels of explosiveness and for the sensitiveness of thesubstance to stimuli; andcategories (UN compatibility groupings) for explosive type.Classification requires allocation to both a subclass and a category. A substance or article is classified asbeing in a particular subclass or category if it meets the criteria set out in Schedule 1 of the classificationregulations for that subclass or category. These criteria are taken from the UN Model Regulations and UNManual of Tests and Criteria, and are described in the sections below. Substances and articles may beclassified only into the combinations of subclasses and categories (divisions and groupings) permitted by theUN Model Regulations, as shown in Table 2.1. The assignment of substances to cells where there is noentry is prohibited.January 2012 EPA0109