User Guide to Thresholds and Classification - Environmental ...

29User Guide for Thresholds and ClassificationsC-metal such as Grignard reagents or organo-lithium compounds;N-metal;Contiguous nitrogen atoms such as azides, aliphatic azo compounds, diazonium salts, hydrazines,and sulphonylhydrazides;Contiguous oxygen atoms such as peroxides and ozonides;N-O such as hydroxylamines, nitrates, nitro compounds, and nitroso compounds;N-oxides and 1,2-oxazoles;N-halogen such as chloramines and fluoroamines; andO-halogen such as chlorates, perchlorates, and iodosyl compounds.The substance contains chemical groups associated with explosive properties that include oxygen butthe calculated oxygen balance is less than -200, where the oxygen balance is calculated for the chemicalreaction:C x H y O z + [x + (y/4) – (z/2)]. O 2 ↔ x. CO 2 + (y/2). H 2 Ousing the formula:oxygen balance = -1,600[2x + (y/2) – z]/molecular weightThe organic substance or a homogeneous mixture of organic substances contains chemical groupsassociated with explosive properties but the exothermic decomposition energy is less than 500 J/g andthe onset of exothermic decomposition is below 500°C.For mixtures of inorganic oxidising substances (subclass 5.1.1) with organic materials, the concentrationof the inorganic oxidising substance is less than 15%, by mass, of the mixture, if the oxidising substanceis classified as 5.1.1A or 5.1.1B (UN 5.1, Packing Group I or Packing Group II); or is less than 30%, bymass, of the mixture, if the oxidising substance is classified as 5.1.1C (UN 5.1, Packing Group III).2.5.3. Mixture rule for explosive substancesIn general, no mixture rules apply to explosive hazards. The direct testing of mixtures for explosive hazardsis usually required since the hazards of a mixture are not always reliably predicted from component data.2.5.4. Criterion of being designed to detonate, deflagrate, or produce a pyrotechnic effectThe criterion of being designed to detonate, deflagrate, or produce a pyrotechnic effect carries over thecurrent scope of the Explosives Act 1957. For example, the criterion covers airbag igniters and modelrockets, which are designed to deflagrate, and caps (amorces), which are designed to produce sound by apyrotechnic effect.The classification of fireworks, signal flares, and model rockets under the previous explosives legislation wascovered by the Schedule to the Explosives Act 1957, the explosives regulations, and the ExplosivesAuthorisation Order. The Schedule to the Act described the three divisions within class 7 Fireworks, with theuse of a quantity (40 g), of firework composition, to differentiate fireworks available to the public and thoseavailable only to permit holders. Signal flares and model rockets were also limited in their availability tocertain persons by the explosives regulations.January 2012 EPA0109