User Guide to Thresholds and Classification - Environmental ...

90User Guide for Thresholds and Classificationsa. The substance is listed in para 2.5.3.2.4 of the UN Model Regulations as an organic peroxide or is listedin the Dangerous Goods List in chapter 3.2 of the UN Model Regulations as having a class or division ofan organic peroxide (division 5.2).b. Any substance that is an organic peroxide or contains organic peroxides and has more than 1.0%available oxygen from the organic peroxides when containing not more than 1.0% hydrogen peroxide bymass.c. Any substance that is an organic peroxide or contains organic peroxides and has more than 0.5%available oxygen from the organic peroxides when containing not less than 1.0% but not more than 7.0%hydrogen peroxide by mass.Definition of ‘available oxygen’ contentWhere any substance or mixture is considered for the purposes of threshold criteria (b) and (c) above, theavailable oxygen content as a percentage by mass is determined by the formula:O% = 16∑(n i (c i /m i ))Where:O% = the percentage of available oxygen content to be determinedn i = number of peroxygen groups per molecule of organic peroxide ic i = concentration (mass %) of organic peroxide im i = molecular mass of organic peroxide iThis formula calculates the availability of oxygen as a percent by mass. The ‗i‘ is a mathematical expressionto allow for adding up the available oxygen for each component in a mixture. Mixtures of different organicperoxides with or without hydrogen peroxide are common.Notes on the threshold criteriaWhere the substance is a mixture and is made up of one or more compounds, any one of which meets oneor both of the threshold criteria (b) and (c) above, then the mixture will have a capacity to oxidise, and will beconsidered hazardous for the purposes of the HSNO Act unless:a. it can be shown that the exact mixture itself does not meet any of the threshold criteria described above;orb. the EPA has previously determined that the mixture is within a range that is considered not to behazardous.Effects of some organic peroxidesSome organic peroxide formulations:may, under increased temperature, evolve oxygen and thus depress the temperature at which otherflammable materials may ignite; andcan form peroxides that are unstable when left to ‗stand‘, and may be explosive on exposure to light orair.January 2012 EPA0109