Oxidizing properties of solids: UN Test O.3

Oxidizing solids are solid substances or mixtures which, although not necessarily combustible themselves, may generally cause or support a fire in other materials by releasing oxygen.

This test is used to determine the oxidizing properties of solid substances and solid mixtures as a criterion for evaluation from a safety perspective or for classification in hazard classes and packing groups within the framework of relevant regulations, in particular pursuant to the UN Manual of Tests and Criteria, Part III, Chapter 34: Oxidizing Substances of Class 5, Division 5.1, Test O.3.

The test substance and a defined combustible substance are mixed in various weight ratios. Each mixture is formed into a truncated conical pile and this is ignited. The determined burning rate is compared with the burning rate of the various reference mixtures.

Themean burning rate of the test substance and cellulose mixtures (4:1 and 1:1) is compared with that of calcium peroxide / cellulose (in each case the mean value from 5 tests). If the mean burning rate of one of the test substance mixtures is equal to or greater than the mean burning rate of the reference mixture calcium peroxide and cellulose (1:2), the test substance is to be classified as oxidizing.

Classification of the test substance in packing groups pursuant to UN transport law and categories pursuant to GHS

Packing group I / category 1: The mean burning rate of one of the test substance mixtures is greater than that of the 3:1 mixture of calcium peroxide and cellulose.
Packing group II / category 2: The mean burning rate of one of the test substance mixtures is the same or greater than that of the 1:1 mixture of calcium peroxide and cellulose. Does not meet the criteria for packing groups I / category 1.
Packing group III / category 3: The mean burning rate of one or more of the test substance mixtures is the same or greater than that of the 1:2 mixture of calcium peroxide and cellulose. Does not meet the criteria for packing groups I and II or categories 1 and 2.
Not classified pursuant to 5.1 / not oxidizing: The mean burning rate is less than that of the 1:2 mixture of calcium peroxide and cellulose or the mixture does not ignite.