Dangerous goods testing Test N.4

Purpose

Dangerous goods are items or substances that can imply a risk for health, safety, property, or the environment. Some items, which may not be harmful by itself, may become a risk when combined with other substances.

Most regulations concerning dangerous goods, such as national regulations, the IMDG Code, IATA etc. are based on the UN Recommendations on the Transport of Dangerous Goods Model Regulations. The guidance document is developed by the United Nations to uniform national and international regulations. 

Dangerous goods are divided into nine different classes, grouped by their physical and chemical properties. Through testing a packaging group is assigned, in accordance with the degree of danger they present.

^{CLASS       SUBSTANCE}
1.          Explosive substances and articles
2.          Gases
3.          Flammable liquids
4.1        Flammable solids
4.2        Substances liable to spontaneous combustion
4.3        Substances which, in contact with water, emit flammable gases
5.1        Oxidizing substances
5.2        Organic peroxides
6.1        Toxic substances 
6.2        Infectious substances
7.          Radioactive materials
8.          Corrosive substances
9.          Miscellaneous dangerous substances and articles

Testing is performed according to UN manual of Tests and Criteria - Sektion 33.4.6 - Test N.4:Test method for self-heating substances and the the generated data can be used to classify dangerous goods and to use as a basis for risk analysis and research.

When testing according to Test N.4, the material may be classified as "Not a self-heating substance", "Self-heating substance - Packing group II/Cat. 1" or "Self-heating substance - Packing group III/Cat. 2". In some cases, the material may be classified as "Not a self-heating substance" if it is transported in smaller quantities, even though the test indicates self-heating.

Method

In Test N.4, the material to be examined is placed inside a wire mesh basket, which is located inside an oven at a fixed elevated temperature. The temperature is then measured in the oven and at the centre of the sample over time.

An initial test is carried out in a metal wire basket with sides of 100 mm (1 dm²) and with an oven temperature of 140°C. This test shows whether the material is self-heating or not. If no self-heating occurs, the test is concluded and the material is reported as "Not a self-heating substance." If self-heating occures, an additional 1-3 tests are needed to determine the final packing group for the material. the occurrence of self-heating (temperature increase in the centre of the material > 60 °C above oven temperature) is examined at a specified oven temperature and test volume.

The definition of self-heating in Test No. 4 is that the temperature increase at the center of the material is 60°C or more above the oven temperature within 24 hours at a given oven temperature and test volume.

Deliveries

The result is summarized by RISE in a written report. The report is delivered in English.