Classification of dangerous goods
What this domain tests
Classification questions ask you to derive class, division and packing group from data such as flash point, boiling point, toxicity or reactivity, rather than from a product name, and to recognise that one substance can carry more than one hazard.
The nine classes
- 1 explosives (divisions 1.1-1.6); 2 gases (2.1 flammable, 2.2 non-flammable non-toxic, 2.3 toxic); 3 flammable liquids; 4 flammable solids (4.1, 4.2 spontaneously combustible, 4.3 dangerous when wet); 5 oxidising substances (5.1) and organic peroxides (5.2); 6 toxic (6.1) and infectious (6.2); 7 radioactive; 8 corrosives; 9 miscellaneous, including environmentally hazardous substances and lithium batteries.
Packing groups
PG I is great danger, PG II medium, PG III minor danger; the group comes from the class criteria, not from the quantity shipped. For class 3 (closed-cup flash point 60 °C or below): PG I when the initial boiling point is 35 °C or below; PG II when the flash point is below 23 °C and the boiling point above 35 °C; PG III when the flash point is 23-60 °C and the boiling point above 35 °C.
Precedence and subsidiary risk
Where two hazards apply, the precedence table in 2.0.3.3 decides which class is primary; the other becomes a subsidiary risk and earns its own label. Marine pollutant status is an additional hazard, not a class.
Worked example
Three liquids: (a) flash point 21 °C, boiling point 55 °C; (b) flash point 21 °C, boiling point 30 °C; (c) flash point 40 °C, boiling point 90 °C. Reasoning: (a) is PG II, (b) is PG I because the boiling point is at or below 35 °C, (c) is PG III. Boiling point, not flash point alone, drives the division between PG I and PG II.
Traps
- Classifying from the trade name or from a safety data sheet summary.
- Using open-cup flash points.
- Reading PG III as 'small quantity'.
- Forgetting the subsidiary risk label.