Loading, segregation, secure stowage and vehicle suitability
This domain tests how to load dangerous goods safely: segregation of incompatible classes, load restraint, and whether the vehicle is suitable. NZS 5433 contains the segregation table, and the Rule requires the vehicle and load to be safe. You must be able to identify incompatible pairs and explain what segregation means in practice.
Core rules and concepts
- Segregate incompatible goods according to the segregation table. For example, Class 5.1 oxidisers must be kept away from Class 3 flammable liquids; Class 4.3 substances react with water; Class 8 acids are incompatible with cyanides and many metals.
- Segregation means separation by distance, a barrier, or stowage in different compartments so that a leak cannot reach the other goods. Placing two incompatible drums side by side is not segregation.
- Secure the load against movement using rated restraints. Do not rely on friction alone.
- The vehicle must be suitable: clean, leak-free, ventilated where required, with fire extinguishers and no incompatible residues.
Worked example
You load 200 kg of Class 8 sulfuric acid and 50 kg of Class 6 sodium cyanide. The segregation table prohibits stowing them together because acid contact with cyanide can release hydrogen cyanide gas. Use separate compartments or a physical barrier so that any spill cannot mix. Placards for both classes are required if the quantities are above threshold.
Traps that cost marks
- Treating tied-down drums as adequate segregation.
- Ignoring residues from a previous load.
- Forgetting that foodstuffs must be segregated from toxic or infectious substances.
- Assuming a curtain-sider is always suitable; some loads need enclosed or ventilated vehicles.