Liquid bulk cargo: what is it and how should it be transported correctly?
Liquid bulk cargo is a liquid product loaded directly into a transport tank. For road deliveries, that tank forms part of the vehicle. A producer might pump sunflower oil from a storage tank into a food-grade road tanker. At the bottling plant, the oil flows into the receiving tank. The entire batch travels in the vehicle’s tank without being divided into individual packages.
The commercial documents may give the quantity in tonnes, while the vehicle’s capacity and the space available at the receiving site are measured in cubic metres. How the liquid behaves during the journey matters too. Syrup may thicken as it cools, and a light-coloured oil may pick up an unwanted odour from residue in a discharge hose.
Which goods travel as bulk liquids?
Food products. Sunflower and rapeseed oils, milk, juices and syrups can all travel in bulk. For edible vegetable oil transport, the tank surfaces must be suitable for food contact. Cleanliness requirements also apply to the hoses and fittings the oil will pass through.
Liquid chemicals. Acid and alkali solutions, alcohols and organic solvents are typical bulk cargoes. The exact product and concentration matter. For solvent transport, for instance, the safety data sheet (SDS) provides the transport classification. Compatibility data help determine which tank and seal materials suit the product.
Petroleum products. Petrol and diesel are delivered in fuel tanks designed for the product. In fuel transport, each grade must retain its specified properties, including when several batches travel in separate compartments of the same vehicle.
Feed ingredients and industrial liquids. Feed-grade molasses, process oils, plasticisers and water-based dispersions have different delivery requirements. For viscous molasses, temperature at discharge matters. A freeze-sensitive dispersion needs to stay within its specified temperature range throughout the journey.
Liquid fertilisers. Urea ammonium nitrate (UAN) solution is one example. When arranging fertiliser transport, check the density and crystallisation temperature of the particular grade. These affect the weight of a tank load and whether the solution can still be pumped on arrival.
How a bulk liquid moves from sender to consignee
Loading. At the dispatch site, the liquid is transferred from storage into the vehicle’s tank through a connection suitable for that product. Use density at loading temperature to relate weight to volume. For example, 18 tonnes of plasticiser at 1.20 t/m³ occupy 15 m³. For bulk plasticiser transport, the tank must also be suitable for that degree of filling, and the laden vehicle must meet the applicable weight limits.
Transit. The product travels in a closed tank. For a temperature-sensitive liquid, the supplier specifies the permitted range. Insulation slows heat gain or loss. If a viscous product needs warming before discharge, establish whether the tank has a suitable heating circuit and where it can be connected.
Discharge and receipt. The consignee confirms the receiving tank and its available capacity. Transfer can be by pump or by gravity where the product and equipment allow it. With viscous syrup, for example, the receiving site’s pump must be able to handle the liquid at its actual arrival temperature. Once discharge is complete, the parties record the quantity received by their agreed method.
Which tanks are used?
For road tanker transport, food-grade tanks carry edible products, chemical tanks carry substances compatible with their shell, lining and fittings, and fuel tanks carry the appropriate petroleum grades. A tank may have one or several isolated compartments. Where grades must be kept separate, check whether the compartments share any part of the discharge system.
Rail tank wagons can serve regular flows between rail-connected sites. A tank container is another option for a route with road and rail legs. It can be lifted from a road chassis onto a rail wagon with the liquid still inside.
Preserving the quality of the batch
Before allocating a reusable tank, establish what it last carried and which previous products the consignee will accept. The guidance on previous cargo compatibility covers this assessment. Check whether cleaning included the pump and hoses and whether the next product requires dry equipment. The guide to road tanker cleaning before loading explains what to look for.
To arrange bulk liquid transport, provide the product and grade, batch weight, density, temperature requirements, route and receiving site’s discharge arrangements. The next steps are covered in the guide to preparing a road tanker for loading, transit and discharge.
