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5. Unitisation and standardisation
A unit is a certain quantity or volume chosen as a standard. Several units can be combined to one larger unit (e.g. pallet) or divided into smaller sub-units (e.g. consumer packages). The advantages of a system where all involved use the same standard sizes and preferably the same type of packaging are:
Combined units are of course most efficiently used if larger quantities of one commodity are transported. Nonetheless, even a small trader with uniform size crates or boxes can benefit from standardisation.
In Europe there is a move towards the ISO/OECD1 standards and the United States Department of Agriculture is supporting the MUM standards in the United States. Both standards are more or less similar using the standard size pallet of 1200 x 1000 mm.
Instruction sheet 1 demonstrates the use and benefits of standardised sizes of packages.
The most common pallet sizes are 1200 mm x 1000 mm and 1200 mm x 800 mm. A standard pallet with sizes 48 x 40 inches (1219 mm x 1016 mm), as used in the United States, is comparable to the 1200 mm x 1000 mm pallet and integrates very well into the metric system. The use of pallets and standard boxes will reduce handling of the boxes and therefore save handling time and reduce post-harvest losses.
The boxes on the pallet should be aligned in such a way that the ventilation holes of the different boxes are aligned and thus air can flow through the stack.
Boxes stacked on the pallet should be secured with posts on the four corners tied together with a rope or with a net over the stack or with glue between the boxes or with tape around and over the stack.
Pallets loaded with rigid wooden or plastic crates can be stacked on top of each other. A higher utilisation grade of the store may be reached since the height of the storeroom is fully utilised.
Sometimes pallets do not fit properly in containers or on trailers, resulting in a loss of available transport space. Shipping containers usually have the following dimensions:
| Type of container | Size | Dimensions | |
| Twenty foot | External | 20 x 8 x 8 feet | (6.10 x 2.44 x 2.44 m) |
| Internal | (5.29 x 2.18 x 2.02 m) | ||
| Forty foot | External | 40 x 8 x 8 feet | (12.19 x 2.44 x 2.44m) |
| Internal | (11.33 x 2.28 x 2.19 m) |
Trailers have according to traffic regulations a maximum outside width of 2.60 meter. With thin, high quality insulation it is just possible to position the pallets in the refrigerated trailer with one pallet using the width (1.20 meter) and one pallet the length (1.00 meter), using a total width of 2.20 meter.
Where containers or smaller trailers are used, pallets should be positioned in the length, thus using only 2.00 meter of the width.
In any case, it is advisable to keep some space between the (hot) wall and the crates. The cold air in the refrigerated container or trailer will form a barrier between the hot wall and the produce.
The use of pallets requires investment in handling and transport devices such as fork-lifts, trucks, hand carts and loading forklift devices on a ship. Also the vessels should have a preferably squared hold to reach the highest efficiency possible, when loading the pallets. Thus practically none of the vessels currently used in the inter-island trade are suitable for loading with palletised loads.
A number of non-standard sizes of packages are in use all over the world and a list of some different sizes is given in Annex I.
The International Standard Organisation (ISO) gives a series of dimensions for rigid rectangular packages based on a standard plan dimension or module of 600 x 400 mm. This is the external size of a package unit when fully loaded (including 'bulge'). No plus tolerance is allowed, although a minus tolerance of up to 10 mm is accepted. ISO standard 3394 gives a most complete picture of multiples and submultiples divided from the module size (See Annex III).
Both the OECD and MUM standards have pallet size 1200 mm x 1000 mm as a standard unit and derive the sub-multiples from these sizes. The OECD and MUM standards are less comprehensive than the ISO standard.
Recommended sizes in mm for OECD and MUM standards are:
| OECD | MUM | |
| Pallet size (mm) | 1200 x 1000 | 1200 x 1000 |
| 1200 x800 | - | |
| Box size (mm) | - | 600 x 500 |
| 600 x400 | 600 x 400 | |
| 500 x 400 | ||
| 500 x300 | 500 x 300 | |
| 400 x300 | 400 x300 |
FIG.1.Mixed load layer concept
FIG.2.Stacking pattern per layer
All standards leave the height of the crate to the discretion of the user. The height is greatly influenced by the commodity, type of crate, required weight/count, stacking method, etc. Using standard heights would simplify the transport of crates.
The United Fresh Fruit and Vegetable Association (UFFVA) together with the United States Development Agency (USDA) tested several package sizes and showed that most of the packages now in use can be replaced by one of the five MUM-sizes with little or no change in volume, weight and/or count. Their suggestions for standardised packages can be found in Annex IV.
