|10.3.1 The significance of interfaces for the cryptoclimate in the container|
|An examination of published incidents of loss due to climatic factors involving container cargoes reveals that such incidents affect the entire range of products with no particular class of product being disproportionately represented. On the basis of the published examples, losses caused by sweating are clearly the most striking. Sweating includes both that which occurs on the cargo itself (cargo sweat) and that which drips down onto the cargo from the upper surfaces of the container (container sweat). All classes of goods are affected by this type of loss. For example, reported losses range from nonhygroscopic gods, such as steel and steel products, canned foods, to hygroscopic goods, such as cocoa, coffee, millet, dried fruit, sago, pepper, milk powder, furs, textiles and rattan furniture.
In addition to the preponderance of losses due to sweat, a second problem is particularly noticeable, namely the care which is required to adapt the goods, loaded under the climatic conditions of the place of departure, to the climatic conditions of the destination while in transit, without causing damage to the goods or making such damage inevitable due to inadequate adaptation. The theoretical basis on which these issues are addressed resides in "interfacial" physics, which take account of the differences in heat and water vapor transfer at interfaces. The most important basic requirement in this connection is to prevent condensation of the water vapor present in the air at an interface, whether on the container wall boundaries, on the surface of the cargo, in air layers in the vicinity of interfaces or within cargo blocks, if the temperature of the interface falls below the dew point temperature of the surrounding body of air. This requirement in turn makes it necessary to adapt the temperature of the cargo to the anticipated air temperature at the destination. Abrupt changes in temperature or humidity or both occur at these interfaces.
The following types of interface in container transport may be distinguished on the basis of their thermal and hygroscopic properties:
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