|11.3 Requirements and interrelationships of goods with regard to storage climate|
|Assignment of goods to a particular class of storage climate conditions (SC) is carried out on the basis of the requirements they place upon their storage atmosphere. Depending on the classification of the product, different parameters have to be taken into account with regard to the risk factors temperature, humidity/moisture and ventilation to prevent a reduction in product quality.
The following definitions apply:
SC 0 Goods not subject to any conditions, which place no requirements on storage climate conditions:
Goods which contain no water (WCC 0) and do not absorb any water vapor when stored in an outdoor atmosphere and which do not have any particular storage temperature requirements belong to this group. Nor do they exude harmful substances. Examples are industrial ceramics, ceramic fittings, porcelain.
This group also includes goods in hermetic packaging, i.e. packaging impermeable to water vapor, irrespective of whether the goods themselves are hygroscopic, e.g. goods in cans or barrels.
SC I - Goods which require particular ventilation conditions:
Goods, which contain no water (WCC 0) and also do not interact hygroscopically with their surroundings and which do not have any particular storage temperature requirements, require particular ventilation conditions in order to eliminate contaminants which are detrimental to health and form explosive mixtures in conjunction with air. Examples of these are motor vehicles, the exhaust gases from which must be removed during ro/ro operation.
Hazardous materials which generate harmful substances which have to be removed by ventilation should also be classified in this group.
SC II - Goods which require particular temperature conditions:
These goods may suffer damage if the temperature exceeds or falls below certain limit values. They include goods which contain no water (WCC 0) or only a little water (WCC 1), for example goods with thermoplastic properties, such as resins, waxes and bitumen, which become soft and deform if the upper temperature limit is exceeded; if they then enter a lower temperature zone, they may become jammed.
SC III - Goods which require particular temperature and ventilation conditions:
This group includes goods whose requirements constitute a combination of groups SC I and SC II, i.e. they are temperature-sensitive and require the removal of harmful substances; examples are hazardous materials, gas-releasing products and chemicals.
SC IV - Goods which require particular humidity/moisture and possibly ventilation conditions:
These include goods which contain no water (WCC 0) and which are damaged by moisture, for example all goods at risk of corrosion, such as metals, machines, instruments. Industrial glass may be damaged by "dulling" due to the action of humidity/moisture.
If the goods are container dry, ventilation is unnecessary. Ventilation is necessary if moisture has to be removed.
Hygroscopic crystalline goods which deliquesce through water vapor adsorption and can then cake due to water vapor release, such as sugar, salts, fertilizers, also belong to this group.
SC V - Goods which require particular humidity/moisture and ventilation conditions:
Goods which react sensitively to moisture and in so doing generate harmful substances, such as hazardous materials and goods which may generate flammable gases on contact with water.
SC VI - Goods which require particular temperature, humidity/moisture and possibly ventilation conditions:
Hygroscopic goods with low water content (WCC 2), which constantly interact with the temperature and humidity/moisture conditions of the ambient medium and display 3rd or 2nd order biotic activity, are damaged by moisture on the on one hand (mold, rot, mildew stains, fermentation, self-heating or by desiccation (solidification, jamming/caking, fragmentation, drying-out) on the other. They include most foodstuffs, semiluxury items and animal feed, and also packaging materials, natural fibers, lumber.
If they are container dry, they do not require ventilation. To achieve the necessary temperature and humidity parameters, ventilation may be required. Since this is impossible in standard containers, damage will have to be expected from the outset with cargo which is not container dry.
SC VII - Goods which require particular temperature, humidity/moisture and ventilation conditions:
In the case of goods with a high water content (WCC 2) and 2nd order biotic activity (BA 2), such as fruit and vegetables, in which respiration processes predominate, ventilation has not only to ensure that temperature and humidity requirements are met but also gas exchange, i.e. removal of carbon dioxide and ethylene and supply of oxygen, as performed in refrigerated containers.
SC VIII - Goods which require a controlled atmosphere (CA containers):
A decisive improvement in storage conditions in the container is achieved by generating a controlled atmosphere (CA = Controlled Atmosphere. As well as lowering the temperature, the oxygen content is reduced from 21% to 3 - 5% and the carbon dioxide content is raised from 0.03% (CO2 content in normal atmosphere) to 5 - 25%, thereby reducing respiration in fruits and extending the shelf life of fruit and vegetables in comparison to conventional chilling. With certain goods, a controlled supply of moisture may be necessary. This technology is not yet fully developed.
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