Drying capacity of oils

[German version]

Fats and fatty oils may dry under the action of atmospheric oxygen, with polyunsaturated fatty acids (e.g. linoleic glycerides) absorbing oxygen and peroxides (e.g. linoxyn) forming a tough, resinified mass. This phenomenon is of particular significance during cargo handling and tank cleaning. Depending on their iodine value, fats and fatty oils are divided as follows in accordance with their drying capacity:

	Nondrying oils: Iodine values are below 100. Contact with oxygen does not cause any appreciable drying. Tanks are easy to clean.
	Semidrying oils: Iodine values range from 100 – 130. These oils dry within acceptable limits, making tank cleaning only slightly more difficult.
	Drying oils: Drying oils have iodine values ranging from 130 – 190. They dry rapidly on contact with atmospheric oxygen. Considerable cargo residues are left on tank walls by rapid drying-on of the oils; these have to be scraped off, making tank cleaning markedly more difficult and causing considerable weight losses.

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