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(This page was automatically translated from German. Sorption)

Sorption steam or water consumption (adsorption and capillary)

For the rapid clearing of moisture fluctuations, for example, in a dwelling, the Sorptionsfähigkeit of surface materials in the area boundary areas and the creation of objects. This is the physical and chemical properties, water vapour steam or other substances (odor, fumes of solvents and disinfectants, plastic monomers) by "absorption" to the walls of cells, pores and capillaries to bind and remove the relative humidity (degree of saturation Air with vapors of all kinds) in the environment by "desorption" re-release.

The adsorption, the water molecules in one or multi added. Are the wall-building materials to kapillar-porous materials, the moisture management at the inner surface.
There are substances that have a high moisture balance, as examples for wood and natural fibers. Metals, glass, plastic foams and other inorganic substances are not as good as sorptionsfähig. The border is a moist through sorption mass of 0.5% with a relative humidity of 80%. For a good moisture regulation of indoor air wall surfaces are therefore not covered with metal (metal wallpaper) to coat plastic sheets. The bathrooms should be as little wall tiles as possible constraints.

The adsorbed water vapor molecules cause for naturally-organic materials such as wood, wool, textiles or paper form visible changes by them under their own weight in the cell walls sunk down streamline and to brace. The materials are beginning to swell, and the greater the more water vapor molecules in the cell wall adsorbed, up to 100% relative humidity of the environment that limit is reached. Even with additional moisture supply - for example by Capillary swells the material no longer or only slightly. At the start desorption the cell walls of the material to shrink again - the material "waning".

Since waning and sources of the amount of adsorbed water vapor molecules and in turn on the degree of relative humidity depend on you for a long time such materials in devices for humidity control. It therefore called it "hygroscopic, which means" hygroscope". In construction materials and equipment to apply the word but now generally to substances with a strong Sorptionsfähigkeit; one speaks for example the "strong hygroscopic effect of untreated wood."

Sorptionsfähig are almost all materials, which means that almost all increases or decreases humidity in the material depending on the relative humidity of the environment until the hygroscopic between the two balance. For substances with great hygroscopic effect is the only much faster, and there are large amounts of water vapor and again. The materials of wood and clay here show good qualities.

In dry air, wood moisture content 8 to 12 M%. It may, however, to more than 30% of its dry weight in water record (hygroscopic balance at 100% relative humidity), before getting wet. For most mineral materials, the highest balance hygroscopic humidity at 2 to 3, a maximum of 5%, for example, has cork 10%, limestone 5.0% sandstone and brick 1.5%.

Sorptionsfähige materials lowered to the general pollution of air by adsorption and neutralization of the pollutants. (There are separate coating systems, by physical or chemical processes that bind pollutants.)

IIn a land with no laminated wood panelled room with upholstered furniture, heavy curtains and Wollteppichen (all made from the finest and purest natural products), for example, the odor caused by tobacco smoke fewer than in a large room with the same glass and steel furniture, tiled floor, walls and tiled concrete ceiling. The sorptionsfähigen materials bind a lot of smell and pollutants from the tobacco smoke - and give them nice slow, even weeks later returned to the room air. A construction and healthy living very unpleasant room made of concrete, steel, glass and ceramics, however, after a vigorous airing once again almost free of air Chad materials (solvents, cleaners and detergents, cosmetics and other)

Quelle: Kur, Friedrich; Wohngifte, Handbuch für gesundes Bauen und Einrichtungen, 3. Aufl. Verlag Eichborn, 1993, S. 572
Eichler, Arndt; Bautechnischer Wärme- und Feuchteschutz, Bauverlag 1989, S. 95
Künzel, Helmut; In Gösel, Karl; Schüle, Walter; Künzel, Helmut; Schall, Wärme, Feuchte Grundlagen, neue Erkenntnisse und Ausführungshinweise für den Hochbau, 10.Aul., 1997, Bauverlag Wiesbaden/Berlin, S. 216

Ingenieurbüro Baubiologie Peter Rauch

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