Desiccation
From Free net encyclopedia
Desiccation is the state of extreme dryness, or the process of extreme drying. It is an extreme form of dehydration (though dessication is not a medical condition).
A desiccant is a substance that absorbs water. It is most commonly used to remove humidity that would normally degrade or even destroy products sensitive to moisture. Silica gel, calcium sulfate, montmorillonite clay, and molecular sieves are commonly used as desiccants.
Contents |
Science
In science, a desiccator is a glass jar used in practical chemistry for making or keeping small amounts of material very dry. The material is placed on a shelf, and a drying agent or desiccant, such as dry silica gel or anhydrous caustic soda, is placed below the shelf.
Often some sort of humidity indicator is included in the desiccator to show, by color changes, the level of humidity. These indicators are in the form of indicator plugs or indicator cards. The active chemical is cobalt chloride (CoCl2). Anhydrous cobalt chloride is blue. When it bonds with two water molecules, (CoCl2•2H2O), it turns purple, and its hexahydrate form (CoCl2•6H2O) is pink.
Broadcasting
In broadcast engineering, a desiccator may be used to pressurize the feedline of a high-power broadcast station. Because it carries very high electrical power levels from the transmitter to the antenna, the feedline must have a good dielectric. Because it must also be lightweight so as not to overload the radio tower, air is often used as the dielectric. Since moisture can condense in these lines, desiccated air or nitrogen gas is pumped in. This pressure also keeps water or other dampness from coming in the line at any point along its length.
Other uses
Desiccated coconut is the dried, finely shredded flesh of the coconut, much used in cooking desserts. It is also used in other types of food preservation.
Mild desiccation of the air can be accomplished with a dehumidifier.
Rice is an effective household desiccant.
Desiccants can also be used in environmentally friendly air conditioning systems.