insulation

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insulation

(ĭn'səlā`shən, ĭn'syo͝o–), use of materials or devices to inhibit or prevent the conductionconduction,
transfer of heat or electricity through a substance, resulting from a difference in temperature between different parts of the substance, in the case of heat, or from a difference in electric potential, in the case of electricity.
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 of heat or of electricity. Common heat insulators are, fur, feathers, fiberglass, cellulose fibers, stone, wood, and wool; all are poor conductors of heat. The use of asbestosasbestos,
common name for any of a variety of silicate minerals within the amphibole and serpentine groups that are fibrous in structure and more or less resistant to acid and fire. Chrysotile asbestos, a form of serpentine, is the chief commercial asbestos.
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, formerly a common insulating material, has been curtailed due to its implication in lung disease. Industrial furnaces are built of brick, which conducts heat so slowly that a high temperature within is barely apparent in the temperature of the outer surface. Steam pipes and water pipes are commonly insulated with thick wrappings of fiberglass pulp. Since insulators prevent the flow of heat in either direction, refrigerators are commonly constructed with double walls separated by an air space (air being a poor conductor) and lined with some insulating material. The use of double walls or hollow tiles in buildings prevents the entrance of heat and its escape. The very effective insulation in a vacuum bottle results almost entirely from the presence of a vacuum between the double walls of the inner flask. In the conduction of electricity from point to point, the conductor acts as a guide for the electric current and must be insulated at every point of contact with its supports to prevent escape, or leakage, of the current. Dry air is a good insulator, or dielectricdielectric
, material that does not conduct electricity readily, i.e., an insulator (see insulation). A good dielectric should also have other properties: It must resist breakdown under high voltages; it should not itself draw appreciable power from the circuit; it must have
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, so that conductors used for electric-power transmission require insulating material only at their points of contact with the supporting steel structures. Glass and porcelain are commonly used, molded in bell-shaped forms or in rods made up of several segments. Underground conductors are insulated with dry cotton or pulp, rubber, and bitumen. In electrical apparatus, ebonite is widely used. Some other insulators are paraffin, sulfur, resin, and varnishes. Since wet materials can become conductors, insulation must often be waterproof. Ordinary household wires are commonly insulated by a thin rubber or plastic coating; the electric cables passing between house walls frequently have in addition a metal wrapping. Depending upon the application, the insulating material may also need to be resistant to various types of corrosion resulting from exposure to saltwater, oils, or other influences.

Insulation

A material used to reduce transmission of sound or heat; types include batt insulation, loose-fill insulation, and urethane foam. Blown-in products or the installation of batts typically decreases the opportunity for air leakage. Typical insulation levels are R-15 in the walls, R-38 in the attic, and R-11 on basement walls.

insulation

[‚in·sə′lā·shən]
(building construction)
Material used in walls, ceilings, and floors to retard the passage of heat and sound.
(electricity)
A material having high electrical resistivity and therefore suitable for separating adjacent conductors in an electric circuit or preventing possible future contact between conductors. Also known as electrical insulation.

electrical insulation, insulating material

A material that is a very poor conductor of electricity.

insulation

material used to insulate a body, device, or region