Polychlorinated biphenyl Capacitor

Chlorodiphenyl (54% Cl) N-Ethyl-2-pyrrolidone Polychlorinated biphenyls capacitors, electroceramic Barium titanate caprolactam mfg. 

Until the 1970s the chemical used as the impregnating and dielectric medium for capacitor units was PCB (polychlorinated biphenyl) liquid. It was found to be toxic and unsafe for humans as well as contamination of the environment. For this reason, it is no longer used. The latest trend is to use a non-PCB, non-toxic, phenyl xylyl ethane (PXE-oil), which is a synthetic dielectric liquid of extremely low loss for insulation and impregnation of the capacitor elements or to use mixed polypropylene or allpolypropylene (PP) liquids as the dielectric. A non-oil dielectric, such as epoxy resin, is also used. 

The water insoluble, highly chemically and thermally stable PCBs used as insulating fluids for transformers and capacitors, in paints, copy paper, etc., are extremely toxic, persistent in the environment and bioaccumulating. PCBs are currently destroyed by incineration of concentrates at high temperatures or chemically with sodium metals or organosodium. Both processes are costly. The cathodic reduction/elimination of the chlorine from polychlorinated biphenyl... 

Polychlorinated biphenyls (PCBs) were manufactured by catalytic chlorination of biphenyl to produce complex mixtures, each containing 60-90 different PCB molecular species or congeners (see Chaps. 1 and 4). In the United States, PCB mixtures were manufactured by Monsanto under the trade name Aroclor and were widely used as dielectric fluids in capacitors and transformers from 1929 to 1978. PCBs are widespread contaminants of aquatic sediments and continue to be a focus of environmental concern because they tend to accumulate in biota and are potentially toxic. The following sections show the most effective bioremediation techniques applied to various PCB contaminated environments ... 

Acquevella JF et al Assessment of clinical, metabolic, dietary, and occupational correlations with serum polychlorinated biphenyl levels among employees at an electric capacitor manufacturing plant. J Occup Med 28 1177-1180, 1986... 

Polychlorinated biphenyls (PCBs) were produced from 1930 to 1983 in the form of complex mixtures for a variety of uses (e.g. dielectric fluids in transformers and capacitors, and plasticizers in paint and rubber sealants). Because of their physical and chemical stability, and also of their lipophilic affinity, they are highly persistent and tend to accumulate in sediments and biota in the aquatic environment [253]. 

Polychlorinated biphenyls (PCBs) were used in electrical capacitors, electrical transformers, vacuum pumps, and gas transmission tribunes. They were also used as hydraulic fluids, plasticizers, adhesives, fire retardants, wax extenders, lubricants and cutting oils, inks, dedusting agents, etc. PCBs are no longer commercially produced in the United States but are still found in the environment. PCB s have been found in at least 500 of the 1598 National Priorities List Sites identified by the Environmental Protection Agency (EPA). 

Chlorobiphenyls (CBs) are used widely by industry, including transformers and capacitors in the electrical industry and inks, paints and paper in the printing and allied industries. Unwanted polychlorinated biphenyls (PCB) formulations and waste materials containing PCBs are normally incinerated. However, PCBs and waste products containing these materials are inadvertently or illegally disposed of at dump sites and landfill sites. Unsealed PCB sources are leached into the terrestrial and aquatic environment and incomplete combustion vaporises these compounds into the atmosphere therefore, they enter the wider global cycle of trace organic compounds and ubiquitous environmental contaminants that occur in bovine milk, milk powders and products as a result of intake via animal feed. 

Fischbein A, Wolff MS, Bernstein J, et al. 1982. Dermatological findings in capacitor manufacturing workers exposed to dielectric fluids containing polychlorinated biphenyls (PCBs). Arch Environ Health 37 69-74. 

Gustavsson P, Hogstedt C. 1997. A cohort study of Swedish capacitor manufacturing workers exposed to polychlorinated biphenyls (PCBs). Am J Ind Med 32(3) 234-239. 

Kimbrough RD, Doemland ML, LeVois ME. 1999a. Mortality in male and female capacitor workers exposed to polychlorinated biphenyls. J Occup Environ Med 41(3) 161-171. 

Lawton RW, Ross MR, Feingold J, et al. 1986. Spirometric findings in capacitor workers occupationally exposed to polychlorinated biphenyls (PCBs). J Occup Med 28 453-456. 

Lee MC, Griffin RA, Miller ML, et al. 1979. Adsorption of water-soluble polychlorinated biphenyl Aroclor 1242 and used capacitor fluid by soil materials and coal chars. J Environ Sci Health A14 415-442. 

Wolff MS, Fischbein A, Thornton J, et al. 1982a. Body burden of polychlorinated biphenyls among persons employed in capacitor manufacturing. Int Arch Occup Environ Health 49 199-208. 

Polychlorinated biphenyls (PCBs) have a variety of industrial applications related to their high chemical and thermal stabilities, electrical resistance and low volatilities. Some of their uses are as dielectric fluids in capacitors and transformers, as lubricants and hydraulic fluids, as heat exchangers and fire retardants and as plasticizers. Commercial production began in the USA in 1929, but restrictions were imposed in the 1970s because of growing concerns about adverse biological effects, and the use of PCBs was banned in the USA in 1986. Some 37 kt were produced in 1970 (Goldberg 1976), and total production to 1980 has been estimated at 1.2 Mt, of which c.65% is still in use or has been deposited in landfills, c.4% has been destroyed and c.31% has been released to the environment (Tanabe 1988). 

Polychlorinated biphenyls (PCBs) were introduced in 1929 as insulators in capacitors and transformers in the electric power industry, as lubricants... 

Polychlorinated biphenyls ( PCBs ) have been manufactured and used commercially for 50 years because of their chemical stability, fire resistance, and electrical resistance properties. PCBs are frequently used in electrical transformers and capacitors. However, concern has been expressed that PCBs may be toxic to humans and to wildlife. Because of these concerns, the major American manufacturer of PCBs limited its sales of PCBs after 1972 to manufacturers of transformers and capacitors and then in 1977 ceased all manufacture of PCBs and shipped the last of its inventory. Today, PCBs are produced in this country only as incidental byproducts of industrial chemical processes. There are known natural sources of PCBs. 

PCBs (polychlorinated biphenyls) have been used industrially since 1929. Industrial mixtures of PCBs are known by commercial names, e.g., Aroclors (United States), Kaneclor (Japan), Chlophen (Germany), Sovol (former USSR), Fenchlor (France). PCBs were widely used in insulating fluids in transformers and capacitors, as well as hydraulic systems, surface coatings, flame retardants, inks and other minor uses. 

Capacitors Items that contain polychlorinated biphenyls (PCBs) or sulfuric acid. 

While any halogen may halogenate a polyphenyl, chlorine and bromine are by far the more usual. They result in a large number of possible polychlorinated biphenyls syn. p.c.b.s, PCBs, PCB s), polyhalogenated biphenyls, and polyhalogenated terphenyls. No longer produced commercially, halogenated polyphenyls were widely used for their exceptional qualities as heat-transfer fluids, solvents, lubricants, dust suppressants, and fire retardants (some equipment that relies on these chemicals, like electrical transformers and capacitors, remains in use). 

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