Pcb 128

Formerly used in electrical transformers, hydraulic fluids, plasticizer in synthetic resins and dedusting agents. Although the production and sale was discontinued in late 1977, it is still present in many of the transformers and capacitors now in use.

As of Jan 1979, Aroclors (including Aroclor 1260) are no longer used in the production of capacitors and transformers. Nevertheless, the life expectancy of transformers containing PCBs is > 30 yrs and the life expectancy of capacitors ranges from 10 to 20 yrs, depending on the electrical application ... In 1981, an estimated 131,200 transformers containing PCBs were in service in the US, representing approx 1% of all operational transformers.

Summary of former end uses for various Aroclors:

Table: Aroclor [Table#3667].

PCBs (were) ... prepared industrially by the chlorination of biphenyl with anhydrous chlorine in the presence of a catalyst such as iron filings or ferric chloride. The products are complex mixtures of chlorobiphenyls, whose degree of chlorination depends principally on the time of contact (12-36 hr) of the biphenyl with anhydrous chlorine. The crude product is blown with air, and a small amount of lime is added to remove hydrogen chloride and ferric chloride. The resulting chlorinated mixtures are batch-distilled to remove color and traces of hydrogen chloride and ferric chloride. (Polychlorinated biphenyls)

The approximate distribution of chlorinated biphenyls in Aroclor 1260 is: <0.3% tri-, <0.3% tetra-, 9.2% penta-, 46.9% hexa-, 36.9% hepta-, 6.3% octa-, and 0.7% nonachlorobiphenyl.