Document 65d6YZrJpy9LJ8xQemD9xVyX6

January 25# 1972 Mr. Paul F. Niedner Attorney at Law 131 Jefferson Street St. Charles# Missouri 63301 Dear Mr. Niedner: Your letter# dated January 4, requesting Information on "closed system electrical uses1' was forwarded to me for response. We use the expression "closed system electrical uses" to describe applications involving electrical appartus when the material known as PCB is sealed in to prevent escape. Because of its excellent insulating qualities and fire-resistant nature, the material is much desired for this use. Electric transformers come within this category. It may be of interest to you that many transformers do not contain PCB liquids. Some are gas filled, some contain a mineral oil base fluid and some are encapsulated in solid plastic type materials. I hope this information is useful to you. If I can be of further service# please let me know. Sincerely, WBP:gw SsJocc: P. Park C1NA W. B. Papageorge Manager Environmental Protection DSW 383208 STLCOPCB4101077