Document pp6qZkp8Ln5ELn2gaEMjkav57

J.7 JUN Ifiyfti 19M BROADWAY CINCINNATI, OHIO 49202 DEPARTMENT OF HEALTH. EDUCATION, AND WELFARE PUBLIC HEALTH SERVICE Consumer Protection and Environmental Health Service Environmental Control Administration > REFER TO: June 13, 1969 Dr. D. E. Hickish Industrial Hygiene Specialist Ford Motor Company Limited Brentwood Essex, England Dear Dr. Hickish: The report you wish to refer to has since been published in the Journal of the Air Pollution Control Association (copy enclosed). I am not sure I agree with the last sentence in your summary of my. conclusions. At bulk lining temperatures of 600-700*F the binder simply burns and lets the asbestos fiber loose. At lower bulk tempera^ tures, within normal operating range, the spot temperature at the point of contact between the lining and drum may be very high, higher even than the decomposition temperature of asbestos. The binder behind the surface remains intact, since it is not nearly as hot, and microablation occurs at the point of contact. This explains why Sinclair at the Johns-Manville laboratories found the magnesium from the chrysotile in the decomposition product but not- the x-ray diffraction pattern of chrysotile. The fibrous asbestos had been changed to another, non-fibrous, mineral by the intense heat at the point of contact. Thus, I do not believe that the asbestos comes off unaltered, encapsulated in the binder. Please let me know if I can provide any further assistance. Sincerely yours. Enclosure Jeremiah R. lynch Chief, Laboratory of Engineering Bureau of Occupational Safety and Health / UFM - nnS7Rfi 8006 1199