Document a4gNv5zYXvjYvBLE5v8JZ3Y3y

au ay @ TUESDAY, OCTOBER 4, 1977 PART VI HFM - 003427 DEPARTMENT OF LABOR Occupational Safety and Health Administration IDENTIFICATION, CLASSIFICATION AND REGULATION OF TOXIC SUBSTANCES POSING A POTENTIAL OCCUPATIONAL CARCINOGENIC RISK (A58E5T os3 8001 159!S .. SCF-ALLF-06730 HFM - 003428 .ir- - ASBESTOS EMISSIOBS PROJECT AUTHORS StMHARY V COHCLU3IOSS Brake & Clutoh Emissions Generated During Vehicle deration. SAB May 14-18,1973 M.G. Jaeko-Bendix R.T. Da Cherms-Bendix J.H. Somers-EPA Asbestos Emissions from Brake A.B. Anderson, Dynamometer Testa. R.L. Gealer, SAB May 14-18,1973 R.G. KcCuns and ' J.V. Sprys- Ford Motor Co. Thin report-outlinea the study . conducted ondisc & drum brakes & dutches utilizing dynamometer testing & actual drlv.'ng cycles in the Detroit area. Cta the average greater than : 99.7% of the asbestos is converted to fosterlie, olivine, polymeric & carbonaceous materials. The contribution to the atmosphere is 3.2% of the total asbestos emissions. _ This report concludes that most of the lining asbestos vas found to he converted: to a non fibrous material by the high flash temp. of the braking surface. less than .02% of the. lining wear was released as asbestos fibers. The concentration of asbestos fibers in tbs urban atm. due to brake usage, vas estimated at less than .P7* 10"^g/m3. The combined total to brake and clutch friction material worn away nrmually la 117 million lhe. for brakes & 6.56 million lhe. for clutches. The total debris la 123.6 million lbs. Assuming theaabeatosoontont la a maximum of 6% by wt. the amount of asbaOtos worn away as friction materiel dabrla la approximately 74 million lbs. . Observutlona relating to emiaelQn trends .were the following: Asbestos emissions were higher for new friction surfaces and decreased with use. '' ; Drum brakes produced more asbestos emission than tbs disc brake with the differeaoe deoreaslng as the friction materials, continued In use. Hsavyduty dldnotnacesaarilygiva a higher percent of . asbestos; the large amount ofdebris produced, however, gave a slgnifloant rise in asbestos emissions. For the disc pads there was an increase In asbestos emissions with increased asbestos content. Ho such trend existed' for the drum materials. Observations: - Ihtsrfsolal temperatures during tanking oould be high enough to decompose the ekrysotlXs asbestos into non fibrous thermal degradation products. Asbestos erodes (large bundles)' were calculated to reaph their rapid deccmpoeltlon temperature during normal' braking speeds between 18-56 mph. and above.' Local flashtemperature and severe mechanical actlon are major factors in the breakdown of asbestos fibers for brakeusege. Examination of lining surfaces revealed .the presence of non: flbrpus magnesium silicate in both eryBtalllne (forsterit) and amorphous phases. - . . Asbestos Bzpoiure During Brake lining Malnanansa aadRspalr. ' i)M. 10, 1975 Project, Ba-Fundad A.H. Rohl, . A.M. longer, H.S. Wolf, tf J. WeismanMt. Stoat School of Medicine The project demonstrated the presence of/unaltered fiber & fibrils of/ohrysetile ranging . from 2-15%-:ln brake drum dusts (ev. 3-6%). Shear causes structural straln &: aubstruotural fragmentation producing material fatigue vhieh, with Under pyrolysis,/, oan oause lining disintegration'1 at temp. far below those required far ohrysotile dehydrosylstloh (650^68000). At lower ts^ersture forsterite has been noted to form during prolonged static heating Vehicle Materials Engineering December 1977 . I ,I