Document 8yXb2baexebx6NVOr0XErjD5

HFM - 003428 i.r - PROJECT Brake & Clutoh Emissions Generated During Vehicle deration. SAB Mqr 14-18,1973 Asbestos Emissions from Brake RyoJBDcaotsr Testa. SAB May 14-18,1973 Asbestos Exposure During Brake lining Malnanansa eadRspalr. i)M. 10, 1975 Project, Re-Fuadad ASBESTOS EMISSIOBS AUTHORS M.G. Jacko-Bandix R.T. Da Chsrms-Bendix J.H. Somers-EPA A.B. Anderson, R.L. Dealer, R.C. McCuna and J.V. SprysFord Motor Co. SUMMARY COHCLU3IOSS Thin report-outlinea the study . conducted ondiac & 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 eonverted to foaterite, 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 was 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 ab/ asbestos fibers. The concentration of asbestos fibers in the 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'assy annually is 117 million lbs. for brakes As 6.56 million lhe. for dutches. Tbs total debris Is 123.6 million lbs. Assuming the aabestos content is a maximum of 6% by vt. the amount of ashebtos worn avay as friction materiel dahrla la approximately 74 million lbs. Observutiona relating to emlaaicn trends vcre the followings Asbestos emissions vers higher for new friction surfaced and decreased with use. . Drum brakes produced more asbestos emission than tbs disc hrakn with the differonoodeoreaaing as the friction materials, continued In use. Hsavyduty dldnotcaceaaarilygive a higher pereent of asbestos; the large amount ofdebris produced, however, gave a significant rise in asbestos emissions. For the disc pads there wad an Increase in asbestos emissions with increased asbestos content. Ho such trend existed' for the drum materials. Observations: Intsrfsolal temperatures during broking oould be high enough to deoompbas the ohrysotlXs asbestos into non fibrous thermal degradation products. Asbestos erodes (large bundles) ware calculated to reach their rapid; decomposition 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 brake usags. Examination of lining surfaces xevsaled the presence of: non fibrous magnesium silicate in both eryBtalllne (forstarite). and amorphous phases. A.H. Rohl, A.M. linger, M.S. Wolf, tf J. Veisman- Mt. Sinai Sohool of Medicine The project: demonstrated the presence of/unaltered fiber & fibrils, ofJchryscftlle ranging . from 2-15%-:ln brake drum dusts (av. 3-6%). Shear ouuisee structural atreln &: aubstruotural fragmentation producing material fatigue which, with binder pyrolysis,/, oenoause lining disintegration'1 at teap. far below those required far ohrysotile dehydroxylation (650^68000). At lower tsmperatne forstarite has been noted to far* during prolonged static heating Vehicle Materials Engineering December 1977 I ,I