Document LKq5RedVMmO1OONRjzMg6b7M3

FEB-02-2005 08:37 SAE CUSTOMER SALES 724 776 0002 P.07 5 Table 1 - Asbestos Emissions from "Normal Use" Braking Dynamometer Data for Production Disc Brake* Background asbestos in ambient air Asbestos liber from brake in exhaust air Total asbestos fiber in exhaust air Estimated brake asbestos fiber in urban air Asbestos fiber from brake In alrborn wear dust Asbestos fiber released from lining wear <19 X uf9 g/m3 <13 X 10T9 g/m3 <32 X 10"9 g/m3 <0.07 XlO-9 g/m3 <0.05% <0.02% and tire. Accurate measurement of this material was not poss ible, due to the added retention of dust from the ambient air. More precise values of brake lining asbestos emissions or the determination of their particle size distributions appear possi ble, for these low fiber concentrations, only by testing brakes in an asbestos-free atmosphere. This approach was used in an EPA sponsored study (9), where prefiltered air was flowed through sealed brakes at a flow rate greatly reduced from normal. CONCLUSIONS `Reported values are 10 times the observed test values to provide upper bounds. collection, processing, and counting. These values, therefore, should provide upper bounds for asbestos emissions from brake uage. For example, the local (Detroit) atmospheric asbestos concentration ranges 0.5-13.4 ng/m3. The observed back ground asbestos value was 1.9 ng/m3, for the normal use test, but is reported in Table 1 as 19 ng/m3. The low asbestos emis 1. Automotive brake usage provides a very small emission of asbestos fiber (less than 0.02% of the lining worn). 2. Automotive brake usage provides a very small asbestos fiber input to urban atmospheres (estimated to be below 0.07 ng/m3). 3. Intense local heating and severe local mechanical action 'causes the decomposition of most asbestos fiber in brake lin ings during typical usage. REFERENCES sions from the test disc brake under "normal use" conditions is underscored by the addition of only 13 ng/m3 (1.3 ng/m3 observed) in the undiluted exhaust air stream. The lining wear rate during the first 82 break-in stops was found to be about live times above the "normal use" rate. As bestos fiber release during break-in was also higher, an average sevenfold increase. However, since the break-in wear is less than 1% of the total lining wear, the increase of emitted as bestos fiber resulting from this temporary sevenfold increase would be about 3%, when averaged over the life of the linings. High temperature brake usage also increased lining wear rates, in this case by a factor of 11. Asbestos fiber emissions increased by less than a factor of three. Frequent vehicle op eration under such high temperature conditions would lower lining life to levels far below present averages. However, even if all brake wear provided the same fiber emission rate as found in the high temperature me test, the percentage fiber release to the atmosphere would still be under 0.06% of the lining wear. The remaining brake wear was a mixture of nonfibrous or ganic and inorganic matter. Of the estimated 62-77% collect able wear debris, 47% were accounted for by the test filter on the normal use test. The remaining 15-30% presumably were retained on the lining edges, the caliper, spindle, rotor, wheel, 1. R. J. Sullivan, et al., "Preliminary Air Pollution Siiivey of Asbestos." NAPCA Publication APTD 69-27 (1969). 2. E. J. Selikoff, et al., "Asbestos Air Pollution." Arch. Environ. Health, Vol. 25, July 1972. 3. J. G. Thomson, "Asbestos and the Urban Dweller." Ann. N. Y. Acad. Sci., Vol. 132, No. 196 (1965). 4. J. R. Lynch, "Brake Lining Decomposition Products." J. Air Pollution Control Assoc., Vol. 18, No. 12 (1968). 5. S. Luxon, "Technical Implementation of file New As bestos Regulations." Ann. Occup. Hyg. (Brit.), Vol. 13 (1970). 6. E. Rabinowicz, "Friction and Wear of Materials." New York: John Wiley and Sons Inc., 1965. 7. A. E. Anderson, "Wear in Brake Materials." ASME Wear Conference, 1969. 8. A. E. Anderson, et al., "A New Laboratory Friction and Wear Test for the Characterization of Brake Linings." SAE Transactions, Vol. 76, paper 670079. 9. M. G. Jacko, et al., "Brake and Gutch Emissions Gen erated During Vehicle Operation." Paper 730548 presented at SAE Automobile Engineering Meeting, Detroit, May 1973. 10. K. Yada, "Study of the Microstructure of Chrysotile ' Asbestos by High Resolution Electron Microscopy." Acta Ciystal, Vol. A, No. 27 (1971). I