Document kmZvMEawkkd7B4e5DR1EEozvb

FILE NAME: Abex (ABX) DATE: 1978 Jan 16 DOC#: ABX222 DOCUMENT DESCRIPTION: Internal Note RE Brake Lining Wear Dust SPNY 004779 OH F . fi. m in a ' Internal Note ' _ . .Harcl-Iant .......... .......date..1$ ! .P.?.HH?.r X..-39.?.?. Brake Lining Wear Oust Reference the query from Mr. Rogers of N u t u m Corporation, the evidence which we have collected over several years shows that there Is very little crystalline material and virtually no fibrous material In lining wear dust. - On heating, chrysotile asbestos first breaks down to-a non-crystalline magnesium silicate anhydride, which is non-flbrous. At higher temperaturesf not usually reacheii-during braking, the anhydride is converted to crystoH i ne^orste^ite"3 but this is also non-flbrous. (The conversion temperature is t m J L ) . We have recently had independent analyses carried out on two samples of wear dust - one from a disc brake and the other from the main dust collection point for the dynamometers in Test House, and I attach a copy of the report of the Government Chemist. The findings confirm our own analyses. The samples Incidentally were taken in the presence of the Factory Inspector for this area. A particle size analysis of the Test House dust, using microscopy methods, showed the following : ' Particle Size (microns) Up to 1 2 3 4 5 ' % Present 91 5 2 1.7 0.3 Ue define a fibre ratio of at least particles did not appear to contain as having a minimum length of 5 microns, with an aspect 3 to 1. In the present sample, even the 5 micron reach this ratio, and the sample does not therefore any fibres within the definition. These results are in agreement with those quoted by Jacko end GuChartne of Bendlx, who found that more than S9.7i of the asbestos used in friction materials is converted to a non-fibril form. .-Their report 68-04-0020, dated March 73 - Brake Emissions : emission measurements from brake and clutch linings from selected mobile sources - was prepared for and should be available from : - Environmental Protection Agency Office of Air and Water Programs . Ann Arbor, Mich. 48105 _________________________________ - 2- I believe that we can state with confidence that brake lining wear dust normally contains substantially leas than 1* of fibrous asbestos. i r .; SPNY004780