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AT&T March 15, 1982 - Mr. D. J. Doyle 19-1A2 Dear Dan: I have reviewed the material you provided regarding the suitability of the Mastercraft series of vacuum cleaners for use by motor vehicle forces performing brake and clutch work. Based on the information provided, it appears that several of the Mastercraft Asbestos models would be suitable. The laboratory test data was obtained using the three stage filter array used on the smaller series of vacuum cleaners. The Model 1510DASB you specifically mentioned uses a similar set of filters, but in a larger size. It is reasonable to predict chat this larger series of cleaners would perform as veil as the smaller series. The only precaution that I can recommend with this system is that of filter replacement. The manufacturer offers such a wide variety of filters and accessories that it would be relatively easy to order the wrong replacements. Unless the specific high efficiency asbestos filters are used, the vacuum system will not provide employee protection. Please advise if we can be of further assistance. James M. Degen District Manager - Occupational and Environmental Safety 003910 : "1 ijpgui ..itnym (po Performance of Mastercraft Vacuum Cleaner System with New Filters 306177, 347515 and 347973 on Collection of Asbestos Dust( for: Mastercraft Industries 420 Broadway Newburgh, fJY 12550 David Leith, Sc.D. Environmental Research 87 Rockland Place Newton, MA 02164 16 October 1978 r CONFIDENTIAL 003911 Summary The efficiency of a Mastercraft vacuum cleaner on asbestos dust ha6 been determined. Clean, new filters were used for alltests: 306177 first stage filter, 347515 second stage filter, and 347973 third stage filter. Tests were made at inlet fiber concentrations ranging from 14 to 93 fibers per cubic centimeter of air, and average collection efficiency of the three stage filter system was found to be 99.21. Because collection efficiency normally increases as the filters baoome loaded with dust and because these taste were made with clean filters, the efficiency reported here is probably lower than that which would be found in practice. TLber concentrations upstream and downstream of^the vacuum cleaner were determined according to the OSHA procedure. Introduction In recent years asbestos dust has been clearly recognised as a health hazard. Stringent standards have been set for asbestos fiber concentration in workroom air by the Occupational Safety and Health Administration (05HA). To meet these standards it is necessary to treat asbestos materials with 'care to see that as little as possible becomes airborne. An effective way to remove asbestos dust from the workspace is by means of a vacuum cleaner system which is properly designed and operated. Accor dingly, tests were run using the Mastercraft vacuum cleaner system with three filter stages, to determine collection ef ficiency for asbestos dust. Asbestos dust is composed primarily of fibers or bundles of fibers. The aerodynamic properties of a fiber are different from those of a spherical particle of equal mass, length, or surface area, so that it la npt pofiible to say that asbestos fibers correspond to spherical particles of any fixed size. When oriented with long axis parallel to the direction of gas flow, relatively long fibers act like small particles, penetrate deeply into the lungs, and can cause lung disease. Because of the peculiar aerodynamic properties of fibers, tests must be run specifically with asbestos dust to determine asbestos collection efficiency for a vacuum cleaner or any other air cleaning device. For this reason asbestos tests were run on the Mastercraft vacuum cleane system with clean, new filters CONFIDENTIAL a 002913 306177, 3u)7SJ5 and 347973 in series, to determine collection efficienry asbestos dust. Procedure m Description of Equipment - The Mastercraft vacuum was placed in the test rig shown schematically in Figure 1. Asbestos duet supplied by Johns-Manvi1le Corporation was aspirated pneumatically from a small flask and fed into a 3 inch i.d. duct leading to the Mastercraft vacuum. A stairmand disk just inside tne entrance to the duct was used to generate turbulence in the air stream and mix the asbestos dust thoroughly with the air before going to the vadium. The aspirator used to feed asbestos dust and the Stairmand disk are shown in Figure 2. The dust and room air are well mixed by the time they travel approximately five duct diameters downstream of the Stairmand disk. At this point a sample of dust was taken isokinetically from the dusty air stream; that is, the sample was taken in such a way that the velocity of the gas in the sampling nozzle was the same as the velocity of the gas in the duct. The i.d. of th? upstream sampling nozzle was 0.187 in. When sampling particles larger than several micrometers in diameter it it essential to sample isokinetically to be sure that a representative sample is obtained. From the upstream sampling location, the asbestos laden air flowed into the Mastercraft vacuum. The vacuum pump in the Mastercraft unit was used to move air through the te&t system. Before each test, all three filters in the vacuum were* changed so tnat clean, new filters were used for each test. The entire r. r V 003914 CONFIDENTIAL Schem atic Diagram o f A pparatus fo r T e s tin g M a s te rc ra ft Vacuum on A sbestos Dust L a b o ra to ry Waste A ir System 4 003915 5 CONFIDENTIAL 003916 6- - f-i F igure CONFIDENTIAL 003917 upstream duct system and the Mastercraft unit are shorn in Figure 3. from the vacuum, the cleaned air flowed past a downstream * isokinetic sampling nozzle similar to the upstream nozzle except that the inside diameter was 0.250 in. The larger nozzle diameter was used downstream so that a larger gas flowrate could be used and more asbestos fibers gathered for analysis on the 'downstream sampling filter. The gas stream next passed through a calibrated venturi sieter so that the total flow of air through the unit could be determined. Pressure difference across the venturi meter was read on a manometer as shown in Figure 4 *nd related to flowrate through the system using the relationship: cfm 44 Jap', in which &P was venturi pressure differential in inches of water. This calibration had been done previous to the present tests. From the venturi the cleaned air stream passed freely into sn open 6 inch i.d. plenum as shown in Figure 5. The plenum was connected to an auxiliary fan which was regulated ao^that the total flow through the plenum was cpnaiderably greater than the flow through the vacuum system alone. In this way, a net flow of air from the room into the plepum could always be main tained, whether the vacuum cleanar was turned off or turned on. The discharge plenum decoupled the vacuum system from the labors- ' tory waste gas system so that fluctuations in the operation of \.he laboratory system did not affect operation of the vacuum. CONFIDENTIAL I 003918