Safe use manual
5. Dust Control Measures for the Chrysotile Product Manufacturing Sectors
Page 11
(5.2 Engineering controls - continued)
Enclosure is practical when the operator does not need to have contact with the operation. In asbestos-cement plants a number of machine operations, such as the interior machining of couplings, can be enclosed. Enclosure is more common for the processing of smaller pieces but it is also used on larger equipment like belt conveyors or carding machines. It is important that all parts of the enclosure should be at a lower pressure than the associated worker's area.
Debagging of asbestos has the potential to produce large quantities of dust. The use of effective and readily available automatic and semi-automatic debagging systems significantly reduces the likelihood of high level exposures. It is important to note that for smaller facilities where the principal source of exposure is bag opening and mixing, there are small independant systems which are now available at modest cost.
Sacks or bags which have contained loose asbestos fibres, or mixtures including loose asbestos fibres, should be deposited in a suitable receptacle, under a dust extraction hood immediately after being emptied. When possible, the bags should be shredded and recycled in the process. For disposal, bags should be sealed in an impermeable bag and deposited in an appropriate landfill. A further method of plastic bag disposal is melting. By melting the empty bags and wrappers, the asbestos residue becomes embedded in the melted plastic. Under no circumstance should bags be reused for packing or other purposes.
5.3 Work practices
The best industrial ventilation system or any other type of well engineered system designed to improve the working environment and reduce the amount of dust generated can be easily defeated by bad work practices of the operators or employees. The result of personal dust samples carried out on two employees working side-by-side, handling the same product on the same type of machine can be extremely different because of the way they work. It is very important when a dust control program is initiated in a factory that, at the same time, work practices of each employee be analyzed. The key to making employees "dust conscious" is information and training.
The work practices necessary in all parts of the plant are straightforward. These work practices include wetting where such a process is applicable, clean-up of any waste generated during manufacturing, vacuuming or wet removal of all chips and small pieces throughout the plant and enforcement of good work practices such as forbidding dry sweeping and the use of compressed air for cleaning purposes.
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