5.4 Vacuuming of dust near the point of origin

The processing of Asbestos containing materials to products, such as gaskets, brake and clutch linings, is only conditionally feasible in closed circuits or in the above-described enclosure. If in these cases, a nonpermissable generation of fibrous dust cannot be achieved through adequately strong binding of fibers in the materials, the arising dust must be directly vacuumed up at the processing point.

The main attention must be on the design of the vacuum element, which guarantees on the one hand that the fine dust does not reach the breathing area of the operating personnel, and on the other hand that the view and tasks of the operating personnel are not impaired. The vacuum element must also be fitted to the special requirements in each case. Basically, the vacuum elements should be positioned on the opposite side of the dust source from the operating person, so that the dust is vacuumed away from the breathing area.

With stamping and pressing machines, the machinery cleaning must be considered. These operations are generally not adequately performed by vacuuming, so that mechanical cleaning procedures are necessary. The cleaning of the machines should not be performed with compressed air guns.

If vacuuming directly at the site of origin is not possible or not adequately effective, an appropriate room ventilation system must be installed. The system of air conduction should be arranged in such a way that the personnel do not work in the stream of contaminated air. The efficiency of the room exhauster is typically less than that of vacuuming directly at the point of origin. With local dust accumulation, an uncontrolled elevation of concentration can temporarily arise.

Generally, the vacuumed air is permitted to be returned to the working area only under strict requirements. Stationary facilities of this kind require permits. The approval of the supervising authority (Trade Supervision Authority, Employers' Association for Accident Insurance) is only given in exceptional cases.

Financial studies show that direct vacuuming at the dust source is typically the less expensive alternative. The safety rules for air quality facilities at the workplace must be followed in operating the exhaust system.