vacuum filter[′vak·yəm ‚fil·tər]
an apparatus for separating suspensions—that is, liquids that contain solid particles in a suspended state. The separation takes place as a result of the pressure difference created by a vacuum pump above and below the filter baffle plate. There are periodic-action and continuous-action vacuum filters. The latter is a horizontal rotating drum that is divided inside by radial hermetic baffle plates into individual cells that are connected by tubes to the distributing head. Depending on the position of the drum in its rotation, a vacuum or excess pressure is created in the cells. During rotation, the drum surface moves through the filtration zone, where the liquid is sucked into the drum and the solid particles settle onto the filter membrane. After the sediment has been washed with water, the drum enters the drying zone, where air is passed through the sediment, and then into the sediment-removal zone. Here compressed air is supplied from the inside of the drum, and the sediment is cut away from the drum surface by a knife. There are also continuous-action disk, conveyor, plate, rotary, and other types of vacuum filters. Vacuum filters are widely used in chemical and other industrial applications.
REFERENCESKasatkin, A. G. Osnovnye protsessy i apparaty khimicheskoi tekhnologii, 7th ed. Moscow, 1961.
Zhuzhikov, V. A. Fil’trovanie, 2nd ed. Moscow, 1968.
V. L. PEBALK