Vacuum Filter is 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.

How Does Vacuum Filtration Work?

Vacuum filtration is an operation of evacuating the air below the filter paper to maintain the pressure differential across the filter medium. It increases the rate of filtration through the force on the solution over gravity.

When setting vacuum filtration, the first step is fitting the Buchner funnel to a suction flask. After that, we can connect the side arm of the flask to our vacuum pump which is of high quality, advanced design, and high efficiency.

Next step is to put the filter paper into the funnel and wash it with the solution. Don’t forget to get the right filter paper which has the right material, pore size, and the right size to your funnel. After that, you can decant the liquid phase into the funnel first and then add the precipitate.

To get the better result, you’d better add a little bit of wash liquid over the surface of the precipitate to wash it. The force of vacuum will draw the liquid through the solid slowly. At the same time, the precipitate will be dry out by drawing a current of air through it.