In vacuum filtration, a vacuum is created by evacuating air from a receiver flask, inducing suction of the liquid through the membrane (performing the filtration). Vacuum filtration is faster than gravity filtration as the solution is forced to go through the filter by the application of vacuum pressure.
Strong vacuum pressure decreases the boiling point of the filtered liquid. You can bring water to boil at lower temperatures under vacuum:
When filtering hot liquids, the vacuum must be weaker than when filtering room-temperate or lukewarm liquids.
In addition to the vacuum filtration unit and the sample to be filtered, you need a vacuum source and tubing to perform filtration.
The vacuum source can be generated with a pump. If the pump cannot forward liquids, it can be damaged if liquids enter the pump. Therefore, it is recommended to use a water trap and suction flask.
You can filter samples > 1 by using several filtration units or several bottles for one bottle-top filter. You can either use Sartolab bottles that are sold separately or glass bottles certified for vacuum filtration.
Glass is brittle. Therefore, it is mandatory to use only glass bottles that are certified for use with vacuum filtration units. It is safer to use plastic bottles like the Sartolab bottles made of polystyrene.