suction flasks

Suction bottles are used for extracting liquids during vacuum filtration (nutsche).

The rubber seal ensures a tight, elastic seal between the Büchner funnel (nutsche) and the suction flask (filter flask).

The vacuum suction flask—also known as a Büchner flask—is a type of thick-walled Erlenmeyer flask with a side arm (tubular olive) in the neck area. A vacuum pump or hose is connected to this side arm. This setup is used for filtration under reduced pressure, where the suction flask acts as a collecting vessel for the filtrate.

A Büchner funnel (nutsche) is placed on the top opening of the flask and is tightly connected using a rubber sleeve and a conical rubber seal (Guko).

Traditionally, Büchner funnels are made of porcelain, but glass and plastic variants are also available. The funnel consists of a cylindrical part with a perforated plate, on which filter paper is placed. The filter paper is moistened to prevent initial leakage. The liquid to be filtered is poured into the cylinder and is pulled through the perforated plate using vacuum suction. This significantly accelerates the filtration process, which would take much longer if relying on gravity alone.