Overview of Buchner Flask

General description

The Buchner flask, also known as the solvent filter, is a kind of glassware used in the laboratory.

Two Existing Sorts of Buchner Flask

There are two kinds of Buchner flasks, taking the 300mL Glass Solvent Filter as an example.

The first is the separate vacuum filter bottle. Its appearance looks extremely like a conical bottle, which the difference is that a thin neck is designed on the side to connect with the vacuum pump. When a funnel is placed at the mouth of the filter bottle, this time the water pump starts to extract air, lowering the air pressure in the bottle. If there is any solution left on the filter paper in the funnel, because of the atmospheric pressure and gravity, the solution would flow through the paper into the bottle below remaining the solids on the filter paper to achieve the purpose of filtration. During the filtering with a suction bottle, the ceramic funnel, instead of the conical glass funnel, is usually placed on it.

The second is the suction bottle suit. It is required that filter paper and a vacuum pump are equipped, and the thin neck on the right side needs to be connected to the vacuum pump.

A Buchner flask, also known as a vacuum flask or suction flask, is a specialized piece of laboratory glassware used in filtration setups. It consists of a flat-bottomed flask with a sidearm and a perforated plate (known as a Buchner funnel) that fits snugly into the neck of the flask. The sidearm of the flask is typically connected to a vacuum source.

Here is an overview of the Buchner flask and its uses:


Flat-Bottomed Flask: The main body of the Buchner flask is a glass vessel with a flat bottom, allowing it to sit securely on a laboratory surface.

Sidearm: Extending from the neck of the flask, the sidearm provides an outlet for attaching tubing to create a vacuum within the flask.

Buchner Funnel: This is a funnel-shaped piece with a perforated plate at the bottom. It fits precisely into the neck of the flask and serves as the filtration surface.


The Buchner flask is primarily used in vacuum filtration processes. Here’s how it works:

Filtration: A filter paper or a porous membrane is placed on the perforated plate of the Buchner funnel. The mixture to be filtered (usually a solid-liquid mixture) is poured onto the filter paper.

Application of Vacuum: A vacuum source (like a vacuum pump or aspirator) is attached to the sidearm of the flask. When the vacuum is applied, it creates a pressure differential, causing the liquid to be drawn through the filter paper, leaving the solid particles behind.

Collection of Filtrate: The liquid, now free from solid particles, passes through the filter paper and into the flask below. This purified liquid is referred to as the “filtrate.”


Efficient Filtration: Buchner flasks facilitate fast and efficient filtration of solids from liquids, especially when large volumes need to be processed.

Reduced Risk of Contamination: Since the filtration is conducted under vacuum, there is less chance of contamination as compared to gravity filtration methods.

Suitable for Fine Particles: Buchner funnels are ideal for filtering solutions containing fine particles that might clog standard filter paper used in gravity filtration.


Buchner flasks are widely used in various scientific disciplines, including:

Chemistry: For separating solids from liquid solutions during chemical reactions.

Biology: In laboratories for filtering cell cultures, separating biomolecules, and other biological applications.

Pharmaceuticals: In the production of pharmaceuticals for processes like crystallization and purification.

Environmental Science: In water treatment facilities for analyzing contaminants in water samples.

Food and Beverage Industry: For quality control and analysis of food and beverage products.

Overall, the Buchner flask is a versatile and essential piece of equipment in many laboratory applications, making filtration processes more efficient and reliable.