Filtering Funnels
Filtering Funnels
Filtering funnels, also known as Buchner and Hirsch funnels, include a cylinder separated from the funnel with a fritted glass disc or perforated plate. Fritted glass disc funnels are immediately ready for use, while perforated plates call for filter paper moistened with liquid to prevent initial leakage.
Vacuum suction then draws the liquid through the filter and into the cylinder. Porcelain filtering funnels are resistant to acids and alkalis, except for hydrofluoric acid, but should not be used in the filtration of extremely corrosive reagents, which can slowly corrode their protective enamel. The funnels are glazed both outside and inside, except the rim, and are autoclavable.
What Is a Buchner Funnel Used for?
Buchner funnels are used in the laboratory for vacuum-assisted liquid filtering. In organic chemistry, these funnels are used to collect recrystallized compounds because they help remove moisture from the final product.
How Does a Buchner Funnel Work?
Buchner funnels consist of an open straight-sided cylindrical chamber that narrows to a tube- or pipe-shaped opening. The tube-like extension can be placed through a stopper, which is then placed into the top of a filtration or Buchner flask. Plastic versions may have a bung hole located at the side of the chamber to which a vacuum may be attached. Buchner funnels are reusable.
What Types of Buchner Funnels Are There?
The bottom of the Buchner funnel chamber may be perforated or contain a separate fritted disc. Filter paper is used for Buchner funnels with perforated lower surfaces. Place the filter paper of the preferred porosity inside the chamber, pre-wet, add the liquid, and apply the vacuum.
Filtration with a Buchner funnel proceeds more quickly than letting the liquid flow simply using gravity. Most Buchner funnels are also rated for a maximum vacuum pressure.
Lenz Laborglasinstrumente™ Borosilicate Glass Filter Funnels
Lenz Laborglasinstrumente™ Filter funnels are ideal for separating solids from liquids via laboratory filtration.
Fisherbrand™ Glass Funnel Filter with Sintered Glass Disc
Constructed of borosilicate glass and available in a variety of capacities. Fisherbrand™ Glass Funnel Filters with Sintered Glass Disc filter medium precipitates ranging from 16 - 40μm and 10 to 14μm pore sizes respectively.
DWK Life Sciences DURAN™ Filter Funnel
Filter funnels are filters that are used for solid-liquid separation by means of vacuum.
BRAND™ Borosilicate Glass 3.3 Filter Funnels
Manufactured from chemically resistant borosilicate glass, these funnels are an excellent option for filtering in the laboratory.
Robu™ Büchner Filter Funnels with Porosity 4 VitraPOR™ Glass Filter Discs
Robu™ Büchner Filter Funnels with Glass Filter Discs are made of pure borosilicate 3.3 glass and are highly resistant to most chemicals, including solvents, acids, and alkalis. The VitraPOR™ filter disc is rated as Porosity 5 (Pore size: 1 to 1.6 μm, Standard: ISO 4793-80).
Robu™ Büchner Filter Funnels with Porosity 3 VitraPOR™ Glass Filter Discs
Robu™ Büchner Filter Funnels with Glass Filter Discs are made of pure borosilicate 3.3 glass and are highly resistant to most chemicals, including solvents, acids, and alkalis. The VitraPOR™ filter disc is rated as Porosity 3 (Pore size: 16 to 40 μm, Standard: ISO 4793-80).
Lenz Laborglasinstrumente™ Borosilicate Glass Conical Filter Funnels
Lenz Laborglasinstrumente™ Borosilicate Glass Conical Filter Funnel is a laboratory funnel used for separating solids from liquids via the process of filtration. In order to achieve this, a cone-like shaped piece of filter paper is usually folded into a cone and placed within the funnel.
PYREX™ 95mm Diameter Glass Buchner Filter Funnel
Manufactured from chemically resistant Pyrex™ borosilicate glass. Pyrex™ 95mm Glass Buchner Filter Funnel includes an integral sintered glass disc also constructed with Pyrex™ glass. High resistance to most corrosive agents, and does not require filter papers.
Pyrex™ 30mm Diameter Glass Büchner Filter Funnel
Manufactured from chemically resistant Pyrex™ borosilicate glass. Pyrex™ 30mm Glass Büchner Filter Funnnel includes an integral sintered glass disc also constructed with Pyrex™ glass. High resistance to most corrosive agents, and does not require filter papers.
Pyrex™175mm Diameter Glass Büchner Filter Funnel
Manufactured from chemically resistant Pyrex™ glass. Pyrex™ 175mm Diameter Glass Büchner Filter Funnel with integral sintered glass disc is highly resistant to most corrosive reagents and eliminates the need for filter papers.
Pyrex™120mm Diameter Glass Büchner Filter Funnel
Manufactured from chemically resistant Pyrex™ glass. Pyrex™ 120mm Diameter Glass Büchner Filter Funnel with integral sintered glass disc is highly resistant to most corrosive reagents and eliminates the need for filter papers.
Pyrex™ 60mm Diameter Glass Büchner Filter Funnel
Manufactured from chemically resistant Pyrex™ borosilicate glass. Pyrex™ 60mm Glass Büchner Filter Funnnel includes an integral sintered glass disc also constructed with Pyrex™ glass. High resistance to most corrosive agents, and does not require filter papers.
Pyrex™ 40mm Diameter Glass Büchner Filter Funnel
Manufactured from chemically resistant Pyrex™ borosilicate glass. Pyrex™ 40mm Glass Büchner Filter Funnnel includes an integral sintered glass disc also constructed with Pyrex™ glass. High resistance to most corrosive agents, and does not require filter papers.