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.
DWK Life Sciences DURAN™ Filter Crucible
Filter crucibles are filters that are used like filter chutes in solid-liquid separation by means of vacuum. They are particularly suitable for precipitation, which must be dried to a constant weight.
Pyrex™ Borosilicate Glass Long Stem Funnels
With 60° bowl angle for precise fitting of filter paper
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™ 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™ Conical Glass Funnel with PTFE Key
Manufactured from chemically resistant Pyrex™ borosilicate glass. Pyrex™ Conical Glass Funnel with interchangeable PTFE stopcock. Complies with ISO 4800 Type 1 Standards.
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.
Sartorius™ Glass Funnels
Use with glass vacuum filter holder assemblies. Sartorius™ Glass Funnels are made of high-quality borosilicate glass. Available in 30, 250 and 400mL capacities.
Pyrex™ Borosilicate Glass Filter tube
Pyrex™ Borosilicate glass filter tubes are perfect for applications with Pyrex™ short stem funnels.
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™ Graduated Funnel
DWK Life Sciences Wheaton™ 47mm 100mL Glass Funnel
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™ Funnel with Sintered Glass Disc
Manufactured from Pyrex™ Borosilicate Glass. Pyrex™ Funnel with Sintered Glass Disc is used for the filtration of solutions. Resistant to most corrosive agents, and eliminates the need for filter paper.
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.