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.
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.
Haldenwanger™ Porcelain Buchner Funnel
Use these funnels for a variety of filtration applications. Haldenwanger™ Porcelain Buchner Funnels are constructed from optimized laboratory porcelain.
Pyrex™ Short Stem Glass Funnel
Manufactured from chemical and heat resistant Pyrex™ Borosilicate Glass. Pyrex™ Short Stem Glass Funnel with 60° bowl angle provides precise fitting of filter paper.
Quickfit™ Glass Büchner Funnel with Glass Sintered Disc
Used in place of conventional filter papers that would be destroyed by acids and alkalis. Quickfit™ Glass Büchner Funnel with Sintered Glass Disc is manufactured from chemical-resistant borosilicate glass. Integral ground glass cone on stem connects to Quickfit™ Büchner flasks and vessels.
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Haldenwanger™ Porcelain Buchner Funnel
Designed with glazed porcelain for excellent thermal and chemical resistance. Haldenwanger™ Porcelain Buchner Funnels are an excellent choice for quick filtration.
DWK Life Sciences DURAN™ Filter Funnel
Filter funnels are filters that are used for solid-liquid separation by means of vacuum.
Kartell™ Polypropylene Analytical Funnels
Manufactured with polypropylene for strength and durability. Kartell™ Polypropylene Analytical Funnels are designed specifically for analytical chemistry.
Merck Glass Funnel for Vacuum Filtration
Designed to replace parts contained in glass vacuum filtration kits or provide for an alternative configuration
Fisherbrand™ Porcelain Buchner Funnels with Fixed Perforated Plates
For suction filtration applications
Quickfit™ Borosilicate Glass Büchner Vacuum Filtration Funnels with Glass Sintered Disc
Useful where conventional filter papers would be destroyed by acids and alkalis
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).
Thermo Scientific™ Nalgene™ Büchner Two-Piece Polypropylene Funnels
Separate the lightweight and durable two-piece polypropylene funnels for easy cleaning. These funnels won't chip, crack or break.
Bel-Art™ SP Scienceware™ Büchner Funnels
Lightweight, but not top-heavy.
Thermo Scientific™ Nalgene™ Reusable Bottle Top Filters
Combine the convenience of a bottle top filter with the savings of a reusable bottle top filter. Screw securely onto glass media bottles with 33 or 45mm neck sizes.