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.
DWK Life Sciences DURAN™ Filter Funnel
Filter funnels are filters that are used for solid-liquid separation by means of vacuum.
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.
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™ 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.
Kartell™ Polypropylene Buchner Funnels
Manufactured from robust, lightweight polypropylene for durability and excellent chemical resistance. Kartell™ Polypropylene Buchner Funnels with an integral filter is ideal for separating solids from liquids in a laboratory.
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Merck Glass Funnel for Vacuum Filtration
Designed to replace parts contained in glass vacuum filtration kits or provide for an alternative configuration
Lenz Laborglasintrumente Filter Funnels
Made of high quality materials. Each manufacturing step is tested through an extensive quality management system, based on DIN ISO 9001/EN 29001.
DWK Life Sciences DURAN™ Filter Funnel, conical shape
The filter funnel has a melted filter plate and is used for filtration without vacuum. When using the filter funnel, a filter paper can be dispensed with.
Bel-Art™ SP Scienceware™ Buchner Table-Top Funnels, 10.25 in. (26cm) I.D.
Filter large volumes quickly with a polyethylene plastic Table-Top Buchner Funnel.
Bel-Art™ SP Scienceware™ Büchner Funnels
Lightweight, but not top-heavy.
Cytiva (formerly Pall Lab) Magnetic Filters Funnel, Non-sterile
Unique magnetic seal allows easy, one-handed vacuum filtration of liquids with compatible membranes.
Pyrex™ Hirsch Pattern Vacuum Filtration Funnel with Sintered Glass Disc
Manufactured from Pyrex™ borosilicate glass for high resistance to chemical corrosion. Pyrex™ Hirsch Pattern Vacuum Filtration Funnel with Sintered Glass Disc is ideal for filtering semi-micro quanitities of material and eliminates the need for filter papers.