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.
Eisco™ Glass Funnel Filters
Eisco™ Glass Funnel Filters are made from high quality borosilicate glass and designed with an angled stem and beaded rim for durability.
Eisco™ Porcelain Buchner Funnel
Eisco™ Porcelain Buchner Funnel features a thick stem and fixed perforated plate.
Eisco™ Plastic Filter Funnels
Eisco™ Plastic Filter Funnels are constructed of polyethylene which is chemical, acid, and alkaline resistant.
GSC Go Science Crazy Sintered Glass Funnels
Quality borosilicate glass funnel with porous filter plate.
Eisco™ Polypropylene Separating Funnel, PTFE Key Stopcock
Polypropylene separatory funnels provide excellent contact clarity and durability. Include push fitted plugs with self lubricating PTFE key stopcocks and polypropylene screw caps. Autoclavable.
Eisco™ Polypropylene Buchner Funnels
Two piece polypropylene Buchner funnels are light weight and autoclavable. The top portion of the funnel cone is fitted with the lower portion of the funnel cone forming a vacuum seal that does not require greasing. Bottom portion of the funnel cone has a perforated filter plate.
Eisco™ Heavy Duty Glass Filter Funnels
Eisco™ Heavy Duty Glass Filter Funnels feature a thick wall design for enhanced durability.
Eisco™ Glass Buchner Funnel - Plain Stem
Glass Buchner funnels with plain stems and G-3 sintered disks
Eisco™ Glass Buchner Funnels with Jointed Stems
Glass Buchner funnels with jointed stems and G-3 sintered disks. Made from high quality borosilicate 3.3 glass.
PYREX™ Hirsch Type, Fritted Disc
Very useful in preparation work.
Bel-Art™ Buchner Table-Top Funnels
Table-Top Funnel constructed of polyethylene is designed to filter large volumes quickly.
Bel-Art™ SP Scienceware™ Büchner Funnels
Lightweight, but not top-heavy.
United Scientific Supplies Table Top Porcelain Buchner Funnel
Autoclavable and ideal for vacuum filtration use
Dynalon™ Büchner Funnels
Easily separated for cleaning.