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.
Bel-Art™ Single-Piece Buchner Funnels
One-piece HDPE with sealed-in, polyethylene Fritware™ porous filter plate
Eisco™ Plastic Filter Funnels
Eisco™ Plastic Filter Funnels are constructed of polyethylene which is chemical, acid, and alkaline resistant.
Bel-Art™ SP Scienceware™ Büchner Funnels
Lightweight, but not top-heavy.
Synthware™ Buchner Filter Funnels
Used to filter particulates from a variety of substances
Bel-Art™ Two-Piece Buchner Funnel
Lightweight and durable funnel for use in filtration
Fisherbrand™ Porcelain Buchner Funnels with Fixed Perforated Plates
For suction filtration applications
Sartorius Funnels for Combisart™
Reusable stainless steel Combisart™ Funnels for microbial enumeration and particle counting.
Labconco™ California Büchner Funnel
For use with Labconco Crude Fiber Apparatus.
Thermo Scientific™ Nalgene™ Reusable Filter Funnel with Clamp
Designed for use in a wide range of applications, Thermo Scientific™ Nalgene™ filtration hardware and accessories can be used in conjunction with our various lines of filtration devices.
Corning™ PYREX™ Buchner Funnels with Fine Porosity Fritted Disc
Useful where filter paper would be attacked by material being filtered
Bel-Art™ Buchner Funnel
Easy-to-clean two-piece, polypropylene with perforated HDPE plastic filter plate
Bel-Art™ Buchner Table-Top Funnels
Filter large volumes quickly with fixed or removable filter plates to suit table-top applications
