What are the best lab funnels?
Various lab funnels are designed for specific tasks. But which funnel is the best for which job?
Removing unwanted solid from liquid
The Buchner funnel (or Hirsch funnel for small amounts) uses vacuum filtration to separate solids from liquids. It is shaped like a bowl with a glass frit or pore plate over the stem.
Materials: Porcelain, plastic, borosilicate glass
Liquid to liquid extraction
The cone shaped separatory funnel is used to separate the liquid in mixtures.
Materials: Borosilicate glass.
Separating solids from liquids
A filter funnel is shaped like a standard funnel with a 600 slope and used with filter paper.
Materials: Plastic, metal and borosilicate glass.
Pouring solids into a container
A powder funnel is wide stemmed funnel that is used to pour fine powders and particulates
Materials: PP plastic or glass.
Adding small doses
A Simple dropping tunnel is a graduated tube. If the dropping funnel has a stopper a female ground joint sits on top.
The Pressure-Equalizing dropping funnel is the same shape but with an additional narrow-bore tube.
Materials: Borosilicate glass.
Transporting and weighing small quantities of solids or liquids
The weighing funnel is a scoop with a funnel at the end. Samples are placed in the scoop and weighed, then funnelled into a container.
Materials: Borosilicate glass or PP.
Ask your laboratory equipment specialist which funnel is the best one for your requirements, materials, and process. Funnels come in many models and types, so make sure your funnel purchase suits your purpose. There are several funnel designs that have been specifically created for laboratory work. Funnels that are used for adding fluids slowly to a flask are the filter funnel, dropping funnel and thistle funnel which is shaped like a thistle.
The types of funnels in the laboratory
A funnel for hot filtration
Two funnels, A – a simple stemmed funnel. B – a ground glass powder funnel
- Plain funnels exist in various dimensions, with longer or shorter necks.
- Filter funnels have a neck of a thin capillary tube and ribs which increase the filter-papers’ effectiveness and thus accelerate the process of filtering.
- Powder funnels have a small and wide neck for fast pouring of powders.
- Separatory funnels are pear-shaped, have a cap and a short neck, with a stopcock for the even pouring of fluids. These are used to decant two immiscible fluids. It can be graduated, though this is not very common.
- Hirsch funnels are shaped much like normal funnels, but contain holes or sintered glass at the base for quick filtrations.
- Dropping funnels are a cylindrical, regularly graduated funnel with standard taper ground glass joints. These are often supplied with a pressure equalizer.
- Buchner funnels are made of porcelain and include a plate of sintered glass or perforated porcelain. These are used in filtration under low pressure with a Buchner flask.
- Hot filtration funnel is a less commonly seen funnel where the funnel is jacketed, and surrounded by a heated fluid.
- Eco funnel is equipped with a latching lid and gasket to reduce chemical contamination and conform to OSHA and EPA regulations.