Magnetic stirrer

A magnetic stirrer is an electrical device which is used in a chemical laboratory for stirring liquids. Usually the setting plate of the stirring device at the same time a hot plate with which the fluid may be heated; this is called a hot stirrer.

The liquid is placed in a beaker, an Erlenmeyer flask or the like on a disk, which rotates at a variable speed magnetic. The magnet acts on a second, e.g., lying in the cup, usually bar-shaped magnets, the magnetic stirring, and causes the fluid to move through this. The so-called stir bar is mostly covered with plastic (eg PTFE) or glass coated to reduce friction and make it chemically inert.

Magnetic allow the mixing of liquids in closed vessels, without - as with agitators with waves - from problems with seals or lubricants to be affected by the drive. Thus, for example under an inert gas atmosphere or with substances be used that require a degree from the environment. The simple design of the magnetic stir bar also facilitates cleaning and sterilization significantly. To get the small magnets out of the vessel, to use a 300 or 450 mm long, PP - encapsulated or a 150, 250 or 350 mm long PTFE - encapsulated magnetic rod, also called Rührfischangel.

The use of a magnetic Heizrührers has over the heating above a Bunsen burner flame or a heating mantle the advantage that the temperature is relatively accurately adjustable and can be controlled, for example, by a switched- temperature controller. The heat supplied is rapidly distributed evenly through the stirring in the vessel contents, thereby avoiding a boiling. In addition, due to the flammability of many solvents, eg, in organic chemistry, not to work with an open flame, which is why one has to rely on the use of a hotplate or a heating mantle.

Magnetic stirring (scale: cm)

Magnetic stirring in use