Magnetic stirrers

Magnetic stirrers are devices present in every laboratory. Working in a laboratory requires a range of tools tailored to the nature of the tasks performed and the activities carried out. However, there are equipment that are present in many types of laboratories regardless of what industry they operate in. One such category is magnetic stirrers, which make certain work easier and faster. There are many types of magnetic stirrers available on the market, so it is worth getting to know this group of tools in order to choose among them the one that will best suit our needs and that will provide us with the necessary operation and conduct of laboratory work. The principle of magnetic stirrers is very simple. Magnetic stirrers are used for non-contact mixing of liquids and suspensions in various types of laboratory vessels with the use of a stirrer or so-called dipole, the size of which must be adjusted to the volume of the liquid being mixed. For their operation, magnetic stirrers use an alternating, rotating magnetic field. Since the movement of the field can be produced by two principles, there are two main categories of these devices. Another type of magnetic stirrer is the motorized stirrer. In this case, the permanent magnets responsible for generating the field are mounted on a base, which is driven using an electric motor. Thanks to the use of the motor, it is possible to smoothly adjust the speed starting from low values. The use of permanent magnets allows the use of large stirrers. This makes it possible to mix large volumes of liquids. In turn, a strong magnetic field gives the possibility to use additional heating plates, which allow to heat the mixed liquids. Static stirrers, on the other hand, work on yet another principle. In these devices, electromagnets are permanently embedded in the housing, and field changes are made by alternately switching them on and off with the help of an electronic controller (similar to brushless electric motors). These devices are characterized by a simple design, and the lack of mechanical components makes them very durable and resistant to the various conditions of use we encounter in the laboratory. They are not infrequently characterized by a small height of 2-3 cm. The disadvantage of such stirrers is sometimes the trouble with the smooth establishment of the speed, especially low. Some models have stepped speed control. Static mixers are best suited for mixing small volumes of liquid. Some models can be supplied with a heating plate. On the market, you can get single and multi-station magnetic mixers. The latter allow simultaneous mixing of multiple samples, which saves not only time, but also space on laboratory tables and countertops. What should guide your choice? First of all, you should specify your needs and not be guided solely by price. Also very important is how a given stirrer is protected from flooding. The element you need to pay attention to is the size of the plates, the materials from which the mixer is made and the maximum volume of liquid to be mixed. For occasional mixing of small volumes, it is best to use small single-plate models. On the other hand, for mixing liquids in large vessels, it is best to get large units. It is also worth noting whether the stirrer has a heater, preferably with a thermostat, which is useful, for example, for dissolving certain chemicals and for maintaining temperature in suspension culture of microorganisms.