Magnetic agitators are laboratory equipment used to stir liquids by rapidly rotating a stirring bar. A rotating magnet beneath the plastic panel rotates the stirring bar and shakes the solution. Because most chemical reactions occur in glass beakers, and glass does not shield the magnetic field, the stirring bar can work normally in a glass beaker.
However, due to the size limitation of the stirring bar (which comes in various models and sizes), magnetic agitators are only suitable for relatively small experiments (with a solution volume of less than about 4 liters). When dealing with large volume or viscous solutions, mechanical agitators are needed. Magnetic agitators are often used in chemical and biological experiments and are more frequently used than traditional mechanical agitators because they are quieter, more efficient, and have no exposed transmission parts, making them less prone to damage.
And compared to other stirring devices, the stirring bars are easier to clean and disinfect. Magnetic agitators does not require lubricating oil, so they do not contaminate the reaction solution during stirring, and they can even be used in completely closed containers without opening an access point for the agitator shaft.
Because magnetic agitators can greatly reduce labor and the use of open flames, thereby relatively improving the safety of the laboratory, high-efficiency electric wires (using Joule's law of heat) should be used, which also saves unnecessary resource waste, making it a cost-effective, environmentally friendly, and safe device.
A heating wire wrapped in a layer of refractory cotton is enveloped in heat-resistant ceramic with a hollow center, in which a magnet or a group of magnets mounted on a motor are placed to drive a PTFE-coated magnetic stirring bar to rotate in the container. These structures are covered by an aluminum plate, an iron plate, or a ceramic plate. There is a knob to adjust the speed of the magnet and another knob to adjust the temperature of the heating plate. The structure may vary by manufacturer.
The stirring function or the heating function can be used separately. When using the heating function, place the object to be heated on the heating plate before turning on the heating button to the desired temperature (if the object is directly placed on the hot heating plate, it may rupture due to the temperature difference). When using the stirring function, insert the magnetic stirring bar into the container and place it on the plate, and then adjust the speed to the desired level (to ensure that the liquid does not overflow due to the rise of the liquid level).
Do not pour large amounts of water onto the surface of the heating plate while it is still hot to cool it down, as this may cause rapid contraction of the plate (especially ceramic plates), which may result in cracks or rupture.