The magnetic stirrer uses the principle of magnetic field and vortex to place the container of liquid to be stirred that sinks into the stirrer on the base of the magnetic stirrer. When the magnetic stirrer is powered on, a rotating magnetic field generated near the base drives the stirrer to circulate in a circle, thus forming a vortex in the container liquid, so as to achieve the purpose of stirring the liquid.
At present, there are mainly two kinds of agitators used in the laboratory: electric agitator and magnetic agitator. Among them, magnetic agitator is applicable to liquid or solid liquid mixture with low viscosity.
Compared with electric agitator, magnetic agitator has the following advantages:
1. High quality DC motor with low noise and stable speed regulation;
2. The agitator is made of high-quality magnetic steel coated with polytetrafluoroethylene, which is heat-resistant, wear-resistant and corrosion-resistant;
3. The mixing can be carried out in a sealed container, which is ideal and convenient to use;
4. The auxiliary heating device can be integrated systematically, which greatly facilitates the application of mixing and heating at the same time.
The general magnetic stirrer can have both stirring and heating functions.
The role of stirring: 1) to make the reactants mix evenly, so that the temperature distribution is uniform, thereby accelerating the reaction speed or evaporation speed, thereby shortening the reaction time; 2) When heated in a closed container, magnetic stirring can prevent boiling. Heating function: of course, this function is aimed at specific applications. The temperature controlled by the heater integrated on the magnetic stirrer is generally between room temperature and 100 ℃. The simple magnetic stirrer only has the function of stirring.
Due to the continuous efforts of many domestic enterprises, the magnetic stirrer has become a kind of conventional laboratory instruments and equipment with a wide variety and low price, which enables our laboratory to choose the magnetic stirrer it needs. How should we choose magnetic stirrers with many kinds and different prices in the market?
1) It is only necessary to use the simple magnetic stirrer with stirring function at room temperature;
2) At the same time, stirring and heating are required, but the requirements for temperature are not very strict, so standard heated magnetic stirrer shall be selected;
3) If it is necessary to display the temperature in real time during the working process, select the digital temperature display heating magnetic stirrer;
4) If you still need to set the working time, stop working when the time is up, and you can choose the timed magnetic stirrer;
5) If the requirements for heating temperature control are strict, the water bath heat collecting magnetic stirrer must be selected. The water bath heat collecting magnetic stirrer is equivalent to a water bath pan integrated on the chassis of the standard heating magnetic stirrer. Everyone knows that water bath heating has the characteristics of uniform heat transfer, precise temperature control and safe heating, Therefore, the water bath collector type magnetic stirrer is particularly suitable for applications where the temperature control requirements are strict and the bottom of the container is uneven (such as a flask) and it is difficult to get heat from the heating chassis;
6) If it is necessary to precisely display the real-time speed in the process of work, the digital display speed heated magnetic stirrer is selected. However, the price of the instrument will be greatly increased with this speed display function. It is recommended to use it in research level occasions with strict requirements;
7) If there is a large volume of liquid to be stirred, a large capacity magnetic stirrer shall be selected. The stirring capacity of a conventional magnetic stirrer is generally less than 2000mL;
8) If conventional electric stirring is required at the same time as magnetic stirring, electric magnetic compound agitator can be selected;
9) If there are complex requirements for mixing characteristics, such as turning for a while, stopping for a while, turning for a while, heating for a certain period of time, holding for a certain period of time, cooling for a certain period of time, low speed for a certain period of time, high speed for a certain period, etc., it is necessary to customize an intelligent program to control the magnetic stirrer. However, integrating so many complex functions will make the price of the instrument rise sharply, It is only recommended to use in research level occasions with extremely strict requirements.
Select the most appropriate type for your application. Avoid the leisure and waste of some functions caused by greedy for big pictures.
We can also see a lot of imported magnetic mixers in the market. The most significant feature of these magnetic mixers is that they are relatively expensive. Is it true that the more expensive the magnetic mixers are, the better the quality is? The answer is usually self-evident, but the question is whether these magnetic mixers, which are often tens of thousands (domestic ones are usually hundreds of thousands), are suitable for us? As you know, with the increasing role of China's "world factory", the domestic magnetic stirrer market has developed rapidly in recent years. Through the tireless efforts of many enterprises, the magnetic stirring technology has gradually become popular. The varieties of magnetic stirrers are increasingly diversified, but the price is increasingly civilian. Although the price of domestic magnetic stirrers is only a fraction or even a tenth of that of imported ones, they are functionally sufficient for most of our applications.
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