Reasonable Selection of MagneticStirrer Stir

The magnetic stirrer is suitable for liquids or solid-liquid mixtures with low viscosity. It can be stirred independently or heated and stirred at the same time. It uses the continuous circular motion of the magnetic stirrer placed in the liquid in the rotating magnetic field to achieve the purpose of stirring the liquid. It has been widely used in laboratories of various universities, colleges and universities, environmental protection, scientific research and health, epidemic prevention, petroleum, metallurgy, chemical industry, medical treatment and other industries.

There are many factors that affect the working state of the stirrer, and we can only list some of the more important ones here. for example:

1) The shape of the stirring bar. Generally speaking, the smaller the contact area between the stirrer and the bottom surface of the container, the better, because the friction between the stirrer and the container is small, but the balance of the stirrer itself is required; a large contact area is good for stability, so the two should be considered in balance.

2) The relationship between the amount of solution and the length of the stir bar. Use a small stir bar for small volumes and a large stir bar for large volumes.

3) The shape of the bottom of the container. The round-bottomed container has a convergent effect on the small stirrer, making it more stable in rotation; since the flat-bottomed container does not have this effect, the small stirrer is prone to revolution while rotating.

4) Whether the bottom surface of the flat-bottomed container is flat. It is obvious that the uneven bottom surface will lead to the revolution phenomenon.

5) The internal structure design of the magnetic stirrer. A common design is to place a magnet of an appropriate size under the disk surface, which is good for the uniformity of the magnetic field on the entire disk surface, and the rotation stability of the longer stirrer is good. We also noticed that some domestic magnetic stirrers use two small magnetic balls very close together, so that the limited magnetic field is completely concentrated in the center of the work plate, so it is more suitable for small stirrers to run stably, but the size of the stirrer is too large will not function properly.

6) The influence of high temperature conditions on the stirring bar. Our commonly used stirrer will gradually demagnetize under high temperature conditions, so after using it for a period of time, it is necessary to confirm whether it is still magnetic enough.

By simulating the experimental conditions to compare the working status of stirrers of different specifications, it is found that the stirring effect of Dalong magnetic stirrer is very comparable to that of a certain foreign brand. Here, the experimental results are recorded in Table 1, and the stirrer can be selected for users. for reference.

Table 1 Suitable stirring bars for different containers