What Is a Rotor?
A rotor is a chemical-resistant magnetic laboratory device used to stir liquids. It is also called a stirrer or stirrer bar. The stirrer in the container rotates with the movement of the magnet of the magnetic stirrer, and the liquid can be stirred.
Uses of Rotors
When using a magnetic stirrer, a rotor can be used to stir and homogenize the solution at a constant rotation speed.
Rotors are used in a wide range of fields, including organic synthesis, pharmaceutical synthesis, and chemical experiments, because they can easily homogenize liquids. Rotors in general use have the surface of the magnet coated with fluororesin such as PTFE, and can be used without being violated by a variety of reagents.
Principle of Rotors
The rotator is used with a magnetic stirrer. The magnetic stirrer has a rotatable magnet placed under the stage, which is structured to rotate, and the liquid inside the container is stirred.
If the viscosity of the solution is high, the size of the rotor is not appropriate, or the bottom of the container is not flat, the rotor may not be able to keep up with the rotation of the magnetic stirrer.
Types of Rotors
1.Types of Magnets
The following magnets are known to be used in rotors:
- Rare Earth Magnets
Manufactured by sintering neodymium, boron, and iron, they have the best magnetic properties. Due to their low temperature characteristics, they should be used at temperatures below 80°C. It is used as a strong magnetic stirrer or super strong magnetic stirrer.
- Ferrite Magnets
Manufactured by sintering barium and iron oxide. It is resistant to heat and produces stable magnetic field lines.
- Samarium Cobalt Magnets
A magnet made of samarium and cobalt. Because it uses a rare metal, it is more expensive than neodymium magnets. It is also used as a stirrer material because its magnetism is stable even at high temperatures.
2. Classification by shape
Rotors are commercially available in a variety of shapes. They come in a variety of sizes and can be used according to the liquid nature of the solution, capacity, and rotation speed.
In addition to fluororesin such as PTFE (polytetrafluoroethylene), which is commonly used for surface coating, there are also glass rotators. Fluoropolymers have excellent chemical resistance and can be used in a variety of solutions, including acids, alkalis, and organic solvents, but wear and discoloration occur over time, so they must be replaced.
How to Select a Rotor
Rotors come in a variety of shapes and sizes. It is necessary to select one that is heat resistant and chemical resistant to the solution to be agitated.
1.Standard Type
The most commonly used type of rotor is the standard type, which is a rod-shaped rotor. Among the standard types, the taper type and pivot ring type have a structure that prevents the rotor from jumping because it has little contact with the container. If the solution has a high viscosity or there are sediments, which require a heavy load for rotation or rotational force for homogenization, a type that is not affected by the shape of the bottom of the container or a type that diffuses sediments should be selected.
2. Type Not Affected by the Number of Revolutions or the Shape of the Bottom of the Container
When stirring a solution, it may not turn well depending on the shape of the bottom. shape of the container.
3. Sediment Diffusing Type
To homogenize a solution with sediment, more stirring force is required than for normal solutions. It is relatively easy to homogenize by using a triangle type, a cross-shaped type, or a double-sided cross-shaped type, which are shaped to roll up sediments as they rotate.
Other types that can be used with test tubes and rotators with more complex shapes are also commercially available.
Other Information on Rotors
1. Contamination Prevention by Rotors
Rotors are a common source of contamination. After removal from solution, they should be cleaned by an appropriate method that removes the solution used.
Also, make sure the surface is clean before use and discard if there is any yellowing.
2. Removal of the Rotors
After using the rotor, remove it by placing a magnet against it from outside the container or by using a rod made of magnets.