Views: 10 Author: Site Editor Publish Time: 2021-09-17 Origin: Site
The heating of the rotary flask of the rotary evaporator is achieved by a bath, which can make the temperature more uniform and easy to control. The rotary flask of the rotary evaporator should be pre-heated before heating, because some containers, such as glass and ceramic containers When it is suddenly subjected to high temperature or low temperature, it will often explode due to excessive temperature rise and uneven heating. Therefore, the container must be pre-heated before the test starts, that is, the container is placed in a hot bath material to make it temperature Rise slowly and then cool down slowly to achieve the purpose of improving the heat transfer performance of the container and making the container evenly heated.
Regarding the heating medium selection of the bath, water bath and oil bath are commonly used. As the name suggests, water and oil are used as heating medium, followed by sand bath heating, electromagnetic heating (electric heating cap), microwave heating, etc.
In the water bath method, water is used as a hot bath material, and the reaction vessel is placed in water to heat the water (note that water cannot enter the vessel). Because the water temperature is as high as 100°C under standard atmospheric pressure, the temperature of the water bath is also 100°C. The method of water bath treatment of container products is: immerse the reaction container in a bath containing water so that the container cannot directly contact the bath, use electric heating or other heating methods to heat the reaction container to an appropriate temperature, and take out the container after cooling. .
Oil bath and water bath are similar to changing oil with water. Commonly used are soybean oil and cottonseed oil. The temperature is higher than that of water-based oil bathtub, generally between 100°C and 250°C. The operation method of the oil bathtub is the same as the water bath method, but the operation of the oil bathtub must be careful to prevent the oil from overflowing or the temperature of the oil bathtub is too high, causing fire, and the rotation speed of the rotating cylinder is controlled to increase slowly to prevent the oil from splashing and causing injury to the experimenter.
The sand bath method is to bury the reaction tank in sand and heat it. Generally, infrared rays are used to heat the sand tank. This method of heating is more uniform. Due to the poor thermal conductivity of the sand, the heat dissipation is very fast, so the sand at the bottom of the container is in contact with the sand bath. The layer should be thinner to facilitate heating. The sand bath is less used, mainly to make the temperature uniform and heat up.
Overview: The temperature of the water bath does not exceed 100°C, the temperature of the oil bath does not exceed 260°C, and the temperature of the sand bath is generally above 260°C.