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 　Rotary evaporator is commonly used equipment in laboratory, which is composed of heating bath, rotating motor, evaporation flask, condensation tube and other parts. Through electronic control, make the evaporation bottle in the most suitable rotation under the constant speed rotation, evaporation flask in the rotation at the same time placed in the heating bath constant temperature heating, so that the evaporation bottle in the material uniform heat. In the rotation of the material attached to the wall of the evaporation flask, increasing the evaporation area. The use of vacuum pump to evaporate the flask in a negative pressure state, the solution in the bottle under negative pressure evaporation temperature is reduced, accelerating the rate of evaporation. High-efficiency cooler spiral tube through the cooling medium, the distillation fraction vapour liquefaction, to achieve separation.

 The core technology of rotary evaporator

 The most important requirement for rotary evaporator is corrosion resistance and maintaining high vacuum. Therefore, the core technology of rotary evaporator is that the moving parts can withstand corrosion in various solvents, and sealing under the movement condition. Using special ceramic bearings, PTFE, Fluorororubber and borosilicate 3.3 glass seals, can withstand (in addition to strong alkali and a few other kinds of) a variety of solvents corrosion, there is a long-lasting and reliable hermeticity. Metal-free design, especially suitable for the extraction of materials to avoid metal ion contaminants.

 Selection of rotary evaporator

 The first step is to select the specification of rotary evaporator.

 The specification of rotary evaporator is distinguished by the volume of evaporation bottle, the size of the required evaporation bottle depends on the number of materials to be evaporated. Generally speaking, 2L, 3L, 5L rotary evaporator is suitable for the laboratory small amount of test; 5L, 10L, 20L is suitable for the pilot test; 20L, 50L is suitable for the pilot test and production.

 ◆The second step Consider rotary evaporator evaporation rate

 For the same specification of rotary evaporator, the factors affecting the evaporation rate of rotary evaporator are mainly the following four.

 1. Heating bath temperature

 The higher the temperature of heating bath, the more intense the evaporation of material. But by the material heat tolerance, the use of security and energy constraints, the most commonly used temperature is 60 ℃. Heating bath temperature minus the evaporation bottle heat transfer temperature difference ΔT1 and evaporation superheat, that is, the material temperature.

 Material thermal tolerance mainly refers to the permissible temperature at which the biologically active substance does not undergo denaturation, and safety in use mainly refers to the lack of danger of scalding during the replacement of the evaporation flask. The heating bath temperature is moderate, the water volatilisation rate is low, and the energy utilisation rate is high.

 2. Vacuum degree in rotary evaporator: recommended vacuum degree is 95～98kPa (absolute pressure 2～5kPa).

 3. condenser cooling medium temperature: material temperature minus condenser heat transfer temperature difference ΔT2 and condensation subcooling degree, that is, the required condenser cooling medium average temperature.

 The relationship between the material temperature and vacuum is consistent with the relationship between the material saturation temperature and saturation pressure, in the heating bath temperature and vacuum to determine the cooling medium temperature depends on the type of material.

 ④ Evaporation bottle speed: the higher the speed of evaporation bottle, the larger the surface of the bottle infiltration area, heat area; but at the same time, the thickness of the liquid film is also the thicker, increasing the heat transfer temperature difference. For different viscosity materials, there is the best speed.

 Since the temperature of heating bath, vacuum degree and cooling medium temperature are related parameters, which are related to the type of material and the recovery rate of condensate, if you need the help of our technicians, please fill in the ‘User Requirement Form’.

 The third step: choose the supporting equipment

 Supporting equipment refers to vacuum equipment and cold source equipment.

 Vacuum pump is recommended to use circulating water vacuum pump or diaphragm vacuum pump which is resistant to corrosion of various solvents. Vacuum controller is optional to achieve more efficient and controllable distillation process.

 Cold source equipment is selected according to the temperature of the cooling medium and evaporation volume.

 Notes:

 The basic use conditions of rotary evaporator are: heating bath temperature 60℃, vacuum degree 95～98 kPa (absolute pressure 2～5 kPa), cooling medium temperature 20℃.

 The range of working parameters is: heating bath temperature ≤ 80 ℃, vacuum ≤ 98 kPa (absolute pressure ≥ 2 kPa), cooling medium temperature -20 ℃ ~ room temperature.

 The condenser of rotary evaporator has two kinds, vertical and oblique, and there is no difference between its heat transfer and flow process. Because the vertical type occupies less space, the general rotary evaporator adopts the vertical condenser.