The following discussion offers a complete guide for optimizing your Büchi Rotary Evaporator application.Choosing the bath and condenser temperature (20-40-60 Rule) The first topic of discussion is the 20-40-60 Rule. The recommended water bath temperature is 60°C. This minimizes evaporation from the bath, reduces the risk of burns, and minimizes the loss of heat energy into the lab environment. The bath temperature should be 20°C higher than the vapor pressure temperature of the solvent. In this example, a vacuum pressure is chosen to produce a vapor pressure temperature of 40°C.
(Calculating vacuum pressure will be discussed in the next section.) The condenser temperature should be 20°C lower than the vapor pressure temperature of the solvent. In this example, the vapor pressure temperature is 40°C so the condenser temperature should be 20°C.
To conserve water and maintain lower condenser temperatures, Lauda® Chillers may be used as an alternative cooling method over standard tap water methods. (Choosing an appropriate Chiller will be discussed in later sections.)
The above example illustrates the 20-40-60 Rule