6 | Operation
BÜCHI Labortechnik AG
60/116
Operation Manual Rotavapor® R-300
6.2.3
Adjusting distillation conditions
To obtain optimum distillation conditions, the energy absorbed by the solvent from the
heating bath must be removed again in the condenser. To achieve that, the following
settings are recommended:
20 °C
∆ 20 °C
∆ 20 °C
40 °C
60 °C
1
1
2
3
Fig. 39: Distillation conditions
1
Coolant temperature: 20 °C
2
Vapor temperature: 40 °C
3
Heating bath temperature: 60 °C
The temperature difference between heating bath and evaporating flask and between
evaporating flask and cooling condenser should be 20 °C in each case.
The pressure in the evaporating flask should be set so that the boiling point of the
solvent is around 40 °C. See Chapter 10.1 "Solvent table", page 79.
The flow rate of the coolant depends on the type of coolant used and the pump
capacity of the cooler but should be at least 40 to 50 L/h.
Those settings offer the following advantages:
The evaporating flask can be replaced without the risk of skin burns.
The evaporation rate of the water in the heating bath is low.
The energy of the heating bath is efficiently utilized.
6.2.4
Optimization distillation
Depending on the solvent involved, it may also be possible to further optimize the
distillation process. The distillation should always be set up so that the condensate
does not cover more than three quarters of the coil in the cooling condenser. There
should be no condensate visible in the top quarter.
