By evaporation - changing of state from liquid to gas - the volume of the sample increases by a factor up to 20,000. In the condenser the gas is re-condensed to a liquid and the volume shrinks immediately. During this evaporation-condensation process, vapor velocity at narrow points of the glass apparatus can be up to 150 km/h.
Distillation efficiency can be significantly increased by reducing the so-called chimney effect.
In order to maximize turbulence inside the condenser, the vacuum is applied at the top middle, however, the vacuum connectors are below. This optimal construction maximizes the movement of vapor inside the condenser, thus preventing fumes escaping to the vacuum source.