Wiped Film Still Components - Part IX - Vacuum Systems

Wiped film still systems are capable of being operated in high vacuum situations.  Many applications depend on wiped film stills being able to volatilize material that conventional distillation can’t touch.  The high vacuum that can be achieved in the wiped film still allows these distillations to take place.  However, wiped film stills can also be operated at low vacuum, or even atmospherically, if desired. 

The vacuum system selected should match the desired vacuum level for your application.  Liquid ring pumps are good for vacuum ranges 20-500 Torr, especially if the distillate can be corrosive.  Diaphragm pumps are effective from about 5-50 Torr.  Rotary vane pumps are used if the desired vacuum is 0.02 Torr  - 50 Torr.  In addition, oil diffusion pumps or blowers can be added to the rotary vane pump if the vacuum need is around 0.001 Torr.  Another option for high vacuum is turbo molecular pumps. 

Vacuum is a key element to wiped film distillation, and is one of the three levers used to control the results of the distillation.

In this picture, the still is equipped with a rotary vane pump and a blower to increase the vacuum.

Picture courtesy of Pope Scientific, Inc.