There are three primary pieces of equipment used for distillation that involve systems under vacuum (all fall under the umbrella of vacuum distillation equipment, which is used, for example, in cannabis and cannabinoid distillation):
Rotary Evaporators/Rotary Extractors
Various materials contain different compounds which are often beneficial to separate or extract. Cannabis, for example,includes cannabinoids, terpenes, and flavonoids. A solvent like ethanol or butane (among several others) is used to extract these components from the plant matter (or “flower”). Once the cannabinoids, terpenes, and flavonoids have been extracted, the solvent that was used needs to be removed. This is where rotary extractors come into play.
Rotary extractors have a flask in a water bath that heats the flask to specific temperatures. Vacuum is then pulled on the system, reducing the boiling point of the solvent and causing it to vaporize, removing it from the other extracted components (or “distillates”). The rotary extractor gets the “rotary” part of its name is because the flask containing the solvent and extract rotates to increase the surface area for evaporation.
Short Path Molecular Distillation
With short path molecular distillation, the extract and solvent are placed in a centrifuge (essentially a spinning cylinder), and vacuum is pulled on the centrifuge. Heat is then applied, and the centrifugal force separates the different components allowing the extract to drain to the bottom. Because the extract is traveling a “short distance”, this process is referred to as short path distillation and it is much more rapid than something like a rotary extractor.
Fractional distillation is similar to a rotary extractor, but instead uses a fractionating column to separate multiple distillates with similar boiling points. The fractionating column has multiple, stacked heated trays which allow the different distillates to condense separately. Similar to the other methods, vacuum is pulled on the fractional column to reduce the boiling points of the distillates. You can reference the chart with various boiling points and see, for example, that the solvent has a very similar boiling point (98 °C) to THCA and CBG, which both have a boiling point of 105 °C.
Vacuum Gauge and Vacuum Controller Solutions
So what’s the best vacuum measurement solution for vacuum distillation? This is a rough vacuum application so you’ll only need to measure to 10-3 Torr (also somewhat confusingly referred to as 1 micron). This lends itself well to the 2A thermocouple vacuum gauge and the 4A convection vacuum gauge.
These vacuum gauges can be paired with a single vacuum controller unit like the MV2A which has a digital display and analog 0 to 5 V output corresponding to the vacuum measurement, and is connected to the 2A vacuum gauge with a cable (giving you a remote display). It also has built-in set points with on/off outputs to add additional control in the system. Alternatively, you can use an active gauge solution like the MX2A or MX4A where the vacuum control electronics are attached directly to the vacuum gauge sensing component. These units have analog and digital outputs including analog 0 to 10 V, RS-485, and EthernetIP.
Why choose Televac? We’ve been providing vacuum gauging since 1935 and our solutions are the most reliable on the market. We’re a family owned, woman-owned small business (WOSB) and our customer service is industry leading. Our staff engineers and sales representatives are always available to help you with anything you need.