Converting plant matter to high purity oil depends on the right process, proper equipment and control methods. Vacuum pumps play a vital role in the extraction process from supporting filtration of winterized extract to separating compounds into discrete fractions. One other step in the extraction process that relies particularly on vacuum is concentrating the extract by removing solvents, which are initially used to break down plant matter, from a mixture. Properly selecting and using a vacuum pump to support this step can improve process time, help prevent sample loss and minimize process monitoring.
What role does the vacuum pump play?
After winterized extract has been filtered, separating unwanted material such as waxes, fats and lipids, the remaining mixture is concentrated by removing most of the remaining solvent. This process is frequently done using a rotary evaporator together with a vacuum pump. The role of a vacuum pump when using a rotary evaporator is to reduce the pressure inside the flask containing the mixture, which allows the solvent to evaporate at a lower temperature. In general, the deeper the vacuum level inside the flask, the lower the bath temperature needs to be for evaporation to occur.
Although high temperatures and low pressures can both accelerate evaporation, you do not want to set each to maximum levels with the thought that your process will be completed faster. Using the deepest vacuum together with the highest bath temperature possible could cause your process to run out of control, potentially damaging temperature sensitive products and evaporating desirables with the solvent.
What should I consider when selecting a vacuum pump?
Properly selecting a vacuum pump that delivers the needed vacuum depth at the appropriate working temperature will allow your process to complete quickly and efficiently. Select a vacuum pump that operates in the same range as the vapor pressure of your solvent at the working temperature. As an example, we can use Antoine Equation to see that ethanol has a vapor pressure of around 179 mbar at 40°C (313.15 K), so select a vacuum pump that can pull down to the vacuum range needed for evaporation to occur at the working temperature. For flow rate, the pump should have sufficient pumping speed to account for the difference between the rate of evaporation and the rate of condensation of the solvent. Insufficient flow rate or pumping speed can slow down your process. Selecting a vacuum pump with the right vacuum depth and flow rate will help generate the proper conditions for your process.
An additional consideration to help increase efficiency for your process is to use a vacuum pump with variable speed and automated controls. This allows the vacuum pump to automatically adjust to the changing process conditions. VACUUBRAND® offers pumps with VARIO® technology, which automatically detects the boiling pressure and adjusts the vacuum to properly evaporate solvents while mitigating the risk of sample loss through bumping or foaming. Variable motor speed and automated control optimizes the evaporation process and prevents the need for continuous process monitoring freeing up precious time.
There exists a variety of vacuum pump technologies, each designed to operate within certain vacuum ranges. Consider the pressure range you need to operate in, ensure the pumping speed is sufficient to remove the vapor generated by the process, select a pump that is compatible with the chemicals you are using and consider the added benefits of automated controls. By properly selecting a vacuum pump, you will reduce sample loss and increase productivity.
To learn more how vacuum influences steps in the extraction process, visit https://vacuu-lan.com/cannabisextraction/.