Vacuum ovens have been used for years in many industries, but in recent years, they have become prominent among commercial cannabis growers. How do they work and how are they utilized in the cannabis industry?

Tim is a technology journalist and was an editor for All About Circuits. His specialty as a historian at Boise State University was cannabis legislation. His favorite things to write and nerd out about are experimental technology, single…

Vacuum ovens have been used for years in many industries, but in recent years, they have become prominent among commercial cannabis growers. How do they work and how are they utilized in the cannabis industry?

Image courtesy of Cascade TEK

How Do Vacuum Ovens Work?

Vacuum ovens are used to remove moisture, gas, and other possibly volatile chemicals from items while preventing reactions. They are often used as the final step in the production process for implantable medical devices, semiconductors, epoxies, essential oils, and many packaged food products. Drying items in a vacuum oven reduces oxidation, consistently and gently dries delicate products, and reduces the risk of employees being exposed to harmful chemicals (because evaporated fluids are stored).

Vacuum ovens are aptly named because they heat things like an over and make a vacuum-sealed chamber. The primary mechanism for drying in a vacuum oven is actually the vacuum chamber. The vacuum chamber reduces pressure which reduces the boiling point of most substances. This allows vacuum ovens to evaporate unwanted materials from their samples without burning them. This effect is similar to how the boiling point of water reduces at higher elevations.

This excerpt from "The Science of Vacuum Oven Drying" by Cascade Tek shows how water boiling temperatures are affected by elevation.

What Are Vacuum Ovens Used For?

In the electronics industry, vacuum ovens are used to dry the electronics and cure the coatings of printed circuit boards. Since the plastics used for PCBs are usually heat-sensitive, which makes them prone to warping. Vacuum processing allows electronics manufacturers to cut bypass the warping and cut down on the time required to get their devices to market. A vacuum oven can also be used to dry smartphones dropped in water without shorting the circuitry and to dry watches that have water under their lenses.

In the medical industry, vacuum ovens are used to remove chemicals that can be toxic inside the human body. This is especially crucial for implanted medical devices like pacemakers, artificial heart valves and joints, and even catheters. Without vacuum processing, these devices will either carry harmful chemicals or be damaged by heat exposure.

In the aerospace industry, vacuum and lab ovens are used to simulate how a device will react in the high vacuum environment of space. Pretty much anything that goes into space is ran through vacuum processing. In a spacecraft, materials are prone to evaporation, which can cause the chemicals from various materials to bond in the air. This can be harmful to human passengers and in extreme cases, even lead to electrical shortages and fires. Without vacuum processing, space travel would be very unstable and dangerous.

Physics get a little weird in a vacuum oven. This video from Ai Vacuum shows what happens to gummy bears under vacuum. Their Youtube channel has videos of various materials inside of their ovens, and are oddly satisfying to watch.

How Are Vacuum Ovens Used in the Cannabis Industry?

For cannabis growers, vacuum ovens most commonly used to process cannabis extracts like BHOs (Butane Hash oil). Residual solvents like Butane are evaporated in the vacuum chamber and are then pulled out of the chamber by the vacuum. This leaves behind a purified oil extract and greatly reduces the risk of fire when using solvents like Butane. This allows for extracts to be processed faster, and more importantly, safer. Producing cannabis oil extracts the old-fashioned way with the massive fire hazard is hard to sustain and even harder to scale.

Although vacuum ovens allow for BHOs to faster and safer, they do have some nuances and take some require some precision to be set up optimally. Some common pitfalls when choosing and setting up vacuum ovens are choosing the wrong model for the desired application (For example, using an oven designed for PCBs on BHOs), setting up the product inside the oven for optimal heat exposure, and adjusting the settings too high to the point where large amount of power and time are wasted. The cost of the vacuum oven itself and the high amounts of power consumption can make the startup cost high, so it’s very important to get your setup right the first time around.

Fortunately, vacuum oven manufacturers produce a lot of technical information about their models along with tutorials for setup and use. These come in the form of datasheets, white papers, and even videos.

Vacuum Oven Manufacturers

Here are some manufacturers of vacuum ovens that are geared for BHO extraction. If there's one I left out, let us know in the comments.