A word about CO2

Apeks Supercritical extraction systems use carbon dioxide (CO2) as a solvent to extract oil from botanical plant material because it yields safer, cleaner and purer oil. Long known for its versatility and high efficiencies, CO2 is commonly used in many types of commercial processing, such as dry cleaning, where it removes dirt without affecting the clothing. CO2 extraction of botanical material works much the same way. The CO2 removes the oil as it passes through the plant, leaving it intact. Remarkably, the plant material will look the same after extraction as before except it no longer contains the oil.

With CO2 extractions, there are no residual components in the extracted material. Other extraction solvents, such as hydrocarbon-based propellants like propane and butane, hexane and pentane, or ethanol/alcohol mixtures, require additional distillation or purging after extraction to separate the solvent from the extracted oil. Consumers prefer products — including manufactured cannabis products — that are made from natural substances, such as CO2. To learn more about the advantages of CO2 extraction, click here.

Extracting oils from plants

Most of our customers use Apeks systems to extract cannabis or hemp oil, but the systems will extract any botanical material – if there’s oil to be had, it will be extracted! So, how do the systems work to extract the oil?

Using high pressure, CO2 is pumped into the first vessel (extraction vessel) containing the plant material. This process converts the CO2 into a liquid, which then passes through the plant material, extracting the oil content. The liquid (CO2 + plant extract) is then pumped into a second vessel (separator vessel) during which the CO2 is converted back into a gas where it separates from the oil. The denser, heavier oil falls to the bottom of the separator vessel into a collection cup. The CO2 continues the loop, circulating around the system, running through the plant material multiple times before the extraction is complete. The COis then redirected back into the gas storage cylinder. Approximately 90% of the CO2 is recycled.


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Subcritical and supercritical extraction (in plain English)

The lighter, terpene-rich oil on the left from a subcritical extraction, the heavier supercritical extraction on the right.

CO2 is unique because its solvency power can change by simply adjusting the temperature and pressure during the extraction. And because the solubility in CO2 varies with pressure, it can be used to extract selected compounds (rather than a combination of all compounds) with just a few small adjustments. CO2 extractions are processed subcritically (low pressure/low temperature) or supercritically (high pressure, high temperature).

Subcritical runs are lighter. The first 20 minutes or so extracts the terpenes (pungent oils) and flavonoids from the plant. Many processors use these extractions just as they are for vape pens and other products where terpenes are very popular. After the terpene run, the extraction continues on its subcritical run to extract more of the oils. These extracts are slightly darker but like the terpene-rich oil, processors can use them just as they are, along with adding a few terpenes back in to give a fragrant boost. Then, they can move on to the supercritical run, where the plant material is processed under high pressure and high temperature. This supercritical process extracts the rest of the oil from the plant, but also the undesirable fats, waxes, and lipids requiring processing after extraction, referred to as winterization.  After winterization, oils can be further refined by short path distillation.


Winterization involves mixing the extract (which has the consistency of soupy peanut butter) into pure alcohol (200 proof), then freezing overnight in an industrial freezer. These freezers go as low as -121 F. The mixture is then filtered through a funnel and filter paper. The fats, waxes, and lipids collect and stick to the filter paper. Next, the alcohol is removed by gently heating the oil using a rotary evaporator. Alcohol boils at a different temperature than the oil so it simply evaporates. Once the alcohol is removed, you have pure concentrated oil, which can then be used in edibles, tinctures, vape pens, etc.

To watch the winterization process, click here:

Short Path Distillation and The Entourage Effect

Cannabis has many different compounds, each with different characteristics. Some processors like to further refine the oil after extraction to capture specific compounds by applying heat. This is known as short path distillation. Each compound boils at a different temperature, so by heating the oil and siphoning off compounds, you can isolate each one. However, there are those who believe the extract is best with all of its compounds so the consumer/patient gets the various benefits of each of them, not just one. This is known as the entourage effect.

Features of Apeks CO2 extraction systems and other advantages

Apeks systems produce essential oils that are pure and safe. Constructed by a team of experienced engineers and fabricators, Apeks extractors range from Introductory to High Production systems, expandable up to 80-liters. For large-scale operations, the High Production systems can process up to 100 pounds per day. Features of all Apeks systems include: lights-out automation with internet messaging and automated controls, the patented Apeks Valveless Expansion Technology (no clogging), and Diaphragm Compressor Technology (20 to 50% faster extractions while consuming half the power). The 5000psi High Production Series also utilizes the Apeks Dual-Phase Pumping System (gas and liquid) for two times the speed of extraction. Other advantages include: simple fractional extraction and cold separation processes which preserve volatile oils for higher-quality and higher-quantity yields, two levels of safety protection, data-tracking capability, and CO2 recovery (up to 90%) — all supported by comprehensive onsite and virtual training.

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