How Safe is CO₂ (Carbon Dioxide) Extraction? Answering Common Extraction Process Questions

In the extraction business, safety is key. In fact, our company philosophy acronym, SQRIPT begins with Safety (followed by Quality, Respect, Innovation, Pride and Transparency). We believe in safety first, from the manufacturing floor to the front of the office, and that extends to our customers as well. Our systems are developed according to the highest industry safety standards to ensure safe CO2 extraction. We have certifications like UL 508A for our control panels as well as a world-first UL 1389 system, which encompasses the whole extraction system, rather than only the control panels. However, these safety certifications relate to the electrical part of the extraction system. CO2 as a solvent is safe because it’s an inert substance and is not flammable or explosive. Other solvents are a safety risk, but can be mitigated with specialized equipment.

Extraction techniques and methods

When one compares different extraction methods, the most common question people ask is: “Is CO2 Extraction better than Butane?” Before we get into that, let’s define a few terms:

CO2 – carbon dioxide, which is the solvent Apeks Supercritical systems uses. It’s a powerful solvent that is used in many applications from dry cleaning to cannabis extraction!

Terpenes – these are the compounds from the cannabis plant that contain the smell and flavor of the plant. They are highly sought after but are also quite fragile and will burn off or be destroyed by some extraction methods.

Hydrocarbons – this is a family of solvent gases, like butane and propane. This is one of the highly flammable solvents and requires special safety equipment.

Extraction – this is the process of using a solvent (or mechanical method) to remove essential oils from the cannabis plant.

There are a variety of extraction techniques that can be broken out into two groups: Mechanical and Solvent-based:


This type of extraction involves an active and manual process. Some examples are dry sieve, ice water hash, and bubble bags. They all need a person to do something to extract the oil from the cannabis and there is no solvent involved.


Solvent based extraction methods involve a solvent such as CO2, Butane/Propane (hydrocarbons), Alcohol/Ethanol or a Naptha is used to extract the oil. These solvents can be used in a closed loop system, like the Apeks Supercritical systems, where the solvent is contained the system, or they can be used to soak the cannabis in, and the solvent extracts the oil that way. Closed loop systems are safer because no fumes can escape, which is particularly important for volatile solvents, like hydrocarbons.

What is CO2 extraction used for?

Among other things, CO2 is used extensively in the cannabis and hemp industry to extract the oil from the plant. CO2 is used as a solvent to dissolve the oil out of the plant as it is passes through the cannabis at specific temperatures and pressures. CO2 is also used in dry cleaning, to remove dirt from clothes without harming the clothes. We have done experiments on a wide variety of botanical substances and if there’s oil in the plant, the CO2 will extract it. We also decided to see what it would do with potato chips – it left the chips intact, but completely flavorless! It is a versatile and considered to be a safe solvent.

What is the difference between CO2 and butane extraction?

CO2 and Butane are both solvents, used to extract oil from cannabis and hemp. CO2 is a natural substance that’s in the air around us. Butane is a gas in the hydrocarbon family, that’s easily liquefied and used in extensively, from heating, to lighters, to extracting oil from cannabis! It is a powerful solvent, but it is highly flammable and requires C1/D1 (Class 1, Division 1) safety equipment in a cannabis laboratory. The cost of the equipment is usually less than CO2 equipment, but it may be outweighed by the cost of the safety equipment.

Is CO2 Extraction better than Butane?

We prefer to avoid claims about the “best” extraction method, simply because none are the best! Everything depends on the desired end product. With cannabis, that could be a multitude of products: from tinctures and dabs to balms and isolates. Extraction companies can create any number of cannabis-derived products – many of which can be produced using CO2, but some, like live resin, are best produced with butane. However, terpenes are destroyed when extracting with certain solvents, like ethanol. CO2 systems are very efficient at extracting terpenes without thermal degradation.

Does CO2 extraction remove Terpenes?

CO2 is excellent at preserving and extracting delicate terpenes. Operators use their systems to gently extract terpenes in the first few minutes of a run (depending on the system). Those terpenes are then set aside to be added to the extraction post-refinement.

Is CO2 extracted CBD oil safe?

Yes, CO2 is a naturally occurring substance that simply bubbles out of the extract and dissipates. Unlike butane, there is no trace left behind, which is why it’s a popular solvent for cannabis. For a visual, think of the way a soda will go flat if left opened. The same thing happens after a CO2 extraction. Have a look at our customer video below – the bubbles are CO2, escaping after a terpene run.

What is the CO2 extraction process?

CO2 is an effective solvent when passed through cannabis under certain temperature and pressure parameters. The whole process can be as short as a couple of hours – the time depends on which system is used, and what parameters are selected.
The cannabis plant material is dried (some customers use a freeze dryer, particularly if they’re in a humid climate), then ground up to a coffee-ground consistency. The material is packed into the extraction vessel before it is sealed. The operator performs several system checks and sets parameters – subcritical or supercritical. Subcritical is low pressure/low temperature (required for terpenes and lighter oils), while supercritical is high pressure/high temperature and will pull crude oil, that contains some undesirable compounds, like fats, waxes and lipids. Supercritical extracts require post-processing work to refine the oil and remove those undesirable compounds.
Once parameters are set, the operator starts the machine. It begins to pressurize and once it’s up to the required pressure/temperature, the CO2 is pumped through the ground up cannabis. As it passes through, it collects the oil in the plant and takes it along to the next vessel. The CO2 stream, containing the oil, passes through an orifice into the separator vessel and depressurizes as it does so. This causes the oil to release from the stream and it drops to the bottom of the vessel, into a collection cup. The CO2 stream continues in a loop, passing over the cannabis multiple times until the run is complete and the extracted oil is in the collection cup.

Post Processing

The extract may require post processing refinement and one method is winterization. This is when the extract is mixed with food-grade ethanol, stored in a deep freezer overnight, and then run through a filter to remove the fats, waxes, and lipids. The ethanol is then removed from the mixture using a rotary evaporator, which gently heats the oil, causing the ethanol to evaporate out of the oil.

Does CO2 extraction kill mold?

Yes, but it is always recommended that the source material is tested before and after extraction. The reason for this is that if there are other contaminants in the plant, like heavy metals, they may not be detected in the first test, but after extraction, the oil is concentrated and trace amounts might show up there. So while CO2 does kill mold, it’s preferred not to use moldy material to begin with.

Which extraction method is the best?

This question is answered with another question: What are you trying to make? The answer to the second question determines the answer to the first question! For vape pens, terpenes and edible oils, CO2 is preferred. However, butane and ethanol are also good for vape pens. On the other hand, CO2 is not good for live resin because the source material needs to be as dry as possible and live resin is produced with fresh plant material, which has a high water content. Ethanol is not good for terpenes – it cannot fractionate the terpenes and simply destroys them as it extracts everything from the plant. Ethanol is excellent for bulk extractions and for infused products. So, it depends on what the end product is going to be – that determines the best extraction method. See chart below for a high level overview of which extraction method is best for which product.

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