Preguntas y Respuestas (FAQ)

When a gas such a carbon dioxide is compressed and heated, its physical properties change and it is referred to as a supercritical fluid. Under these conditions, it has the solvating power of a liquid and the diffusivity of a gas. In short, it has the properties of both a gas and a liquid. This enables supercritical fluids to work extremely well as a processing media for a wide variety of chemical, biological, and polymer extraction.

Near liquid densities increase the probability of interactions between the carbon dioxide and the substrate, similar to a liquid solvent. The gas-like diffusivities of supercritical fluids are typically one to two orders of magnitude greater than liquids, allowing for exceptional mass transfer properties. Moreover, near zero surface tension as well as low viscosities similar to gases, allow supercritical fluids to easily penetrate a microporous matrix material to extract desired compounds. The synergistic combination of density, viscosity, surface tension, diffusivity, and pressure and temperature dependence, allow supercritical fluids to have exceptional extraction capabilities.

Another powerful aspect of supercritical fluid extraction (SFE) is the ability to precisely control which component(s) in a complex matrix are extracted and which ones are left behind. This is accomplished through precise control of several key parameters such a temperature, pressure, flow rates and processing time. Yields from SFE are typically much greater than those of extractions performed by traditional techniques. Product purity is high, and decomposition of material almost never occurs due to the relatively mild processing temperatures.

Supercritical fluid extraction has emerged as an attractive separation technique for the food and pharmaceutical industries due to a growing demand for “natural” processes that do not introduce any residual organic chemicals. Supercritical carbon dioxideis by far the most commonly used supercritical fluid. The unique solvent properties of supercritical carbon dioxide have made it a desirable compound for separating antioxidants, pigments, flavors, fragrances, fatty acids, and essential oils from plant and animal materials. In the supercritical state, carbon dioxidebehaves as a lipophillic solvent and therefore, is able to extract most nonpolar solutes. Separation of the carbon dioxidefrom the extract is simple and nearly instantaneous. No solvent residue is left in the extract as would be typical with organic solvent extraction. Unlike liquid solvents, the solvating power of supercritical carbon dioxidecan be easily adjusted by slight changes in the temperature and pressure, making it possible to extract particular compounds of interest. With the addition of small amounts of polar co-solvents, even polar materials can be extracted. Additional advantages of carbon dioxide are that it is inexpensive, it is available in high purity, it is FDA approved, and it is generally regarded as a safe compound (GRAS). Supercritical carbon dioxideis also desirable for extraction of compounds that are sensitive to extreme conditions because it has a relatively low critical temperature (31°C).

The properties which make supercritical carbon dioxide an attractive solvent for extraction also apply to its use as a medium for reaction chemistry. A fluid’s most important physical and transport properties that influence the kinetics of a chemical reaction are intermediate between those of a liquid and a gas in the supercritical carbon dioxide. The reactants and the supercritical carbon dioxide frequently form a single supercritical fluid phase.  Supercritical fluids share many of the advantages of gas phase reactions including: miscibility with other gases, low viscosities, and high diffusivities, thereby providing enhanced heat transfers and the potential for fast reactions.  Supercritical fluids are especially attractive as a reaction medium for diffusion-controlled reactions involving gaseous reagents such as hydrogen or oxygen.

An example of using supercritical fluids as a reaction medium is the hydrogenation of pharmaceuticals to promote enantio selective hydrogenation to favor a cis or trans version of a molecule during hydrogenation. By performing the reaction in two, instead of three phases, the rate of hydrogenation reactions can be increased over 1,000 times. As a results, the size of the reactor and the associated equipment is less than 1/10th that of conventional autoclave systems. Oils and fatty acid esters, as well as hydrogenare soluble in supercritical carbon dioxide. The reaction rate is increased because excess hydrogenis always available for reaction, and the catalyst pores are not filled with stagnant liquid.

Various types of pumps can be used for supercritical fluid applications. For medium to large volume processes, a pneumatic booster pump is most often used. A diaphragm pushes against a piston to compress the liquid carbon dioxide to a set pressure point. The air that drives the pump increases the liquid carbon dioxide pressure (boosts) in a ratio of about 100 to 1. So, for every 1 psi of air delivered to the pump, the carbon dioxide pressure is boosted by 100 psi (i.e. air at 50 psi will deliver about 5,000 psi of carbon dioxide). The CO2 pressure is controlled by an air regulator which in turn controls the pump operation. Once the desired pressure is selected, the pump pressurizes the overall system to this set point. When the restrictor valve is opened, the pump will continue to actuate to maintain the desired set point.

Yes, the pump will fill/pressurize the extraction vessel up to the set point. If there is no flow of material out of the vessel, the pump will shut off. As soon as the variable restrictor is opened, dissolved materials (analyte) and carbon dioxide begin to flow out of the pressure vessel. The pump will begin to actuate to maintain a pressure set point. Think of the restrictor as a Back Pressure Regulator. As you adjust the restrictor to various flows, the pump will speed up or slow down accordingly to maintain the overall system set point pressure.

The chiller is used to transfer heat away from the pump head. Cooling the pump head ensures that only liquid carbon dioxide reaches the pump. This is important because the unit cannot pump gaseous carbon dioxide. The chiller essentially does two things. It counteracts the heat of compression which occurs inside the pump head, and it removes heat caused by friction of the piston moving back and forth. Both of these heat sources need to be controlled. If the pump head is not cooled, liquid carbon dioxide will enter and immediately flash to gas. The pump will cavitate and will operate inefficiently or not at all.

The chiller eliminates the need for helium headspace carbon dioxide tanks. The action of pumping heats up the liquid carbon dioxide causing the liquid carbon dioxide to flash in the pumping head to gas. This results in cavitations and low pump efficiency. Cavitation can be eliminated two ways: first, by use of a chiller assembly to cool the pump head and/or carbon dioxide fluid to about –5 degrees Celsius, eliminating the cavitation problem. Or, second, by use of a higher delivery pressure of carbon dioxide (as delivered in a helium headspace tank at 1,500 psi). Higher delivery pressure keeps the carbon dioxide from flashing to gas, causing the cavitation problem. However, helium headspace tanks cost about $145.00/tank. A standard carbon dioxide is on the order of $30/tank. The chiller assembly pays for itself quickly after about 4-6 months of standard operation. Supercritical Fluid Technologies, Inc. holds a Patent on its “Chill Can” assembly.

A small amount of a co-solvent increases the ability of supercritical carbon dioxide to dissolve polar compounds.  Neat supercritical CO₂ has dissolving properties similar to hexane.  This means that, by itself, carbon dioxide is very good for dissolving relatively non-polar materials.  The addition of just a small quantity of co-solvent enhances the solubilizing power of the supercritical carbon dioxide, making it possible to extract much more polar molecules. Typical co-solvents include: methanol, ethanol, and water.

Co-solvent addition is typically done using an HPLC type pump. There are two traditional methods a co-solvent pump can be used. Firstly, as a co-solvent doping module where co-solvent is added to the sample to a desired % of the vessel’s overall volume and then the CO₂ pump is actuated to bring the vessel up to the desired set pressure for extraction. Secondly, the CO₂ and co-solvent pump are both actuated at the same time with the restrictor valve open to maintain a set ratio of co-solvent to CO₂ in the sample vessel.

Is there a correlation to use with the flow rate of CO₂ to maintain a fixed percentage of ethanol in the vessel? Base the amount of co-solvent in the system as a function of the vessel volume.  If your vessel is a 100 ml and you want 5% ethanol in your extraction, you would want to add 5 ml of co-solvent to the vessel before you begin the extraction. Once the dynamic flow/extraction has begun, you want to replace the amount of co-solvent that is flushed out of the vessel with the carbon dioxide, maintaining a 5% level throughout the vessel. A Mass Flow Meter (a simple flow meter will suffice) can be used to gauge the amount of carbon dioxide flowing out of the vessel under your dynamic extraction flow step. Take 5% of this volume of carbon dioxide flow adding back that amount of ethanol to the vessel with the co-solvent pump. This is the least complex method of keeping a constant amount of co-solvent in the vessel throughout your extraction.

A liquid CO2 pre-heater is recommended for all extraction work. Regardless of vessel size and despite the use of band heaters, heating efficiency is limited because of the relatively small vessel surface area relative to the total vessel volume. Especially at high flow rates, SFE’s with larger vessels but no preheater will not hold temperatures with a high degree of accuracy during dynamic flow. To compensate for the physical limitations of the vessel heaters, a fluid pre-heater is used to regulate the temperature of the carbon dioxide and co-solvent before they reach the main sample vessel. For the most efficient and reproducible extraction work, it is highly recommended that a pre-heater always be used.

Supercritical Fluid Technologies, Inc. offers a wide variety of sample vessels and options to meet our clients’ needs. Vessels ranging from 5 ml up to 5000 ml are available for our standard bench scale units. 20 liter and larger vessels may be used in our pilot scale processing systems. Many options are available for these vessels from windows to mixing, as required by the application. One issue to keep in mind as you decide on a vessel for your application is that these are ASME designed vessels and they are heavy! For example, a 4000 ml vessel in our bench scale system weighs in at 280 lbs. You will need an engine hoist to move this vessel around the laboratory! Fortunately, vessels in both the SFT-150 and SFT-250 are mounted on sliding racks. The weight of the vessel becomes an issue only when interchanging vessels. The 5 ml, 25 ml, 50 ml, 100 ml, 300 ml, 500 ml, and 1000 ml vessels, which are ideal for preliminary work, can be handled with little difficulty.

The “over temperature” logic controller keeps the vessel’s outer wall temperature from getting extremely hot and, in turn, going beyond the internal set temperature of the sample vessel. For example, if you have an internal vessel temperature set to 40oC, you would set the external wall temperature or “over temperature” controller to 45oC. In this way, you maintain the internal temperature at 40oC without exceeding the desired temperature. Keep in mind you are heating a very large metal mass in the sample vessel. There is a certain amount of histolysis of heat through the vessel wall. To maintain accurate temperature control, management of both the internal vessel temperature and external wall temperature is the best solution.

Remove the existing o-ring carefully. Be sure that you do not scratch the vessel’s o-ring groove surface with any tools. We recommend using a plastic or wood stick to remove existing o-ring. Clean all surfaces thoroughly with solvent. Clean the inside of the vessel seal. The inside surface is where the o-ring actually seals. Carefully install the new o-ring in the groove of the cover. New o-rings tend to be stiff and may need to be slowly worked into position. It is sometimes helpful to heat the o-ring in a pot of hot water before installation. This will help relax the o-ring material long enough for installation. Lubricate the o-ring and seal area of the vessel with o-ring grease. A small amount of grease works best. Also lubricate the threads of the nut with process compatible thread lubricant. Thread the cover into the body of the vessel until you feel the resistance of the o-ring being forced into the seal area. Do not try to force the o-ring all at once.  Work the threads back and forth gently until the o-ring has worked into the seal area. Continue to tighten until the threads bottom out.

Click Here for Downloadable PDF of Vessel Seal Replacement

The “single ended” (SE) vessels only open on one end (one cap). The “double ended” (DE) sample vessels have vessel covers on both ends and can be opened on both ends. The smaller vessels are double ended to make it easier to clean inside the vessel. The larger vessels have a sufficient diameter, so opening only one end is acceptable. From a costing standpoint, once you get above 100 ml in sample vessel size, the cost savings for a single ended vessel is significant versus a double ended vessel.

Click Here for Downloadable PDF of SE and DE Sample Vessel Drawings

A variable restrictor, also known as a Back Pressure Regulator (BPR) is a key component in the successful application of supercritical fluid technology. You will note that all of our products have this key component. The restrictor valve allows for the controlled and metered release of the pressure built up in the sample vessel into the collection assembly. Materials that have been solubilized in the SCF CO2 can now be collected at atmospheric pressure. Beyond the metering out of the flow, the restrictor valve assembly also compensates for the Joule-Thompson cooling that occurs through expansion of pressurized CO2 by adding heat to the assembly. The heating ensures that the valve will not freeze and solubilized analytes precipitate plugging this valve.

Applications for water as a process media range from subcritical water extraction to supercritical water oxidation to supercritical water reaction processes in this application niche. Supercritical Water Oxidation (SCWO) is among the most challenging applications of supercritical technology. Very high temperatures (over 400oC) and moderately high pressures are required to achieve the critical point of water. An additional difficulty is corrosion, which is a problem for all sub-critical and supercritical water systems. Special materials for vessel linings and tubing are needed to resist the highly reactive chemical species generated during the process.
These challenges demand superior engineering and design expertise for all system components. The water and process streams must both be pumped to high initial pressures under exact flow and pressure control. The heat exchangers are subjected to high heat transfer rates at high temperatures, but must maintain precise temperature control. The reaction vessel requires exact temperature, pressure and flow control. The vessel must seal reliably and be leak free each time it is used, regardless of the harsh operating environment. Downstream processing such as cooling heat exchangers, collection vessels, gas/liquid separation and pressure control must be efficient.

It would be much less expensive to purchase a dedicated supercritical water type unit than go through the detailed modifications needed to change the traditional SFE unit to use water as the supercritical fluid.

The term a “cyclonic separator” is used to designate a type of collection assembly that allows the material that has been extracted from the sample vessel to be collected through running the outlet tubing of the sample vessel/back pressure regulator at an angle along the walls of the collection vessel creating a cyclonic vortex that deposits materials on the walls of the collection vessel and the gaseous CO2 to evacuate to vent. Cyclonic separation minimizes the amounts of materials that get carried out with the gaseous CO2 through the venting process. This is very similar to the technology used in something as simple as the Dyson vacuum cleaner!

Some SFE suppliers use an actual SS pressure vessel to act as the cyclonic separator/collector and others employ vials and jars in place of the SS collection vessel, but both essentially carryout the same cyclonic separation/collection process. In the case of vials or jars, the outlet tube from sample vessel/BPR deposits extracted materials along the walls of the vial/jar and allows the CO2 to evacuate the collection vessel thus minimizing the loss of materials with the CO2 gas.

The 5 micron discs typically have loose tolerances from our supplier (meaning they tend to fall out like you are experiencing, because they are slightly smaller than the slot for them to fit in within the sample vessel cover). What you need to do is take a “center punch” tool. This is similar to a punch used by woodworkers to punch nails into the wood past the surface. A center punch can also simply be a piece of stainless steel that is the shape of a pencil like a traditional nail. You want to slightly “deform” the edge of the 5-micron filter part by making the edge stick out further so when you press the disc back into the filter assembly it stays in position.

Place the disc on the work bench and use the center punch or similar tool to punch the edge of the disc with a hammer on 4 sides (90 degrees apart), deforming the edge slightly making the edge wider and thus giving the filter assembly holder something to grab onto when you press the filter back into the assembly.

The SFT-110, SFT-110XW, SFT-150, SFT-250, and SFT-NPX-10 units are not designed and manufactured to Class I Division II explosion proof standards and therefore cannot safely be operated with these liquid gas solvents.

Unfortunately, Dewar tanks have too low of a delivery pressure and temperature for our pumping systems in these units. Typically what a client will do when processing a lot of material on the SFT-150/SFT-250 scale unit in a lengthy “dynamic flow” mode is manifold 4-6 tanks together for CO2 delivery. On the larger scale NPX units, there are 2 options for CO2 delivery. You can either go with a manifold in combination with a recycle system which allows long processing runs OR a bulk delivery tank, which is approximately 6000 lbs, with booster pump to deliver the liquid CO2 to the system.

Our testing has successfully shown that traditional vegetable oil has been able to pump through our co-solvent pumps.  As long as the solvent of choice is less viscous than vegetable oil and compatible with our systems (see manual for a complete list of incompatible solvents), it should be able to be pumped with the SFT-Co-Solvent pumps.

Optional flow meters can be purchased as an upgrade to the SFT-110, 110XW, 150, and 250 SFE Units.  Locate the “L shaped tube” with sharp end (90° bend S/S tubing), the septa lid jar, 2 flow meter fittings, and 2 pieces of flexible tubing (as seen below).

Insert sharp end of “L” shaped tube into jar (or vial) with septa lid.  Slide the septa jar (with the “L” shaped metal tube) into the collection assembly of the SFE outlet (see below).

Connect two (2) “Flow meter fittings into the back of the flow meter.

Use one piece of flexible tubing to connect the blunt end of the “L” shaped metal tube to the bottom of the flow meter.  Use the other piece of flexible tubing to vent or hood (if desired)

Note: The flow meter measures the expanded CO₂ gas.  From this measurement, the amount of CO₂ must be calculated. Typically under standard conditions 1ml of CO₂ liquid = 450mls of CO₂ gas

By extracting with CO2 only, it was possible to effectively separate the dark plant pigments and light volatile oils from the bulk extract (Figure 6). By generating three distinct fractions from a single extraction, extraction facilities are able to generate multiple processing streams and products from a single extraction. For example, in this scenario the dark CS1 fraction, ~20% of the total extract, was directed towards a CBD-A purification pathway encompassing chlorophyll and wax removal followed by SFC purification. Fractions 2 and 3 were combined and directed towards a more traditional pathway involving only wax removal.
The flexibility of CO2 extraction allowed for the generation of three distinct hemp extract fractions from a single extraction. Since there is variability inherent in working with natural products, the ability to generate multiple distinct processing streams from a single extraction is a major benefit to high pressure SFE with fractionation; this allows processors to develop specific workflows for a particular consistent desired outcome.

Yes, Supercritical Fluid Technologies provides extraction systems specifically designed for the Cannabis market with the CannabisSFE 3x5000ml platform and with our NPX SFE Processing Platform configured for Cannabis Extraction you can specify 3x 5L, 3x 20L, 3x 40L, and 3x60L. Both the CannabisSFE 3x5000ml and he NPX family of products have significantly higher flow rates of liquid CO2 and full closed loop recycle to maximize product throughout and yields.?

SFT works with various accredited PE Engineers, who are able to sign off on our design to meet local municipal codes. Sometimes the local municipality requires a design review, while for others, they only require a review of the Piping and Instrument Design (P&ID) flow diagrams. We work closely with the customer to provide the support they need.

The vessels used in our CannabisSFE 3×1 and CannabisSFE 3×5 systems do not require ASME stamps according to ASME regulations, due to their smaller size. However, both vessel sizes used (1000ml and 5000ml) meet the strict ASME Code parameters. Documentation of this design point can be provided.

THC and other cannabinoids are best soluble at 4500-5000 psi. The CannabisSFE has a significant advantage vs. competitor’s operating pressure, which enhances the solubility of the cannabinoids in the CO2. Therefore, we can extract very fast.

The key parameter you desire to optimize for the extraction of natural products is throughput. Therefore, our family of Supercritical CO2 processing platforms from the CannabisSFE up to the NPX SFE units process with liquid CO2. Liquid CO2 at any given pressure and temperature of operation has a higher “loading capacity” of extract. Liquid CO2 can hold more extract than gaseous CO2 and therefore provides a more efficient extraction. The most efficient extraction processes offering the highest yields are always liquid CO2. Other systems that use gaseous CO2 claim a higher flow rate, but if you convert a gaseous CO2 flow rate of say 5L/min of gaseous CO2, it is only 12.5 mls/min of liquid CO2, so the systems that claim to have a 5 L/min flowrate of gaseous CO2 do not provide fast processing times of your raw materials.

A: You charge all 3 vessels to start the process. Depending on micron size (200 microns is recommended for maximum extraction efficiency), the vessels can hold the following amounts:
• CannabisSFE 3×1 = 400-454 grams
• CannabisSFE 3×5 = 2000-2200 grams
You begin CO2 flow through vessel #1 into vessel #2 and then into the collection vessel. After about 30 minutes, vessel #1 is fully extracted and vessel #2 is one half extracted.
Next, you switch the system to flow CO2 through vessel #2 into vessel #3, and then into the collection vessel. In about 30 minutes, vessel #2 is fully extracted and vessel #3 is one half extracted.
While in this step, you unload processed feedstock from vessel #1 and reload a fresh charge into vessel #1. At completion of the vessel #2 extraction and the reloading of vessel #1 you switch CO2 flow to go through vessel #3 into vessel #1 and then into the collection vessel.
Repeat the process. You are now operating in cascade mode, which is significantly more efficient than any other extraction mode.
Look at attached P&ID (Piping and Instrumentation Design) to better visualize the valve and flow path for this operation mode.

The cycle time is 20 minutes for the CannabisSFE1x1L and CannabisSFE3x1L systems. You can figure a 30-minute cycle time for the 3x5L and larger systems. The functions that must be done are: load raw materials, pressurize, cycle, depressurize, and reload with raw materials.

Although the cost of Ethanol equipment for larger scale extractions is cheaper than similar scale SFE equipment, the extract that you get from ethanol extraction requires much more post-processing because you are left with a very sticky resin. CO2 does not require as much post-processing and is a better choice than ethanol.

BHO Basics: Butane hash oil, also known as BHO, is a cannabis-derived oil made using butane as the solvent. In a basic BHO extraction the first step, known as a ‘wash,’ involves passing butane through a column containing the plant material. The butane strips the cannabinoids, terpenes, waxes, lipids, and other chemical compounds from the plant material. The butane must then be separated, or ‘purged’ from the extracted plant oil. This can be done through heating, by vacuum, or through some combination of the two.

BHO extraction time can vary depending on the size and model of the extraction equipment, though typical run times average from 5-10 lbs of plant material processed per hour. Excluding the price of Butane, you must factor in the cost of ventilation, or a protected explosion proof environment. Although the install can pose hazards, closed loop systems significantly decrease operating risks for owners.
Butane is a highly flammable colorless gas. The flash point, or the lowest temperature at which vapors will ignite when given an ignition source, is -60 °C (−76 °F). Thus, a spark from a light switch, an electric hand tool, or even a static charge can trigger an explosion. Furthermore, the autoignition temperature, or the lowest temperature at which a substance will spontaneously ignite in normal atmospheric pressure without an ignition source, is 288 °C (550 °F), which is a temperature easily reached by a stovetop or oven element.

The National Fire Protection Association has assigned a flammability rating of 4 (on a scale of 0 to 4), classifying n-butane as extremely hazardous. For these reasons, most states that allow for BHO extraction systems require a properly ventilated Class 1/Division 1 explosion-proof room. Both the room and BHO extraction system must be inspected by a certified industrial hygienist or engineer to be sure they conform to regional and municipal codes and nationally recognized accreditations. Workers must be adequately trained and understand the hazards associated with working with closed loop BHO extraction systems.
Even with proper training, equipment, and environment, BHO extraction systems can be dangerous. In 2014 in the US, there were 3 BHO extraction explosions, 30 injuries, and 32 explosion related deaths. This is in comparison to 12 explosions and 18 injuries in 2013.

Supercritical CO2 Extraction (SCE):
Supercritical CO2 Extraction is quickly becoming the preferred solvent in the Cannabis and Hemp industry. Despite having a costlier initial setup, CO2 is cheaper than butane, making the system more cost-effective to run. As CO2 is produced by natural means, if it is released back to the environment it does not have a negative impact on the atmosphere, making it a much safer and environmentally responsible choice than BHO. SCE does not require the same explosion-proof facility setup that BHO does, or safety equipment and training for operators to work with.

CO2 is also non-toxic- it is a natural waste product from human bodies and fermentation. Due to this and its gaseous state at atmospheric pressure, all extracts made from SCE are pure and completely clean of any potential toxic or heavy metal residues that can be left behind in BHO.
The conditions of a SCE system can be manipulated to fractionate desired compounds like terpenes, cannabinoids, waxes and esters out of the oil mixture in differing concentrations. This also provides the opportunity to refuse undesired compounds like chlorophyll from the extract. Manipulation in this manner makes SCE the perfect option for drug manufacturers looking to obtain higher concentrations of different biologically active components.
CO2 has solvency power at a much lower set of extraction parameters in comparison to other solvents, and therefore can extract compounds that usually are degraded at higher temperatures or pressures such as terpenes. Carbon dioxide extracts are accordingly stronger in aroma and flavour and bear a profile that most closely resembles the original plant. These extracts are preferred in market as their scent and flavoring are highly valued by purveyors.

SUMMARY:
Although BHO products may appear to be easy to make, the underlying risk involved with the extraction process and requirements for a Class 1/Division 1 explosion-proof room are additional factors that must be taken into consideration. On the other hand, CO2 extraction provides a cleaner and safer option for operators to process cannabis, with the bonus of being able to produce a full spectrum cannabinoid-rich product with an enriched perceived value.

Ethanol is what is called a “polar” solvent and it will be more hydrotropic, meaning it will want to bind to the water-soluble components of the plant. The result is a less pure, and a generally less potent end product that needs more post processing than CO2 extracts. Most ethanol extraction proponents argue that these drawbacks can be avoided by keeping very cold temperatures below -5F. This is true, but what needs to be considered is the additional work to make the crystalline is costly and hard to scale up for production.

Ethanol Pros -Generally more lenient storage requirements for large amounts -If done properly, elimination of a de-wax step
Ethanol Cons -polar solvent and will pull more water-soluble components like chlorophyll -higher boiling point making recovery slower and more difficult -post processing requires more labor. The CannabisSFE 3×1 allows continuous extraction with an easy to use system.