By Harry Resin November 11, 2015
Solvent-processed cannabis extracts are here to stay—along with the dangers that go with making them. However, we can all breathe a little easier these days with the adoption of the closed-loop extraction system by most concentrate producers. This type of system has already been in use for decades in scientific labs and by the various industries that need essential oils for things like perfume, beauty products and food additives.
Indeed, closed-loop extraction is the norm in industries where compounds and essential oils play an important role in product manufacturing. In these industries, carefully crafted regulations and standards have been put in place to ensure that any lab performing such extractions is safe and in compliance with the industry’s best practices.
This has started to become the norm in the cannabis industry as well. Today, closed-loop extraction is providing a safer (and much saner) way of creating extracts for the industry, offering an alternative to the riskier methods of open blasting. Companies like BHOgart in California and Terpp Extractors in Colorado have become industry leaders in this regard—and states like Colorado require a license in order to open an extraction lab.
The biggest benefit of closed-loop extraction is that it offers a method of working with flammable (and explosive) materials with equipment that has no openings for the solvents to escape or leak through. This is especially important when working with pressurized liquids that become gaseous in the absence of pressure. Closed-loop systems deliver two important benefits for extract artists: first, allowing them to reuse their chemical solvents, which means less waste and more money saved; and, second, significantly reducing the risk of explosion, because the system is extremely well-sealed.
How It Works
A closed-loop extraction system can seem daunting at first when you look at all of the components. Bear in mind that it’s a professional setup and requires a basic understanding of things like maintaining pressure and operating control valves. In general, a closed-loop system is made up of a large tank and attached tube, which is where the confined “blasting” occurs; a recovery tank; a recovery pump; a refrigerant pump; and a refrigerant scale to measure the weight of the recovery tank.
Finally, when making BHO, you will also need an oven and a pump, which are used in combination with each other, creating a vacuum oven. This “cleansing” system ensures that your product is purged of any residual solvents. However, for our purposes here, we will discuss only the extraction and not the purging process.
Here’s a quick thumbnail sketch of how the system works: Ground-up cannabis material is packed into the extraction tube—but not too tightly, since that will decrease potential yields. (It is also recommended that you use fresh-frozen buds or just-harvested plants, as they contain the most terpenes.) A tank of pressurized solvent is then attached to the tube, using a series of lock-down clamps and valves to ensure that the solvent stays under pressure throughout the process.
As the liquid solvent passes over the compacted cannabis material, the trichomes—or resin glands, which cover the buds and contain most of the plant’s cannabinoids—are stripped away and deposited in the basin of the extractor. The residual solvents are collected separately in the recovery tank and can be stored for later use.
Even though the closed-loop technique is safer, it’s still important to have tremendous respect for the system and the process, since any small faults (such as a blown gasket) can mean big trouble. For this reason, frequent and regular safety checks on your equipment are a must. It is also important to set up your blasting facility like a true lab, meaning proper ventilation and fire-safety controls.
Top Five Safety Tips for Making Extractions
Never open-blast! This process is extremely wasteful and dangerous to boot. Always use a closed-loop extraction system to recover and reuse your solvent.
Always have adequate ventilation. Never extract indoors unless you’re in a lab that meets all state and local laws, including fire codes. Following these regulations creates a safe working environment for yourself and your employees.
Never smoke! Butane and propane are odorless, invisible gasses that are heavier than air. They sink to the ground, pool up and do not easily dissipate. You never know if flammable gas is still lingering around.
Don’t skimp on safety precautions. Remove all ignition sources from your extraction area. Use a butane detector to help warn you of any leaks, as well as an explosion-proof fan with static-resistant ducting for additional ventilation.
Know your source. It’s important to know where your solvent and cannabis material came from, since contaminates in either may be concentrated in the extract. Start with fresh, organic plant material whenever possible, and be sure to filter and distill your solvent in the extractor before running your material. This will help in removing most contaminates.