What Is Supercritical CO2 Extraction?
Supercritical fluid extraction (SFE) is the process of separating components from each other by use of a particular type of solvent. These types of solvents are labelled “supercritical” by virtue of the fact that when they are exposed to extreme temperatures and pressures, they display structures that fluctuate between intermediate states of solid, liquid, and gaseousness.
When in this state, supercritical fluids are capable of breaking down structures where they can then be separated, or fractioned. Among the variety of supercritical solvents used for this process, the most common by far is CO2.
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Supercritical (sc-CO2) extraction has been around for decades, appearing first in the 1980s and 90s as a cleaner and more viable alternative to other methods of separation and extraction. From the decaffeination of coffee and tea to the extraction of essential oils for perfumes, this process has become commonplace in many industries.
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The attached are general guidelines for safety and not to be construed as all encompassing. Always consult with your local permitting office, fire department, NFPA 58, equipment manufacturer and all other applicable authorities regarding regulations in your area
Since 2012, when the first two states – Colorado and Washington - approved marijuana for recreational use, up to the present, when cannabis is legal in 33 states, this industry has experimented to create more value for its crops. And it brought new safety hazards into the processing and extraction operations.
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In the 33 states where cannabis is legal, at least 10 fires or explosions have occurred in the past 5 years at facilities that extract hash oil. At least 19 people have been killed and 126 people injured by hash-oil fires in California since 2014, the DEA reports.
So, the need for gas detection and monitoring systems at manufacturing facilities has become imperative. Let’s discuss gas detection solutions for this industry.
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Explosions across the United States
The booming cannabis industry is prone to safety hazards.In 2016, more than 40 adults and three children were injured from hash-oil lab explosions in the State of California, according to child-safety advocate Sue Webber-Brown, quoted by Reuters. In the same year, Washington federal prosecutors have brought charges in five cases involving explosions during hash oil production, one of which killed the former mayor. And last year, OSHA fined a cannabis manufacturer $50k after an explosion burned worker handling propane to extract oil.
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Respiratory risks
“If the release of hazardous material can cause immediate harm to a person or property, a means to mitigate the release shall be provided”, Chapter 50 of International Fire Code (IFC) states. Cannabis plant cultivation and oil extraction processes carry a variety of toxic and combustible gasses that often reach alarm activation levels and need to be continuously monitored for safety. Greenhouse heating and ventilation can also pose concerns during a leak. Combustible gases such as carbon dioxide, butane, propane, hexane, ethanol, or carbon monoxide are the byproduct of solvent-based cannabis oil extraction. Solvent extraction is used to remove the essential oils from plant matter. and should not exceed 20% LEL.
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Carbon Dioxide (CO2) – toxic, asphyxiator gas used in the growth process of marijuana – is typically caused stored in cryogenic liquid cylinders, compressed gas cylinders or dry ice. The OSHA PEL for CO2 is 5,000 ppm TWA. There is also a danger of oxygen deficiency. Furnaces, boilers and portable generators using fossil fuels, where incomplete combustion may occur, are the main source of carbon monoxide (CO) release. The OSHA permissible limit here is 50ppm (TWA). Refrigerant leaks from the chiller rooms/HVAC systems are also a potential source of toxic gases. Natural gas – methane – is often present in the boiler room, as the result of fuel for gas-powered equipment. Growing cannabis plants also releases VOC emissions, namely toxic and flammable gases. Spaces that prohibit natural ventilation, like storage tanks, open pits found in boiler, extraction and cultivation rooms may pose asphyxiation risks that need to be addressed.
Safety standards, a state matter
Consumption hasn’t been legalized at the federal government level, thus, worker safety protections are inadequate even in states that do offer environment, health, and safety (EHS) guidance. Federal EHS standards apply, but many companies are too small to fall under the Occupational Safety and Health Administration (OSHA). As additional states have legalized marijuana, they have responded to challenges by enacting tighter safety controls.
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Above content credit: Honeywell: https://safety.honeywell.com/en-us/news-and-events/blog/top-gas-safety-concerns-and-solutions-for-cannabis-manufacturers