Hydrocarbons are a class of chemicals that include butane, propane, and liquefied petroleum gas.
Butane extraction is the most common form of hydrocarbon extraction in the cannabis industry. Butane is popular as an extraction solvent because of its physicochemical properties and its low cost. Propane can be used instead of butane, depending on the extraction method used by the processor and the attributes of the desired end product. Both butane and propane extraction require careful temperature management to avoid the risk of an explosion.
Regardless of the method used, the fundamentals of hydrocarbon extraction are similar, regardless of a processor's approach: a solvent (such as butane) is “run" through raw cannabis to dissolve the desired cannabinoids and other active ingredients from the plant matter to create a liquid resin that can be further refined. Part of that refinement is the removal of residual solvent vapors still present in the resin after the extraction run has finished. Commercial-grade vacuum ovens are a safe and reliable way to remove excess extraction solvent from resin.
Hydrocarbon extraction systems can be used only within in Class 1, Division 1 locations to reduce the risk of fire and explosions and to meet the requirements of the Oregon Electrical Specialty Code. A Class 1 designation means that flammable gases or vapors may be present at the location. A Division 1 designation means that gases exist under normal operating conditions. Because butane and propane readily evaporate and are highly flammable, they must be managed carefully to minimize the risk of a fire or explosion – particularly when they are loaded, unloaded, and stored. It is essential to identify any potential ignition hazards before extraction begins.
Areas where butane or propane are used must have intrinsically safe exhaust ventilation located within 12 inches of the floor that provides a minimum of one cubic foot per minute per square foot of solid floor.
All equipment in the extraction room must also be rated for use in Class 1, Division 1 locations – including any lighting, power receptacles, vacuum pumps, recovery pumps, and any other electrical equipment (including cellphones). To reduce the possibility of a spark from a static discharge, the extraction equipment and all metal objects, including ductwork, hand sinks, and water pipes, must be grounded or bonded in accordance with the Oregon Electrical Specialty Code. Adequate precaution must be taken to prevent the ignition of flammable vapors. Ignition sources include:
- Open flames
- Cutting and welding
- Hot surfaces
- Frictional heat
- Spontaneous ignition from heat-producing tools, radiant heat, and cellphones
A fixed continuous flammable gas detector is required in hydrocarbon extraction rooms. A portable flammable gas detector should be available to ensure flammable oil and plant material are not removed from the extraction room. This calibrated detector will alert workers when conditions inside the extraction room reach or exceed 10 percent of the lower flammable limit (LEL) for the gas. This helps workers identify leaks during the extraction process, as well as when resin and the extracted plant materials can be safety removed from the extraction room.