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Dangers of extracting cannabis using equipment at high pressure

What is the potential risk?

Extracting cannabis is complex and requires special equipment operating under high pressure. This type of equipment is used in laboratory settings and, more recently, manufacturing. Firms in the cannabis industry use the equipment to make a crude extract. The extract is then processed into vapes, oils, dabs, edibles, topicals, and juices.

The process can require extremely high pressure (up to 10,000 pounds per square inch or psi). The amount of pressure depends on the extraction method used and the products being made. In the event of an inadvertent pressure release, a pressure blast could cause serious injury or loss of life.

The following are examples of situations in which uncontrolled pressure releases can cause a blast:

  • Failure of pressurized equipment components such as sanitary clamps
  • Discharge of pressure relief valve into the facility
  • Industrial sewage systems
  • Opening a pressure vessel while it’s under pressure
  • Clogged gauges or lines misleading operators to believe the system is depressurized

The risks associated with the use of pressurized equipment can be overlooked. As a result, control measures that can prevent serious injuries or death from a blast are not implemented.

Which industries and workers are at risk?

Any employer that uses pressurized systems is at risk of an accidental pressure release. While the extraction of cannabis is new, this method has been used for some time to extract substances such as essential oils, soybase, and coffee.

Cannabis processing has seen large growth over the past few years. New participants are joining this industry, investing in capital equipment, and hiring workers. It’s essential that they have health and safety knowledge about the hazards and risks in extracting cannabis.

Technicians who operate extraction equipment are most at risk of harm, but an incident can also affect others in the workplace and surrounding area.

How can I reduce the risk in my workplace?

When assessing risks, consider the following elements:

  • Extraction methods
  • Extraction equipment
  • Solvent and/or chemical properties
  • Facility design
  • Worker interactions

Once you have assessed the risks, you must put in place effective and reliable controls. When considering how to reduce the risk, follow the order of the hierarchy of controls:

  • Elimination (physically remove the hazard)
  • Substitution (replace the hazard)
  • Engineering controls (isolate people from the hazard)
  • Administrative controls (change the way people work)
  • Personal protective equipment (protect the worker with PPE)

Due to the nature and use of pressurized equipment in the extraction process, opportunities for elimination and substitution may be limited. Consider the following engineering and administrative controls for pressure vessels and systems.

Engineering controls

  • Facility design allows equipment to operate safely. For example, piping is used to redirect pressure from the pressure relief devices to a safe location outside of the building. Further, emergency ventilation and monitoring systems are used for any contaminants.
  • Pressure equipment has effective safeguarding.
  • Equipment such as extraction filter bags or socks is used to prevent clogging or obstruction of lines and gauges.
  • Replacement parts or modifications follow instructions from the manufacturer or/and a qualified engineer.
  • Pressurized extraction equipment meets Canadian standards for pressure vessels and extraction.
  • Pressure vessels have a design registration with Technical Safety BC.

The following have specific engineering requirements that must be met:

  • Equipment and/or process
  • Facility design
  • System operations

See the end of this advisory for some of the applicable standards and regulatory requirements.

Administrative controls

  • Written safe work procedures are in place for operating the equipment.
  • All technicians are trained on the safe use of the equipment.
  • Manufacturers’ instructions are followed to ensure clamps are used correctly for safe, leak-free connections, and torque wrenches are used to set bolts.
  • Pressure gauges are regularly inspected to ensure they are in good working order.
  • Equipment is inspected regularly and is continuously well maintained. A replacement plan is followed.
  • An emergency plan is in place. The plan includes how to respond to an uncontrolled pressure release from extraction equipment.

You may need to use a combination of engineering and administrative controls. Appropriate personal protective equipment may also be needed to reduce the risk to workers to an acceptable level.

Other risks related to solvents

Solvents used in extraction can also harm workers. Solvents can cause fires, cryogenic burns, poisoning, and asphyxiation. You must consider the characteristics of each solvent and apply control measures to reduce the risk.

Where can I find more information?

For requirements relating to pressure vessels, refer to the following sections of the Occupational Health and Safety Regulation:

The following are some standards and codes that support safe cannabis processing:

  • CAN/ULC-S4400: Standard for Safety of Premises, Buildings and Equipment Utilized for the Cultivation, Processing and Production of Cannabis
  • ANSI/CAN/UL/ULC 1389: Plant Oil Extraction Equipment for Installation and Use in Ordinary (Unclassified) Locations and Hazardous (Classified) Locations
  • National Fire Protection Association (NFPA): NFPA 1, Fire Code — Chapter 38: Marijuana Growing, Processing, or Extraction Facilities

Other relevant WorkSafeBC resources include:

Learn more about managing risk in your workplace.

Publication Date: Oct 2022 Asset type: Risk Advisory Reference: RA 2022-03