Alert: Fire and explosion hazard – opening oxygen cylinder valves
Learn about the suggested precautions when using compressed oxygen cylinders.
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This alert is to raise awareness about the potential for serious injuries if oxygen cylinder valves are opened in an unsafe manner. Opening the valve on a compressed oxygen cylinder or within an oxygen system too quickly can cause an explosion or fire, particularly if any contamination is present in the system (e.g. grease, oil, tape, particulate).
This resource does not replace the Occupational Health and Safety Act (OHSA) and its regulations and should not be used as or considered legal advice. Health and safety inspectors apply and enforce these laws based on the facts they find in the workplace.
On May 20, 2014 a worker was preparing to weld and went outside to turn on the oxygen supply from a 100-lb compressed oxygen cylinder. While the worker was in the process of opening the valve between the cylinder and oxygen system, the oxygen cylinder exploded, resulting in serious burns to the worker.
An oxygen cylinder is a storage vessel that contains compressed oxygen. The oxygen cylinder then forms part of the oxygen system when it is attached to valves, piping, manifolds, torches, oxygen masks, etc. which transport the oxygen for its intended use.
Oxygen behaves differently from air, compressed air, nitrogen and other inert gases. It is very reactive and a very efficient oxidizer. Pure oxygen at high pressure (e.g. in compressed gas cylinders) can react violently with common materials such as oil and grease. Many materials including textiles, rubber and even metals will burn vigorously in oxygen.
This alert applies to all workplaces where compressed oxygen cylinders are used.
Recommended precautions and control measures
Precautions and control measures to protect against fire or explosion hazards from the use of compressed oxygen cylinders/systems may include the following:
- Follow manufacturer recommendations to ensure only suitable materials and safe components are used as part of a compressed oxygen system.
- Employers must only use appropriate types of metals with the compressed oxygen system (e.g. piping), as approved for use by the system designer/manufacturer.
- All material used/introduced into the compressed oxygen system must be cleaned and kept clean to prevent contamination with flammable or non-oxygen compatible substances.
- Only approved lubricants should be used and in the smallest possible amounts.
- The system should be designed to protect operators from hazards by installing shields (panels) in front of valves and other components or by installing remote-controlled valves that can be operated from a safe distance.
- Good design may effectively reduce the risk of fire. Oxygen systems should be designed according to applicable standards.
Administrative and work practices
It is essential to open the valves slowly. Rapid opening of oxygen cylinder valves can result in high oxygen velocities which will generate frictional heat and create a potential ignition source. Alternatively, if the system has a dead end, such as where a pressure regulator is connected to an oxygen cylinder, heat can be generated through compression of the oxygen. Both cases can result in a fire or explosion.
Legal requirements under the Occupational Health and Safety Act
Requirements under the Occupational Health and Act (OHSA) and its regulations that may be applicable include:
Occupational Health and Safety Act – general duties:
- Employers must take every precaution reasonable in the circumstances to protect against fire or explosion hazards from the use of compressed oxygen cylinders/systems.
- Sections 25 to 28 of the OHSA set out the roles and responsibilities of employers, supervisors and workers to protect the health and safety of workers. These requirements apply to all activities in the workplace, including when workers are required to use compressed oxygen cylinders independently or integrated into an oxygen system.
The following sector specific regulations under the OHSA prescribe requirements for the use of compressed gas cylinders, including oxygen.
- Industrial Establishments Regulation (O. Reg. 851) section 49
- Construction Projects Regulation(O. Reg. 231/91) sections 42, 122, 124 and 255
- Mines and Mining Plants Regulation (O. Reg. 854) sections 36 and 194
- Health Care and Residential Facilities Regulation (O. Reg. 67/93) section 74
- Oil and Gas – Offshore Regulation (O. Reg. 855) section 33
- Diving Operations Regulation(O. Reg. 629/94) sections 15(5) and 31
Occupational Health and Safety Act and Regulations
ASTM G88-13 Standard Guide for Designing Oxygen Systems
National Fire Protection Association (NFPA) 51: Design and Installation of Oxygen-Fuel Gas Systems for Welding, Cutting, and Allied Processes
NFPA 50: Standard for Bulk Oxygen Systems at Consumer Sites
Related standards may also be available from the Canadian Standards Association and the International Organization for Standardization.