Oxygen is used in workplaces all over Australia for a wide range of applications including welding and cutting; medical assistance and first aid, food preservation and packaging, water treatment and laboratory tasks. But oxygen is a very reactive gas and may cause or intensify fires when in contact with incompatible substances or heat. This blog identifies the risks of using oxygen cylinders in the workplace and discusses the overall safety precautions for storing and handling O2.
NOTE: Oxygen is classified as a Class 2.2 (5.1) non-flammable, oxidizing gas.
Risks of oxygen cylinders
The air that surrounds us and sustains our life contains about 21% oxygen, and even very small increases to oxygen levels in the air can create an atmosphere where fires start much easier, burn much hotter and are almost impossible to extinguish. This situation is known as oxygen enrichment. Workers are extremely vulnerable in an oxygen enriched atmosphere as their hair and clothes can easily catch fire causing 2nd and 3rd degree burns that are often fatal.
1. Leaking cylinders
Oxygen gas leaks can quickly create an oxygen enriched environment, especially in confined spaces and rooms with poor ventilation. Leaking oxygen can be caused from:
- Damaged hoses, pipes and valves
- Worn fittings and loose connections
- Leaving valves open when not using the cylinder
- Using too much oxygen when welding or flame cutting
- Accidentally opening the valve
Cylinders and equipment should be inspected regularly for leaks and serviced by qualified staff or contractors.
2. Contacting incompatible materials and gases
Materials like oil and grease, as well as certain metals and plastics can react explosively (or catch fire spontaneously) when in contact with pure oxygen under pressure. Many fires and explosions have been caused by O2 contacting:
- O-rings and gaskets containing rubber or petroleum based substances
- Metal components
- Incorrect pressure hoses and regulators
Only use materials and components that have been tested and certified safe for use with oxygen gas.
3. Using oxygen gas incorrectly
Oxygen cylinders have caused fires, explosions and serious injuries when workers have incorrectly substituted oxygen for compressed air or other gases. Some examples include:
- Using oxygen to drive pneumatic tools instead of compressed air
- Inflating vehicle tyres
- Starting diesel engines
- Attempting to increase oxygen levels in a confined space
Remember: AS4332-2004 - The storage and handling of gases in cylinders clearly states that gases must only be used for the purpose for which they were intended.
4. Careless handling of oxygen cylinders
Dropping oxygen cylinders or exposing them to heat can lead to catastrophic fires and explosions. It’s a requirement under AS4332-2004 that workers must fully understand the risks and hazards of using oxygen gas in cylinders and be trained in safe handling and storage methods.
Safety precautions for oxygen cylinders
O2 cylinders must be handled with extreme care and best kept on a purpose-built gas bottle trolley while being used. Safety precautions include the following essentials:
- Keep cylinders upright and restrained at all times: cylinders can easily fall or be knocked over
- Open valves slowly: rapid release can cause frictional heat and cause a fire/explosion
- Keep cylinders valves and connections clean: dust, dirt, sand, oils, and greases are potential fire hazards
- Only use fittings, lubricants and components certified safe for use with O2: incompatible fittings can cause fires and explosions
- When work halts close cylinder valves — don’t nip or kink a hose to arrest the gas flow
- Keep O2 cylinders away from flammables and toxic gases: contacting flammables and incompatible toxic gases can create catastrophic fires, explosions and chemical reactions.
- Wear proper clothing and PPE: clothing containing oil and grease residues can ignite
Storing oxygen gas cylinders
Oxygen cylinders should be stored according to the guidelines of AS 4332-2004 - The storage and handling of gases in cylinders. Some of the essential requirements include:
- Storing cylinders upright with attachments removed and valves closed
- Ensuring O2 cylinders are individually restrained (chains/safety straps) inside a secure Class 5.1 - Oxidising Agent Gas Cylinder Store.
- Locating the gas bottle cage outside, away from heat, ignition sources, combustibles, refuse, and vegetation
- Segregating oxygen from Class 2.1 Flammable Gases and Class 2.3 Toxic Gases by at least 3 metres
- Ensuring cylinder valves are protected at all times
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