This blog looks at Class 2.2 Non-Flammable, Non-Toxic Gases: why they are dangerous and how to store them in a safe and compliant manner. Sometimes inert gases are overlooked as ‘harmless’ instead of being treated with extreme care — like other Dangerous Goods. In Australia the management of Dangerous Goods (including Class 2.2 Non-Flammable, Non-Toxic Gases) is informed by a number of different Regulations and Standards. This blog focuses on storage essentials and identifies the key documents required for compliance.
Non-flammable, Non-toxic Gases Defined
Class 2.2 Non-Flammable, Non-Toxic Gases are classified by the Australian Dangerous Goods Code (also known as the ADG Code). The ADG Code follows the guidelines of the Globally Harmonised System of Classification and Labeling of Chemicals (GHS) (adopted and released by the United Nations). The official definition of Class 2.2 Non-flammable, non-toxic gases is:-
Gases which are asphyxiants (gases which dilute or replace the oxygen in the atmosphere); or are oxidizing (gases which may, generally by providing oxygen, cause or contribute to the combustion of other material more than air does).
Australian Dangerous Goods Code of Practice (ADG)
Examples of non-flammable, non-toxic gases regularly used in workplaces include: compressed air, nitrogen, argon, carbon dioxide, and helium. It is important to remember that non-flammable, non-toxic gases have been responsible for many serious workplace incidents as well as fatalities.
Risks and Hazards of Non-flammable, Non-toxic Gases
Numerous risks and hazards surround Class 2.2 non-flammable, non-toxic gases. These include the following:-
The air we breathe contains approximately 21.1% oxygen and environments with an oxygen content below 19.5% are considered unsafe. Any gases (including Class 2.2 non-flammable, non-toxic gases) that leak into a confined space, can displace the oxygen in the air creating an asphyxiation hazard.
Cylinder stores should be well ventilated and located outside. Regular inspections should be conducted on gas cylinders and their valves, checking for leaks, worn threading and other structural damage.
2. Damage to cylinders
Dropped or impacted cylinders can rapidly disperse gas, rupture or even explode. When gas cylinders rapidly disperse gases, they can generate enough speed and force to fly through the air like torpedos — many workers have been killed or seriously injured from out-of-control gas cylinders.
Use mechanical lifting devices to move or handle cylinders and keep them restrained with safety straps or chains when in storage.
3. Exposure to dangerous events
Gas cylinders containing non-flammable, non-toxic gases are also capable of rupturing and exploding when exposed to dangerous events. Heat from fires, industrial machinery, and even direct sunlight can cause cylinders to rupture violently from pressure build-up. Cylinder explosions often result in deaths, environmental and property damage.
Gas cylinders must be stored correctly away from sources of heat, incompatible substances, hazardous chemicals, and combustibles.
4. Contact with incompatible substances
Many Class 2.2 non-flammable, non-toxic gases (though relatively harmless themselves) can react dangerously with other substances. Oxidising gases can be especially dangerous when in contact with heat, flames, or flammable substances as they can:
- Start fires quickly, making them burn hotter and more intense
- Make slow burning combustibles ignite and burn faster
- React with combustible materials and create fires without ignition sources
Carry out thorough risk assessments of gas compatibility by reviewing the Safety Data Sheet (SDS) of gases plus other hazardous chemicals used and stored in the workplace.
Storing Non-flammable, Non-toxic Gases
Class 2.2 non-flammable, non-toxic gases are Dangerous Goods and must be stored safely in a way that is 100% compliant with AS4332-2004 - The storage and handling of gases in cylinders. There are three key elements to storing non-flammable, non-toxic gases:
Compressed gases in cylinders should be stored outdoors wherever possible. Because Class 2.2 gases present asphyxiation risks, outdoor storage is ideal because the natural ventilation often disperses leaked gases safely.
The standard requires that cylinder stores are level and located at least 3 metres away from any source of industrial heat as well as combustible materials, vegetation and refuse.
Cylinder stores must have ventilation that provides enough fresh air from the outside to reduce any risk of asphyxiation. Utilising the natural movement of air is ideal, but if this does not achieve safe oxygen levels than a mechanical ventilation system must be installed. A mechanical ventilation system may include exhaust fans, ducting, alarms and monitoring controls. Section AS4332-2004 (Section 4.3) outlines the ventilation requirements of a cylinder store in detail.
3. Cylinder Restraints
All gases in cylinders must be stored upright, preferably in a secure gas bottle cage. Each cylinder must be individually restrained using safety straps or chains. Cylinder valves must be closed, attachments removed, and safety caps/plugs in place.
To learn more about managing the risks and hazards associated with compressed gases stored in cylinders, download our free eBook Gas Cylinder Storage: compliance and safety requirements. Our eBook unpacks the requirements of AS4332-2004 - The storage and handling of gases in cylinders and provides practical advice for getting your workplace 100% safety compliant. Download it today by clicking on the image below: