What are flammable gases
Flammable refrigerant gases are those refrigerant gases classified as Division 2.1 flammable gases under the Australian Dangerous Goods Code or classified as Flammable Gas Category 1 using the Globally Harmonized System (GHS).
Flammable gases can easily ignite and be potentially explosive. Workplace incidents involving flammable refrigerant gas have caused death, serious injury and property damage.
Small gas leaks can cause catastrophic events. Leaking compressed gases can quickly fill a room or confined space, with the accumulated gas remaining within its explosive range.
Flammable gases that are denser than air are dangerous because they can travel considerable distances to ignition sources.
Cylinders dropped, struck, impacted or ignited can cause gases to disperse or rupture and explode. Treat cylinders carefully and do not roll along the ground, drop or throw them when loading.
Combustion products of some refrigerants and mixtures are toxic. For example, halogenated refrigerants can release two dangerous chemicals hydrogen fluoride or carbonyl dichloride (phosgene) in a fire.
Some refrigerants are a blend of gases called zeotropic mixtures. When there is a leak, the composition of these refrigerants can change because they have different boiling points and can create unpredictable hazard properties.
How to manage the risks
Mark and label systems
Mark and label service access points, refrigeration systems and machinery room entries containing flammable refrigerants. Mark and label with warning signs stating that these systems contain class 2.1 flammable refrigerants.
Clearly mark flammable refrigerants in gas cylinders with one of the class 2.1 flammable gas labels.
Manage equipment location
Managing the location of equipment containing flammable refrigerants can help reduce the risks associated with flammable refrigerants. This can be done by:
- locating refrigeration and air conditioning equipment in a well-ventilated area outdoors and above ground;
- using additional risk controls to prevent the dangerous accumulation of leaked refrigerant in any space when its unavoidable to locate refrigeration and air conditioning equipment outdoors; and
- limiting the quantity of refrigerant in a refrigeration or air conditioning system confined, or ducted into, a building. If this limited quantity of the refrigerant leaked into the space, it would not create a concentration in air above 20% of lower flammable limit (LFL).
Use compatible refrigerant gases
Refrigerant gases must be compatible with the refrigerant system. A person with training and experience in refrigerant gases should decide if refrigerant gases are compatible. For example, when deciding if flammable refrigerants can replace non-flammable refrigerants.
A qualified or registered engineer can also complete an assessment to decide if a system can be converted to use a flammable refrigerant.
Use refrigerant odourants
Refrigerant odourants, such as mercaptan, can provide a warning of refrigerant leaks by emitting an unpleasant smell when released.
Risk control measures to reduce fire and explosions
Limit the quantity of flammable refrigerant injected into refrigeration or air-conditioning systems within a confined area, ducted into a building or an enclosed space. Ensure a concentration of RFG does not reach above 20 of its lower flammable limit (LFL). Use the flammable refrigerant charge table below to decide when to put these additional risk controls in place:
* Charge room limit g/m3 of net room volume (based on LFL)
^ Maximum allowable charge per system in the enclosed space (kg)
# Can the charge limit in either column be exceeded if risk control measures are used
Additional risk control measures could include using detectors such as:
Gas detectors in air conditioning spaces
Use gas detectors inside the space being air-conditioned. These gas detectors should be alarmed and interlocked to ensure a failsafe isolation shutdown of the air-conditioning system if there is a flammable gas leak.
Floor level flammable gas detectors
Use floor-level flammable gas detectors when refrigeration equipment is within a building. These gas detectors should be interlocked with a floor-level mechanical extraction system and have an alarm that activates when there is a gas leak.
The detection and extraction system should be at floor level because most flammable refrigerants are heavier than air. Operate the mechanical extraction system continuously if there are no gas detectors installed. Other risk control measures could include:
- eliminating ignition sources where possible
- having emergency procedures for a gas leak
- keeping equipment maintenance and repair records, including date, contractor's details and other relevant information, use of ultrasonic leak detectors to detect the ultrasonic sound of a leak
- refrigeration engineers, technicians, service persons and emergency responders must be aware of the hazards associated with flammable refrigerants, including the need to use appropriate gas detection equipment. If uncertain about how the system is charged, proceed with extreme caution and identify the refrigerant, by testing if necessary, before engaging with the system.
Occupiers of premises must identify all hazards and use appropriate risk controls to comply with the Dangerous Goods Act 1985 and the Dangerous Goods (Storage and Handling) Regulations 2012 (Regulations).
Under the Regulations, occupiers must obtain material safety data sheets (MSDS) or safety data sheets (SDS) from the supplier of the refrigerant. Occupiers of premises should ensure personnel adhere to the safety requirements set out in the MSDS/SDS.
Other duty holders include:
- Importers and manufacturers of flammable refrigerant gases
- Designers of refrigeration systems
- Manufacturers, importers and suppliers of refrigeration equipment used in workplaces
- Refrigeration technicians, engineers and businesses that install or maintain workplace refrigeration systems
- Installers of complex refrigeration systems may hold relevant tertiary qualifications
- Businesses employing refrigeration technicians
- Flammable refrigerant gases are used in refrigeration or air-conditioning systems
- The recovery, reclamation or disposal of refrigerant gases
AS ISO 817:2016 Refrigerants - Designation and safety classification
AS 5149.1:2016 Refrigerating systems and heat pumps - Safety and environmental requirements
AS 60079.10.1:2009 Explosive atmospheres - Classification of Areas - Explosive gas atmospheres
AS 60079.14:2009 Explosive atmospheres - Electrical installations design, selection and erection
Safe Work Australia - Classifying chemicalsExternal link
Safe Work Australia - Preparation of safety data sheets for hazardous chemicalsExternal link
Standards Australia - Refrigerants - Designation and safety classificationExternal link
DITCRD - Australian Dangerous Goods Code Edition 7.5External link
Ozone Protection and Synthetic Greenhouse Gas Management Regulations 1995External link