Refrigerant Gas Explained: Types, Uses and Common Safety Questions

Refrigerant gas is the working fluid that makes refrigeration and air conditioning possible, yet it sits out of sight inside sealed equipment and is widely misunderstood. For Australian businesses that run cold rooms, chillers, transport refrigeration or process cooling, knowing the main refrigerant types, how they are classified and what the rules require is now a commercial issue as much as a technical one, because the gases on the market are changing under a national phase-down. This guide explains what a refrigerant gas is, the categories in use, how they are named and regulated in Australia, and the safety questions that come up most often.

What is a refrigerant gas?

A refrigerant is a substance that absorbs heat from one place and releases it in another by repeatedly changing state between liquid and gas. In a typical system a compressor raises the pressure of the refrigerant vapour, a condenser rejects heat as the vapour turns back to liquid, an expansion device drops the pressure, and an evaporator absorbs heat from the space or product being cooled as the liquid boils back to vapour. The cycle then repeats.

The refrigerant never leaves that sealed loop in normal operation. It is not consumed like a fuel; it circulates. What matters is choosing a fluid with the right boiling point, pressure behaviour, efficiency and safety profile for the application, which is why so many different refrigerants exist.

The main types of refrigerant gas

Refrigerants are usually grouped by their chemistry, and each generation has been driven by environmental concerns about the one before it.

Chlorofluorocarbons (CFCs), such as R12, were the first widely used refrigerants. They damage the ozone layer and have been phased out under the international Montreal Protocol.
Hydrochlorofluorocarbons (HCFCs), such as R22, were the transitional replacement. They cause less ozone damage than CFCs but are still controlled, and bulk R22 has been phased out in Australia.
Hydrofluorocarbons (HFCs), such as R134a, R410A and R32, do not damage the ozone layer and became the mainstream choice for air conditioning and refrigeration. Their drawback is a high global warming potential, which is why they are now being phased down rather than out.
Hydrofluoroolefins (HFOs), such as R1234yf, are a newer class with very low global warming potential. They are used in newer car air conditioning and in blends designed to replace high-impact HFCs.
Natural refrigerants are naturally occurring substances with very low environmental impact. The main ones are carbon dioxide (R744), ammonia (R717) and hydrocarbons such as propane (R290) and isobutane (R600a). Carbon dioxide is increasingly used in supermarket and cold-storage systems, ammonia in large industrial plants, and hydrocarbons in smaller self-contained units.

Where refrigerant gases are used

The same basic cycle, with different refrigerants and equipment, runs cooling across the economy.

Air conditioning, from household split systems to large building chillers, mostly uses HFCs such as R32 and R410A, with HFOs and HFO blends appearing in newer equipment.
Commercial refrigeration, including supermarket display cases, cold rooms and cool stores, is increasingly built around carbon dioxide and HFC or HFO blends.
Transport refrigeration on trucks, trailers and shipping containers keeps chilled and frozen freight in condition over long Australian distances.
Industrial and process cooling in food and beverage production, manufacturing and cold storage often uses ammonia or carbon dioxide in larger plants.
Heat pumps for hot water and space heating run the refrigeration cycle in reverse to move heat into a space or tank rather than out of one.

Across all of these the direction of travel is the same: toward refrigerants with a lower global warming potential, whether that is a low-impact synthetic gas or a natural refrigerant.

How refrigerants are named and classified

The R-number on a cylinder or nameplate, such as R134a or R410A, is a standard code that identifies the refrigerant. The numbering follows the chemistry of the molecule, and blends are given codes in the 400 and 500 series. Carbon dioxide is R744 and ammonia is R717 under the same system.

Refrigerants also carry a safety classification, used in Australian standards including AS/NZS 1677 and the AS/NZS 5149 series, that combines a toxicity and a flammability rating. A letter indicates toxicity: A is lower toxicity, B is higher. A number indicates flammability: 1 means no flame propagation, 2L means lower (mild) flammability, 2 means flammable and 3 means higher flammability. So R134a and R410A are A1 (low toxicity, non-flammable), R32 and R1234yf are A2L (mildly flammable), propane (R290) is A3 (highly flammable), and ammonia is B2L (higher toxicity, mildly flammable). The industry is gradually shifting from high-warming A1 gases toward lower-impact A2L and natural options, which is why mild flammability is becoming more common and why charge limits and ventilation matter more than they once did.

Two environmental measures are used alongside the safety class. Ozone depletion potential measures how much a gas harms the ozone layer; modern refrigerants are designed to be zero. Global warming potential measures how strongly a given mass of the gas traps heat compared with carbon dioxide over a set period, so a refrigerant with a global warming potential of 2,000 has, kilogram for kilogram, two thousand times the warming effect of carbon dioxide. These two numbers are what the regulations and the shift to newer refrigerants are built around.

Australian refrigerant regulations

Synthetic refrigerants are regulated nationally under the Ozone Protection and Synthetic Greenhouse Gas Management framework, administered by the Department of Climate Change, Energy, the Environment and Water.

The key change shaping the market is the HFC phase-down, which began in 2018. It works by capping and steadily reducing the quantity of bulk HFCs that can be imported each year, stepping down to 15 per cent of the baseline by 2036. This follows the Kigali Amendment to the Montreal Protocol. The phase-down reduces supply of high-warming gases over time rather than banning them outright, which gradually pushes equipment toward lower-impact refrigerants.

Anyone who installs, services or decommissions equipment containing fluorocarbon refrigerant needs a Refrigerant Handling Licence issued by the Australian Refrigeration Council, and a business buying or selling those refrigerants needs a Refrigerant Trading Authorisation. One point that surprises many operators: the mandatory national licence covers fluorocarbon gases (CFCs, HCFCs and HFCs). Natural refrigerants such as carbon dioxide, ammonia and hydrocarbons sit outside that particular licensing scheme, though state work health and safety rules and the relevant Australian Standards still apply to how they are handled and stored. Fluorocarbon refrigerants must never be vented to atmosphere; they have to be recovered for reclaim or destruction.

What the phase-down means for Australian businesses

For a business that owns refrigeration or air conditioning, the phase-down has practical effects worth planning for. As the supply of high-warming HFCs tightens, the price of those gases tends to rise and availability can become less certain, which makes topping up an older, leaky system progressively more expensive over its life. Equipment using gases such as R404A, which has a very high global warming potential, is most exposed.

None of this forces an immediate change. Existing systems can keep running and being serviced, and refrigerant remains available. The sensible response is to factor refrigerant type into decisions you are already making: when replacing plant, favour equipment designed for a lower-impact refrigerant; keep systems well maintained so they leak less and use less gas; and make sure whoever services your equipment holds the right licence and recovers refrigerant properly. Choosing well-maintained, lower-impact systems also tends to improve energy efficiency, which lowers running costs alongside the environmental benefit.

Common refrigerant safety questions

Are refrigerant gases toxic?

Most modern refrigerants are class A, meaning lower toxicity, and are safe in normal use inside sealed equipment. Ammonia is the main exception; it is classed as higher toxicity, though its sharp smell gives early warning of a leak. The bigger everyday risk with most refrigerants is not poisoning but oxygen displacement in a confined space.

Are refrigerants flammable?

It depends on the class. Older HFCs such as R134a and R410A and the natural refrigerant carbon dioxide are non-flammable. Newer low-warming gases such as R32 and R1234yf are mildly flammable (A2L), and hydrocarbons such as propane and isobutane are highly flammable (A3). Mildly and highly flammable refrigerants require ventilation, charge limits and the removal of ignition sources during service.

Can a refrigerant leak cause asphyxiation?

Yes. Even non-toxic, non-flammable refrigerants, along with carbon dioxide and nitrogen, can displace oxygen if they leak into a poorly ventilated plant room or cold room. This is the single most important shared hazard across all refrigerant and industrial gases, and it is why gas detection and ventilation are built into plant room design.

Why are refrigerants stored under pressure?

A refrigerant has to be easy to liquefy and circulate, so it is held under pressure in equipment and cylinders. Carbon dioxide systems in particular run at very high pressures. Cylinders must be secured, stored correctly and protected against trapped liquid, and pressure relief is required where liquid could otherwise be locked between closed valves.

What happens to old refrigerant?

Fluorocarbon refrigerant recovered during service or decommissioning cannot be released to the air. It is collected by a licensed technician and sent for reclaim or safe destruction through the national recovery scheme, which keeps high-warming gases out of the atmosphere.

Which refrigerants have the lowest environmental impact?

Natural refrigerants generally have the lowest impact. Carbon dioxide has a global warming potential of one, used as the reference point for all others, and ammonia and hydrocarbons are also very low. Among synthetics, HFOs have a much lower warming potential than the HFCs they replace. The trade-off is that several low-impact options are mildly or highly flammable, or run at high pressure, so they call for the right system design and handling rather than being a drop-in swap.

Refrigerant gas versus the industrial gases that support refrigeration

It helps to separate two things that often get mixed up. A refrigerant gas, the R-number fluid, lives inside the cooling circuit and, for fluorocarbons, can only be handled by a licensed technician. That is a different category from the industrial gases used to build, charge and service refrigeration systems.

Two industrial gases sit right alongside the refrigeration trade. Carbon dioxide is both a genuine natural refrigerant (R744) and a widely supplied industrial gas, used in modern refrigeration as well as in freezing, carbonation and food packaging. Nitrogen is not a refrigerant in air conditioning, but it is the trade’s everyday service gas: it is used to purge moisture and air from pipework before a system is charged, and to pressure-test and leak-test new refrigeration lines. Knowing which gas does which job avoids a common mix-up between the sealed refrigerant and the support gases around it.

Carbon dioxide and nitrogen supply from Pacific Gas

Pacific Gas is an industrial gas supplier, not a refrigerant wholesaler, so it does not sell fluorocarbon R-number gases or design and install systems. What it does supply are the gases that sit around refrigeration work: food-grade and industrial carbon dioxide, the natural refrigerant and process gas behind cooling, freezing and carbonation, and nitrogen for purging and pressure-testing refrigeration pipework. Both come in cylinders through a network of local distributors across Australia, on rental or customer-owned terms and swapped empty-for-full like a BBQ gas bottle. For the engineering detail on carbon dioxide cooling, see our guide to CO2 refrigeration systems. To set up supply, find a local distributor or contact Pacific Gas.