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Refrigerants and Freon

Air conditioner freon and refigerants

Air Conditioner refrigerants, often known as freon, are gases that we need to make our air conditioners, refrigerators and freezers work.

So what are refrigerants, how do they work, how do we know which ones to use and why?

Unfortunately many types of refrigerant are damaging the atmosphere and contributing to climate change.

Some refrigerants (chloroflourocarbons or CFC)are banned while others (hydrochlorofluorocarbons or HCFC) are being phased out.

These are being replaced with hydroflourocarbons (HFC) sold as R-32, R410a and R-134a. These will also be phased out to be replaced by new generations of refrigerants such as Hydro flouro oelfins (HFO).

We look at other refrigerants such as ammonia, propane and butane and discuss the colour coding of refrigerant cylinders and how to tell which your appliances are using.

See also:

How does an air conditioner work?

Refrigerants and Freon

The the best refrigerant to use these days is R-32.

Why? Well first we need to understand about refrigerants, the gases we use to make refrigerators work. These gasses are sometimes known as Freon (in fact freon is a tradename used by DuPont for their refrigerants).

How does a refrigerant work?

Basically it evaporates and condenses easily and at a convenient temperature.

In the "indoor" unit of a split air conditioner the refrigerant is a liquid, it absorbs heat from the room which makes it evaporate into a gas. The gas then runs along a pipe to the condensor/compressor in the "outdoor" unit where it is pumped up to a higher pressure to condense it back into liquid. As it condenses it gives off heat which is blown away by the fan. (Boyle’s Law) The refrigerant is then pumped back to the "indoor" unit and the cycle starts again. The pressure on the liquid is released allowing it to expand, the freon evaporates soaking up heat from the room. The cycle continues ad nauseum.

For a more detailed explanation see: How an air conditioner works

Unfortunately refrigerant is pretty thin stuff and, being under pressure, has a tendency to leak out easily. Bad for the environment and bad for you because you have to get it refilled now and then.

The Montreal Agreement and Worldwide Controls

Many types of gas have been used for refigeration. Many are toxic, flammable, damage the ozone layer or contribute to climate change and so they are strictly controlled through worldwide agreements.

In 1987, a worldwide phaseout in the manufacture of CFCs (Chlorofluorocarbon) was agreed by “developed” nations and in 1995 its manufacture was discontinued because it is destroying the ozone layer.

Since then further agreements have been made to progressively phase out other damaging refrigerants HCFCs (Hydrochlorofluorocarbon) and HFCs (hydroflourocarbons).

Note that many nations are not classified as “developed” including India, China and, of course, Indonesia and so have a less rigid application of the Montreal Agreement.

A Summary of the Present Situation

Refrigerants can be categorised by the type of chemicals in them.

CFCs Are Banned Refrigerants

CFCs are Chlorofluorocarbon gasses. They include refrigerants R-11,R-12 and R-13. R-12 was widely used in refrigerators and as an aerosol propellant. They are very damaging to the earth's ozone layer that protects us from the sun's rays and are now totally banned.

HCFCs replaced CFCs

HCFCs are Hydrochlorofluorocarbon gasses, they include refrigerants R-21, R-22 and R-23. While they are not as destructive as CFCs they contain ozone destroying chlorine. In addition the manufacture of HCFCs results in a by product that contributes significantly to global warming. They were to be fully phased out by 2020.

HFCs (hydroflourocarbons) replaced HCFCs

HFCs are Hydroflourocarbon gasses, they include the present generation of refrigerants R-32, R-410a and R-134a which are widely used in home and car air conditioners, heat pumps, refrigerators, freezers, chillers and dehumidifyers.

Most air conditioners these days have standardised on refrigerants R-32 and R-410A however R-32 is more efficient that R-410a and so has become the preferred refrigerant. R32 does not directly damage the ozone layer but gases that may be released during its manufacture do (see: hydrocarbons - R32 may be affecting the ozone layer).

While they are not as destructive as CFCs and HCFCs, HFCs are a significant threat to climate change and will also be phased out in coming years. R404a has already been phased out while R-134a is being phased out for cars but allowed for chillers.

Permitted Gasses

HCs are Hydrocarbon gasses, they include R-290 (propane) and R-600 (butane) these are not destructive to the ozone layer. These work very well and are said to reduce the amount of power required to compress the gas resulting in savings in electricity and less wear and tear on the air conditioner compressor. They do, however, have one serious drawback, unlike more commonly used air conditioner refrigerants, LPG refrigerants are highly flammable. With this danger in kind it is important that LPG refrigerants are installed by people who know what they are doing.

Ammonia has been used as a refrigerant for decades most notable in gas refrigerators

Other gasses include CO2 and air

New generations of gasses are constantly being developed such as Hydro flouro oelfins (HFO), these have been found to be stable in refrigeration systems while they breakdown quickly in the atmosphere causing less damage.

How To Check The Gas Being Used

It is fairly easy to check what is being used. Check the specification labels on air conditioners or refrigerators which usually state the refrigerant gas they use.

The refrigerant that your technician will bring should be in a steel canister about 33cms high and 24cms in diameter. These are painted a colour according to the type of refrigerant and on the side of the canister will be a printed the letters such as R-12(white), R-22(light green), R-134a (light blue), R-32(blue) or R-410a(rose pink).

The Most Commonly Used Refigerant Gasses

Code Chemical Type Status Comments
R-744 CO2 CO2 Ok for use Was widely used before the development of CFCs. No harm to the ozone layer, non toxic, non flammable. May become widely used again.
R-717 Ammonia Ok for use Widely used for refigeration (notably in gas refrigerators) before modern refrigerants were developed. Does not damage the ozone layer and does not contribute to climate change. Little used due to toxicity and corrosion to refigerator components.
R-12 Dichlorodifluoromethane CFC Totally Banned Known as freon. Created in 1928 by Thomas Midgley Jr. the first non-flammable, non-toxic chlorofluorocarbon gas. Seriously damages the ozone layer and contributes to climate change.
R-22 Chlorodifluoromethane HCFC Being phased out Not as bad as CFCs but still damages the ozone layer and contributes to climate change.
R-32 Difluoromethane HFC Widely used but will be phased out A widely used replacement for R-22, Not as bad as HCFCs but still damages the ozone layer and contributes to climate change.
R-152a Difluoroethane HFC widely used 210% (3 floors)
R-410a Difluoromethane + Pentafluoroethane HFC Widely used but will be phased out A widely used replacement for R-22, Not as bad as HCFCs but still damages the ozone layer and contributes to climate change.
R-134a Tetrafluoroethane HFC Widely used but will be phased out A widely used replacement for R-22, Not as bad as HCFCs but still damages the ozone layer and contributes to climate change.
R-290 Propane HC Increasing use A hydrocarbon (HC). It is low cost, widely available and efficient but it is flammable. Does not damage the ozone layer or contribute to climate change. Usage is expected to increase.
R-600a Isobutane HC Increasing use A hydrocarbon (HC). It is low cost and widely available and efficient but it is flammable. Does not damage the ozone layer or contribute to climate change. Usage is expected to increase.

Check the Refrigerant Being Used

So take a look at the canister your air conditioner technician is using and note the colour and refrigerant number on the side. If you ask your technician he may tell you that a canister with R12 on the side actually contains R-134a –, it probably won’t since the canisters are not supposed to be refilled.

Take Care What Gas Is Being Used

R-12 may still be being used in older car air conditioning systems and refrigerators. If you buy a new air conditioner, refrigerator or a car it will use a modern refigerant such as R-32, R-410a or R-134a.

Unfortunately gassing an air conditioner can be expensive because modern refrigerants are expensive, and perhaps a lot more expensive than using older gasses. As a result we have to be careful that technicians are not regassing with R-12 to save a bit of money.

Refrigerants Are Not Interchangable

Any particular appliance is designed to use a specific refrigerant, you cannot simply replace the gas with a substitute.

There are exceptions, some propane based refrigerants (such as Petamina's Musicool product) can be used in R-32 equipment.

If the wrong refrigerant has been used some work may be needed to replace it with the correct gas. It may be necessary to change the operating oil in the compressor, probably the seals and fittings and perhaps the compressor itself may have to be changed.

Recycling Refrigerants

Something you may not know is that machines are available that salvage and recycle refrigerants. If an air conditioner is being moved the refrigerant can be sucked out of the system and saved to be used again later.

Unfortunately it may well be that your air conditioner technician or car mechanic does not use such a machine and might never have heard of one. would not know where to find one and certainly wouldn’t bother to use one if he could. When working on cooling equipment the gas is usually released into the atmosphere. The customer pays the bill for regassing and the bengkel makes more money.

See also:

Copyright © Phil Wilson
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