R-12 and R-134a, General information

R-12 or Freon(R), was used in BMW air conditioning Systems prior to 1992. It is a member of the class of compounds called "chlorofluorocarbons" (CFC's).

Characteristics:

- Very durable.
- Transports heat very efficiently.
- Non-explosive when mixed with air.
- odorless; not harmful to human health when handled correctly.
- Boils at -22 °F (-30 °C).
- Absorbs a large amount of heat when boiling.
- Does not react with most metals (except lead).
- Reacts with many synthetics.
- Reacts with water to produce acid.
- Mixes readily with mineral-based oil.

Skin should not be exposed to liquid R-12. Since R-12 boils at -22 °F (-30 °C), it can cause severe frostbite or freezing damage.

R-12 should never be exposed to an open flame. when it burns in air, it produces phosgene, a poisonous gas.

A serious environmental problem has been created by discharging R-12 refrigerant into the atmosphere. CFC's cause very long-term damage to the stratospheric ozone layer

One CFC Molecule Destroys Many Ozone Molecules:

One molecule of R-12 can destroy many molecules of ozone. In the upper atmosphere, ultraviolet light breaks off a chlorine atom from an R-12 molecule.

The chlorine attacks an ozone molecule, breaking it apart. An ordinary oxygen molecule and a molecule of chlorine monoxide are formed.

A free oxygen atom breaks up the chlorine monoxide. The chlorine is then free to repeat the process.

Damage to Stratospheric Ozone Allows UV-B Penetration:

The ozone in the stratosphere blocks most of the ultraviolet-B radiation from the sun, thus preventing it from damaging plants and animals. Without the protection of stratospheric ozone, plants and animals are exposed to damaging levels of UV-B.

For this reason, a new refrigerant, R-134a, has been developed. It does not contain chlorine (it's a "hydrofluoro-carbon," or "HFC"). It causes much less damage to stratospheric ozone.

Environmental Compatibility of R-12 and R-134a:

Despite the much lower risk of environmental damage, it's still important to handle R-134a responsibly. BMW technicians should do their part to maintain a safe environment for future generations.

Characteristics of R-134a:

- Very durable.
- Transports heat very efficiently (although slightly less efficiently than R-12).
- Density; pressure, boiling point similar to R-12.
- Extremely hygroscopic (absorbs water very readily).
- Non-toxic, non-flammable; slight ether-like smell.
- Contains no chlorine atoms; will not damage stratospheric ozone.
- R-134a pressures tend to rise sooner and higher as temperature increases.







IDENTIFICATION OF R-12 AND R-134a CONTAINERS







Although R-12 and R-134a are similar in some ways, the refrigerants must never be mixed or combined in any way.