Refrigerant

Gas is used for the cooling system is a REFRIGERANT
Refrigerant is a fluid that is used to cool the low temperature environment and heat to a high temperature environment. One of the most famous current refrigerant is CFC aka FREON (R-11, R-12, R-21, R-22 and R-502)
CFC (Chloro-Fluoro-Carbon) alias R22 plays an important role in the refrigeration system, since it was discovered in 1930 This is because CFCs have physical properties and good thermal as a refrigerant, stable, non-flammable, non-toxic and compatible to most material components in the refrigeration system.
But after the public know that the hypothesis of Ozone Depleting Substances including CFCs (ODS), a substance that can cause damage to the ozone, people began to try to discontinuation ODS and poured into several conventions, such as the Vienna Convention in March 1985, the Montreal Protocol in September 1987 and several other amendments.
R134a as an alternative has some good properties, non-toxic, non-flammable and relatively stable.

R-134a also has a weakness in them, can not serve as a replacement for R-12 directly without modifying the refrigeration system (drop in subtitute), relatively expensive, and still has potential as a substance that can cause global warming because it has a Global Warming Potential (GWP) were significant.
In addition, R-134a is very dependent on synthetic lubricant which often leads to problems with the hygroscopic nature.
Another alternative offered is a hydrocarbon refrigerant. Actually hydrocarbons as refrigerants have been known to the public since early 1920 refrigeration technology with natural working fluids such as ammonia, and carbon dioxide. Hydrocarbons are often used as a refrigerant is propane (R-290), isobutane (R-600A), n-butane (R-600). The mixture is often used in between the R-290 / 600A, R-290/600 and R-290 / R-600 / R-600A.
Hydrocarbons have several advantages such as environmentally friendly, as indicated by the value of Ozone Depleting Potential (ODP) of zero, and negligible GWP, termofisika properties and good heat transfer characteristics, low density vapor phase, and good solubility with mineral lubricants.
The use of hydrocarbons with the issue of energy efficient and environmentally friendly is still not widely accepted as the use of freon as a refrigerant.
This is due to public concern over the nature of hydrocarbons that can burn. This trait is actually not harmful if used according to the correct procedure. To understand the correct procedure to work with, inevitably requires knowledge of the characteristics of hydrocarbons.