Freons

Refrigerant gases were created to preserve food. The first to be used were carbon dioxide (CO2), sulphur dioxide (SO2), chloroethane (C2H5Cl), chloromethane (CH3Cl), ammonia (NH3) and certain hydrocarbons. 

There are many other refrigerants fluids classified according to their properties:  

CFCs: Chlorofluorocarbons are halogenated fluorinated gases composed of carbon (CO), chlorine (Cl) and fluoride atoms (F).

HCFCs: Hydrochlorofluorocarbons are hydrogenated CFC gases that act as greenhouse gases to reduce the ozone layer. This is why it is forbidden to produce and use them. 

HFCs: Hydrofluorocarbons are third-generation refrigerants that have replaced freons, which are banned from the market. More efficient, they are less harmful and have a better impact on the environment.

HFOs: Hydrofluoroolefins are the fourth generation of gases. They pollute very little, making them ideal for use in air conditioning and commercial refrigeration. 

Among the natural gases with refrigerant properties, the most commonly used is ammonia. It is the refrigerant gas of choice in industrial refrigeration systems, large pump systems, the food industry and high-power industrial coolers.

• Asphyxiation: most freons are asphyxiating gases, even CO2 natural gas. Their density puts weight on the atmosphere and depletes the air of oxygen.
• Toxicity: refrigerants (such as ammonia) can cause cold burns, irritation, anaesthesia, heart problems, etc. when exposed for long periods of time.
• Explosives: some refrigerant gases (such as propane - R290 or ethylene) are flammable and explosive when they come into contact with a combustion source.