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Refrigerant gases are used in cooling systems, with different types including CFCs, HCFCs, HFCs, PFCs, and ammonia and carbon dioxide blends. Early refrigerators used toxic gases, leading to the discovery of CFCs. However, their use was banned due to environmental concerns. HCFCs and HFCs are now commonly used, but natural refrigerants like ammonia and carbon dioxide blends are gaining popularity. Strict standards for equipment and maintenance have helped mitigate any negative environmental impacts.
Refrigerant gas is a chemical used in refrigerators, freezers, air conditioners, and heating, ventilating, and air conditioning (HVAC) units. These gases, which have very low evaporation points, are condensed under pressure to cool the air. Through a process of repeated evaporation and condensation of gases, heat is extracted from the air and the temperature inside the room or unit is reduced. Different types of refrigerant gases include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and blends of ammonia and carbon dioxide.
Early refrigerators built from the 1800s through the 1920s primarily used toxic gases such as ammonia (NH3), methyl chloride (CH3Cl), and sulfur dioxide (SO2). Unfortunately, the units occasionally leaked and caused several deaths, prompting the refrigeration industry to make a concerted effort to find a safer refrigerant gas. The result was the discovery of chlorofluorocarbon gas (CFC), which was a mixture of chlorine, fluorine and carbons. Freon® has become the trade name for a CFC gas primarily used as a refrigerant. This gas was colorless, odorless, non-flammable, and non-toxic, and soon became the predominant gas used as a refrigerant.
In the 1970s, scientists discovered that when CFCs escaped into the atmosphere, a chemical change occurred as a result of exposure to ultraviolet rays from the sun, resulting in a greenhouse effect and ozone depletion. Since that time, Freon® has been banned in many countries in North America and the European Union. In the United States, the Environmental Protection Agency (EPA) and the Clean Air Act have established strict guidelines for the installation, repair, recovery and recycling of refrigerant gas. The European Union (EU) has also put in place strict controls through EU regulations on F-gases.
Some applications have replaced CFCs with HCFCs, which are a mixture of hydrogen, chlorine, fluorine and carbon. These have a shorter life when exposed to the atmosphere, resulting in less potential damage to the ozone layer. Another popular refrigerant gas is HFC, which contains no chlorine and is believed to have no adverse effect on the ozone layer. PFCs are man-made chemicals composed only of fluorine and carbon ions and are also considered safe for ozone. These substitute gases continue to cause environmental problems if they leak into the atmosphere because they are considered greenhouse gases and can contribute to climate change.
Many industrial applications have reverted to natural refrigerant gases such as ammonia and carbon dioxide blends, and research continues to look for more environmentally friendly ways to meet refrigeration needs. Refrigeration units also have to be built to specific standards and commercial applications are subject to strict controls. Many countries, such as Canada, UK, EU members, Australia, New Zealand, Japan and the USA require technicians working on any unit containing refrigerant gas to be licensed and certified.
Refrigeration has had a significant positive impact on life and society in the fields of nutrition, medicine and physical comfort. The toxic gases of the early days have been replaced by the refrigerant gas which works effectively and poses no danger to health. There are environmental concerns about the use of these compounds, but many believe that strict standards for equipment and maintenance have mitigated any negative environmental impacts.
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