A refrigerant is a chemical used in cooling systems for mechanical devices such as refrigerators, walk-in freezers, or air conditioners. Most refrigeration units depend on the chemical reactions of refrigerant gas to remove heat from an enclosed area. There are actually numerous gases that have been used as refrigerants. Early refrigerants were highly toxic and dangerous chemicals. The modern gases that replaced them are safer, but many can have a damaging effect on the global environment.
Artificial refrigeration using mechanical and chemical processes was developed in the 19th century. Chemists had long known that some chemical reactions absorb or divert heat, lowering the temperature in a given area. The food and beverage industry of the time needed an alternative to costly and inefficient refrigeration methods involving the transport and storage of ice. Inventors such as American Thaddeus Lowe created complex systems using chemicals to draw heat from enclosed areas, creating a refrigerated compartment. Most of these systems involved some form of refrigerant gas.
A mechanical refrigeration system depends on storing a certain quantity of refrigerant gas or gases. The device creates controlled chemical reactions by forcing the gas to change state or combining it with other chemicals, drawing heat from the refrigerated compartment. Early commercial and home refrigeration units used gases such as ammonia and methyl chloride. These gases are highly toxic and could cause injuries if they escaped containment or required maintenance. For this reason, most early refrigerant gases are no longer in use.
By the 1950s, home refrigeration units were common in most households in developed countries. The manufacturers of these devices replaced toxic refrigerant gases with synthetic refrigerants called chlorofluorocarbons. These were safer to handle and store, but soon scientists discovered they had their own problems. In the 1970s, studies revealed that chlorofluorocarbons used in refrigeration units and other devices contribute to ozone depletion. Ozone depletion, which can increase the damaging health effects of solar radiation, was one of the first environmental crises to be widely understood, and international conventions soon banned chlorofluorocarbons.
Continuing advances in refrigeration technology have produced safe alternative refrigerants and efficient machines that require a fraction of the refrigerant chemicals used by older units. The older refrigerants are still required, however, for older devices that are still in use, such as in cars or industrial freezers. These cannot be converted to modern refrigerants without prohibitive expense. Government bodies such as the United States Environmental Protection Agency have strict regulations on the use and disposal of refrigerants. Individuals requiring the maintenance of refrigeration units should always consult with a qualified technician.