Editing Refrigerant (section)

{{short description|Substance in a refrigeration cycle}}
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[[File:Can of DuPont R-134a refrigerant.jpg|thumb|A [[DuPont]] [[R-134a]] refrigerant]]
A '''refrigerant''' is a [[working fluid]] used in the cooling, heating, or reverse cooling/heating [[Heat pump and refrigeration cycle|cycles]] of [[air conditioning]] systems and [[Heat pump|heat pumps]], where they undergo a repeated [[phase transition]] from a [[liquid]] to a [[gas]] and back again. Refrigerants are heavily regulated because of their [[toxicity]] and [[flammability]],<ref>{{cite web |last1=United Nations Environment Programme (UNEP) |title=Update on New Refrigerants Designations and Safety Classifications |url=https://www.ashrae.org/file%20library/technical%20resources/bookstore/factsheet_ashrae_english_november2022.pdf |access-date=6 October 2024 |publisher=ASHRAE}}</ref> as well as the contribution of CFC and HCFC refrigerants to [[ozone depletion]]<ref>{{cite web |date=22 July 2015 |title=Phaseout of Class II Ozone-Depleting Substances |url=https://www.epa.gov/ods-phaseout/phaseout-class-ii-ozone-depleting-substances |access-date=October 6, 2024 |publisher=US Environmental Protection Agency}}</ref> and the contribution of HFC refrigerants to [[climate change]].<ref>{{cite web |date=8 February 2021 |title=Protecting Our Climate by Reducing Use of HFCs |url=https://www.epa.gov/climate-hfcs-reduction |access-date=6 October 2024 |publisher=United States Environmental Protection Agency}}</ref>

Refrigerants are used in a direct expansion (DX) circulating system to transfer energy from one environment to another, typically from inside a building to outside or vice versa. These can be air conditioner cooling only systems, cooling & heating reverse DX systems, or heat pump and heating only DX cycles.

Refrigerants are controlled substances that are classified by several international safety regulations and, depending on their classification, may only be handled by qualified engineers due to extreme [[pressure]], [[temperature]], [[Combustibility and flammability|flammability]], and [[toxicity]].