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<h2 id="history">History</h2> <p>The first air conditioners and <a href="/facts/Refrigerator/TGb5ozLY">refrigerators</a> employed toxic or flammable gases, such as <a href="/facts/Ammonia/MtLtJFtz">ammonia</a>, <a href="/facts/Sulfur_dioxide/jDK1fIDs">sulfur dioxide</a>, <a href="/facts/Methyl_chloride/DvmeEgDS">methyl chloride</a>, or <a href="/facts/Propane/E0b23KGh">propane</a>, that could result in fatal accidents when they leaked.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p><p>In 1928 <a href="/facts/Thomas_Midgley_Jr./ga3B55Ax">Thomas Midgley Jr.</a> created the first non-flammable, non-toxic <a href="/facts/Chlorofluorocarbon/uLApxm7K">chlorofluorocarbon</a> gas, <i><a href="/facts/Freon/JkfAjIb9">Freon</a></i> (R-12). The name is a <a href="/facts/Trademark/B23H8IS0">trademark</a> name owned by <a href="/facts/DuPont/kCUfkJzE">DuPont</a> (now <a href="/facts/Chemours/shaTInJF">Chemours</a>) for any <a href="/facts/Chlorofluorocarbon/uLApxm7K">chlorofluorocarbon</a> (CFC), <a href="/facts/HCFC/uLApxm7K">hydrochlorofluorocarbon</a> (HCFC), or <a href="/facts/Hydrofluorocarbon/mUNTbYch">hydrofluorocarbon</a> (HFC) refrigerant. Following the discovery of better synthesis methods, CFCs such as <a href="/facts/Trichlorofluoromethane/bx7YxsjC">R-11</a>,<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> <a href="/facts/Dichlorodifluoromethane/KdMmfral">R-12</a>,<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> R-123<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> and R-502<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> dominated the market. </p> <h3>Phasing out of CFCs</h3> <p class="note">See also: <a href="/facts/Montreal_Protocol/Hmf70BQK">Montreal Protocol</a></p> <p>In the mid-1970s, scientists discovered that CFCs were causing major damage to the <a href="/facts/Ozone_layer/v4KfjalC">ozone layer</a> that protects the earth from ultraviolet radiation, and to the <a href="/facts/Ozone_hole/ssGWpcx3">ozone holes</a> over polar regions.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a><a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> This led to the signing of the <a href="/facts/Montreal_Protocol/Hmf70BQK">Montreal Protocol</a> in 1987 which aimed to phase out CFCs and HCFC<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> but did not address the contributions that HFCs made to climate change. The adoption of HCFCs such as <a href="/facts/Chlorodifluoromethane/D1pGLBP0">R-22</a>,<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a><a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a><a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> and R-123<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> was accelerated and so were used in most U.S. homes in air conditioners and in <a href="/facts/Chiller/DpdaocSf">chillers</a><a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> from the 1980s as they have a dramatically lower <a href="/facts/Ozone_depletion_potential/CngkPwdu">Ozone Depletion Potential</a> (ODP) than CFCs, but their ODP was still not zero which led to their eventual phase-out. </p><p><a href="/facts/Hydrofluorocarbon/mUNTbYch">Hydrofluorocarbons</a> (HFCs) such as <a href="/facts/R-134a/hy99tyHU">R-134a</a>,<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a><a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> <a href="/facts/R-407A/SP4El8IL">R-407A</a>,<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> <a href="/facts/R-407C/yT5DmTE9">R-407C</a>,<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a> <a href="/facts/R-404A/U1x2WD9Q">R-404A</a>,<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> <a href="/facts/R-410A/eg3z47m6">R-410A</a><a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a> (a 50/50 blend of <a href="/facts/R-125/bdmy557C">R-125</a>/<a href="/facts/Difluoromethane/XQ4tkYVJ">R-32</a>) and R-507<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a><a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a> were promoted as replacements for CFCs and HCFCs in the 1990s and 2000s. HFCs were not ozone-depleting but did have <a href="/facts/Global_warming_potential/tgTbpwbJ">global warming potentials</a> (GWPs) thousands of times greater than CO2 with atmospheric lifetimes that can extend for decades. This in turn, starting from the 2010s, led to the adoption in new equipment of Hydrocarbon and HFO (<a href="/facts/Hydrofluoroolefin/nAg3sNqf">hydrofluoroolefin</a>) refrigerants R-32,<a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a> R-290,<a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a> R-600a,<a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a> <a href="/facts/R-454B/qQgl0YBl">R-454B</a>,<a class="footnote-ref" id="fnref:28" href="#fn:28"><sup>28</sup></a> <a href="/facts/R-1234yf/gmJzRqbP">R-1234yf</a>,<a class="footnote-ref" id="fnref:29" href="#fn:29"><sup>29</sup></a><a class="footnote-ref" id="fnref:30" href="#fn:30"><sup>30</sup></a> R-514A,<a class="footnote-ref" id="fnref:31" href="#fn:31"><sup>31</sup></a> R-744 (CO2),<a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a> <a href="/facts/R-1234ze(E)/DgU6uaNy">R-1234ze(E)</a><a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a> and <a href="/facts/1-Chloro-3%2c3%2c3-trifluoropropene/zGoYK7eT">R-1233zd(E)</a>,<a class="footnote-ref" id="fnref:34" href="#fn:34"><sup>34</sup></a> which have both an ODP of zero and a lower GWP. Hydrocarbons and CO2 are sometimes called natural refrigerants because they can be found in nature. </p><p>The environmental organization <a href="/facts/Greenpeace/nB8x6RJL">Greenpeace</a> provided funding to a former East German refrigerator company to research alternative ozone- and climate-safe refrigerants in 1992. The company developed a hydrocarbon mixture of <a href="/facts/Propane/E0b23KGh">propane</a> and <a href="/facts/Isobutane/Bd8H7rsH">isobutane</a>, or pure isobutane,<a class="footnote-ref" id="fnref:35" href="#fn:35"><sup>35</sup></a> called "Greenfreeze", but as a condition of the contract with Greenpeace could not patent the technology, which led to widespread adoption by other firms.<a class="footnote-ref" id="fnref:36" href="#fn:36"><sup>36</sup></a><a class="footnote-ref" id="fnref:37" href="#fn:37"><sup>37</sup></a><a class="footnote-ref" id="fnref:38" href="#fn:38"><sup>38</sup></a> Policy and political influence by corporate executives resisted change however,<a class="footnote-ref" id="fnref:39" href="#fn:39"><sup>39</sup></a><a class="footnote-ref" id="fnref:40" href="#fn:40"><sup>40</sup></a> citing the flammability and explosive properties of the refrigerants,<a class="footnote-ref" id="fnref:41" href="#fn:41"><sup>41</sup></a> and <a href="/facts/DuPont/kCUfkJzE">DuPont</a> together with other companies blocked them in the U.S. with the U.S. EPA.<a class="footnote-ref" id="fnref:42" href="#fn:42"><sup>42</sup></a><a class="footnote-ref" id="fnref:43" href="#fn:43"><sup>43</sup></a> </p><p>Beginning on 14 November 1994, the <a href="/facts/Federal_government_of_the_United_States/VJCxUaf7">U.S.</a> <a href="/facts/United_States_Environmental_Protection_Agency/ghI985SI">Environmental Protection Agency</a> restricted the sale, possession and use of refrigerants to only licensed technicians, per rules under sections 608 and 609 of the Clean Air Act.<a class="footnote-ref" id="fnref:44" href="#fn:44"><sup>44</sup></a> In 1995, Germany made CFC refrigerators illegal.<a class="footnote-ref" id="fnref:45" href="#fn:45"><sup>45</sup></a> </p><p>In 1996 <a href="/facts/Eurammon/m4MTSvAf">Eurammon</a>, a European non-profit initiative for <a href="/facts/Natural_refrigerant/WqLNgXMy">natural refrigerants</a>, was established and comprises European companies, institutions, and industry experts.<a class="footnote-ref" id="fnref:46" href="#fn:46"><sup>46</sup></a><a class="footnote-ref" id="fnref:47" href="#fn:47"><sup>47</sup></a><a class="footnote-ref" id="fnref:48" href="#fn:48"><sup>48</sup></a> </p><p>In 1997, FCs and HFCs were included in the <a href="/facts/Kyoto_Protocol/88twzpDf">Kyoto Protocol</a> to the Framework Convention on Climate Change. </p><p>In 2000 in the UK, the Ozone Regulations<a class="footnote-ref" id="fnref:49" href="#fn:49"><sup>49</sup></a> came into force which banned the use of ozone-depleting HCFC refrigerants such as R22 in new systems. The Regulation banned the use of R22 as a "top-up" fluid for maintenance from 2010 for virgin fluid and from 2015 for recycled fluid. </p> <h3>Addressing greenhouse gases</h3> <p>With growing interest in <a href="/facts/Natural_refrigerant/WqLNgXMy">natural refrigerants</a> as alternatives to synthetic refrigerants such as CFCs, HCFCs and HFCs, in 2004, <a href="/facts/Greenpeace/nB8x6RJL">Greenpeace</a> worked with multinational corporations like <a href="/facts/Coca-Cola/wbnCJYb6">Coca-Cola</a> and <a href="/facts/Unilever/9dnFaVFR">Unilever</a>, and later <a href="/facts/PepsiCo/eIyvU5fF">Pepsico</a> and others, to create a corporate coalition called Refrigerants Naturally!.<a class="footnote-ref" id="fnref:50" href="#fn:50"><sup>50</sup></a><a class="footnote-ref" id="fnref:51" href="#fn:51"><sup>51</sup></a> Four years later, Ben & Jerry's of Unilever and General Electric began to take steps to support production and use in the U.S.<a class="footnote-ref" id="fnref:52" href="#fn:52"><sup>52</sup></a> It is estimated that almost 75 percent of the refrigeration and air conditioning sector has the potential to be converted to natural refrigerants.<a class="footnote-ref" id="fnref:53" href="#fn:53"><sup>53</sup></a> </p><p>In 2006, the EU adopted a Regulation on <a href="/facts/Fluorinated_gases/hXs7VmyX">fluorinated greenhouse gases</a> (FCs and HFCs) to encourage to transition to natural refrigerants (such as hydrocarbons). It was reported in 2010 that some refrigerants are being used as <a href="/facts/Recreational_drug_use/eoBD3vKn">recreational drugs</a>, leading to an extremely dangerous phenomenon known as <a href="/facts/Inhalant_abuse/usdwDeWh">inhalant abuse</a>.<a class="footnote-ref" id="fnref:54" href="#fn:54"><sup>54</sup></a> </p><p>From 2011 the European Union started to phase out refrigerants with a <a href="/facts/Global_warming_potential/tgTbpwbJ">global warming potential</a> (GWP) of more than 150 in automotive air conditioning (GWP = 100-year warming potential of one kilogram of a gas relative to one kilogram of CO2) such as the refrigerant <a href="/facts/HFC-134a/hy99tyHU">HFC-134a</a> (known as R-134a in North America) which has a GWP of 1526.<a class="footnote-ref" id="fnref:55" href="#fn:55"><sup>55</sup></a> In the same year the EPA decided in favour of the ozone- and climate-safe refrigerant for U.S. manufacture.<a class="footnote-ref" id="fnref:56" href="#fn:56"><sup>56</sup></a><a class="footnote-ref" id="fnref:57" href="#fn:57"><sup>57</sup></a><a class="footnote-ref" id="fnref:58" href="#fn:58"><sup>58</sup></a> </p><p>A 2018 study by the nonprofit organization "<a href="/facts/Drawdown_(climate)/8DjxhWJa">Drawdown</a>" put proper refrigerant management and disposal at the very top of the list of climate impact solutions, with an impact equivalent to eliminating over 17 years of US carbon dioxide emissions.<a class="footnote-ref" id="fnref:59" href="#fn:59"><sup>59</sup></a> </p><p>In 2019 it was estimated that CFCs, HCFCs, and HFCs were responsible for about 10% of direct <a href="/facts/Radiative_forcing/VSLpzv66">radiative forcing</a> from all long-lived anthropogenic greenhouse gases.<a class="footnote-ref" id="fnref:60" href="#fn:60"><sup>60</sup></a> and in the same year the <a href="/facts/UNEP/2P9vPoSU">UNEP</a> published new voluntary guidelines,<a class="footnote-ref" id="fnref:61" href="#fn:61"><sup>61</sup></a> however many countries have not yet ratified the <a href="/facts/Kigali_Amendment/de9aMTdg">Kigali Amendment</a>. </p><p>From early 2020 HFCs (including R-404A, R-134a, and R-410A) are being superseded: Residential air-conditioning systems and heat pumps are increasingly using <a href="/facts/Difluoromethane/XQ4tkYVJ">R-32</a>. This still has a GWP of more than 600. Progressive devices use refrigerants with almost no climate impact, namely R-290 (propane), R-600a (isobutane), or <a href="/facts/R-1234yf/gmJzRqbP">R-1234yf</a> (less flammable, in cars). In commercial refrigeration also CO2 (R-744) can be used. </p> <h2 id="requirements-and-desirable-properties">Requirements and desirable properties</h2> <p>A refrigerant needs to have: a <a href="/facts/Boiling_point/E2BK9QoS">boiling point</a> that is somewhat below the target temperature (although boiling point can be adjusted by adjusting the <a href="/facts/Pressure/eyc37GRG">pressure</a> appropriately), a high <a href="/facts/Heat_of_vaporization/TbEWQDNl">heat of vaporization</a>, a moderate <a href="/facts/Density/92p6hh9I">density</a> in liquid form, a relatively high density in gaseous form (which can also be adjusted by setting pressure appropriately), and a high <a href="/facts/Critical_point_(thermodynamics)/pkM7RLJK">critical temperature</a>. Working pressures should ideally be containable by <a href="/facts/Copper_tubing/P6CNx07l">copper tubing</a>, a commonly available material. Extremely high pressures should be avoided. </p><p>The ideal refrigerant would be: <a href="/facts/Corrosive/7LXjT1XE">non-corrosive</a>, <a href="/facts/Toxicity/qa96rs60">non-toxic</a>, <a href="/facts/Flammability/1QexTQ4T">non-flammable</a>, with no <a href="/facts/Ozone_depletion/ssGWpcx3">ozone depletion</a> and <a href="/facts/Global_warming_potential/tgTbpwbJ">global warming</a> potential. It should preferably be natural with well-studied and low environmental impact. Newer refrigerants address the issue of the damage that CFCs caused to the ozone layer and the contribution that HCFCs make to climate change, but some do raise issues relating to toxicity and/or flammability.<a class="footnote-ref" id="fnref:62" href="#fn:62"><sup>62</sup></a> </p> <h2 id="common-refrigerants">Common refrigerants</h2> <h3>Refrigerants with very low climate impact</h3> <p>With increasing regulations, refrigerants with a very low <a href="/facts/Global_warming_potential/tgTbpwbJ">global warming potential</a> are expected to play a dominant role in the 21st century,<a class="footnote-ref" id="fnref:63" href="#fn:63"><sup>63</sup></a> in particular, R-290 and R-1234yf. Starting from almost no market share in 2018,<a class="footnote-ref" id="fnref:64" href="#fn:64"><sup>64</sup></a> low GWPO devices are gaining market share in 2022. </p> <table><tbody><tr><th>Code</th><th>Chemical</th><th>Name</th><th><a href="/facts/Global_warming_potential/tgTbpwbJ">GWP</a> 20yr<a class="footnote-ref" id="fnref:65" href="#fn:65"><sup>65</sup></a></th><th>GWP 100yr<a class="footnote-ref" id="fnref:66" href="#fn:66"><sup>66</sup></a></th><th>Status</th><th>Commentary</th></tr><tr><td><a href="/facts/R-290_(refrigerant)/E0b23KGh">R-290</a></td><td>C3H8</td><td><a href="/facts/Propane/E0b23KGh">Propane</a></td><td></td><td>3.3<a class="footnote-ref" id="fnref:67" href="#fn:67"><sup>67</sup></a></td><td>Increasing use</td><td>Low cost, widely available, and efficient. They also have zero <a href="/facts/Ozone_depletion_potential/CngkPwdu">ozone depletion potential</a>. Despite their flammability, they are increasingly used in domestic refrigerators and heat pumps. In 2010, about one-third of all household refrigerators and freezers manufactured globally used isobutane or an isobutane/propane blend, and this was expected to increase to 75% by 2020.<a class="footnote-ref" id="fnref:68" href="#fn:68"><sup>68</sup></a></td></tr><tr><td><a href="/facts/R-600a/Bd8H7rsH">R-600a</a></td><td>HC(CH3)3</td><td><a href="/facts/Isobutane/Bd8H7rsH">Isobutane</a></td><td></td><td>3.3</td><td>Widely used</td><td>See R-290.</td></tr><tr><td><a href="/facts/R-717/MtLtJFtz">R-717</a></td><td>NH3</td><td><a href="/facts/Ammonia/MtLtJFtz">Ammonia</a></td><td>0</td><td>0<a class="footnote-ref" id="fnref:69" href="#fn:69"><sup>69</sup></a></td><td>Widely used</td><td>Commonly used before the popularisation of CFCs, it is again being considered but does suffer from the disadvantage of toxicity, and it requires corrosion-resistant components, which restricts its domestic and small-scale use. Anhydrous ammonia is widely used in industrial refrigeration applications and hockey rinks because of its high <a href="/facts/Energy_conversion_efficiency/gSqXlWoI">energy efficiency</a> and low cost.</td></tr><tr><td>R-1234yf <a href="/facts/HFO-1234yf/gmJzRqbP">HFO-1234yf</a></td><td>C3H2F4</td><td><a href="/facts/2%2c3%2c3%2c3-Tetrafluoropropene/gmJzRqbP">2,3,3,3-Tetrafluoropropene</a></td><td></td><td><1</td><td></td><td>Less performance but also less flammable than R-290.<a class="footnote-ref" id="fnref:70" href="#fn:70"><sup>70</sup></a> GM announced that it would start using "hydro-fluoro olefin", <a href="/facts/HFO-1234yf/gmJzRqbP">HFO-1234yf</a>, in all of its brands by 2013.<a class="footnote-ref" id="fnref:71" href="#fn:71"><sup>71</sup></a></td></tr><tr><td><a href="/facts/R-744/xGzpppEp">R-744</a></td><td>CO2</td><td><a href="/facts/Carbon_dioxide/xGzpppEp">Carbon dioxide</a></td><td>1</td><td>1</td><td>In use</td><td>Was used as a refrigerant prior to the discovery of CFCs (this was also the case for propane)<a class="footnote-ref" id="fnref:72" href="#fn:72"><sup>72</sup></a> and now having a renaissance due to it being non-ozone depleting, non-toxic and non-flammable. It may become the working fluid of choice to replace current HFCs in cars, supermarkets, and <a href="/facts/Heat_pump/JAprSmeL">heat pumps</a>. <a href="/facts/Coca-Cola/wbnCJYb6">Coca-Cola</a> has fielded CO2-based beverage coolers and the <a href="/facts/United_States_Army/WACWBEK9">U.S. Army</a> is considering CO2 refrigeration.<a class="footnote-ref" id="fnref:73" href="#fn:73"><sup>73</sup></a><a class="footnote-ref" id="fnref:74" href="#fn:74"><sup>74</sup></a> Due to the need to operate at pressures of up to 130 bars (1,900 psi; 13,000 kPa), CO2 systems require highly resistant components, however these have already been developed for mass production in many sectors.</td></tr></tbody></table> <h3>Most used</h3> <table><tbody><tr><th>Code</th><th>Chemical</th><th>Name</th><th><a href="/facts/Global_warming_potential/tgTbpwbJ">Global warming potential</a> 20yr<a class="footnote-ref" id="fnref:75" href="#fn:75"><sup>75</sup></a></th><th>GWP 100yr<a class="footnote-ref" id="fnref:76" href="#fn:76"><sup>76</sup></a></th><th>Status</th><th>Commentary</th></tr><tr><td>R-32 HFC-32</td><td>CH2F2</td><td><a href="/facts/Difluoromethane/XQ4tkYVJ">Difluoromethane</a></td><td>2430</td><td>677</td><td>Widely used</td><td>Promoted as climate-friendly substitute for R-134a and R-410A, but still with high climate impact. Has excellent heat transfer and pressure drop performance, both in condensation and vaporisation.<a class="footnote-ref" id="fnref:77" href="#fn:77"><sup>77</sup></a> It has an <a href="/facts/Greenhouse_gas/HXaHqrT8">atmospheric lifetime</a> of nearly 5 years.<a class="footnote-ref" id="fnref:78" href="#fn:78"><sup>78</sup></a> Currently used in residential and commercial <a href="/facts/Air_conditioning/bK2sIKQd">air-conditioners</a> and <a href="/facts/Heat_pump/JAprSmeL">heat pumps</a>.</td></tr><tr><td><a href="/facts/R-134a/hy99tyHU">R-134a</a> HFC-134a</td><td>CH2FCF3</td><td><a href="/facts/1%2c1%2c1%2c2-Tetrafluoroethane/hy99tyHU">1,1,1,2-Tetrafluoroethane</a></td><td>3790</td><td>1550</td><td>Widely used</td><td>Most used in 2020 for hydronic heat pumps in Europe and the United States in spite of high GWP.<a class="footnote-ref" id="fnref:79" href="#fn:79"><sup>79</sup></a> Commonly used in automotive air conditioners prior to phase out which began in 2012.</td></tr><tr><td><a href="/facts/R-410A/eg3z47m6">R-410A</a></td><td></td><td>50% R-32 / 50% R-125 (<a href="/facts/Pentafluoroethane/bdmy557C">pentafluoroethane</a>)</td><td>Between 2430 (R-32) and 6350 (R-125)</td><td>> 677</td><td>Widely Used</td><td>Most used in split heat pumps / AC by 2018. Almost 100% share in the USA.<a class="footnote-ref" id="fnref:80" href="#fn:80"><sup>80</sup></a> Being phased out in the US starting in 2022.<a class="footnote-ref" id="fnref:81" href="#fn:81"><sup>81</sup></a><a class="footnote-ref" id="fnref:82" href="#fn:82"><sup>82</sup></a></td></tr></tbody></table> <h3>Banned / Phased out</h3> <table><tbody><tr><th>Code</th><th>Chemical</th><th>Name</th><th><a href="/facts/Global_warming_potential/tgTbpwbJ">Global warming potential</a> 20yr<a class="footnote-ref" id="fnref:83" href="#fn:83"><sup>83</sup></a></th><th>GWP 100yr<a class="footnote-ref" id="fnref:84" href="#fn:84"><sup>84</sup></a></th><th>Status</th><th>Commentary</th></tr><tr><td>R-11 CFC-11</td><td>CCl3F</td><td><a href="/facts/Trichlorofluoromethane/bx7YxsjC">Trichlorofluoromethane</a></td><td>6900</td><td>4660</td><td>Banned</td><td>Production was banned in developed countries by <a href="/facts/Montreal_Protocol/Hmf70BQK">Montreal Protocol</a> in 1996</td></tr><tr><td>R-12 CFC-12</td><td>CCl2F2</td><td><a href="/facts/Dichlorodifluoromethane/KdMmfral">Dichlorodifluoromethane</a></td><td>10800</td><td>10200</td><td>Banned</td><td>Also known as Freon, a widely used <a href="/facts/Chlorofluorocarbon/uLApxm7K">chlorofluorocarbon</a> <a href="/facts/Halomethane/R0lmPP5u">halomethane</a> (CFC). Production was banned in developed countries by <a href="/facts/Montreal_Protocol/Hmf70BQK">Montreal Protocol</a> in 1996, and in developing countries (Article 5 countries) in 2010.<a class="footnote-ref" id="fnref:85" href="#fn:85"><sup>85</sup></a></td></tr><tr><td>R-22 HCFC-22</td><td>CHClF2</td><td><a href="/facts/Chlorodifluoromethane/D1pGLBP0">Chlorodifluoromethane</a></td><td>5280</td><td>1760</td><td>Being phased out</td><td>A widely used <a href="/facts/Hydrochlorofluorocarbon/uLApxm7K">hydrochlorofluorocarbon</a> (HCFC) and powerful <a href="/facts/Greenhouse_gas/HXaHqrT8">greenhouse gas</a> with a GWP equal to 1810. Worldwide production of R-22 in 2008 was about 800 Gg per year, up from about 450 Gg per year in 1998. R-438A (MO-99) is a R-22 replacement.<a class="footnote-ref" id="fnref:86" href="#fn:86"><sup>86</sup></a></td></tr><tr><td>R-123 HCFC-123</td><td>CHCl2CF3</td><td><a href="/facts/2%2c2-Dichloro-1%2c1%2c1-trifluoroethane/k9Lc63ap">2,2-Dichloro-1,1,1-trifluoroethane</a></td><td>292</td><td>79</td><td>US phase-out</td><td>Used in large tonnage centrifugal chiller applications. All U.S. production and import of virgin HCFCs will be phased out by 2030, with limited exceptions.<a class="footnote-ref" id="fnref:87" href="#fn:87"><sup>87</sup></a> R-123 refrigerant was used to retrofit some chiller that used R-11 refrigerant <a href="/facts/Trichlorofluoromethane/bx7YxsjC">Trichlorofluoromethane</a>. The production of R-11 was banned in developed countries by <a href="/facts/Montreal_Protocol/Hmf70BQK">Montreal Protocol</a> in 1996.<a class="footnote-ref" id="fnref:88" href="#fn:88"><sup>88</sup></a></td></tr></tbody></table> <h3>Other</h3> <table><tbody><tr><th>Code</th><th>Chemical</th><th>Name</th><th><a href="/facts/Global_warming_potential/tgTbpwbJ">Global warming potential</a> 20yr<a class="footnote-ref" id="fnref:89" href="#fn:89"><sup>89</sup></a></th><th>GWP 100yr<a class="footnote-ref" id="fnref:90" href="#fn:90"><sup>90</sup></a></th><th>Commentary</th></tr><tr><td>R-152a HFC-152a</td><td>CH3CHF2</td><td><a href="/facts/1%2c1-Difluoroethane/STzHeaxv">1,1-Difluoroethane</a></td><td>506</td><td>138</td><td>As a compressed air duster</td></tr><tr><td><a href="/facts/R-407C/yT5DmTE9">R-407C</a></td><td></td><td>Mixture of difluoromethane and <a href="/facts/Pentafluoroethane/bdmy557C">pentafluoroethane</a> and 1,1,1,2-tetrafluoroethane</td><td></td><td></td><td>A mixture of R-32, R-125, and R-134a</td></tr><tr><td><a href="/facts/R-454B/qQgl0YBl">R-454B</a></td><td></td><td>Difluoromethane and 2,3,3,3-Tetrafluoropropene</td><td></td><td></td><td>HFOs blend of refrigerants Difluoromethane (<a href="/facts/Difluoromethane/XQ4tkYVJ">R-32</a>) and 2,3,3,3-Tetrafluoropropene (<a href="/facts/R-1234yf/gmJzRqbP">R-1234yf</a>).<a class="footnote-ref" id="fnref:91" href="#fn:91"><sup>91</sup></a><a class="footnote-ref" id="fnref:92" href="#fn:92"><sup>92</sup></a><a class="footnote-ref" id="fnref:93" href="#fn:93"><sup>93</sup></a><a class="footnote-ref" id="fnref:94" href="#fn:94"><sup>94</sup></a></td></tr><tr><td>R-513A</td><td></td><td>An HFO/HFC blend (56% R-1234yf/44%R-134a)</td><td></td><td></td><td>May replace R-134a as an interim alternative<a class="footnote-ref" id="fnref:95" href="#fn:95"><sup>95</sup></a></td></tr><tr><td>R-514A</td><td></td><td>HFO-1336mzz-Z/trans-1,2- dichloroethylene (t-DCE)</td><td></td><td></td><td>An hydrofluoroolefin (HFO)-based refrigerant to replace R-123 in low-pressure centrifugal chillers for commercial and industrial applications.<a class="footnote-ref" id="fnref:96" href="#fn:96"><sup>96</sup></a><a class="footnote-ref" id="fnref:97" href="#fn:97"><sup>97</sup></a></td></tr></tbody></table> <h2 id="refrigerant-reclamation-and-disposal">Refrigerant reclamation and disposal</h2> <p class="note">Main article: <a href="/facts/Refrigerant_reclamation/38WN9C2S">Refrigerant reclamation</a></p> <p>Coolant and refrigerants are found throughout the industrialized world, in homes, offices, and factories, in devices such as refrigerators, air conditioners, central air conditioning systems (HVAC), freezers, and dehumidifiers. When these units are serviced, there is a risk that refrigerant gas will be vented into the atmosphere either accidentally or intentionally, hence the creation of technician training and certification programs in order to ensure that the material is conserved and managed safely. Mistreatment of these gases has been shown to deplete the ozone layer and is suspected to contribute to <a href="/facts/Global_warming/rEN4BDE7">global warming</a>.<a class="footnote-ref" id="fnref:98" href="#fn:98"><sup>98</sup></a> </p><p>With the exception of isobutane and propane (R600a, R441A, and R290), ammonia and CO2 under <a href="/facts/Section_608/CKS5FXLx">Section 608</a> of the United States' <a href="/facts/Clean_Air_Act_(United_States)/zfdgfHjP">Clean Air Act</a> it is illegal to knowingly release any refrigerants into the atmosphere.<a class="footnote-ref" id="fnref:99" href="#fn:99"><sup>99</sup></a><a class="footnote-ref" id="fnref:100" href="#fn:100"><sup>100</sup></a> </p><p><a href="/facts/Refrigerant_reclamation/38WN9C2S">Refrigerant reclamation</a> is the act of processing used refrigerant gas that has previously been used in some type of <a href="/facts/Vapor-compression_refrigeration/oT3EM4nS">refrigeration loop</a> such that it meets specifications for new refrigerant gas. In the <a href="/facts/United_States/P0sCdLe5">United States</a>, the <a href="/facts/Clean_Air_Act_(United_States)/zfdgfHjP">Clean Air Act</a> of 1990 requires that used refrigerant be processed by a certified reclaimer, which must be licensed by the <a href="/facts/United_States_Environmental_Protection_Agency/ghI985SI">United States Environmental Protection Agency</a> (EPA), and the material must be recovered and delivered to the reclaimer by EPA-certified technicians.<a class="footnote-ref" id="fnref:101" href="#fn:101"><sup>101</sup></a> </p> <h2 id="classification-of-refrigerants">Classification of refrigerants</h2> <p class="note">Main article: <a href="/facts/List_of_refrigerants/U1x2WD9Q">List of refrigerants</a></p> <p>Refrigerants may be divided into three classes according to their manner of absorption or extraction of heat from the substances to be refrigerated: </p> <ul><li>Class 1: This class includes refrigerants that cool by phase change (typically boiling), using the refrigerant's <a href="/facts/Latent_heat/QCIWSGln">latent heat</a>.</li> <li>Class 2: These refrigerants cool by temperature change or '<a href="/facts/Sensible_heat/VRytSLvb">sensible heat</a>', the quantity of heat being the specific heat capacity x the temperature change. They are air, calcium chloride brine, sodium chloride brine, alcohol, and similar nonfreezing solutions. The purpose of Class 2 refrigerants is to receive a reduction of temperature from Class 1 refrigerants and convey this lower temperature to the area to be cooled.</li> <li>Class 3: This group consists of solutions that contain absorbed vapors of liquefiable agents or refrigerating media. These solutions function by the nature of their ability to carry liquefiable vapors, which produce a cooling effect by the absorption of their heat of solution. They can also be classified into many categories.</li></ul> <h3>R numbering system</h3> <p>The R- numbering system was developed by <a href="/facts/DuPont/kCUfkJzE">DuPont</a> (which owned the <a href="/facts/Freon/JkfAjIb9">Freon</a> trademark), and systematically identifies the molecular structure of refrigerants made with a single halogenated hydrocarbon. ASHRAE has since set guidelines for the numbering system as follows:<a class="footnote-ref" id="fnref:102" href="#fn:102"><sup>102</sup></a> </p><p>R-X1X2X3X4 </p> <ul><li>X1 = Number of unsaturated carbon-carbon bonds (omit if zero)</li> <li>X2 = Number of carbon atoms minus 1 (omit if zero)</li> <li>X3 = Number of hydrogen atoms plus 1</li> <li>X4 = Number of fluorine atoms</li></ul> <h4>Series</h4> <ul><li>R-xx <a href="/facts/Methane/kBHneYnh">Methane</a> Series</li> <li>R-1xx <a href="/facts/Ethane/BGCzc6yh">Ethane</a> Series</li> <li>R-2xx <a href="/facts/Propane/E0b23KGh">Propane</a> Series</li> <li>R-4xx <a href="/facts/Zeotropic_mixture/zRBQfQpg">Zeotropic blend</a></li> <li>R-5xx <a href="/facts/Azeotrope/ItfBAN1N">Azeotropic blend</a></li> <li>R-6xx Saturated hydrocarbons (except for propane which is R-290)</li> <li>R-7xx Inorganic Compounds with a <a href="/facts/Molar_mass/m2laJErl">molar mass</a> < 100</li> <li>R-7xxx Inorganic Compounds with a molar mass ≥ 100</li></ul> <h4>Ethane Derived Chains</h4> <ul><li>Number Only Most symmetrical <a href="/facts/Isomer/PXlvDVdg">isomer</a></li> <li>Lower Case Suffix (a, b, c, etc.) indicates increasingly unsymmetrical isomers</li></ul> <h4>Propane Derived Chains</h4> <ul><li>Number Only If only one isomer exists; otherwise:</li> <li>First lower case suffix (a-f): <ul><li>a Suffix Cl2 central carbon substitution</li> <li>b Suffix Cl, F central carbon substitution</li> <li>c Suffix F2 central carbon substitution</li> <li>d Suffix Cl, H central carbon substitution</li> <li>e Suffix F, H central carbon substitution</li> <li>f Suffix H2 central carbon substitution</li></ul></li> <li>2nd Lower Case Suffix (a, b, c, etc.) Indicates increasingly unsymmetrical isomers</li></ul> <h4>Propene derivatives</h4> <ul><li>First lower case suffix (x, y, z): <ul><li>x Suffix Cl substitution on central atom</li> <li>y Suffix F substitution on central atom</li> <li>z Suffix H substitution on central atom</li></ul></li> <li>Second lower case suffix (a-f): <ul><li>a Suffix =CCl2 <a href="/facts/Methylene_group/sdGv7zMu">methylene</a> substitution</li> <li>b Suffix =CClF methylene substitution</li> <li>c Suffix =CF2 methylene substitution</li> <li>d Suffix =CHCl methylene substitution</li> <li>e Suffix =CHF methylene substitution</li> <li>f Suffix =CH2 methylene substitution</li></ul></li></ul> <h4>Blends</h4> <ul><li>Upper Case Suffix (A, B, C, etc.) Same blend with different compositions of refrigerants</li></ul> <h4>Miscellaneous</h4> <ul><li>R-Cxxx <a href="/facts/Cyclic_compound/TH2ReKIQ">Cyclic compound</a></li> <li>R-Exxx <a href="/facts/Ether/jwDg0IKr">Ether group</a> is present</li> <li>R-CExxx Cyclic compound with an ether group</li> <li>R-4xx/5xx + Upper Case Suffix (A, B, C, etc.) Same blend with different composition of refrigerants</li> <li>R-6xx + Lower Case Letter Indicates increasingly unsymmetrical isomers</li> <li>7xx/7xxx + Upper Case Letter Same molar mass, different compound</li> <li>R-xxxxB# <a href="/facts/Bromine/oLfj3C7D">Bromine</a> is present with the number after B indicating how many bromine atoms</li> <li>R-xxxxI# <a href="/facts/Iodine/JlfMecMf">Iodine</a> is present with the number after I indicating how many iodine atoms</li> <li>R-xxx(E) Trans Molecule</li> <li>R-xxx(Z) Cis Molecule</li></ul> <p>For example, <a href="/facts/1%2c1%2c1%2c2-Tetrafluoroethane/hy99tyHU">R-134a</a> has 2 carbon atoms, 2 hydrogen atoms, and 4 fluorine atoms, an empirical formula of tetrafluoroethane. The "a" suffix indicates that the isomer is unbalanced by one atom, giving <a href="/facts/1%2c1%2c1%2c2-Tetrafluoroethane/hy99tyHU">1,1,1,2-Tetrafluoroethane</a>. R-134 (without the "a" suffix) would have a molecular structure of 1,1,2,2-Tetrafluoroethane. </p><p>The same numbers are used with an R- prefix for generic refrigerants, with a "Propellant" prefix (e.g., "Propellant 12") for the same chemical used as a propellant for an <a href="/facts/Aerosol_spray/8SfNdfYs">aerosol spray</a>, and with trade names for the compounds, such as "Freon 12". Recently, a practice of using abbreviations HFC- for <a href="/facts/Hydrofluorocarbon/mUNTbYch">hydrofluorocarbons</a>, CFC- for <a href="/facts/Chlorofluorocarbon/uLApxm7K">chlorofluorocarbons</a>, and HCFC- for <a href="/facts/Hydrochlorofluorocarbon/uLApxm7K">hydrochlorofluorocarbons</a> has arisen, because of the regulatory differences among these groups. </p> <h2 id="refrigerant-safety">Refrigerant safety</h2> <p>Refrigerants are classified under regulations such as <a href="/facts/International_Organization_for_Standardization/IacYR7Yg">ISO</a> 817/5149, AHRAE 34/15, & BS EN 378. The <a href="/facts/Pressure/eyc37GRG">pressures</a> of these gases can range from 700–1,000 kPa (100–150 psi). They can also be at temperatures as low as −50 °C [−58 °F] and as high as over 100 °C [212 °F]. Refrigerants have varying classifications of <a href="/facts/Combustibility_and_flammability/1QexTQ4T">flammability</a>: A1 class are non-flammable, A2/A2L class are flammable, and A3 class are extremely flammable and/or <a href="/facts/Explosive/sUme5Pp8">explosive</a>. <a href="/facts/Toxicity/qa96rs60">Toxicity</a> also varies; B1 class refrigerants have low toxicity, while B2 refrigerants are moderately toxic and B3 refrigerants are highly toxic. These regulations relate to situations where these refrigerants are released into the <a href="/facts/Atmosphere/oUpLaGRF">atmosphere</a> in the event of an accidental leak, not while circulated.<a class="footnote-ref" id="fnref:103" href="#fn:103"><sup>103</sup></a> Due to these regulations, most refrigerants may only be handled by qualified/certified engineers for the relevant classes; in the UK, C&G 2079 is required for A1-class refrigerants, while C&G 6187-2 is required for A2, A2L, and A3-class refrigerants. Due to their non-flammability, non-explosivity, and non-toxicity, A1 class refrigerants have been used in open systems (where they are consumed when used rather than circulated) like <a href="/facts/Fire_extinguisher/Lh96vD2x">fire extinguishers</a>, <a href="/facts/Inhaler/2VcjtkkJ">inhalers</a>, computer rooms, and insulation since 1928. </p><p>ASHRAE Standard 34, <i>Designation and Safety Classification of Refrigerants</i>, assigns safety classifications to refrigerants based upon <a href="/facts/Toxicity/qa96rs60">toxicity</a> and <a href="/facts/Flammability/1QexTQ4T">flammability</a>. ASHRAE assigns a capital letter to indicate toxicity and a number to indicate flammability. The letter "A" is the least toxic and the number 1 is the least flammable.<a class="footnote-ref" id="fnref:104" href="#fn:104"><sup>104</sup></a> </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Brine/xsN2GcLF">Brine (Refrigerant)</a></li> <li><a href="/facts/Section_608/CKS5FXLx">Section 608</a></li> <li><a href="/facts/List_of_refrigerants/U1x2WD9Q">List of Refrigerants</a></li></ul> <h3>Sources</h3> <h4>IPCC reports</h4> <ul><li><a href="/facts/IPCC/sh76du1u">IPCC</a> (2013). Stocker, T. F.; Qin, D.; Plattner, G.-K.; Tignor, M.; et al. (eds.). <a href="http://www.climatechange2013.org/images/report/WG1AR5_ALL_FINAL.pdf"><i>Climate Change 2013: The Physical Science Basis</i></a> (PDF). Contribution of Working Group I to the <a href="/facts/IPCC_Fifth_Assessment_Report/aYz6LE8H">Fifth Assessment Report</a> of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-1-107-05799-9. (pb: 978-1-107-66182-0). <a href="https://archive.ipcc.ch/report/ar5/wg1/">Fifth Assessment Report - Climate Change 2013</a> <ul><li>Myhre, G.; Shindell, D.; Bréon, F.-M.; Collins, W.; et al. (2013). <a href="https://archive.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter08_FINAL.pdf">"Chapter 8: Anthropogenic and Natural Radiative Forcing"</a> (PDF). <i>Climate Change 2013: The Physical Science Basis</i>. Contribution of Working Group I to the <a href="/facts/IPCC_Fifth_Assessment_Report/aYz6LE8H">Fifth Assessment Report</a> of the Intergovernmental Panel on Climate Change. pp. 659–740.</li></ul></li> <li><a href="/facts/IPCC/sh76du1u">IPCC</a> (2021). Masson-Delmotte, V.; Zhai, P.; Pirani, A.; Connors, S. L.; et al. (eds.). <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Full_Report.pdf"><i>Climate Change 2021: The Physical Science Basis</i></a> (PDF). Contribution of Working Group I to the <a href="/facts/IPCC_Sixth_Assessment_Report/Dc5drLUK">Sixth Assessment Report</a> of the Intergovernmental Panel on Climate Change. Cambridge University Press (In Press).</li> <li>Forster, Piers; Storelvmo, Trude (2021). <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter07.pdf">"Chapter 7: The Earth's Energy Budget, Climate Feedbacks, and Climate Sensitivity"</a> (PDF). <i>IPCC AR6 WG1 2021</i>.</li></ul> <h4>Other</h4> <ul><li><a href="https://ww2.arb.ca.gov/resources/documents/high-gwp-refrigerants">"High GWP refrigerants"</a>. California Air Resources Board. Retrieved 13 February 2022.</li> <li><a href="https://www.bsria.com/us/news/article/bsrias_view_on_refrigerant_trends_in_ac_and_heat_pump_segments/">"BSRIA's view on refrigerant trends in AC and Heat Pump segments"</a>. 2020. Retrieved 2022-02-14.</li> <li>Yadav, Saurabh; Liu, Jie; Kim, Sung Chul (2022). "A comprehensive study on 21st-century refrigerants - R290 and R1234yf: A review". <i>International Journal of Heat and Mass Transfer</i>. 122: 121947. <a href="/facts/Bibcode_(identifier)/9HtdQSGB">Bibcode</a>:<a href="https://ui.adsabs.harvard.edu/abs/2022IJHMT.18221947Y">2022IJHMT.18221947Y</a>. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1016%2Fj.ijheatmasstransfer.2021.121947">10.1016/j.ijheatmasstransfer.2021.121947</a>. <a href="/facts/S2CID_(identifier)/ldJsHa2Y">S2CID</a> <a href="https://api.semanticscholar.org/CorpusID:240534198">240534198</a>.</li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="https://web.archive.org/web/20041112075806/http://www.epa.gov/nonco2/econ-inv/table.html">US Environmental Protection Agency page on the GWPs of various substances</a></li> <li><a href="http://www.green-cooling-initiative.org/">Green Cooling Initiative on alternative natural refrigerants cooling technologies</a></li> <li><a href="http://www.iifiir.org/medias/medias.aspx?instance=EXPLOITATION&setlanguage=EN">International Institute of Refrigeration</a> <a href="https://web.archive.org/web/20180925041045/http://www.iifiir.org/medias/medias.aspx?instance=EXPLOITATION&setlanguage=EN">Archived</a> 2018-09-25 at the <a href="/facts/Wayback_Machine/nmQ3a6JC">Wayback Machine</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>United Nations Environment Programme (UNEP). "Update on New Refrigerants Designations and Safety Classifications" (PDF). ASHRAE. Retrieved 6 October 2024. <a href="https://www.ashrae.org/file%20library/technical%20resources/bookstore/factsheet_ashrae_english_november2022.pdf" target="_blank">https://www.ashrae.org/file%20library/technical%20resources/bookstore/factsheet_ashrae_english_november2022.pdf</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"Phaseout of Class II Ozone-Depleting Substances". US Environmental Protection Agency. 22 July 2015. Retrieved October 6, 2024. <a href="https://www.epa.gov/ods-phaseout/phaseout-class-ii-ozone-depleting-substances" target="_blank">https://www.epa.gov/ods-phaseout/phaseout-class-ii-ozone-depleting-substances</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"Protecting Our Climate by Reducing Use of HFCs". United States Environmental Protection Agency. 8 February 2021. 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