This table gives physical properties, safe exposure limits, and climate change potential for compounds that have been used as working fluids in traditional refrigeration systems or are under consideration as replacements in newer systems. Some are also used as solvents, blowing agents, and fire suppressants. This table includes both traditional chlorofluorohydrocarbon (CFC) abd hydrochlorofluorocarbon (HCFC) refrigerants, which are now largely phased out because of their environment as well as new fluids that are less harmful to the environment.
Column definitions for the table are as follows. Note the critical temperature is in kelvin (K), while other temperatures (melting point and boiling point) are in °C.
Column heading | Definition |
Name | Chemical name of refrigerant; listed alphabetically by name |
ASHRAE Desig. | ASHRAE standard refrigerant designation (Ref. 1); see text for discussion |
Mol. form. | Molecular formula for refrigerant |
CAS Reg. No. | Chemical Abstracts Service Registry Number |
tmp | Normal melting point, in °C (“tp” indicates a triple point) |
tbp | Normal boiling point, in °C at 101.325 kPa or 760 mmHg (“sp” indicates a sublimation point) |
Tc | Critical temperature, in K |
pc | Critical pressure, in MPa |
TLV/TWA | Threshold limit value, expressed as the time-weighted average over an 8-hr workday and 40-hr workweek, for safe exposure to the vapor; in units of parts per million (ppm) by volume |
STEL | Short-term exposure limit, which should not be exceeded for more than 15 min, in units of parts per million (ppm) |
GWP | Global warming potential, 100-year time horizon, data value is relative to the GWP for CO2 = 1 |
ODP |
Ozone depletion potential, data value is relative to CFC-11 (trichlofluoromethane) = 1 |
The ASHRAE codes are often prefixed by symbols such as CFC- (for chlorofluorocarbon), HCFC- (for hydrochlorofluorocarbon), or simply R- (for refrigerant). The “R” number assigned to refrigerants is specified by ANSI/ASHRAE Standard 34. This system is most useful for the hydrocarbons and halocarbons with one to three carbons; for such molecules the chemical composition can be determined from the number and vice versa. The first digit on the far right is the number of fluorine atoms in the compound. The second digit from the right is one more than the number of hydrogen atoms. The third digit from the right is one less than the number of carbon atoms; for single-carbon compounds, this digit is omitted. The fourth digit from the right is equal to the number of unsaturated carbon–carbon bonds; for saturated compounds, this digit is omitted. The number of bromine and iodine atoms is indicated, if needed, by appending “Bn” or “In” to the digits specified by the above rules, where “n” is the number of bromine or iodine atoms. All atoms not specified by the above are assumed to be chlorine. Appended lowercase letter(s) designate different isomers. Appended (E) and (Z) indicate trans and cis forms, respectively. Additional rules are used to specify cyclic compounds, ethers, inorganic fluids (R700- and R7000-series), miscellaneous organic compounds (R600-series), and blends (R400- and R500-series).
Note that many of the fluids in this section have not been classified by ASHRAE Standard 34 and are not currently used as refrigerants, although their “R-numbers” can be deduced based on the rules laid out in the standard. Such fluids are indicated with a footnote.
The physical properties tmp, tbp, Tc, and pc listed below are from Refs. 2-5, and additional details including uncertainties may be found therein. Details on TLV/TWA and STEL are given in Section 16. When available, values for GWP are for a 100-year time horizon relative to CO2 and are taken from Ref. 6. Otherwise, the GWP and ODP are taken from Refs. 5-8.
Name | ASHRAE Desig. | CAS Reg. No. | tmp/ºC | tbp/ºC | Tc/K | pc/MPa | STEL/ppm | GWP | ODP |
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Ammonia | 717 | 7664-41-7 | -77.66 | -33.32 | 405.56 | 11.358 | 35 | <1 | 0 |
Bis(difluoromethyl) ethera | E134 | 1691-17-4 | -123.15 | 5.7 | 420.25 | 4.15 | 5560 | 0 | |
Bromochlorodifluoromethane | 12B1 | 353-59-3 | -159.5 | -3.91 | 427.70 | 4.31 | 1750 | 3 | |
Bromodifluoromethanea | 22B1 | 1511-62-2 | -145.15 | -15.63 | 411.98 | 5.18 | 376 | 0.74 | |
Bromotrifluoromethane | 13B1 | 75-63-8 | -174.38 | -57.83 | 340.06 | 3.96 | 6290 | 10 | |
Butane | 600 | 106-97-8 | -138.26 | -0.49 | 425.13 | 3.80 | 1000 | 0 | |
Carbon dioxide | 744 | 124-38-9 | -56.56tp | -78.46sp | 304.13 | 7.375 | 30000 | 1 | 0 |
1-Chloro-1,1-difluoroethane | 142b | 75-68-3 | -130.43 | -9.12 | 410.26 | 4.06 | 1980 | 0.023-0.057 | |
1-Chloro-2,2-difluoroethanea | 142 | 338-65-8 | -130.79 | 35 | 478 | 175 | 0.019 | ||
Chlorodifluoromethane | 22 | 75-45-6 | -157.42 | -40.81 | 369.30 | 4.99 | 1760 | 0.055 | |
Chloroethanea | 160 | 75-00-3 | -138.35 | 12.30 | 460.35 | 5.24 | <1 | ||
Chloroethenea | 1140 | 75-01-4 | -153.84 | -13.71 | 424.96 | 5.59 | <<1 | ||
1-Chloro-1-fluoroethanea | 151a | 1615-75-4 | 16.14 | 466 | 5.01 | 55 | 0.015 | ||
1-Chloro-2-fluoroethanea | 151 | 762-50-5 | 53.02 | 510.20 | 5.04 | 10 | 0.008 | ||
Chlorofluoromethane | 31 | 593-70-4 | -135.15 | -12.75 | 455 | 5.76 | 65 | 0.02 | |
Chloromethane | 40 | 74-87-3 | -97.64 | -23.98 | 416.30 | 6.69 | 100 | 12 | 0.14-0.17 |
Chloropentafluoroethane | 115 | 76-15-3 | -99.4 | -39.22 | 353.10 | 3.13 | 7670 | 0.6 | |
1-Chloro-1,1,2,2-tetrafluoroethanea | 124a | 354-25-6 | 35.65 | 396 | 3.62 | 1825 | 0.026 | ||
1-Chloro-1,2,2,2-tetrafluoroethane | 124 | 2837-89-0 | -199.15 | -11.96 | 395.43 | 3.62 | 527 | 0.022 |
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