This table gives physical properties and safe exposure limits 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 and blowing agents. Many of the compounds listed are believed to be less harmful to the environment than the traditional halocarbon refrigerants.
Column definitions for the table are as follows.
Column heading | Definition |
Name | Chemical name of refrigerant; listed alphabetically by name |
ASHRAE code | ASHRAE standard refrigerant designation (Ref. 1); see text for discussion |
Mol. form. | Molecular formula for refrigerant |
CAS Reg. No. | Chemical Abstracts Service Registry Number |
tm | Normal melting point, in °C ("tp" indicates a triple point) |
tb | Normal boiling point, in °C at 101.325 kPa or 760 mmHg ("sp" indicates a sublimation point) |
tc | Critical temperature, in °C |
pc | Critical pressure, in MPa |
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) |
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. 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).
Further references and additional data on the critical properties may be found in the tables “Critical Constants of Organic Compounds” and “Critical Constants of Inorganic Compounds” in this section. Details on threshold limits are given in Section 16.
Name | ASHRAE code | Synonym | Mol. form. | Formula | CAS Reg. No. | Mol. wt. | tm/ºC | tb/ºC | tc/ºC | pc/MPa | TWA/ppm | STEL/ppm |
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Ammonia | 717 | R-717 | H3N | NH3 | 7664-41-7 | 17.031 | -77.65 | -33.33 | 132.41 | 11.357 | 25 | 35 |
Bis(difluoromethyl) ether | E134 | HFE-134 | C2H2F4O | (CF2H)2O | 1691-17-4 | 118.030 | 5.5 | 147.1 | 4.16 | |||
Bromochlorodifluoromethane | 12B1 | Halon-1211 | CBrClF2 | CF2BrCl | 353-59-3 | 165.365 | -159.5 | -3.9 | 155 | 4.31 | ||
Bromodifluoromethane | 22B1 | Halon 1201 | CHBrF2 | 1511-62-2 | 130.920 | -145 | -15.6 | 138.9 | 5.2 | |||
Bromotrifluoromethane | 13B1 | Halon-1301 | CBrF3 | CF3Br | 75-63-8 | 148.910 | -174.4 | -57.8 | 66.91 | 3.96 | 1000 | |
Butane | 600 | C4H10 | C4H10 | 106-97-8 | 58.122 | -138.2 | -0.5 | 152.1 | 3.79 | 1000 | ||
Carbon dioxide | 744 | Carbonic anhydride | CO2 | CO2 | 124-38-9 | 44.010 | -56.561 tp | -78.464 sp | 30.98 | 7.375 | 5000 | 30000 |
1-Chloro-1,1-difluoroethane | 142b | HCFC-142b | C2H3ClF2 | CH3CClF2 | 75-68-3 | 100.495 | -130.43 | -9.12 | 137.16 | 4.06 | ||
1-Chloro-2,2-difluoroethane | 142 | C2H3ClF2 | 338-65-8 | 100.495 | 35 | |||||||
Chlorodifluoromethane | 22 | HCFC-22 | CHClF2 | CHClF2 | 75-45-6 | 86.469 | -157.41 | -40.8 | 96.15 | 4.98 | 1000 | |
Chloroethane | 160 | Ethyl chloride | C2H5Cl | C2H5Cl | 75-00-3 | 64.514 | -138.4 | 12.3 | 187.2 | 5.24 | 100 | |
Chloroethene | 1140 | Vinyl chloride | C2H3Cl | CH2=CHCl | 75-01-4 | 62.498 | -153.84 | -13.8 | 152 | 5.60 | 1 | |
1-Chloro-1-fluoroethane | 151a | C2H4ClF | CH3CHClF | 1615-75-4 | 82.504 | 16 | ||||||
1-Chloro-2-fluoroethane | 151 | C2H4ClF | 762-50-5 | 82.504 | 53.1 | |||||||
Chlorofluoromethane | 31 | HCFC-31 | CH2ClF | CH2ClF | 593-70-4 | 68.478 | -135.1 | -9.1 | 154 | |||
1-Chloro-1,2,2,3,3,4,4-heptafluorocyclobutane | C317 | Refrigerant C317 | C4ClF7 | 377-41-3 | 216.485 | -39.1 | 25 | |||||
Chloromethane | 40 | Methyl chloride | CH3Cl | CH3Cl | 74-87-3 | 50.488 | -97.6 | -24.1 | 143.09 | 6.72 | 50 | 100 |
Chloropentafluoroethane | 115 | CFC-115 | C2ClF5 | CF3CF2Cl | 76-15-3 | 154.466 | -99.4 | -39.2 | 79.9 | 3.141 | 1000 | |
1-Chloro-1,1,2,2-tetrafluoroethane | 124a | C2HClF4 | 354-25-6 | 136.476 | -117 | -13 | 126.8 |