Substitutes in Propellants
Substitutes are reviewed on the basis of environmental and health risks, including factors such as ozone depletion potential, global warming potential, toxicity, flammability, and exposure potential. Lists of acceptableThis designation means that a substitute may be used, without restriction, to replace the relevant ODS within the end-use specified. For example, HCFC-22 is an acceptable substitute for R-502 in industrial process refrigeration. Note that all SNAP determinations apply to the use of a specific product as a substitute for a specific ODS in a specific end-use. and UnacceptableThis designation means that it is illegal to use a product as a substitute for an ODS in a specific end-use. For example, HCFC-141b is an unacceptable substitute for CFC-11 in building chillers. Note that all SNAP determinations apply to the use of a specific product as a substitute for a specific ODS in a specific end-use. substitutes are updated several times each year. The list of substitutes is provided on this page.
Many acceptable substitutes under SNAP may be restricted under the Technology Transitions Program. For more information on Technology Transitions Program restrictions, visit: https://www.epa.gov/climate-hfcs-reduction/technology-transitions-program
Note: SNAP-related information published in the Federal Register takes precedence over all information on this page.
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| Substitute | Trade Name(s) | ODPA number that refers to the amount of ozone depletion caused by a substance. The ODP is the ratio of the impact on ozone of a chemical compared to the impact of a similar mass of CFC-11. Thus, the ODP of CFC-11 is defined to be 1.0. Other CFCs and HCFCs have ODPs that range from 0.01 to 1.0. The halons have ODPs ranging up to 10. Carbon tetrachloride has an ODP of 1.2, and methyl chloroform's ODP is 0.11. HFCs have zero ODP because they do not contain chlorine. A table of all ozone-depleting substances (http://www.epa.gov/ozone/science/ods/index.html) shows their ODPs, GWPs, and CAS numbers. | GWPThe index used to translate the level of emissions of various gases into a common measure in order to compare the relative radiative forcing of different gases without directly calculating the changes in atmospheric concentrations. GWPs are calculated as the ratio of the radiative forcing that would result from the emissions of one kilogram of a greenhouse gas to that from the emission of one kilogram of carbon dioxide over a period of time (usually 100 years). Gases involved in complex atmospheric chemical processes have not been assigned GWPs. See lifetime. | Flammable | SNAP Listing Date | Listing Status | Further Information |
| Alternative processes (pumps, mechanical pressure dispensers, non-spray dispensers) | 0 | 0 | no | March 18, 1994 | Acceptable | ||
| C3-C6 Saturated light hydrocarbons (e.g., propane, n-butane, isobutane) | 0 | 3 to 10 | yes | March 18, 1994 | Acceptable | Use with the necessary precautions due to flammability. | |
| Compressed Gases (carbon dioxide, air, nitrogen, nitrous oxide) | 0 to 0.017 | 0 to 300 | no | March 18, 1994 | Acceptable | ||
| Dimethyl Ether | 0 | <5 | yes | March 18, 1994 | Acceptable | Use with the necessary precautions due to flammability. Blends of DME with HCFCs are subject to section 610 restrictions. | |
| HCFC-142b | 0.065 | 2,310 | yes | March 18, 1994; July 20, 2015 (pdf) (686 KB) |
Unacceptable as of September 18, 2015. | All aerosol propellant uses of HCFC-22 and HCFC-142b are already prohibited as of January 1, 1994, under Section 610(d) of the Clean Air Act. Only one exemption exists. It is described in the section on aerosol substitutes in 59 FR 13044. It is illegal to manufacture or sell aerosols containing HCFC-22 or HCFC-142b as the propellant as of January 1, 2010, as per 40 CFR 82.15(g)(2). | |
| HCFC-22 | 0.055 | 1,810 | no | March 18, 1994; July 20, 2015 (pdf) (686 KB) |
Unacceptable as of September 18, 2015. | All aerosol propellant uses of HCFC-22 and HCFC-142b are already prohibited as of January 1, 1994, under Section 610(d) of the Clean Air Act. Only one exemption exists. It is described in the section on aerosol substitutes in 59 FR 13044. It is illegal to manufacture or sell aerosols containing HCFC-22 or HCFC-142b as the propellant as of January 1, 2010, as per 40 CFR 82.15(g)(2). | |
| HFC-125 | 0 | 3,500 | no | March 18, 1994; July 20, 2015 (pdf) (686 KB) |
Unacceptable as of January 1, 2016. | ||
| HFC-134a | 0 | 1,430 | no | March 18, 1994; July 20, 2015 (pdf) (686 KB) |
Unacceptable as of July 20, 2016 except for uses listed as acceptable, subject to use conditions. Acceptable with Use Conditions: From July 20, 2016 to January 1, 2018, acceptable subject to use conditions for products for which new formulations require federal governmental review and products for smoke detector functionality testing. As of July 20, 2016, acceptable subject to use conditions for a number of additional uses specified in the rule. As of July 20, 2016, blends of HFC-134a acceptable for FDA-approved MDIs for medical purposes. |
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| HFC-152a | 0 | 124 | yes | March 18, 1994 | Acceptable | ||
| HFC-227ea | 0 | 3,220 | no | May 22, 1998; July 20, 2015 (pdf) (686 KB) |
Unacceptable as of July 20, 2016 except for uses listed as acceptable, subject to use conditions. Acceptable as of July 20, 2016 for FDA-approved MDIs for medical purposes. |
Despite the relatively high global warming potential of this compound, the agency has listed this substitute as acceptable since it meets a specialized application in metered dose inhalers where other substitutes do not provide acceptable performance. | |
| HFO-1234ze(E) (trans-1,3,3,3-tetrafluoroprop-1-ene) | 0 | 6 | no | June 16, 2010 (pdf) (229 KB) | Acceptable | CAS Reg. No. is 29118-24-9. It has a recommended workplace exposure limit of 1000 ppm and a preliminary recommended acute consumer exposure limit of 420 ppm. | |
| SF6 | 0 | 22,800 | no | October 16, 1996 | Unacceptable | SF6 has the highest GWP of all industrial gases, and other compressed gases meet user needs equally well. |