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Step forward for Low-GWP refrigerants as US proposes acceptance of hydrocarbons and R32

Move by the Environmental Protection Agency marks major step towards use of natural refrigeration in US. Proposed acceptance of R32 mirrors European moves towards mildly flammable ‘transitional’ HFCs

The US has proposed a range of acceptable uses for flammable hydrocarbon refrigerants – R600a, R290, R170 and R441A along with the mildy flammable R32 under the EPA’s Significant New Alternatives Policy (SNAP):
The EPA announced: “This rule lists as acceptable subject to use conditions a number of flammable refrigerant substitutes that EPA believes present overall lower risk to human health and the environment compared to other available or potentially available alternatives in the same end-uses.”

The refrigerants are R32, ethane, isobutane, propane, and the blend R441A. The Agency said: “This proposed rule, if finalised as proposed, would list one or more of these substitutes as acceptable subject to use conditions in a number of stationary air conditioning and refrigeration end-uses under the SNAP program, including: household refrigerators and freezers, retail food refrigeration, very low temperature refrigeration, non-mechanical heat transfer, vending machines, and residential and light commercial AC and heat pumps. The use conditions would set requirements to ensure that these substitutes do not present significantly greater risk in the end-use than other substitutes that are currently or potentially available.”

At the same time it is removing the prohibition on venting, release or disposal of the hydrocarbons, following evidence that this doesn’t affect the environment.

However, the EPA stressed that other environmental controls would be necessary to mitigate the flammability and that individual States may impose additional controls.

The move is highly significant for the use of natural refrigerants in the US, since the use of hydrocarbons was long-prohibited under a 1995 EPA ruling. The EPA said that the new ruling follows submissions from the supply chain and increased safe use of the refrigerants in other countries.

It said: “With the exception of HFC-32, the refrigerants proposed acceptable subject to use conditions in this action are hydrocarbons or blends consisting solely of hydrocarbons. Hydrocarbon refrigerants have been in use for over 15 years in countries such as Germany, the United Kingdom, Australia, and Japan in household and commercial refrigerators and freezers. To a lesser extent, hydrocarbon refrigerants have also been used internationally in small AC units such as mini-splits and portable room air conditioners.

Because hydrocarbon refrigerants have zero ozone depletion potential (ODP) and very low GWPs compared to most other refrigerants, many companies recently have expressed interest in using hydrocarbons in the United States. Also, some companies have reported improved energy efficiency with hydrocarbon refrigerants.”

The EPA goes on to say: “This action proposes to find acceptable, for specific end-uses and subject to use conditions, several alternatives that have GWPs significantly lower than both the ozone-depleting substances and HFC substitute refrigerants currently used in those end-uses. For example, this action, if finalised, would allow the use of isobutane (R600a) and the hydrocarbon blend R441A in stand-alone commercial refrigerators. The GWPs of these hydrocarbon refrigerants are less than 10, while HFCs typically used in this end-use - R134a and R404A - have GWPs of 1,430 and approximately 3,920, respectively. In addition, this action proposes to find propane (R290) acceptable for use in household refrigerator-freezers, subject to use conditions. The GWP of R290 is 3.3 compared to the GWP of 1430 for R134a, which is typically used in such equipment at present in the U.S. Finally, this action, if finalised, would allow for the use of propane, R441A, and difluoromethane (R32) in stand-alone room air conditioners.”

Natural refrigerants information specialist hydrocarbons21.com has summarised the proposed new applications in a user-friendly fashion:

·        Household refrigerators and freezers: The EPA proposes to list propane (R290), as acceptable subject to use conditions as a substitute in household refrigerators and freezers and combination refrigerator/freezers subject to the following use conditions. The charge size for any household refrigerator, freezer, or combination refrigerator and freezer for each circuit using R290 must not exceed 57 grams (2.01 ounces).

·        Retail food refrigeration: The EPA proposes to list isobutane (R600a) and the hydrocarbon blend R441A as acceptable subject to use conditions as substitutes in retail food refrigeration (new stand alone commercial refrigerators and freezers only). The EPA proposes a charge size limit of 150 grams (5.29 ounces).

·        Very low temperature refrigeration and non-mechanical heat transfer (intended to maintain temperatures considerably lower than for refrigeration of food, for example, -80°C (-170°F) or lower): The EPA proposes to list ethane (R170) as acceptable, subject to use conditions, in very low temperature refrigeration equipment and in non-mechanical heat transfer. The EPA proposes a charge size limit of 150 grams (5.29 ounces).

·        Vending machines: The EPA proposes to list R441A, isobutane and propane as acceptable substitutes in vending machines. The proposed charge size limit amounts to 150 grams (5.29 ounces).

·        Residential and light commercial AC and heat pumps: The EPA proposes to list hydrocarbons propane (R290) and R441A, as well as HFC32 as acceptable subject to use conditions as substitutes in residential and light commercial AC for self-contained room air conditioners, including packaged terminal air conditioners and packaged terminal heat pumps, window AC units, and portable AC units designed for use in a single room. The EPA proposes that charge size limits be determined based on the type of equipment (e.g. window AC, wall-mounted AC, etc), the alternative refrigerant used, and the normal rated capacity of the unit. For example, the maximum design charge size for a 10,000 BTU/hr window AC Unit would amount to 260 g of R290, 280 g of R441A, and 3.47 kg of R32.

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