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Proposed Rule2025-19812

Protection of Stratospheric Ozone: Listing of Substitutes Under the Significant New Alternatives Policy Program in Refrigeration and Air Conditioning and Fire Suppression

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Published

November 10, 2025

Issuing agencies

Environmental Protection Agency

Abstract

Pursuant to the U.S. Environmental Protection Agency's Significant New Alternatives Policy program, this action proposes to list several substitutes as acceptable, subject to use conditions, for residential and light commercial air conditioning and heat pumps, chillers, household refrigerators and freezers, motor vehicle air conditioning, and fire suppression and explosion protection. This action also proposes to update use conditions for substitutes previously listed for certain air conditioning end-uses and for water coolers.

Full Text

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<title>Federal Register, Volume 90 Issue 215 (Monday, November 10, 2025)</title>
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[Federal Register Volume 90, Number 215 (Monday, November 10, 2025)]
[Proposed Rules]
[Pages 50766-50811]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-19812]

[[Page 50765]]

Vol. 90

Monday,

No. 215

November 10, 2025

Part II

Environmental Protection Agency

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40 CFR Part 82

Protection of Stratospheric Ozone: Listing of Substitutes Under the
Significant New Alternatives Policy Program in Refrigeration and Air
Conditioning and Fire Suppression; Proposed Rule

Federal Register / Vol. 90 , No. 215 / Monday, November 10, 2025 /
Proposed Rules

[[Page 50766]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 82

[EPA-HQ-OAR-2024-0503; FRL-12207-01-OAR]
RIN 2060-AW45

Protection of Stratospheric Ozone: Listing of Substitutes Under
the Significant New Alternatives Policy Program in Refrigeration and
Air Conditioning and Fire Suppression

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: Pursuant to the U.S. Environmental Protection Agency's
Significant New Alternatives Policy program, this action proposes to
list several substitutes as acceptable, subject to use conditions, for
residential and light commercial air conditioning and heat pumps,
chillers, household refrigerators and freezers, motor vehicle air
conditioning, and fire suppression and explosion protection. This
action also proposes to update use conditions for substitutes
previously listed for certain air conditioning end-uses and for water
coolers.

DATES: Comments must be received on or before December 26, 2025 unless
a public hearing is held. If a public hearing is held, comments on this
notice of proposed rulemaking must be received on or before date 30
days after date of public hearing. Public hearing: Any party requesting
a public hearing must notify the contact listed in the FOR FURTHER
INFORMATION CONTACT section, which is Emily Maruyama at email address:
<a href="/cdn-cgi/l/email-protection#8ce1edfef9f5ede1eda2e9e1e5e0f5cce9fceda2ebe3fa">[email&#160;protected]</a> by 5 p.m. Eastern Daylight Time on or before
November 17, 2025. If a public hearing is held, it will take place on
or around November 25, 2025. Please refer to the SUPPLEMENTARY
INFORMATION section for additional information on the public hearing.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2024-0503 by any of the following methods:
<bullet> Federal Rulemaking Portal: <a href="https://www.regulations.gov">https://www.regulations.gov</a>
(our preferred method). Follow the online instructions for submitting
comments.
<bullet> Email: <a href="/cdn-cgi/l/email-protection#59387438373d742b741d363a323c2d193c2938773e362f">[email&#160;protected]</a>. Include Docket ID No. EPA
HQ-OAR-2024-0503 in the subject line of the message.
<bullet> Mail: U.S. Environmental Protection Agency, EPA Docket
Center, Air and Radiation Docket, Mail Code 28221T, 1200 Pennsylvania
Avenue NW, Washington, DC 20460.
<bullet> Hand Delivery or Courier: EPA Docket Center, WJC West
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004.
The Docket Center's hours of operations are 8:30 a.m. to 4:30 p.m.,
Monday-Friday (except Federal Holidays).
Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received may be posted without change
to <a href="https://www.regulations.gov">https://www.regulations.gov</a>, including personal information
provided. For detailed instructions on sending comments and additional
information on the rulemaking process, see the ``Public Participation''
heading of the SUPPLEMENTARY INFORMATION section of this document. For
information on EPA Docket Center services, please visit us online at
<a href="https://www.epa.gov/dockets">https://www.epa.gov/dockets</a>.
If a public hearing is requested on or before November 17, 2025,
the EPA will post an update at <a href="https://www.epa.gov/snap">https://www.epa.gov/snap</a>. The EPA does
not intend to publish a document in the Federal Register announcing
updates. The public hearing will be held on or around November 25,
2025. Information on the hearing including the time and URL will be
posted at EPA's Stratospheric Ozone website at <a href="https://www.epa.gov/snap">https://www.epa.gov/snap</a>. Refer to the section titled, Public Participation for additional
information.

FOR FURTHER INFORMATION CONTACT: For information about this proposed
rule, contact Emily Maruyama, Stratospheric Protection Division, Office
of Atmospheric Protection (Mail Code 6205A), Environmental Protection
Agency, 1200 Pennsylvania Ave. NW, Washington, DC 20460; telephone
number: (202) 564-2809; email address: <a href="/cdn-cgi/l/email-protection#731e1201060a121e125d161e1a1f0a331603125d141c05">[email&#160;protected]</a>. Notices
and rulemakings under the EPA's Significant New Alternatives Policy
(SNAP) program are available on the EPA's SNAP website at <a href="https://www.epa.gov/snap/snap-regulations">https://www.epa.gov/snap/snap-regulations</a>.

SUPPLEMENTARY INFORMATION:
Preamble acronyms and abbreviations. Throughout this preamble the
use of ``we,'' ``us,'' or ``our'' is intended to refer to the EPA. We
use multiple acronyms and terms in this preamble. While this list may
not be exhaustive, to ease the reading of this preamble and for
reference purposes, the EPA defines the following terms and acronyms
here:

2-BTP--2-bromo-3,3,3-trifluoropropene
AC--Air Conditioning
AIHA--American Industrial Hygiene Association
AIM--American Innovation and Manufacturing
ANSI--American National Standards Institute
APU--Auxiliary Power Unit
ASHRAE--American Society of Heating, Refrigerating and Air-
Conditioning Engineers
ASTM--American Society for Testing and Materials
BTMS--Battery Thermal Management Systems
CAA--Clean Air Act
CAS Reg. No.--Chemical Abstracts Service Registry Identification
Number
CBI--Confidential Business Information
CFC--Chlorofluorocarbon
CFR--Code of Federal Regulations
CMAQ--Community Multiscale Air Quality
CO<INF>2</INF>--Carbon Dioxide
CRP--Cooperative Research Program
DIY--Do it yourself
DOT--United States Department of Transportation
EEAP--Environmental Effects Assessment Panel
EPA--United States Environmental Protection Agency
ER&R--Emissions Reduction and Reclamation
EV--Exchange Value
FMEA--Failure Mode and Effects Analysis
FR--Federal Register
GHG--Greenhouse Gas
GSHP--Ground-Source Heat Pump
HC--Hydrocarbon
HCFC--Hydrochlorofluorocarbon
HCFO--Hydrochlorofluoroolefin
HCR--Hydrocarbon Refrigerant
HD--Heavy-Duty
HDOH--Heavy-Duty On-Highway
HFC--Hydrofluorocarbon
HFO--Hydrofluoroolefin
ICF--ICF International, Inc.
IEC--International Electrotechnical Commission
IPCC--Intergovernmental Panel on Climate Change
IPR--Industrial Process Refrigeration
IRC--International Residential Code
LD--Light-Duty
LFL--Lower Flammability Limit
LMDV--Light- and Medium-Duty Vehicle
MIR--Maximum Incremental Reactivity
MVAC--Motor Vehicle Air Conditioning or Motor Vehicle Air
Conditioner
MY--Model Year
NAAQS--National Ambient Air Quality Standard
NAICS--North American Industrial Classification System
NCEL--New Chemical Exposure Limit
NFPA--National Fire Protection Association
NRTL--Nationally Recognized Testing Laboratory
ODP--Ozone Depletion Potential
ODS--Ozone-Depleting Substances
OECD--Organisation for Economic Co-operation and Development
OEL--Occupational Exposure Limit
OEM--Original Equipment Manufacturer
OMB--United States Office of Management and Budget
OSHA--United States Occupational Safety and Health Administration
PBI--Proprietary Business Information
PEL--Permissible Exposure Limit
PFAS--Per- and Polyfluoroalkyl Substances

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PFC--Perfluorocarbon
PMN--Pre-Manufacture Notice
PMS--Pantone[supreg] Matching System
PPE--Personal Protective Equipment
ppm--Parts Per Million
PRA--Paperwork Reduction Act
PTAC--Packaged Terminal Air Conditioner
PTHP--Packaged Terminal Heat Pump
RAL--``Reichs-Ausschu[szlig] f[uuml]r Lieferbedingungen und
G[uuml]tesicherung,'' Germany's National Commission for Delivery
Terms and Quality Assurance
RCRA--Resource Conservation and Recovery Act
RFA--Regulatory Flexibility Act
RfC--Reference Concentration
SAE--SAE International, previously known as the Society of
Automotive Engineers
SDS--Safety Data Sheet
SIP--State Implementation Plan
SNAP--Significant New Alternatives Policy
SNUR--Significant New Use Rule
TEAP--Technology and Economic Assessment Panel
TFA--Trifluoroacetic Acid
TLV--Threshold Limit Value
TWA--Time Weighted Average
UL--UL, formerly known as Underwriters Laboratories, Inc.
UMRA--Unfunded Mandates Reform Act
VOC--Volatile Organic Compounds
VRF--Variable Refrigerant Flow
WEEL--Workplace Environmental Exposure Limit
WMO--World Meteorological Organization
WSHP--Water-Source Heat Pump

Table of Contents

I. Executive Summary
A. Purpose of the Regulatory Action
B. Summary of the Major Provisions of the Regulatory Action
II. Public Participation
A. Written Comments
B. Participation in Virtual Public Hearing
C. Public Access to Voluntary Consensus Safety Standards
III. General Information
A. Does this action apply to me?
B. What action is the Agency proposing to take?
C. What is the Agency's authority for taking this action?
D. What are the guiding principles of the SNAP program and what
are the SNAP criteria for evaluating substitutes?
IV. Residential and Light Commercial Air Conditioning and Heat Pumps
A. What is the EPA proposing in this action?
B. Background on Residential and Light Commercial AC and Heat
Pumps
C. What are the ASHRAE groups for refrigerant flammability and
toxicity?
D. What are the refrigerants the EPA is proposing to list as
acceptable in the residential and light commercial AC and heat pumps
end-use and how do they compare to other refrigerants in this end-
use?
E. What are the refrigerants for which the EPA is proposing to
update use conditions and how do they compare to other refrigerants
in the residential and light commercial AC and heat pumps end-use?
F. What use conditions is the EPA proposing in this action for
new and updated listings in this residential and light commercial AC
and heat pumps end-use?
G. What additional information is the EPA including in these
proposed listings?
V. Household Refrigerators and Freezers
A. What is the EPA proposing in this action?
B. Background on Household Refrigerators and Freezers
C. What are the ASHRAE groups for refrigerant flammability and
toxicity?
D. What is HCR 4141 and how does it compare to other
refrigerants in the household refrigerators and freezers end-use?
E. What use conditions is the EPA proposing in this action for
the new listing for HCR 4141 in new household refrigerators and
freezers?
F. What additional information is the EPA including in this
proposed listing?
VI. Water Coolers
A. What is the EPA proposing in this action?
B. Background on Water Coolers
C. What are the ASHRAE groups for refrigerant flammability and
toxicity?
D. What is R-290 and how does it compare to other refrigerants
in the water coolers end-use?
E. What use conditions is the EPA proposing in this action for
the updated listing for R-290 in new water coolers?
F. What additional information is the EPA including in this
proposed listing?
VII. Chillers
A. What is the EPA proposing in this action?
B. Background on Centrifugal Chillers and Positive Displacement
Chillers
C. What are the ASHRAE classifications for refrigerant
flammability and toxicity?
D. What is R-516A and how does it compare to other refrigerants
in the centrifugal chillers and positive displacement chillers end-
uses?
E. What use conditions is the EPA proposing in this action for
the new listing for R-516A in new centrifugal chillers and positive
displacement chillers?
F. What additional information is the EPA including in this
proposed listing?
VIII. Motor Vehicle Air Conditioning
A. What is the EPA proposing in this action?
B. Background on Motor Vehicle Air Conditioning
C. What are the ASHRAE classifications for refrigerant
flammability and toxicity used in MVACs?
D. What are refrigerants HFO-1234yf, R-444A, R-453A, R-456A, and
R-480A and how do they compare to other refrigerants in the same
end-use?
E. What use conditions is the EPA proposing in this action that
apply to proposed listings in this end-use?
F. Modification of ``unacceptability'' Listing Applicable to
Flammable Refrigerants in MVAC
G. Modifications to MVAC SNAP Requirements
IX. Fire Suppression and Explosion Protection
A. What is the EPA proposing in this action?
B. Background on Total Flooding Fire Suppression
C. What is 2-BTP/CO<INF>2</INF> and how does it compare to other
fire suppressants in the same end-use?
D. What use conditions is the EPA proposing?
E. Why is the EPA proposing these specific use conditions?
F. What Additional Information Is the EPA Including in This
proposed listing?
X. On Which Topics Is the EPA Specifically Requesting Comment?
A. Residential and Light Commercial AC and Heat Pumps, Household
Refrigerators and Freezers, and Water Coolers
B. Chillers
C. Motor Vehicle Air Conditioning
D. Fire Suppression and Explosion Protection
XI. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
B. Executive Order 14192: Unleashing Prosperity Through
Deregulation
C. Paperwork Reduction Act (PRA)
D. Regulatory Flexibility Act (RFA)
E. Unfunded Mandates Reform Act (UMRA)
F. Executive Order 13132: Federalism
G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
H. Executive Order 13045: Protection of Children From
Environmental Health and Safety Risks
I. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
J. National Technology Transfer and Advancement Act
XII. References

I. Executive Summary

A. Purpose of the Regulatory Action

The EPA is proposing new and revised listings after our evaluation
of human health and environmental information for certain substitutes
under Clean Air Act (CAA) section 612, Significant New Alternatives
Policy (SNAP) program. The Agency is proposing action on these new
listings in the refrigeration and air conditioning (AC), and fire
suppression and explosion protection sectors based on the information
that the EPA has included in the docket. This proposed action would
provide new refrigerant and fire suppressant options in specific uses,
thereby increasing flexibility for industry. It also would revise
certain existing requirements under the SNAP program to allow for
greater consistency and compatibility with current industry

[[Page 50768]]

safety standards such as those for AC equipment and for water coolers.

B. Summary of the Major Provisions of the Regulatory Action

This action proposes to list new alternatives as well as to revise
use conditions for existing alternatives for the refrigeration and AC
sector and to list a new alternative for the fire suppression and
explosion protection sector. Specifically, the EPA is proposing to:
<bullet> Update existing use conditions for hydrofluorocarbon
(HFC)-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-290, and R-441A in
residential and light commercial AC and heat pumps;
<bullet> List the hydrocarbon refrigerant (HCR) blend HCR 4141,
hydrofluoroolefin (HFO)-1234ze(E), and the HFO/HFC blend R-516A as
acceptable, subject to use conditions, in residential and light
commercial AC and heat pumps;
<bullet> List HCR 4141 as acceptable, subject to use conditions, in
household refrigerators and freezers;
<bullet> Update existing use conditions for R-290 in water coolers;
<bullet> List R-516A as acceptable, subject to use conditions, in
positive displacement chillers and centrifugal chillers;
<bullet> List HFO-1234yf as acceptable, subject to use conditions,
in retrofit light- and medium-duty vehicle (LMDV) motor vehicle air
conditioning (MVAC), in new MVACs on buses, and in new MVACs in heavy-
duty on-highway (HDOH) vehicles;
<bullet> List the blend R-444A as acceptable, subject to use
conditions, in retrofit LMDV MVACs and retrofit heavy-duty (HD) pickup
trucks and van MVACs (complete and incomplete);
<bullet> List the blend R-456A as acceptable, subject to use
conditions, in retrofit LMDV MVACs, retrofit HD pickup trucks and van
MVACs (complete and incomplete), retrofit HDOH MVACs, and retrofit
MVACs on buses and trains;
<bullet> List the blend R-480A as acceptable, subject to use
conditions, in retrofit LMDV MVACs, retrofit MVACs on HD pickup trucks
and vans (complete and incomplete), retrofit HDOH MVACs, and retrofit
MVACs on buses and trains;
<bullet> List the blend R-453A as acceptable, subject to use
conditions, in retrofit MVACs on buses and trains; and
<bullet> List 2-bromo-3,3,3-trifluoropropene/carbon dioxide (2-BTP/
CO<INF>2</INF>) as acceptable, subject to use conditions, as a total
flooding agent in fire suppression for use in normally unoccupied
spaces onboard aircraft including engine nacelles, auxiliary power
units (APUs), and cargo bays.
In summary, the common use conditions proposed for new household
refrigerators and freezers, residential and light commercial AC and
heat pumps, water coolers, and chillers are as follows:
(1) These refrigerants may be used only in new equipment, designed
specifically and clearly identified for use with the refrigerant. None
of these substitutes may be used as a conversion or ``retrofit''
refrigerant for existing equipment.
(2) These refrigerants must be used with warning labels on the
equipment and packaging that are similar to or match verbatim those
required by the relevant Underwriters Laboratories (UL) standard.
(3) Equipment must be marked with distinguishing red color-coded
hoses and piping to indicate use of a flammable refrigerant and marked
service ports, pipes, hoses, and other devices through which the
refrigerant is serviced.
Additional use conditions specific to particular end-uses also
apply and are discussed with each proposed listing. The regulatory text
of the proposed listings, including the proposed use conditions and
further information, appears in tables in the docket for this
rulemaking under the title ``Proposed Regulatory Text for SNAP Rule
27.'' All proposed new listings appear in proposed appendix Z of 40
Code of Federal Regulations (CFR) part 82, subpart G. The proposed
updated listings for HFC-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-
290, and R-441A in residential and light commercial AC and heat pumps
and for R-290 in new water coolers appear as proposed changes in
appendix R, appendix W, and appendix V of 40 CFR part 82, subpart G.

II. Public Participation

A. Written Comments

Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2024-
0503 at <a href="https://www.regulations.gov">https://www.regulations.gov</a> (our preferred method), or the
other methods identified in the ADDRESSES section. Once submitted,
comments cannot be edited or removed from the docket. The EPA may
publish any comment received to its public docket. Do not submit to the
EPA's docket at <a href="https://www.regulations.gov">https://www.regulations.gov</a> any information you
consider to be Confidential Business Information (CBI), Proprietary
Business Information (PBI), or other information whose disclosure is
restricted by statute. Multimedia submissions (audio, video, etc.) must
be accompanied by a written comment. The written comment is considered
the official comment and should include discussion of all points you
wish to make. The EPA will generally not consider comments or comment
contents located outside of the primary submission (i.e., on the web,
cloud, or other file sharing system). Please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a> for additional submission methods; the
full EPA public comment policy; information about CBI, PBI, or
multimedia submissions; and general guidance on making effective
comments.

B. Participation in Virtual Public Hearing

The EPA may hold a virtual public hearing if the agency receives a
request to hold one. Any party requesting a public hearing must notify
the contact listed in the FOR FURTHER INFORMATION CONTACT section,
which is Emily Maruyama at email address: <a href="/cdn-cgi/l/email-protection#6904081b1c10080408470c04000510290c1908470e061f">[email&#160;protected]</a> by 5
p.m. Eastern Daylight Time on or before November 17, 2025. If a virtual
public hearing is held, it will take place on or around November 25,
2025 and further information will be provided on the EPA's
Stratospheric Ozone website at <a href="https://www.epa.gov/snap">https://www.epa.gov/snap</a>.
The EPA will make every effort to follow the schedule as closely as
possible on the day of the hearing; however, please plan for the
hearings to run either ahead of schedule or behind schedule. Each
commenter will have 3-5 minutes to provide oral testimony. The EPA
encourages commenters to provide a copy of their oral testimony
electronically by emailing it to <a href="/cdn-cgi/l/email-protection#305d51424549515d511e555d595c49705540511e575f46">[email&#160;protected]</a>. The EPA also
recommends submitting the text of your oral comments as written
comments to the rulemaking docket EPA-HQ-OAR-2024-0503. Written
statements and supporting information submitted during the comment
period will be considered with the same weight as oral comments and
supporting information presented at the public hearing. The EPA may ask
clarifying questions during the oral presentations but will not respond
to the presentations at that time.
Please note that any updates made to any aspect of the hearing are
posted online at <a href="https://www.epa.gov/snap">https://www.epa.gov/snap</a>. While the EPA expects the
hearing to go forward as set forth above, please monitor our website or
contact Emily Maruyama, 202-564-2809, <a href="/cdn-cgi/l/email-protection#771a1605020e161a1659121a1e1b0e3712071659101801">[email&#160;protected]</a> to
determine if there are any updates. The EPA does

[[Page 50769]]

not intend to publish a document in the Federal Register announcing
updates.

C. Public Access to Voluntary Consensus Safety Standards

The EPA is proposing to incorporate by reference the American
National Standards Institute/American Society of Heating, Refrigerating
and Air-Conditioning Engineers (ANSI/ASHRAE) Standard 15-2024, ``Safety
Standard for Refrigeration Systems'' (hereafter ``ASHRAE 15-2024'') in
the use conditions for one refrigerant proposed to be listed for use in
chillers. The standard concerns the safe design, construction,
installation, and operation of refrigeration systems. This standard is
available at <a href="https://www.ashrae.org/technical-resources/bookstore/ashrae-refrigeration-resources">https://www.ashrae.org/technical-resources/bookstore/ashrae-refrigeration-resources</a> and may be purchased by mail at: 180
Technology Parkway NW, Peachtree Corners, Georgia 30092; by telephone:
1-800-527-4723 in the United States or Canada. ASHRAE 15-2024 and
ASHRAE 34-2024 are available as a bundle costing $178.00 for an
electronic copy or hard copy. The cost of obtaining this standard is
not a significant financial burden for equipment manufacturers or for
those selling, installing, and servicing the equipment. Therefore, the
ASHRAE standard the EPA is proposing to incorporate by reference is
reasonably available.
As one of two co-proposed options for use conditions for listings
in the residential and light commercial AC and heat pumps, household
refrigerators and freezers, and water coolers end-uses, the EPA
proposes to incorporate by reference several industry safety standards
from UL. The EPA is also proposing to incorporate by reference an
industry safety standard from UL in the use conditions for one
refrigerant proposed to be listed for use in chillers. The 2022
revision of the standard UL 60335-2-40, ``Household And Similar
Electrical Appliances--Safety--Part 2-40: Particular Requirements for
Electrical Heat Pumps, Air-Conditioners and Dehumidifiers'' (hereafter
``UL 60335-2-40''), 4th edition, December 15, 2022 is available at:
<a href="https://www.shopulstandards.com/ProductDetail.aspx?UniqueKey=43802">https://www.shopulstandards.com/ProductDetail.aspx?UniqueKey=43802</a>, and
may be purchased by mail at: COMM 2000, 151 Eastern Avenue,
Bensenville, IL 60106; Email: <a href="/cdn-cgi/l/email-protection#107f62747562635063787f60657c6364717e74716274633e737f7d">[email&#160;protected]</a>; Telephone: 1-
888-853-3503 in the United States or Canada (other countries dial 1-
415-352-2178); internet address: <a href="https://ulstandards.ul.com">https://ulstandards.ul.com</a> or <a href="https://www.shopulstandards.com">https://www.shopulstandards.com</a>. The cost of the 2022 revision to UL 60335-2-40
is $521 for an electronic copy and $652 for a hard copy.
The 2024 revision of the standard UL 60335-2-24, ``Household And
Similar Electrical Appliances--Safety--Part 2-24: Particular
Requirements for Refrigerating Appliances, Ice-Cream Appliances and
Ice-Makers,'' (hereafter ``UL 60335-2-24''), 3rd edition, July 29,
2022, and revisions through February 29, 2024, is available at: <a href="https://www.shopulstandards.com/ProductDetail.aspx?productId=UL60335-2-24_3_S_20220729">https://www.shopulstandards.com/ProductDetail.aspx?productId=UL60335-2-24_3_S_20220729</a>. It may be purchased by mail, email, or telephone as
described in the previous paragraph for UL 60335-2-40. The cost of the
2024 revision to the 3rd edition of UL 60335-2-24 is $555 for an
electronic copy and $694 for a hard copy.
The February 2024 revision of the standard UL 399, ``Drinking Water
Coolers'' (hereafter ``UL 399''), 8th edition, March 30, 2017, and
revisions through February 28, 2024, is available at: <a href="https://www.shopulstandards.com/ProductDetail.aspx?productId=UL399_8_S_20170330">https://www.shopulstandards.com/ProductDetail.aspx?productId=UL399_8_S_20170330</a>. It may be purchased by
mail, email, or telephone as described in the previous paragraphs for
UL 60335-2-40 and UL 60335-2-24. The cost of the February 2024 revision
to the 8th edition of UL 399 is $798 for an electronic copy and $998
for a hard copy.
UL also offers a subscription service to the Standards
Certification Customer Library that allows unlimited access to their
standards and related documents. The cost of obtaining these standards
is not a significant financial burden for equipment manufacturers and
purchase is not necessary for those selling, installing, and servicing
the equipment. Therefore, the UL standards the EPA is proposing to
incorporate by reference are reasonably available.

III. General Information

A. Does this action apply to me?

The following list identifies regulated entities that may be
affected by this rule and their respective North American Industrial
Classification System (NAICS) codes:
<bullet> New Single-Family Housing Construction (except For-Sale
Builders) (236115).
<bullet> Commercial and Institutional Building Construction
(236220).
<bullet> Plumbing, Heating, and Air Conditioning Contractors
(238220).
<bullet> All Other Basic Organic Chemical Manufacturing (325199).
<bullet> Air Conditioning and Warm Air Heating Equipment and
Commercial and Industrial Refrigeration Equipment Manufacturing
(333415).
<bullet> Aircraft Manufacturing (336411).
<bullet> Motor Vehicle Manufacturing (3361).
<bullet> Motor Vehicle Parts Manufacturing (3363).
<bullet> Refrigeration Equipment and Supplies Merchant Wholesalers
(423740).
<bullet> Recyclable Material Merchant Wholesalers (423930).
<bullet> Convenience Stores (445120).
<bullet> General Automotive Repair (811111).
<bullet> Appliance Repair and Maintenance (811412).
<bullet> Fire Protection (922160).
This list is not intended to be exhaustive, but rather to provide a
guide for readers regarding entities likely to be affected by this
action. To determine whether your facility, company, business, or
organization could be affected by this action, you should carefully
examine the regulations at 40 CFR part 82, subpart G, and the proposed
revisions. If you have questions regarding the applicability of this
action to a particular entity, consult the person listed in the FOR
FURTHER INFORMATION CONTACT section.

B. What action is the Agency proposing to take?

The EPA is proposing to list new alternatives for the refrigeration
and AC sector and for the fire suppression and explosion protection
sector. The Agency also proposes to revise use conditions for existing
alternatives for the refrigeration and AC sector and list a new
alternative for the fire suppression and explosion protection sector.

C. What is the Agency's authority for taking this action?

This action is based upon the EPA's authority under CAA section
612. The SNAP program implements CAA section 612. The first SNAP
rulemaking was promulgated in 1994, and set forth the framework for the
program in addition to finalizing listings for a number of alternatives
as acceptable. Since that time, EPA has issued 26 final rules and 39
Federal Register notices under the SNAP program. Several major
provisions of CAA section 612 are as follows:
CAA section 612(c) requires the EPA to promulgate rules making it
unlawful to ``replace any class I [(chlorofluorocarbon (CFC), halon,
carbon tetrachloride, methyl chloroform, methyl bromide,
hydrobromofluorocarbon, and chlorobromomethane)] or class II
[(hydrochlorofluorocarbon (HCFC))] substance with any substitute
substance which the Administrator determines

[[Page 50770]]

may present adverse effects to human health or the environment, where
the Administrator has identified an alternative to such replacement
that (1) reduces the overall risk to human health and the environment;
and (2) is currently or potentially available.'' CAA section 612(c)
requires the EPA to publish a list of the substitutes that it finds to
be unacceptable for specific uses and to publish a corresponding list
of acceptable substitutes for specific uses. Since its inception, the
SNAP program has continually responded to petitions and submissions
using either a rulemaking or notice to convey listing decisions.
CAA section 612(d) grants the right to any person to petition the
Administrator to add a substance to, or delete a substance from, the
lists published in accordance with section 612(c).
CAA section 612(e) directs the EPA to require ``any person who
produces a chemical substitute for a class I substance . . . to notify
the [Agency] not less than 90 days before new or existing chemicals are
introduced into interstate commerce for significant new use as
substitutes for a class I substance.'' The producer must also provide
the Agency with the producer's unpublished health and safety studies on
such substitutes.
The regulations for the SNAP program are promulgated at 40 CFR part
82, subpart G, and the Agency's process for reviewing SNAP submissions
is described in regulations at 40 CFR 82.180. Under these rules, the
Agency identified five types of listing decisions: acceptable;
acceptable, subject to use conditions; acceptable, subject to narrowed
use limits; unacceptable; and pending. Use conditions and narrowed use
limits are both considered ``use restrictions.'' Substitutes that are
deemed acceptable with no use restrictions (no use conditions or
narrowed use limits) can be used for all applications within the
relevant end-uses in the sector. After reviewing a substitute, the
Agency may determine that a substitute is acceptable if certain
conditions in the way that the substitute is used are met to minimize
risks to human health and the environment. The EPA describes such
substitutes as ``acceptable, subject to use conditions.'' \1\ For some
substitutes, the Agency may permit a narrowed range of use within an
end-use or sector. For example, the Agency may limit the use of a
substitute to certain end-uses or specific applications within an
industry sector. The EPA describes these substitutes as ``acceptable
subject to narrowed use limits.'' \2\ Under the narrowed use limit,
users intending to adopt these substitutes ``must ascertain that other
alternatives are not technically feasible.'' \3\ CAA section 612 and
the EPA regulations do not allow the introduction of substitutes on the
``unacceptable'' list into interstate commerce unless and until the
effective date of a final rule that changes an unacceptable listing to
acceptable, acceptable subject to use conditions, or acceptable subject
to narrowed use limits.
---------------------------------------------------------------------------

\1\ 40 CFR 82.180(b)(2).
\2\ 40 CFR 82.180(b)(3).
\3\ Id.
---------------------------------------------------------------------------

Many SNAP listings include ``comments'' or ``further information''
to provide additional information on substitutes. Since this additional
information is not part of the regulatory decision under SNAP, these
statements are not binding for use of the substitute under the SNAP
program. The EPA encourages users of substitutes to apply all
statements in the ``Further Information'' column in their use of these
substitutes. Regulatory requirements so listed may be binding under
other regulatory programs (e.g., worker protection regulations
promulgated by United States Occupational Safety and Health
Administration (OSHA) or Department of Transportation (DOT)
requirements for transport of flammable gases). In many instances, the
information simply refers to sound operating practices that have
already been identified in existing industry and/or building codes or
safety standards. Thus, many of the statements, if adopted, would not
require the affected user to make significant changes in existing
operating practices.
The ``Further Information'' column also does not necessarily
include all other legal obligations pertaining to the manufacture, use,
handling, and disposal of the listed substitute. Flammable refrigerants
being recovered or otherwise disposed of from commercial or industrial
air conditioning equipment are likely to be considered hazardous waste
under the Resource Conservation and Recovery Act (RCRA).\4\ Lower
flammability ignitable spent refrigerants that are recycled for reuse
can follow alternative safety standards under 40 CFR part 266, subpart
Q, instead of the full RCRA Subtitle C hazardous waste requirements.
---------------------------------------------------------------------------

\4\ 40 CFR parts 260-270.
---------------------------------------------------------------------------

For additional information on the SNAP program, visit the EPA's
SNAP website at <a href="https://www.epa.gov/snap">https://www.epa.gov/snap</a>. The lists of acceptable
substitutes for Ozone-Depleting Substances (ODS) in all industrial
sectors are available at <a href="https://www.epa.gov/snap/snap-substitutes-sector">https://www.epa.gov/snap/snap-substitutes-sector</a>. For more information on the Agency's process for administering
the SNAP program or criteria for evaluation of substitutes, refer to
the initial SNAP rulemaking, codified at 40 CFR part 82, subpart G.\5\
SNAP decisions and the appropriate Federal Register (FR) citations can
be found at <a href="https://www.epa.gov/snap/snap-regulations">https://www.epa.gov/snap/snap-regulations</a>. Substitutes
listed as unacceptable; acceptable, subject to narrowed use limits; or
acceptable, subject to use conditions, are also listed in the
appendices of 40 CFR part 82, subpart G.
---------------------------------------------------------------------------

\5\ See 59 FR 13044; March 18, 1994.
---------------------------------------------------------------------------

D. What are the guiding principles of the SNAP program and what are the
SNAP criteria for evaluating substitutes?

The guiding principles of the SNAP program are described in the
preamble to the first SNAP rule.\6\ These principles, reiterated and
described in many subsequent SNAP rulemakings, are:
---------------------------------------------------------------------------

\6\ Ibid.
---------------------------------------------------------------------------

1. Evaluate substitutes within a comparative risk framework: The
SNAP program evaluates the risk of substitutes compared to available or
potentially available substitutes which the new substitutes are
intended to replace.
2. Do not require that substitutes be risk free to be found
acceptable: Substitutes found to be acceptable must not pose
significantly greater risk than other substitutes, but they do not have
to be risk free.
3. Restrict those substitutes that are significantly worse: The EPA
does not intend to restrict a substitute if it has only marginally
greater risk.
4. Evaluate risks by use: Central to SNAP's evaluations is the
intersection between the characteristics of the substitute itself and
its specific end-use application.
5. Provide the regulated community with information as soon as
possible.
6. Do not endorse products manufactured by specific companies.
7. Defer to other environmental regulations when warranted: In some
cases, the EPA and other federal agencies have developed extensive
regulations under other sections of the CAA or other statutes that
address potential environmental or human health effects that may result
from the use of certain substitutes. The SNAP program takes existing
regulations under other programs into account when reviewing
substitutes.

[[Page 50771]]

In making decisions regarding whether a substitute is acceptable or
unacceptable, and whether substitutes present risks that are lower than
or comparable to risks from other substitutes that are currently or
potentially available in the end-uses under consideration, the EPA
examines the following criteria in 40 CFR 82.180(a)(7): ``(i)
atmospheric effects and related health and environmental impacts; (ii)
general population risks from ambient exposure to compounds with direct
toxicity and to increased ground-level ozone; (iii) ecosystem risks;
(iv) occupational risks; (v) consumer risks; (vi) flammability; and
(vii) cost and availability of the substitute.'' To enable the EPA to
assess these criteria, we require submitters to include various
information including but not limited to ozone depletion potential
(ODP), flammability, and the potential for human exposure. The EPA
applies the same criteria to all evaluations; however, the Agency
notes, for different sectors, the relevance of the factors may vary.
For example, for the fire suppression sector, flammability would be
considered differently than for the other sectors.
To assess atmospheric effects, the EPA uses both the ODP of class I
and class II ODS in appendix A of 40 CFR part 82, subpart A and where
appropriate the exchange values for HFCs listed in the American
Innovation and Manufacturing (AIM) Act and codified at 40 CFR part 84,
subpart A. For both ODP and exchange values, there are equivalent
values listed in Montreal Protocol on Substances that Deplete the Ozone
Layer (Montreal Protocol) annexes.\7\ For substitute compounds without
these values, the Agency uses information provided in the World
Meteorological Organization (WMO) 2022 assessment,\8\ and other
relevant sources. For chemical blends, such as the fire suppressant
blend proposed as acceptable in this document, the EPA calculates
atmospheric effects values as a mass weighted average of each component
of the blend.
---------------------------------------------------------------------------

\7\ <a href="https://ozone.unep.org/treaties/montreal-protocol/montreal-protocol-substances-deplete-ozone-layer">https://ozone.unep.org/treaties/montreal-protocol/montreal-protocol-substances-deplete-ozone-layer</a>.
\8\ WMO, Scientific Assessment of Ozone Depletion: 2022, GAW
Report No. 278, 509 pp.; WMO: Geneva, 2022. Available at: <a href="https://ozone.unep.org/system/files/documents/Scientific-Assessment-of-Ozone-Depletion-2022.pdf">https://ozone.unep.org/system/files/documents/Scientific-Assessment-of-Ozone-Depletion-2022.pdf</a>. (WMO, 2022).
---------------------------------------------------------------------------

In a future notice and comment rulemaking, the EPA plans to revisit
the criteria used for these evaluations particularly regarding
atmospheric effects. The EPA acknowledges that there is an important
relationship between ODS and HFCs. Therefore, this future rulemaking
may be combined with other relevant proposals in order to consider the
provisions regarding substitutes under CAA Title VI and the AIM Act
subsection (i) paragraph (5) holistically. The Agency is not proposing
or seeking comment on these topics in this rulemaking.
The SNAP program uses exposure assessments to estimate
concentration levels of substitutes to which workers, consumers, the
general population, and environmental receptors may be exposed over a
determined period of time. These assessments are based on personal
monitoring data or area sampling data if available. Exposure
assessments may be conducted for many types of releases including: (1)
releases in the workplace and in homes; (2) releases to ambient air and
surface water; (3) releases from the management of solid wastes.
The SNAP program uses toxicity data to assess the possible health
and environmental effects of exposure to substitutes. We use broad
health-based criteria such as: (1) Permissible Exposure Limits (PELs)
for occupational exposure; (2) inhalation reference concentrations
(RfCs) for noncarcinogenic effects on the general population; and (3)
cancer slope factors for carcinogenic risk to members of the general
population. When considering risks in the workplace, if OSHA has not
issued a PEL for a compound, the EPA then considers Recommended
Exposure Limits from the National Institute for Occupational Safety and
Health, Workplace Environmental Exposure Limits (WEELs) set by the
American Industrial Hygiene Association (AIHA), or Threshold Limit
Values (TLVs) set by the American Conference of Governmental Industrial
Hygienists. If limits for occupational exposure or exposure to the
general population are not already established, then the EPA derives
these values following the Agency's peer reviewed guidelines. Exposure
information is combined with toxicity information to explore any basis
for concern. Toxicity data are used with existing EPA guidelines to
develop health-based limits for interim use in these risk
characterizations.
The SNAP program examines flammability as a safety concern for
workers and consumers. The EPA assesses flammability risk using data
on: (1) flash point and flammability limits (e.g., OSHA flammability/
combustibility classifications); (2) data on testing of blends with
flammable components; (3) test data on flammability in consumer
applications conducted by independent laboratories; and (4) information
on flammability risk mitigation techniques.
The SNAP program also examines other potential environmental
impacts such as ecotoxicity and local air quality impacts. A compound
that is likely to be discharged to water may be evaluated for impacts
on aquatic life. Some substitutes are volatile organic compounds (VOC).
The EPA also notes whenever a potential substitute is considered a
hazardous or toxic air pollutant (under CAA sections 112(b) and 202(l))
or hazardous waste under the RCRA subtitle C regulations.
The EPA also notes that the U.S. government has not adopted a
single definition of per- and polyfluoroalkyl substances (PFAS) and has
not included HFCs, HFOs, 2-BTP, or trifluoroacetic acid (TFA) in any
PFAS-related restrictions. There also is no consensus definition of
PFAS as a class of chemicals, and different definitions can result in
more or fewer chemicals being classified as PFAS. There are several
HFCs and HFOs, among other chemicals such as 2-BTP and TFA, that are
defined as PFAS by some states and other jurisdictions. The EPA is not
proposing or seeking comment on any definitions of PFAS in this
rulemaking.
As described above, the proposed listing decisions consider whether
substitutes present risks that are lower than or comparable to risks
from other substitutes that are currently or potentially available in
the end-uses under consideration. The EPA does not assume any
substitute is risk free.

IV. Residential and Light Commercial Air Conditioning and Heat Pumps

A. What is the EPA proposing in this action?

The EPA is proposing to list R-516A and HFO-1234ze(E) as
acceptable, subject to use conditions, for use in all applications
under the residential and light commercial AC and heat pumps end-use.
The EPA is also proposing to list HCR 4141 as acceptable, subject to
use conditions, for use in self-contained room AC, a limited subset of
equipment covered by this end-use.
SNAP use conditions are designed to ensure that refrigerants are
listed for specific end-uses and in a way that mitigates risks to human
health and the environment. The use conditions proposed for these new
listings are discussed in Section IV.F. They include a requirement that
these refrigerants be used in new equipment only and specific
requirements for warning labels and markings. The EPA is also co-
proposing two options for an additional use condition related to
equipment

[[Page 50772]]

certification or industry safety standard requirements. These options
are described in detail in Section IV.F.4. One option would incorporate
by reference a new edition of the safety standard for this end-use. The
second option would require residential and light commercial AC and
heat pump equipment to be certified to a U.S. industry consensus safety
standard by an organization that is recognized as a Nationally
Recognized Testing Laboratory (NRTL).
The proposed regulatory text for listings using the third-party
certification option can be found in the docket for this rulemaking
under the title ``Proposed Regulatory Text for SNAP Rule 27'' in the
section ``Proposed revisions to Appendices R, V, W, and new Appendix
Z--Third-Party Certification Option (co-proposed as an alternative to
Section III).'' The proposed regulatory text for listings using the
incorporate by reference option can be found in the docket for this
rulemaking under the title ``Proposed Regulatory Text for SNAP Rule
27'' in the section ``Proposed revisions to Appendices R, V, W, and new
Appendix Z--Incorporate by Reference Option.'' If one of the use
condition options is finalized, the EPA would publish corresponding
finalized listings for R-516A, HCR 4141, and HFO-1234ze(E) in new
residential and light commercial AC and heat pump equipment in appendix
Z of 40 CFR part 82, subpart G.
The EPA is also proposing to update use conditions for the
previously listed refrigerants HFC-32, R-452B, R-454A, R-454B, R-454C,
R-457A, R-290, and R-441A for use in the residential and light
commercial AC and heat pumps end-use. Information on the previous
listing locations and the existing use conditions for these
refrigerants can be found in Section IV.E.
The EPA proposes that the same use conditions described previously
in this section for the new listings in this end-use would also apply
to these updated listings. The EPA is also co-proposing the same two
options for a use condition related to equipment certification or
industry safety standard requirements. For these updated listings, the
EPA intends to finalize one of these co-proposed options along with an
appropriate transition period to provide manufacturers with opportunity
for a smooth transition between the existing and updated use
conditions. Throughout Sections IV. and VI. in this document, the term
``updated use conditions'' refers to the set of use conditions being
proposed that would apply to new equipment manufactured after the
effective date of a final rule. The updated use conditions would
neither apply to nor affect equipment manufactured before the effective
date of the final rule. All the proposed use conditions are described
in detail in Section IV.F. The EPA would update the existing listings
for these substitutes in the following locations:
<bullet> HFC-32 in new residential and light commercial AC and heat
pumps--self-contained room AC only in appendix R of 40 CFR part 82,
subpart G;
<bullet> HFC-32 in new residential and light commercial AC and heat
pumps excluding self-contained room AC in appendix W of 40 CFR part 82,
subpart G;
<bullet> R-452B, R-454A, R-454B, R-454C, and R-457A in new
residential and light commercial AC and heat pumps in appendix W of 40
CFR part 82, subpart G; and
<bullet> R-290 and R-441A in new residential and light commercial
AC and heat pumps--self-contained room AC only in appendix R of 40 CFR
part 82, subpart G.
This proposal would also add listing numbers to each row in the
end-use column of appendix W in the table ``Refrigerants--Substitutes
Acceptable Subject to Use Conditions.'' Additionally, this proposal
would fix a typographical error in appendix R and appendix V where the
name of a standard was written as ``UL 60355-2-89'' instead of ``UL
60335-2-89'' in the ``Further information'' column. These formatting
and typographical edits would not substantively change any listings in
the tables and would improve clarity and readability.

B. Background on Residential and Light Commercial AC and Heat Pumps

The residential and light commercial AC and heat pumps end-use
includes equipment for cooling air in individual rooms, single-family
homes, and small commercial buildings. Heat pumps are equipment types
that offer both air heating and cooling options for such locations.
This end-use differs from commercial comfort AC, which uses chillers to
cool water that is then circulated to cool air throughout a large
commercial building, such as an office building or hotel. This end-use
includes both self-contained and split systems. Self-contained systems
include some rooftop AC units (e.g., those ducted to supply conditioned
air to multiple spaces) and many types of room ACs, including packaged
terminal air conditioners (PTACs), packaged terminal heat pumps
(PTHPs), window AC units, portable room AC units, and wall-mounted
self-contained ACs, designed for use in a single room. The EPA refers
to the variety of self-contained equipment for cooling a single room
using the phrase ``residential and light commercial AC and heat pumps--
self-contained room AC,'' irrespective of whether they are air
conditioners, providing space cooling, or heat pumps that can either
heat or cool a space. Split systems include ducted and non-ducted mini-
splits (which might also be designed for use in a single room), multi-
splits and variable refrigerant flow (VRF) systems, and ducted unitary
splits. Water-source and ground-source heat pumps (WSHPs/GSHPs) often
are packaged systems similar to self-contained equipment but could be
applied with the condenser separated from the other components similar
to split systems. Examples of equipment for residential and light
commercial AC and heat pumps include:
<bullet> Unitary AC or unitary split systems, also called central
air conditioners: These systems include an outdoor unit with a
condenser and a compressor, refrigerant lines, an indoor unit with an
evaporator, and ducts to carry cooled air throughout a building.
Central heat pumps are similar but offer the choice to either heat or
cool the indoor space.
<bullet> Multi-split and mini-split air conditioners and heat
pumps: Multi-split systems include one or more outdoor unit(s) with a
condenser and compressor, and multiple indoor units, each of which is
connected to the outdoor unit by refrigerant lines. Mini-split systems
are similar to multi-split systems, but they have only a single outdoor
unit and a single indoor unit, and they cool a single room. Non-ducted
multi-splits and mini-splits provide cooled or heated air directly from
the indoor unit rather than providing the air through ducts.
<bullet> Rooftop AC units: These are units that combine the
compressor, condenser, and evaporator in a single package and may
contain additional components for filtration and dehumidification. Most
units also include dampers to control air intake. Rooftop AC units cool
or heat outside air that is then delivered to the space directly
through the ceiling or a duct network. Rooftop AC units are common in
small commercial buildings such as a single store in a mall with no
indoor passageways between stores (e.g., a ``strip-mall''). They can
also be set up in an array to provide cooling or heating throughout a
larger commercial establishment such as a department store or
supermarket.

[[Page 50773]]

<bullet> Window air conditioners: These are self-contained units
that fit in a window with the condenser extending outside the window.
<bullet> PTACs and PTHPs: These are self-contained units that
consist of a separate, un-encased combination of heating and cooling
assemblies mounted through a wall. PTACs and PTHPs are intended for use
in a single room and use no ducts to carry cooled air and no external
refrigerant lines. Typical applications include motel or dormitory air
conditioners.
<bullet> Portable room air conditioners: These are self-contained
units that usually have wheels and are designed to be moved easily from
room to room. They may contain an exhaust hose that can be placed
through a window or door to eject heat to the outside.
<bullet> WSHPs and GSHPs: These are similar to unitary split
systems except that, when in cooling mode, heat is ejected from the
condenser through a second circuit rather than directly with outside
air. The second circuit transfers the heat to the ground, ground water,
or another body of water such as a lake. Water is used for this
transfer, but brine can be used if temperatures would risk freezing.
Some systems can perform heating in a similar matter with the
refrigerant circuit running in reverse. Regardless, the term ``heat
pump'' is most often used.
Unless specified, all these types of AC and heat pump equipment
would be subject to the listing decisions under this rule for the
identified substitutes. Of these types of equipment, window air
conditioners, PTACs, PTHPs, rooftop AC units, portable room air
conditioners, and often GSHPs and WSHPs are self-contained equipment
with the condenser, compressor, evaporator, and tubing all within a
single unit casing. In contrast, unitary split systems, multi-split
systems, and mini-split systems have an outdoor condenser that is
separate from an indoor unit. Compared to these split systems, self-
contained equipment typically has smaller charge sizes, fewer locations
that are prone to leak, and is less likely to require servicing by a
technician. These types of AC and heat pump equipment, both self-
contained and split systems, typically fall under the scope of UL
60335-2-40.

C. What are the ASHRAE groups for refrigerant flammability and
toxicity?

ASHRAE 34-2024 assigns a safety group for each refrigerant, which
consists of two to three alphanumeric characters (e.g., A2L or B1).\9\
The initial character indicates the toxicity, and the numeral, with or
without suffix letter, denotes the flammability. ASHRAE classifies
Class A refrigerants as refrigerants for which toxicity has not been
identified at concentrations less than or equal to 400 parts per
million (ppm) by volume, based on data used to determine threshold
limit value-time-weighted average (TLV-TWA) or consistent indices.
Class B signifies refrigerants for which there is evidence of toxicity
at concentrations below 400 ppm by volume, based on data used to
determine TLV-TWA or consistent indices.
---------------------------------------------------------------------------

\9\ ASHRAE, 2024b. ANSI/ASHRAE Standard 34-2024: Designation and
Safety Classification of Refrigerants.
---------------------------------------------------------------------------

ASHRAE 34-2024 also assigns refrigerants a flammability class of 1,
2, 2L, or 3. Tests for flammability are conducted in accordance with
American Society for Testing and Materials (ASTM) E681 using a spark
ignition source at 140 [deg]F (60 [deg]C) and 14.7 psia (101.3 kPa).
The flammability class ``1'' is given to refrigerants that, when
tested, show no flame propagation. The flammability class ``2'' is
given to refrigerants that, when tested, exhibit flame propagation,
have a heat of combustion less than 19,000 kJ/kg (8,169 BTU/lb), and
have a lower flammability limit (LFL) greater than 0.10 kg/m\3\. The
flammability class ``2L'' is given to refrigerants that meet the
requirements of the ``2'' class and have a maximum burning velocity of
10 cm/s or lower when tested in dry air at 73.4 [deg]F (23.0 [deg]C)
and 14.7 psia (101.3 kPa). Throughout this document, refrigerants in
the flammability class of ``2L'' are referred to as lower flammability
refrigerants. The flammability class ``3'' is given to refrigerants
that, when tested, exhibit flame propagation and either have a heat of
combustion of 19,000 kJ/kg (8,169 BTU/lb) or greater or have an LFL of
0.10 kg/m\3\ or lower. Throughout this document, refrigerants in the
flammability class of ``3'' are referred to as higher flammability
refrigerants.\10\ Flammability for refrigerant blends are designated
based on the worst case of formulation for flammability and the worst
case of fractionation for flammability determined for the blend.
Information about refrigerant safety groups is consistent with that in
prior rules under the SNAP program. See Section II.A.2. of SNAP Rule 26
\11\ for more detail. Using these safety groups, HFO-1234ze(E), HFC-32
and the refrigerant blends R-452B, R-454A, R-454B, R-454C, R-457A, and
R-516A are in the A2L Safety Group, while R-290, R-441A, and the
components of HCR 4141 are in the A3 Safety Group.
---------------------------------------------------------------------------

\10\ To see a diagram depicting these classifications, see SNAP
Rule 26, 89 FR 50417; June 13, 2024.
\11\ See 89 FR 50410; June 13, 2024.
---------------------------------------------------------------------------

D. What are the refrigerants the EPA is proposing to list as acceptable
in the residential and light commercial AC and heat pumps end-use and
how do they compare to other refrigerants in this end-use?

The EPA is proposing to list HCR 4141, HFO-1234ze(E), and R-516A as
acceptable, subject to use conditions, for this end-use. HCR 4141 is a
higher flammability refrigerant blend with each component in the A3
Safety Group. HFO-1234ze(E) and R-516A are lower flammability
refrigerants, both in the A2L Safety Group. HCR 4141 is a blend of the
saturated hydrocarbons (HCs) isobutane (R-600a), n-butane (R-600), and
propane (R-290); the percentages of each component in the blend are
claimed as CBI. The respective Chemical Abstracts Service Registry
Identification Numbers (CAS Reg. Nos.) of R-600a, R-600, and R-290 are
75-28-5, 106-97-8, and 74-98-6. HFO-1234ze(E), also known by the trade
names ``Solstice[supreg] ze and Solstice[supreg] 1234ze,'' is also
known as trans-1,3,3,3-tetrafluoroprop-1-ene (CAS Reg. No. 29118-24-9).
R-516A, also known by the trade name ``Forane[supreg] 516A,'' is a
blend consisting of 77.5 percent HFO-1234yf (also known as 2,3,3,3-
tetrafluoroprop-1-ene, CAS Reg. No. 754-12-1), 14 percent HFC-152a
(also known as 1,1-difluoroethane, CAS Reg. No. 75-37-6), and 8.5
percent HFC-134a (also known as 1,1,1,2-tetrafluoroethane, CAS Reg. No.
811-97-2).
Redacted submissions and supporting documentation for HCR 4141,
HFO-1234ze(E), and R-516A are provided in the docket. The EPA performed
a risk screening assessment to examine the human health and
environmental risks of each of these substitutes which are available in
the docket.\12\ \13\ \14\
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\12\ ICF, 2025a. Risk Screen on Substitutes in Residential and
Light Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: HCR 4141.
\13\ ICF, 2025b. Risk Screen on Substitutes in Residential and
Light Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: HFO-1234ze(E) (Solstice[supreg] ze, Solstice[supreg]
1234ze).
\14\ ICF, 2025c. Risk Screen on Substitutes in Residential and
Light Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: R-516A (Forane[supreg] 516A).
---------------------------------------------------------------------------

Environmental information: The specific atmospheric effects values
can be found in the individual risk screens for HCR 4141, HFO-
1234ze(E), and R-

[[Page 50774]]

516A. These were determined consistent with the source information
noted in Section III.C. above as well as using the methodology for
determining values for blends of chemicals (i.e., determined by the
percentage of each component). HFO-1234ze(E) and the components of R-
516A--HFC-134a, HFC-152a, and HFO-1234yf--are excluded from the EPA's
regulatory definition of VOC \15\ addressing the development of State
Implementation Plans (SIPs) to attain and maintain the National Ambient
Air Quality Standards (NAAQS).\16\
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\15\ 40 CFR 51.100(s).
\16\ 40 CFR 51.100(s) states that ``any compound of carbon''
which ``participates in atmospheric photochemical reactions'' is
considered a VOC unless expressly excluded in that provision based
on a determination of ``negligible photochemical reactivity'' when
compared to ethane's photochemical reactivity.
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HCR 4141 is a blend of saturated HCs, all of which fall under the
EPA's regulatory definition of VOC \17\ for the purpose of developing
SIPs to attain and maintain the NAAQS. The maximum incremental
reactivities (MIRs) \18\ of the components of this blend are as high or
higher and more reactive than that of ethane (MIR of 0.26 g
O<INF>3</INF>/g ethane), which the EPA uses as a threshold to determine
whether substances may have negligible photochemical reactivity in the
lower atmosphere (troposphere). The MIR of the blend HCR 4141 is
expected to be less than that of R-600a (MIR of 1.23 g O<INF>3</INF>/g
isobutane) and R-290 (MIR of 0.49 g O<INF>3</INF>/g propane). The EPA
has previously listed R-290 as acceptable, subject to use conditions,
in residential and light commercial AC and heat pumps--self-contained
room AC.
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\17\ 40 CFR 51.100(s).
\18\ MIR values are from ``Development of the SAPRC-07 Chemical
Mechanism and Updated Ozone Reactivity Scales,'' Report to the
California Air Resources Board by William P.L. Carter. Revised
January 27, 2010. (Carter, 2010).
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The EPA has previously performed air quality modeling on various
scenarios to determine whether emissions of HC refrigerants could have
a significant impact on local air quality, particularly in certain
cities with challenges in achieving attainment of the NAAQS for ground-
level ozone. The EPA prepared an analysis in 2014 \19\ and a follow-on
analysis in 2016 \20\ to evaluate the potential impact of the use of HC
refrigerants on ground-level ozone concentrations in the United States.
These analyses estimated refrigerant emissions from refrigeration and
AC equipment which were all assumed to contain propylene, R-600a, R-
290, and/or the HC blends R-441A and R-443A under different scenarios.
The EPA concluded that potential emissions of saturated HC refrigerants
used in refrigeration and AC equipment, such as R-290 and R-600a, do
not have a significant impact on local air quality and would not have a
greater overall impact on human health and the environment than other
acceptable refrigerants, even if their market share grew much greater
than anticipated.\21\
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\19\ ICF, 2014. Assessment of the Potential Impact of
Hydrocarbon Refrigerants on Ground Level Ozone Concentrations.
February, 2014.
\20\ ICF, 2016. Additional Follow-on Assessment of the Potential
Impact of Hydrocarbon Refrigerants on Ground Level Ozone
Concentrations. September, 2016.
\21\ ICF, 2014.
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The analysis evaluated HC refrigerant in the following end-uses:
cold storage warehouses, chillers, residential and light commercial AC
and heat pumps, and specific small, self-contained refrigeration and
air-conditioning units. The EPA considered it possible that HC
refrigerants may be used in those end-uses because either SNAP had
received applications for HCs in these end-uses or UL standards that
specifically address higher flammability refrigerants existed for these
end-uses, showing industry interest in using HC refrigerants. The
scenarios for these end-uses were modeled to consider whether they were
or were not exempted from the CAA section 608 venting prohibition.\22\
The HC emissions used for these scenarios were estimated based on the
EPA's Vintaging Model, and their potential contributions to ozone
concentrations were assessed using the EPA's Community Multiscale Air
Quality (CMAQ) model.
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\22\ ICF, 2016.
---------------------------------------------------------------------------

CMAQ modeling was performed for the Atlanta, Houston, and Los
Angeles regions, due to their distinctive geographic settings and
chronic high levels of ground-level ozone. Their ozone concentrations
were used to estimate and scale for national emission estimates. Ozone
concentrations due to HC refrigerant emissions were compared to 70 ppb
for the purposes of illustrating that even under a worst-case scenario,
the projected impacts on ground-level ozone would be small.\23\ We
found that even if all the HC refrigerants in appliances in end-uses
listed as acceptable, subject to use conditions, and listed as
acceptable in previous rules were to be emitted, as well as two
unsaturated HC refrigerants that the EPA ultimately listed as
unacceptable in certain end-uses, there would be a worst-case impact of
less than 0.15 ppb for ground-level ozone in the Los Angeles area.\24\
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\23\ The current NAAQS for ozone and other photochemical
oxidants is 0.070 ppm, as the fourth-highest daily maximum 8-hour
concentration, averaged across three consecutive years. The level of
the NAAQS, 0.070 ppm, is equivalent to 70 ppb.
\24\ ICF, 2016. Op cit.
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In 2022, the EPA conducted a more recent air quality analysis,
which considered additional end-uses and recently listed acceptable
refrigerants (e.g., R-1150 [ethylene] in very low temperature
refrigeration). This analysis did not include the refrigerants
propylene and R-443A due to the EPA's listing of these refrigerants as
unacceptable in certain end-uses, citing their potential for local air
quality impacts.\25\ The analysis utilized updated models and projected
future impacts out to 2040.\26\ The EPA found that the revised air
quality models showed slightly greater impacts compared to our 2014 and
2016 analyses when using the same refrigerants in the same end-uses.
For example, when looking at a worst-case scenario where the most
reactive HC refrigerant analyzed, propylene, was used broadly in all
refrigeration and AC end-uses, the largest incremental amount of
O<INF>3</INF> generated was 7.80 ppb in the 2016 analysis, which
increased to 8.62 ppb in the 2022 analysis. Changes to the CMAQ model,
more updated refrigerant emissions estimates from the EPA's Vintaging
Model, as well as the longer time-period considered, resulted in the
changes in impacts. However, the 2022 analysis also included analyses
that accounted for updates in the SNAP listings since the prior
analysis. In the 2022 analysis scenarios that estimated emissions if HC
refrigerants then listed as acceptable, subject to use conditions,
reached 100 percent market penetration in the end-uses in SNAP Rule 25,
the worst-case increase in ground-level ozone in Los Angeles was 0.012
ppb, in Houston was 0.009 ppb, and in Atlanta was 0.006 ppb. Unlike the
2016 analysis, the 2022 analysis only examined impacts of propylene in
the worst-case scenario and did not otherwise model propylene or the
propylene blend R-443A in the more reasonable scenarios, as those
refrigerants were listed as unacceptable in SNAP Rule 21.\27\ Because
propylene and R-443A had a much higher potential impact on local air
quality than the saturated HCs, removing propylene and R-443A from the
modeling resulted in lower projected impacts on local air quality in
the 2022 analysis compared to the 2016 analysis in the more reasonable
scenarios. The

[[Page 50775]]

EPA considers the 2022 modeling to further support the Agency's earlier
conclusions in 2015 and 2016 that use of saturated HCs as refrigerants
would not result in a significant increase in ground-level ozone.
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\25\ See SNAP Rule 21, 81 FR 86778; December 1, 2016.
\26\ ICF, 2022. Additional Assessment of the Potential Impact of
Hydrocarbon Refrigerants on Ground Level Ozone Concentrations. May
2022.
\27\ See 81 FR 86778; December 1, 2016.
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HCR 4141 is a blend of saturated HCs. The potential of this
refrigerant blend to form ground-level ozone, as determined by the MIRs
of its components, is expected to be less than that of R-600a or the
blend R-441A, and greater than that of R-290, as mentioned earlier in
this section. The EPA is proposing to list HCR 4141 as acceptable,
subject to use conditions, for use in household refrigerators and
freezers, where other HC refrigerants with comparable MIRs are listed
as acceptable, subject to use conditions, and for use in residential
and light commercial AC and heat pumps--self-contained room AC. Thus,
the EPA considers the potential impacts of HCR 4141 on local air
quality, as well as the overall risk to human health and the
environment, to be no greater than that of other substitutes available
and already listed as acceptable in the same end-uses.
Flammability information: HCR 4141 has higher flammability, with
all its components having an ASHRAE flammability classification of 3.
HFO-1234ze(E) and R-516A have lower flammability, with an ASHRAE
flammability classification of 2L.
Toxicity and exposure data: HFO-1234ze(E) and R-516A have an ASHRAE
toxicity classification of A (lower toxicity). HCR 4141 has not yet
been reviewed by ASHRAE's committee that develops the ASHRAE 34
standard, ``Refrigerant Designation and Safety Classification;''
however, its components all have an ASHRAE toxicity classification of
A.
Potential health effects of exposure to these substitutes include
drowsiness or dizziness. The substitutes may also irritate the skin or
eyes or cause frostbite. At sufficiently high concentrations, the
substitutes may cause irregular heartbeat. The substitutes could cause
asphyxiation if air is displaced by vapors in a confined space. These
potential health effects are common to many refrigerants.
The AIHA has established WEELs of 1,000 ppm as an 8-hr TWA for HFC-
134a and HFC-152a and 500 ppm as an 8-hr TWA for HFO-1234yf. ASHRAE has
adopted an Occupational Exposure Limit (OEL) of 800 ppm as an 8-hr TWA
for HFO-1234ze(E). ASHRAE also has adopted an OEL of 590 ppm as an 8-hr
TWA for R-516A.\28\ ASHRAE has adopted OELs of 1,000 ppm for each of
the components of HCR 4141. The EPA anticipates that users can meet the
AIHA WEELs and ASHRAE OELs and address potential health risks by
following requirements and recommendations in the manufacturers' safety
data sheets (SDSs), the proposed use conditions, and other safety
precautions common to the refrigeration and AC industry.
---------------------------------------------------------------------------

\28\ ANSI/ASHRAE Standard 34-2024. Designation and Safety
Classification of Refrigerants.
---------------------------------------------------------------------------

Comparison to other substitutes in this end-use: The atmospheric
effects for HCR 4141, HFO-1234ze(E), and R-516A are overall better than
or comparable to many of the substitutes currently listed as acceptable
in this end-use such as R-290, R-457A, R-454C, R-454A, R-454B, or R-
513A. More specifically, for new residential and light commercial AC
and heat pump applications, R-516A, HFO-1234ze(E), and HCR 4141 have
better than or comparable profiles to other acceptable substitutes
already listed in this end-use such as R-457A, R-454C, R-454A, R-454B,
R-513A, and HFC-32. The EPA acknowledges that the atmospheric effects
of ammonia absorption, acceptable in this end-use, may be lower than R-
516A, HFO-1234ze(E), and HCR 4141; however, the EPA is unaware of any
ammonia absorption systems that are being used in the United States for
this end-use. Other regulations also may limit the use of ammonia
absorption; therefore, the SNAP program does not consider this
substitute to be available or potentially available for new equipment
in the affected applications. Furthermore, as noted above, the EPA does
not intend to restrict a substitute if it has only marginally greater
risk. The EPA does not consider the atmospheric effects of these three
substitutes to be significantly greater and the Agency recognizes that
they can provide an additional option for situations where other
refrigerants are not viable, such as for use in split-systems and
equipment requiring larger charge sizes, or where equipment using other
generally available alternatives may be restricted in some
jurisdictions. For new residential and light commercial AC and heat
pumps--self-contained room AC, the atmospheric effects of HCR 4141 are
comparable to or lower than that of other acceptable substitutes in
this end-use category such as HFC-32, R-290, R-441A, and R-454B.
Toxicity risks of use, determined by the likelihood of exceeding
the exposure limit of these refrigerants in this end-use, are evaluated
in the previously referenced risk screens. The toxicity risks of using
HCR 4141, HFO-1234ze(E), and R-516A are comparable to or lower than
toxicity risks of other available substitutes in the same end-use.\29\
Toxicity risks of the proposed refrigerants can be minimized by use
consistent with the proposed use conditions and best industry
practices.
---------------------------------------------------------------------------

\29\ See previous listing decisions for information regarding
the toxicity of other available alternatives (see <a href="https://www.epa.gov/snap/substitutes-residential-and-light-commercial-air-conditioning-and-heat-pumps">https://www.epa.gov/snap/substitutes-residential-and-light-commercial-air-conditioning-and-heat-pumps</a>).
---------------------------------------------------------------------------

The flammability risks associated with HCR 4141, HFO-1234ze(E), and
R-516A in this end-use, determined by the likelihood of exceeding their
respective LFLs, are evaluated in the risk screens referenced earlier
in this section. While these refrigerants are more flammable than
available, acceptable A1 refrigerants in the same end-use, this risk
can be minimized by use consistent with the proposed use conditions, as
well as recommendations in the manufacturers' SDS and other safety
precautions common in the refrigeration and AC industry. The
flammability risks of these refrigerants are comparable to or less than
other available lower flammability (e.g., HFC-32, R-454B) or higher
flammability refrigerants (e.g., R-290) that the EPA has previously
listed as acceptable, subject to use conditions. The EPA is proposing
use conditions that mitigate human health and environmental risks
associated with the flammability of these alternatives so that they
will not pose greater overall risk than other acceptable substitutes in
this end-use category.
The EPA is proposing to list R-516A, HCR 4141, and HFO-1234ze(E) as
acceptable, subject to use conditions. Given the wide range of
applications for residential and light commercial AC and heat pumps,
not all refrigerants listed as acceptable under SNAP will be suitable
for the full range of equipment in this end-use. This proposal would
provide additional refrigerant options for the full range of
residential and light commercial AC and heat pump equipment.

E. What are the refrigerants for which the EPA is proposing to update
use conditions and how do they compare to other refrigerants in the
residential and light commercial AC and heat pumps end-use?

The EPA is proposing to update the use conditions for eight
previously listed refrigerants in the residential and light commercial
AC and heat pumps end-use. The EPA previously listed HFC-32, R-452B, R-
454A, R-454B, R-454C, and R-457A as acceptable, subject to use
conditions, for use in all residential and light commercial AC and heat
pump applications, and R-290 and R-441A as acceptable, subject to use

[[Page 50776]]

conditions, for use in residential and light commercial AC and heat
pumps--self-contained room AC.
R-290 is a HC refrigerant with three carbons and the formula
C<INF>3</INF>H<INF>8</INF>. R-441A is a HC blend \30\ consisting of 55
percent R-290, 36 percent R-600, six percent R-600a, and three percent
R-170 (ethane) by weight. R-290 and R-441A are higher flammability
refrigerants in the A3 Safety Group.
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\30\ The EPA notes that under the SNAP program, we review and
list refrigerants with specific compositions (59 FR 13044; March 18,
1994). To the extent possible, we follow ASHRAE's designations for
refrigerants. Blends of refrigerants must be reviewed separately.
For example, we consider each blend of R-290 with R-600a to be a
different and unique refrigerant, and each would require separate
submission, review and listing. Thus, blends of the refrigerants
that we are listing as acceptable, subject to use conditions, in
this rule are not acceptable.
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HFC-32 is also known as difluoromethane. R-452B, also known by the
trade names ``OpteonTM XL 55,'' and ``Solstice[supreg]
L41y,'' is a blend consisting of 67 percent by weight HFC-32; seven
percent HFC-125, also known as 1,1,1,2,2-pentafluoroethane; and 26
percent HFO-1234yf. R-457A, also known by the trade name
``Forane[supreg] 457A,'' is a blend consisting of 18 percent HFC-32, 12
percent HFC-152a, and 70 percent HFO-1234yf. R-454A, also known by the
trade name ``OpteonTM XL 40,'' is a blend consisting of 35
percent HFC-32 and 65 percent HFO-1234yf. R-454B, also known by the
trade names ``OpteonTM XL 41'' and ``Puron
AdvanceTM,'' is a blend consisting of 68.9 percent HFC-32
and 31.1 percent HFO-1234yf. R-454C, also known by the trade name
``OpteonTM XL 20,'' is a blend consisting of 21.5 percent
HFC-32 and 78.5 percent HFO-1234yf. R-457A, also known by the trade
name ``Forane[supreg] 457A,'' is a blend consisting of 70 percent HFO-
1234yf, 18 percent HFC-32, and 12 percent HFC-152a.
HFC-32, R-452B, R-454A, R-454B, R-454C, and R-457A are lower
flammability refrigerant blends in the A2L Safety Group. Additional
information on the refrigerants and their components can be found in
the docket for this rulemaking under the title ``Section IV.E.
Information on Refrigerants and Their Components--Residential and Light
Commercial AC and Heat Pumps.''
Redacted submissions and supporting documentation for HFC-32, R-
452B, R-454A, R-454B, R-454C, R-457A, R-290, and R-441A are provided in
the docket. The EPA performed updated risk screening for two proposed
updated A2L listings, R-454C and R-457A, and one proposed updated A3
listing, R-441A, to examine the human health and environmental risks of
these substitutes and to evaluate the impact of applying the 4th
edition of UL 60335-2-40. The EPA chose these three representative
substitutes which had the most conservative (lowest) LFLs and most
conservative short- and long-term exposure limits among the group of
refrigerants proposed for updated use conditions. These representative
refrigerants were selected because it was presumed that substances with
higher LFLs and exposure limits that were modeled for the same
scenarios and end-uses would also pass the risk screens. The EPA
proposes to conclude from these comparisons that while some calculated
concentrations changed due to different assumptions and requirements,
the refrigerants still could be used without exceeding the LFL and
therefore did not increase flammability or exposure risks compared to
the EPA's previous risk screens that assumed equipment followed UL
60335-2-40, 3rd edition. Thus, the risk screens demonstrated no greater
overall risk to human health and the environment than other
refrigerants being used when considering the impact of the co-proposed
use conditions requiring use that meets the requirements of UL 60335-2-
40, 4th edition. These risk screens are available in the docket.\31\
\32\ \33\
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\31\ ICF, 2025e. Risk Screen on Substitutes in Residential and
Light Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: R-441A.
\32\ ICF, 2025f. Risk Screen on Substitutes in Residential and
Light Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: R-454C (OpteonTM XL20).
\33\ ICF, 2025g. Risk Screen on Substitutes in Residential and
Light Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: R-457A (Forane[supreg] 457A).
---------------------------------------------------------------------------

Environmental information: The specific atmospheric effects values
can be found in the individual risk screens for HFC-32, R-290, R-441A,
R-452B, R-454A, R-454B, R-454C, and R-457A. These were determined
consistent with the source information noted in Section III.C. above
(e.g., CAA, the AIM Act) as well as using the methodology used for
determining values for blends of chemicals (i.e., determined by the
percentage of each component).
The refrigerant blends R-452B, R-454A, R-454B, R-454C, and R-457A
are made up of the components HFC-125, HFC-32, HFC-152a, and HFO-
1234yf. R-441A is made up of HC components and R-290 is a neat HC
refrigerant.
The components of the refrigerant blends, HFC-125, HFO-1234yf, HFC-
152a, and HFC-32, are excluded from the EPA's regulatory definition of
VOC \34\ for the purpose of addressing the development of SIPs to
attain and maintain the NAAQS. See Section IV.D. for discussion of air
quality analysis that was performed, which the EPA used to evaluate
potential air quality impacts due to emissions of R-290, R-441A, and
other HC refrigerants that are VOC under the EPA's regulatory
definition of VOC.\35\ The EPA has also established certain exemptions
to the CAA section 608 venting prohibition, as listed in 40 CFR
82.154(a)(1), and none of those exemptions apply to HFC-32, R-452B, R-
454A, R-454B, R-454C, or R-457A. The EPA previously exempted R-290 and
R-441A in self-contained room air conditioners for residential and
light commercial AC and heat pumps from the venting prohibition under
CAA section 608(c)(2), finding that such venting, release, or disposal
does not pose a threat to the environment.\36\ The EPA is not proposing
to change either of these decisions and is not reopening them for
comment.
---------------------------------------------------------------------------

\34\ 40 CFR 51.100(s).
\35\ Id.
\36\ See 80 FR 19454; April 10, 2015.
---------------------------------------------------------------------------

Flammability information: HFC-32, R-452B, R-454A, R-454B, R-454C,
and R-457A have lower flammability, with an ASHRAE flammability
classification of 2L. R-290 and R-441A have higher flammability, with
an ASHRAE flammability classification of 3.
Toxicity and exposure data: HFC-32, R-290, R-441A, R-452B, R-454A,
R-454B, R-454C, and R-457A have an ASHRAE toxicity classification of A
(lower toxicity). Potential health effects of exposure to these
substitutes include drowsiness or dizziness. The substitutes may also
irritate the skin or eyes or cause frostbite. At sufficiently high
concentrations, the substitutes may cause irregular heartbeat. The
substitutes could cause asphyxiation if air is displaced by vapors in a
confined space. These potential health effects are common to many
refrigerants.
The AIHA has established WEELs of 1,000 ppm as an 8-hr TWA for HFC-
32, HFC-125, HFC-134a, and HFC-152a and 500 ppm as an 8-hr TWA for HFO-
1234yf. ASHRAE also has adopted OELs of 1,000, 1,000, 870, 690, 850,
620, and 650 ppm as an 8-hr TWA for R-290, R-441A, R-452B, R-454A, R-
454B, R-454C, and R-457A, respectively.\37\ The EPA anticipates that
users can meet the AIHA WEELs and ASHRAE OELs and address potential
health risks by following requirements and recommendations in the
manufacturers'

[[Page 50777]]

SDS, the proposed use conditions, and other safety precautions common
to the refrigeration and AC industry.
---------------------------------------------------------------------------

\37\ OELs are those in ASHRAE 34-2024, ``Designation and Safety
Classification of Refrigerants.''
---------------------------------------------------------------------------

Comparison to other substitutes in this end-use: The atmospheric
effects for HFC-32, R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and
R-457A are overall better than or comparable to many of the substitutes
currently listed as acceptable. For new residential and light
commercial AC and heat pump applications (the full category), HFC-32,
R-452B, R-454A, R-454B, R-454C, and R-457A have comparable or higher
individual values than some other substitutes listed as acceptable in
part of this end-use such as R-290 and ammonia absorption and lower
values than other acceptable substitutes listed in this end-use (e.g.,
the exchange value of HFC-32 is lower than HFC-134a, R-407C, and R-
410A). However, the EPA is unaware of any ammonia absorption systems
being used in the United States for this end-use and due to its
flammability, R-290 is listed as acceptable for use in self-contained
room AC only and is not an available substitute for any of the other
end-uses within the sector. As noted above, the EPA does not intend to
restrict a substitute if it has only marginally greater risk. The EPA
does not consider the atmospheric effects of these proposed substitutes
to be significantly greater than other acceptable substitutes and the
Agency recognizes that they can provide an additional option for
situations where other refrigerants are not viable.
Toxicity risks of HFC-32, R-290, R-441A, R-452B, R-454A, R-452B, R-
454C, and R-457A in this end-use, determined by the likelihood of
exceeding their respective exposure limits, are evaluated in the
previously referenced risk screens. The toxicity risks of using HFC-32,
R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A are
comparable to or lower than toxicity risks of other available
substitutes in the same end-use.\38\ Toxicity risks of the proposed
refrigerants can be minimized by use consistent with the proposed use
conditions and best industry practices.
---------------------------------------------------------------------------

\38\ See previous listing decisions for information regarding
the toxicity of other available alternatives (<a href="https://www.epa.gov/snap/substitutes-residential-and-light-commercial-air-conditioning-and-heat-pumps">https://www.epa.gov/snap/substitutes-residential-and-light-commercial-air-conditioning-and-heat-pumps</a>).
---------------------------------------------------------------------------

The flammability risks of HFC-32, R-290, R-441A, R-452B, R-454A, R-
454B, R-454C, and R-457A in this end-use, determined by the likelihood
of exceeding their respective LFLs, are evaluated in the previously
referenced risk screens. While these refrigerants may pose greater
flammability risk than other available substitutes in the same end-use,
this risk can be minimized by use consistent with the proposed use
conditions, as well as recommendations in the manufacturers' SDS and
other safety precautions common in the refrigeration and AC industry.
The EPA is proposing use conditions that maintain the low potential
risk associated with the flammability of these alternatives so that
they will not pose greater overall risk than other acceptable
substitutes in this end-use category. A full discussion of the proposed
use conditions may be found in Section IV.F.
While R-290 and R-441A have higher flammability than many
substitutes listed as acceptable in this end-use, the proposed updated
use conditions would reduce the potential risk associated with the
flammability of these alternatives so that they would not pose greater
overall risk than other acceptable substitutes in this end-use. The
proposed substitutes HFC-32, R-452B, R-454A, R-454B, R-454C, and R-457A
would provide additional options for situations where other
refrigerants are not viable, such as for use in split-systems or
equipment requiring larger charge sizes, or where equipment using other
generally available alternatives may be restricted in some
jurisdictions.
The EPA proposes to find that updating the use conditions for the
existing listings for HFC-32, R-452B, R-454A, R-454B, R-454C, and R-
457A as acceptable, subject to use conditions, for use in all types of
residential and light commercial AC and heat pumps and for R-290 and R-
441A in residential and light commercial AC and heat pumps--self-
contained room AC, is appropriate to maintain a broad list of
acceptable substitutes available for the full range of applications
under this end-use and to continue safe use of these refrigerants.
These updated listings would help establish and maintain an equal
playing field for substitutes used in the market.
HFC-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-290, and R-441A
are currently listed as acceptable, subject to use conditions, for use
in the residential and light commercial AC and heat pumps end-use. The
EPA is not proposing to move any of these listings to any other listing
category (e.g., unacceptable). Rather, the EPA is proposing to update
the use conditions because the industry consensus safety standards that
were incorporated by reference at the time of the listing have since
been either updated \39\ or superseded.\40\
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\39\ UL 60335-2-40.
\40\ UL 484.
---------------------------------------------------------------------------

This list provides a summary of the existing listings for each
refrigerant in the residential and light commercial AC and heat pumps
end-use that the EPA is proposing to update:
<bullet> HFC-32 is listed as acceptable, subject to use conditions,
in all new residential and light commercial AC and heat pump
applications. The current use conditions incorporate by reference UL
60335-2-40, 3rd edition. Previous listings for this refrigerant in this
end-use and detailed information on the use conditions, listing
decision, and rationale for these previous listings can be found in
SNAP Rule 19,\41\ SNAP Rule 23,\42\ and SNAP Rule 25.\43\
---------------------------------------------------------------------------

\41\ See 80 FR 19454; April 10, 2015.
\42\ See 86 FR 24444; May 6, 2021.
\43\ See 88 FR 26382; April 28, 2023.
---------------------------------------------------------------------------

<bullet> R-452B, R-454A, R-454B, R-454C, and R-457A are listed as
acceptable, subject to use conditions, in all new residential and light
commercial AC and heat pump applications. The current use conditions
incorporate by reference UL 60335-2-40, 3rd edition. Previous listings
for these refrigerants in this end-use and detailed information on the
use conditions, listing decision, and rationale for these previous
listings can be found in SNAP Rule 23.\44\
---------------------------------------------------------------------------

\44\ See 86 FR 24444; May 6, 2021.
---------------------------------------------------------------------------

<bullet> R-290 and R-441A are listed as acceptable, subject to use
conditions, in new residential and light commercial AC and heat pumps--
self-contained room AC only. The current use conditions incorporate by
reference Supplement SA and Appendices B through F of the 8th edition
of UL 484. Previous listings for these refrigerants in this end-use and
detailed information on the use conditions, listing decision, and
rationale for these previous listings can be found in SNAP Rule 19.\45\
---------------------------------------------------------------------------

\45\ See 80 FR 19454; April 10, 2015.
---------------------------------------------------------------------------

F. What use conditions is the EPA proposing in this action for new and
updated listings in this residential and light commercial AC and heat
pumps end-use?

The proposed use conditions described in this section would apply
to newly listed refrigerants HCR 4141, HFO-1234ze(E), and R-516A in
this end-use and to previously listed refrigerants HFC-32, R-452B, R-
454A, R-454B, R-454C, R-457A, R-290, and R-441A in this end-use. For
these eight previously listed refrigerants, the proposed use conditions
would apply to new equipment manufactured after the effective date of
the final rule. The proposed updated use conditions would neither apply
to nor affect equipment

[[Page 50778]]

manufactured before the effective date of the final rule.
Many of the proposed use conditions described in this section
mirror the SNAP program's historical approach to requirements for lower
flammability and higher flammability refrigerants. For example, the
proposed use condition related to use only in new equipment is
consistent with previously listed lower flammability and higher
flammability refrigerants in this end-use. The proposed use conditions
related to labels and markings are very similar to previous
requirements for lower and higher flammability refrigerants in this
end-use, with a few changes to better align the EPA's requirements with
updated industry consensus safety standards. The co-proposed option
that would incorporate by reference UL 60335-2-40 described in Section
IV.F.4.a. would simply update the required safety standard to the
latest edition in a manner consistent with the EPA's historical
practice of incorporating portions of or entire industry consensus
safety standards by reference. The other co-proposed option described
in Section IV.F.4.b., while different than the EPA's historical
practice, would address situations where agency regulations require
adherence to editions of industry consensus safety standards that have
been updated and replaced subsequent to the issuance of a final rule.
The EPA is proposing to remove the existing use conditions specific
to refrigerant charge size limits for R-290, R-441A, R-452B, R-454A, R-
454B, R-454C, and R-457A in residential and light commercial AC and
heat pump applications. SNAP Rule 19 \46\ included a specific use
condition for R-290 and R-441A in self-contained room AC for
refrigerant charge size limits based on cooling capacity and type of
equipment. SNAP Rule 23 \47\ included a specific use condition for R-
452B, R-454A, R-454B, R-454C, and R-457A in all residential and light
commercial AC and heat pump applications for charge size based on UL
60335-2-40 and the room size where the equipment is used. The EPA is
not proposing to eliminate charge size restrictions. Rather, the EPA is
co-proposing two use condition options related to equipment
certification or industry consensus safety standards, which both
include requirements to ensure that equipment is designed using safe
refrigerant charge sizes. The EPA is proposing to rely on the charge
size restrictions inherent in that proposed requirement rather than
duplicate charge size restrictions in a separate use condition. The EPA
proposes the following use conditions:
---------------------------------------------------------------------------

\46\ See 80 FR 19454; April 10, 2015.
\47\ See 86 FR 24444; May 6, 2021.
---------------------------------------------------------------------------

1. New Equipment Only; Not Intended for Use as a Retrofit Alternative
The EPA is proposing that all refrigerants covered by this action
in the residential and light commercial AC and heat pumps end-use,
including the applicable applications (e.g., unitary split AC systems,
mini-splits, and heat pumps), may be used only in new equipment
designed to address concerns unique to lower and higher flammability
refrigerants. In other words, none of these substitutes may be used as
a conversion or ``retrofit'' refrigerant for existing equipment. These
lower and higher flammability refrigerants were not submitted under the
SNAP program to be used in retrofitted equipment, and no information
was provided on how to address hazards if they were to be used in
equipment that was designed for nonflammable refrigerants.
2. Labels
The EPA is proposing to require labels for residential and light
commercial AC and heat pump equipment. These labels would need to be
permanently attached at the locations provided. The following text
would be required for residential and light commercial AC and heat pump
equipment containing an A2L refrigerant that is proposed to be listed
in this rule:
a. On the outside of the equipment: ``WARNING--Risk of Fire.
Flammable Refrigerant Used. To Be Repaired Only by Trained Service
Personnel. Do Not Puncture Refrigerant Tubing.''
b. On the outside of the equipment: ``WARNING--Risk of Fire.
Dispose of Properly in Accordance with Federal or Local Regulations.
Flammable Refrigerant Used.''
c. On the inside of the equipment near the compressor: ``WARNING--
Risk of Fire. Flammable Refrigerant Used. Consult Repair Manual/Owner's
Guide Before Attempting to Service This Product. All Safety Precautions
Must be Followed.''
d. For any equipment pre-charged at the factory, on the equipment
packaging: ``WARNING--Risk of Fire due to Flammable Refrigerant Used.
Follow Handling Instructions Carefully in Compliance with National
Regulations''
e. On the indoor unit near the nameplate: A label stating the
minimum installation height (if applicable), in m and ft, and the
minimum room area (operating or storage), in m\2\ and ft\2\. These
values shall be calculated according to a U.S. industry consensus
safety standard for AC and heat pump equipment.
f. On the outside of non-fixed equipment, such as portable air
conditioners and window air conditioners and heat pumps: ``WARNING--
Risk of Fire--Store in a well ventilated room without continuously
operating flames or other potential ignition.''
g. For fixed equipment such as packed terminal air conditioners,
packaged terminal heat pumps, rooftop units, and split air
conditioners: ``WARNING--Risk of Fire--Auxiliary devices which may be
ignition sources shall not be installed in the ductwork, other than
auxiliary devices listed for use with the specific appliance. See
instructions.''
The EPA has previously stated that it would be difficult to see
warning labels with the minimum lettering height requirement for A2L
refrigerants of \1/8\ inch as required by the UL standard. Therefore,
as in previous rules,\48\ the EPA is proposing that the minimum height
for lettering be \1/4\ inch (6.4 mm) as opposed to \1/8\ inch, which
would make it easier for technicians, consumers, retail storeowners,
first responders, and those disposing of the appliance to view the
warning labels. Other than the proposed label under paragraph e, the
text of the labels is similar or verbatim in language to those required
by the 4th edition of UL 60335-2-40. They are also aligned with
labeling requirements for A2L refrigerants in previous SNAP Rules 23
\49\ and 25.\50\
---------------------------------------------------------------------------

\48\ See 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.
\49\ See 86 FR 24444, May 6, 2021.
\50\ See 88 FR 26382, April 28, 2023.
---------------------------------------------------------------------------

The proposed label under paragraph e describes the required content
of a label rather than exact language that the label would need to
contain. The same change is being proposed for one of the labels for
equipment using A3 refrigerants, see paragraph l, later in this
section. This proposed change would allow the EPA's use conditions to
remain consistent with the requirements of the latest edition of UL
60335-2-40 while giving flexibility for the use condition to remain
applicable even if the third-party certification option described in
Section IV.F.4.b. is finalized, and the UL standard is not incorporated
by reference. This proposed change is intended to avoid potential
conflict between the regulatory requirements and the industry safety
standards if the specific requirements in those standards are changed.
The EPA is also proposing labels for residential and light
commercial AC and

[[Page 50779]]

heat pump equipment using A3 refrigerants proposed in this rule. The
following text would need to be permanently attached at the locations
provided:
h. On the outside of the equipment: ``DANGER--Risk of Fire or
Explosion. Flammable Refrigerant Used. To Be Repaired Only by Trained
Service Personnel. Do Not Puncture Refrigerant Tubing.''
i. On the outside of the equipment: ``WARNING--Risk of Fire or
Explosion. Dispose Of Properly in Accordance with Federal or Local
Regulations. Flammable Refrigerant Used.''
j. On the inside of the equipment near the compressor: ``DANGER--
Risk of Fire or Explosion. Flammable Refrigerant Used. Consult Repair
Manual/Owner's Guide Before Attempting to Service This Product. All
Safety Precautions Must Be Followed.''
k. For any equipment pre-charged at the factory, on the equipment
packaging: ``DANGER--Risk of Fire or Explosion due to Flammable
Refrigerant Used. Follow Handling Instructions Carefully in Compliance
with National Regulations.''
l. On an indoor unit near the nameplate: A label stating the
minimum installation height (if applicable), in m and ft, and the
minimum room area (operating or storage), in m\2\ and ft\2\. These
values shall be calculated according to a U.S. industry consensus
safety standard for AC and heat pump equipment.
m. On the outside of non-fixed equipment, such as portable air
conditioners and window air conditioners and heat pumps: ``WARNING--
Risk of Fire or Explosion--Store in a well ventilated room without
continuously operating flames or other potential ignition.''
The EPA is proposing that the minimum height for lettering be at
least \1/4\ inch (6.4 mm), consistent with the labeling requirements
for A3 refrigerants under the 4th edition of UL 60335-2-40. This text
size makes it easier for technicians, consumers, retail storeowners,
first responders, and those disposing the appliance to view the warning
labels. The text of the proposed labels is similar or verbatim in
language to those that required by the 4th edition of UL 60335-2-40.
This proposed text differs from that in SNAP Rule 19 \51\ for A3
refrigerants in this end-use. For example, the proposed labels under
paragraphs k and m do not currently exist as use conditions for R-290
and R-441A but are consistent with the latest labeling requirements for
A3 refrigerants under the 4th edition of UL 60335-2-40. Additionally,
the proposed labels under paragraphs i and j use the words ``WARNING''
and ``DANGER'' in lieu of ``CAUTION.'' The EPA proposes these updates
to the labeling requirements to be consistent with the 4th edition of
UL 60335-2-40 and with the SNAP labeling requirements for other higher
flammability refrigerants. The EPA proposes to find that using a common
set of labels would aid in compliance, especially for a manufacturer
that uses more than one of these refrigerants or produces both self-
contained room ACs and heat pumps and other types of residential and
light commercial AC and heat pumps. The labels for residential and
light commercial AC and heat pump equipment using A3 refrigerants are
listed in paragraphs a through f in appendices R and Z in the proposed
regulatory text for the A3 listings in this end-use. The proposed
regulatory text can be found in the docket for this rulemaking under
the title ``Proposed Regulatory Text for SNAP Rule 27'' in the sections
``Proposed revisions to Appendices R, V, W, and new Appendix Z--
Incorporate by Reference Option'' and ``Proposed revisions to
Appendices R, V, W, and new Appendix Z--Third-Party Certification
Option (co-proposed as an alternative to Section III).'' The proposed
labeling requirements are identical in both sections.
---------------------------------------------------------------------------

\51\ See 80 FR 19454; April 10, 2015.
---------------------------------------------------------------------------

3. Color-Coded Hoses and Piping
The EPA is proposing to require that equipment have distinguishing
red (Pantone[supreg] Matching System [PMS] #185 or ``Reichs-
Ausschu[szlig] f[uuml]r Lieferbedingungen und G[uuml]tesicherung,''
[RAL] 3020 from Germany's National Commission for Delivery Terms and
Quality Assurance) color-coded hoses and piping to indicate use of a
flammable refrigerant. The equipment would need to have red marked
service ports, pipes, hoses, and other devices through which the
refrigerant is serviced. This color would need to be present at all
service ports and where service puncturing or otherwise creating an
opening from the refrigerant circuit to the atmosphere might be
expected. Markings would need to extend at least one inch (25 mm) from
the servicing port and would need to be replaced if removed. The EPA
has applied this proposed use condition in past actions for lower and
higher flammability refrigerants.\52\ The EPA is proposing that such
markings apply to both A2L and A3 refrigerants to establish a common,
familiar, and standard means of identifying the use of a lower or
higher flammability refrigerant. Being able to immediately identify the
use of a lower or higher flammability refrigerant would reduce the risk
of a technician using sparking equipment or otherwise having an
ignition source nearby. The AC and refrigeration industry currently
uses red-colored hoses and piping as means for identifying the use of a
lower or higher flammability refrigerant based on previous SNAP
listings. Likewise, distinguishing coloring is used elsewhere to
indicate an unusual and potentially dangerous situation, for example in
the use of orange-insulated wires in hybrid electric vehicles.
---------------------------------------------------------------------------

\52\ See 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.
---------------------------------------------------------------------------

The use of color-coded hoses and piping would be in addition to the
proposed use of warning labels. Having two such warning methods is
reasonable and consistent with other general industry practices. This
approach is the same as in our previous rules on A2L and A3
refrigerants.\53\
---------------------------------------------------------------------------

\53\ See 76 FR 78832, December 20, 2011; 80 FR 19454, April 10,
2015; 88 FR 26382, April 28, 2023.
---------------------------------------------------------------------------

4. Use Condition Options Related to Equipment Certification or Industry
Safety Standard Requirements
The EPA is co-proposing two options for a use condition related to
equipment certification or industry safety standard requirements. Under
the first option, the EPA would incorporate by reference a new edition
of the industry consensus safety standard for this end-use. Under the
second option, the EPA would require residential and light commercial
AC and heat pump equipment to be certified by an organization that is
recognized as an NRTL to a U.S. industry consensus safety standard that
is designed to allow for safe use of flammable refrigerants and
mitigates risks such that the listed refrigerants can be used in a
manner that does not pose a greater overall risk to human health and
the environment than other substitutes in this end-use.
a. Incorporate by Reference UL 60335-2-40, 4th Edition Option
Since 2008, the EPA has listed numerous A2, A2L, and A3
refrigerants as acceptable, subject to use conditions, addressing use
of lower and higher flammability refrigerants in end-uses where the EPA
has determined it is necessary to mitigate risks. Most often, the EPA
has relied in part on incorporating by reference industry consensus
safety standards to ensure these risks are mitigated. Industry
consensus safety standards are developed in cooperation with parties
with an interest in participating in the

[[Page 50780]]

development or use of the standard. For example, UL uses a process
where experts with various interests, including manufacturers,
government agencies, and academia, come together to agree on the safety
requirements for a product, resulting in a standard that reflects a
collective consensus on best practices for safety. These standards are
typically under continuous maintenance, meaning that they are updated
and superseded by newer editions. This often means that regulations and
safety standards are out of step; and thus, the EPA often updates its
regulations to incorporate the newer version of the standard. The
revision cycle for the 4th edition of UL 60335-2-40, including final
recirculation, concluded with its publication on December 15, 2022.
Under this first option, the EPA is proposing to set a use
condition consistent with the latest version of UL standards through
incorporation by reference. Thus, the EPA proposes to list new
refrigerants and update existing listings for refrigerants in the
relevant end-use covered by this action with a use condition that these
refrigerants may be used only in equipment that meets all requirements
in UL 60335-2-40, 4th edition. This option continues the practice of
updating regulations to align with newer editions of standards.
Specifically, the EPA is proposing to update the condition to meet
all requirements listed in UL 60335-2-40, 3rd edition, ``Household and
Similar Electrical Appliances--Safety--Part 2-40: Particular
Requirements for Electrical Heat Pumps, Air Conditioners and
Dehumidifiers,'' dated November 1, 2019 (for A2L refrigerants), or
Supplement SA and Appendices B through F of UL Standard 484 8th
edition, ``Room Air Conditioners,'' dated August 2, 2012 (for R-290 and
R-441A), with the proposed condition to meet all requirements listed in
the 4th edition of UL 60335-2-40, ``Household and Similar Electrical
Appliances--Safety--Part 2-40: Particular Requirements for Electrical
Heat Pumps, Air Conditioners and Dehumidifiers,'' dated December 15,
2022. This proposed use condition incorporating the 4th edition would
apply to new equipment manufactured after the effective date of any
final action. In cases where this rule includes requirements that are
different than those of UL 60335-2-40 (e.g., font size), the EPA is
proposing that the requirements of this rule apply.
UL 60335-2-40 applies to the SNAP applications of window unit room
air conditioners, PTACs and PTHPs, portable air conditioners, central
air conditioners, non-ducted AC systems, packaged rooftop units, WSHPs,
GSHPs, and other products. This UL standard indicates that refrigerant
charges greater than a specific amount (called ``m3'' in the UL
standard and based on the refrigerant's LFL) are beyond its scope and
that national safety standards might apply, such as ANSI or ASHRAE
15.2. Because the EPA has not evaluated such situations, this proposal
only covers residential and light commercial AC and heat pump equipment
that fits within the scope of the UL standard.
UL 60335-2-40 was developed in an open and consensus-based
approach, with the assistance of experts in the refrigeration and AC
industry as well as experts involved in assessing the safety of
products. Participants of the UL 60335-2-40 consensus standard process
reviewed results of testing on equipment for flammability risk in
residential applications and evaluated the relevant scientific studies.
Further, UL has developed safety standards for construction and system
design, markings, and performance tests concerning refrigerant leakage,
ignition of switching components, surface temperature of parts, and
component strength after being scratched. Aspects of system
construction and design, including charge size, ventilation, and
installation space, and greater detail on markings, are discussed later
in this section. While similar safety standards exist from other
bodies, such as the International Electrotechnical Commission (IEC), we
are proposing in this option to use specific UL standards that are most
applicable and used by U.S. manufacturers. The EPA used this approach
in previous SNAP rules concerning lower and higher flammability
refrigerants.\54\
---------------------------------------------------------------------------

\54\ See 76 FR 78832, December 20, 2011; 80 FR 19454, April 10,
2015; 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.
---------------------------------------------------------------------------

The EPA has evaluated the revisions and proposes to find that
construction and use of equipment in accordance with the 4th edition
would not pose greater overall risk to human health and the environment
than use in accordance with the 3rd edition. The 4th edition makes
changes that address potential hazards of flammable refrigerants
including refined requirements for leak detection systems to
accommodate various methods, increase robustness and reliability, and
account for deviation and drift over the system life cycle.
The requirements in UL 60335-2-40 would reduce the risk to workers
and consumers. Incorporating the latest edition of the UL standard as a
use condition would also reduce conflict between federal regulations,
building codes, and other authorities that require compliance with the
latest version of the UL standard. This section summarizes relevant
aspects of UL 60335-2-40 for information only and is not meant to be a
complete review of the standard or how it is applied.
UL 60335-2-40 limits the amount of refrigerant allowed in each type
of appliance based on several factors explained in that standard. The
EPA is proposing to require charge size limits for each of the proposed
refrigerants by equipment type in accordance with UL 60335-2-40, 4th
edition. Annex GG of the standard provides the charge limits,
ventilation requirements, and requirements for secondary circuits. The
standard specifies requirements for installation space of an appliance
(i.e., room floor area) and/or ventilation or other requirements which
are determined according to the refrigerant charge used in the
appliance, the installation location, and the type of ventilation of
the location or of the appliance. Within Annex GG, table GG.1DV
provides guidance on how to apply the requirements to address the
potential flammability hazards of flammable refrigerants.
UL 60335-2-40, 4th edition also contains new specific requirements
for determining releasable charge. As opposed to total refrigerant
charge, which is the actual refrigerant charge of a single
refrigerating system, releasable charge is the mass of refrigerant that
can be released into the indoor space from a refrigerating system in
the event of a leak. While accounting for releasable charge results in
larger total refrigerant charges allowed under the 4th edition when
compared to the 3rd edition, the EPA proposes to find that the
mitigation requirements in the 4th edition of the standard, such as
leak detection systems and safety shutoff valves, effectively reduce
risk and address the hazards of flammable refrigerants even at larger
total charge sizes.
UL 60335-2-40, 4th edition contains provisions for safety
mitigation that were developed to ensure the safe use of flammable
refrigerants over a range of appliances. In general, as larger charge
sizes are used, more stringent mitigation requirements apply. In
certain applications, refrigerant detection systems (as described in
Annex LL, Refrigerant detection systems for A2L refrigerants),
refrigerant sensors (as described in Annex MM, Refrigerant sensor
location confirmation test), and safety alarms are required. The 4th
edition includes significantly improved requirements for refrigerant
detection systems, including clarified sensor

[[Page 50781]]

location requirements and better test methods for leak simulation
tests.
Where mechanical ventilation (i.e., fans) is required in accordance
with Annex GG, it must be initiated by a separate refrigerant detection
system either as part of the appliance or installed separately. In a
room with no mechanical ventilation, Annex GG provides requirements for
openings to rooms based on several factors including the charge size
and the room area. The minimum opening is intended to be sufficient so
that natural ventilation would reduce the risk of using a flammable
refrigerant. The standard also includes specific requirements for split
system appliances covering construction, instruction manuals, and
allowable charge sizes, mechanical ventilation, safety alarms, and shut
off valves for A2L refrigerants.
In addition to Annex GG and table GG.1DV, UL 60335-2-40 has a
requirement for the maximum charge for an appliance using an A2L
refrigerant, such as HFC-32, HFO-1234ze(E), R-452B, R-454A, R-454B, R-
454C, R-457A, and R-516A. The 4th edition sets more comprehensive
requirements on A2L refrigerants than the 3rd edition, and the EPA
proposes to consider these additional safety mechanisms, including
charge size limitations, to be more protective of human health and the
environment. If the appliance is a portable appliance, a non-fixed
factory-sealed single package, or a cord-connected appliance, which may
be periodically or seasonally relocated (excluding servicing) by the
end user, there are no additional requirements for room area,
ventilation, or other risk mitigation if the charge is sufficiently
small--under three times the LFL. Additional requirements exist for
charge sizes exceeding three times the LFL.
For A3 refrigerants, including R-290, R-441A, and HCR 4141, UL
60335-2-40 requires a maximum charge of three times the LFL for an
appliance that is a portable appliance, a non-fixed factory-sealed
single package, or a cord-connected appliance which may be periodically
or seasonally relocated (excluding servicing) by the end user. For
example, for R-290 this maximum charge for non-fixed appliances would
be 114 g.
The EPA compared the effect that requirements from previous
standards (UL 484 and UL 60335-2-40, 3rd edition) versus UL 60335-2-40,
4th edition, would have on the results of the EPA's comparative risk
screens, which are included in the docket. The EPA conducted updated
risk screening on two proposed A2L listings and one proposed A3
listing, which had the most conservative (lowest) LFLs and most
conservative short- and long-term exposure limits among the proposed
alternatives. As discussed in Section IV.E., these risk screens
demonstrated that use of these refrigerants in the residential and
light commercial AC and heat pumps end-use would not pose greater
overall risk to human health and the environment than other
refrigerants being used when considering the impact of the co-proposed
use condition requiring use that meets the requirements of UL 60335-2-
40, 4th edition.
As discussed earlier in this section, the EPA is proposing to
remove the existing use conditions specific to refrigerant charge size
limits for R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A in
residential and light commercial AC and heat pump applications. Rather
than duplicate charge size restrictions in a separate use condition,
the EPA is proposing to rely on the charge size restrictions inherent
in the requirements of UL 60335-2-40, 4th edition. Consistent with
previous listings for other lower and higher flammability refrigerants
in this end-use, the EPA is not proposing to include a use condition
related to adherence to ASHRAE 15 or ASHRAE 15.2. As discussed in this
section, the 4th edition of UL 60335-2-40 includes changes from the 3rd
edition that specifically address the potential flammability hazards of
lower and higher flammability refrigerants. The EPA proposes to find
that these refrigerants can be used safely provided the use conditions
in this proposed rule are followed, including compliance with the 4th
edition of UL 60335-2-40. The EPA recognizes that in certain clauses,
UL 60335-2-40 refers to ASHRAE 15 and ASHRAE 15.2 for compliance. We
also note that other authorities might impose additional requirements,
such as the adoption of ASHRAE 15 and 15.2 in building codes, that
would provide an additional layer of safety above what the EPA is
proposing to require under SNAP.
Under this incorporate by reference option, all three of the new
refrigerant listings and the eight updated refrigerant listings
proposed for this end-use would include the use conditions described in
Sections IV.F.1., IV.F.2., and IV.F.3., as well as a use condition that
the refrigerant may only be used in equipment that meets all the
requirements of UL 60335-2-40, 4th edition.
The EPA performed assessments to examine the human health and
environmental risks of each of these substitutes. These assessments are
available in the docket.\55\ The proposed regulatory text for new and
updated listings under this option can be found in the docket under the
title ``Proposed Regulatory Text for SNAP Rule 27'' in the section
``Proposed revisions to Appendices R, V, W, and new Appendix Z--
Incorporate by Reference Option.''
---------------------------------------------------------------------------

\55\ See in section XII., ``References'': ICF, 2025a; ICF,
2025b; ICF, 2025c; ICF, 2025e; ICF, 2025f; and ICF, 2025g.
---------------------------------------------------------------------------

b. Third-Party Certification Option
As noted elsewhere, in recent rulemakings for listings of lower and
higher flammability refrigerants, the EPA has incorporated by reference
portions of or entire industry consensus safety standards as use
conditions for SNAP listings. The Agency recognizes that these
standards are under continuous maintenance, meaning that they are
updated and superseded by newer editions. This often means that
regulations and safety standards are out of step; and thus, the EPA
often updates its regulations to incorporate the newer version of the
standard and to avoid directing regulated entities to editions of
standards that have been updated and replaced subsequent to the
issuance of a final rule. This is time-consuming, increases
administrative burden, and there is often time between the issuance of
a new edition of a standard and a later revised regulation which could
result in confusion for the regulated community as well as slowing down
adoption of revised requirements based upon the most recent science and
industry experience.
This approach also may result in the EPA's requirements including
sections of standards that are not needed to address the flammability
risks of refrigerants. For example, UL 60335-2-40 includes certain
tests that apply to all parts of the equipment, not just to the
refrigerating system, and specifications about leakage current and
electrical strength, which are not needed specifically to address
flammability of refrigerants. Therefore, the EPA is proposing another
option to streamline use conditions and to maintain consistency with
the latest version of the relevant standards. This option allows for
the EPA to address flammability risks while recognizing that a specific
edition of a relevant standard applicable for the residential and light
commercial AC and heat pumps end-use may be replaced by a later
edition. This option is described in this Section IV.F.4.b.
Under this potential option, the EPA proposes that all residential
and light commercial AC and heat pump

[[Page 50782]]

equipment using the refrigerants listed in this rulemaking would need
to be certified by an OSHA-recognized NRTL to a U.S. industry consensus
safety standard that is designed to allow for safe use of flammable
refrigerants in residential and light commercial AC and heat pump
equipment, and mitigates risks such that the listed refrigerants can be
used in a manner that does not pose a greater overall risk to human
health and the environment than other substitutes in this end-use. For
listings in this end-use under this option, the EPA is proposing
replacing the practice of incorporating by reference portions of or
entire industry consensus safety standards with a use condition that
relies on NRTLs certifying equipment to a U.S. industry consensus
safety standard that mitigates risks. The industry consensus safety
standard would need to be designed for use in the United States and be
consistent with best industry safety practices (e.g., UL 60335-2-40).
The EPA proposes that an industry consensus safety standard used to
meet this use condition would need to contain requirements for:
<bullet> Refrigerant charge sizes and risk mitigation measures that
are designed to allow for safe use of flammable refrigerants (e.g.,
refrigerant detection systems, ventilation to maintain refrigerant
concentrations below the LFL in the case of a leak); and
<bullet> Markings that communicate the risks.
Definitions and requirements for the OSHA NRTL Program can be found
at 29 CFR 1910.7. The term ``NRTL'' means an organization recognized by
OSHA in accordance with appendix A to 29 CFR 1910.7, and which tests
for safety, lists or labels or accepts equipment or materials, and
meets the criteria described in 29 CFR 1910.7. Any testing agency or
organization considering itself to meet the definition of an NRTL as
specified in Sec. 1910.7 may apply for OSHA recognition.
While the EPA is proposing reliance on certification by these
NRTLs, the EPA is not opening OSHA's regulations at 29 CFR 1910.7 for
comment, including definitions or requirements, nor is the EPA seeking
comment on the OSHA program itself. For listings in this end-use under
this option, the EPA is proposing a use condition based on
certification by NRTLs instead of incorporation by reference of
portions of or entire industry consensus safety standards. In addition
to meeting the requirements laid out above, the U.S. industry consensus
safety standard used to meet this requirement would also need to be
deemed an appropriate test standard and approved by OSHA. The NRTL
Program regulation at 29 CFR 1910.7(c) sets forth the criteria for
determining whether a test standard is appropriate. An appropriate test
standard is a document which specifies the safety requirements for
specific equipment or class of equipment and is (1) recognized in the
United States as a safety standard providing an adequate level of
safety; (2) compatible with and maintained current with periodic
revisions of applicable national codes and installation standards; and
(3) developed by a standards developing organization under a method
providing for input and consideration of views of industry groups,
experts, users, consumers, governmental authorities, and others having
broad experience in the safety field involved; or (4) in lieu of
paragraphs (c) (1), (2), and (3), the standard is currently designated
as an ANSI safety-designated product standard or an ASTM test standard
used for evaluation of products or materials. The various procedures
for approval of appropriate test standards are found in the OSHA NRTL
Program Policies, Procedures, and Guidelines CPL-01-00-004 (Program
Directive). NRTLs and a list of appropriate test standards that are
recognized by OSHA are publicly available, and updated periodically, on
OSHA's website.\56\
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\56\ <a href="https://www.osha.gov/nationally-recognized-testing-laboratory-program/current-list-of-nrtls">https://www.osha.gov/nationally-recognized-testing-laboratory-program/current-list-of-nrtls</a> and <a href="https://www.osha.gov/nationally-recognized-testing-laboratory-program/list-standards">https://www.osha.gov/nationally-recognized-testing-laboratory-program/list-standards</a>.
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As discussed earlier in Section IV.F.4.a., industry consensus
safety standards are developed in cooperation with parties with an
interest in participating in the development or use of the standard.
The EPA has confidence in this safety standards development process, as
it relies on consensus built by the industry. For example, UL uses a
process where experts with various interests, including manufacturers,
government agencies, and academia, come together to agree on the safety
requirements for a product, resulting in a standard that reflects a
collective consensus on best practices for safety.
One example of an appropriate test standard for equipment in the
residential and light commercial AC and heat pumps end-use is UL 60335-
2-40. UL 60335-2-40 was developed in an open and consensus-based
approach. The EPA proposes to view this standard as one example of a
U.S. industry consensus safety standard that could be used to meet this
requirement, as the requirements of the standard align with the levels
of safety that the EPA expects in terms of mitigating risks to human
health and the environment. As mentioned in Sections IV.D. and IV.E.,
the EPA performed risk screening assessments to examine the human
health and environmental risks of the refrigerants being proposed in
this action for this end-use. These risk screens demonstrated that use
of these refrigerants in the residential and light commercial AC and
heat pumps end-use consistent with the latest edition of UL 60335-2-40
would not pose greater overall risk to human health and the environment
than other acceptable substitutes for new equipment in this end-use.
One potential downside of this third-party certification option is
that future revisions could be made to OSHA-recognized appropriate test
standards that do not align with the SNAP program's criteria for
mitigating risks to human health and the environment. However, the EPA
already monitors the development and revision process for industry
consensus safety standards that apply to equipment in the residential
and light commercial AC and heat pumps end-use and other end-uses. If
this option is finalized, the EPA would continue monitoring these
standards, and if revisions are made to industry safety standards that
impact their alignment with the SNAP program's risk mitigation
criteria, the EPA would raise concerns and could revisit and propose
changes to refrigerant listing categories and/or use conditions through
rulemaking.
OSHA recognizes NRTLs at the organizational-level as opposed to the
laboratory-level. Therefore, the laboratory that performs the equipment
testing would need to be part of an NRTL that is recognized by OSHA and
have the necessary equipment and training required to test to a
specific standard that would be most applicable to the equipment
applications in this section.
OSHA requires all electrical equipment used in the workplace to be
tested and certified by an NRTL or otherwise determined to be
``acceptable'' as defined in 29 CFR 1910.399. The EPA is proposing that
equipment in the residential and light commercial AC and heat pumps
end-use using the refrigerants proposed in this action would need to be
certified to a U.S. industry consensus safety standard by an OSHA-
recognized NRTL. In accordance with Annex B of the OSHA NRTL Program
Directive and section 4 of ISO/IEC 17065:2012, NRTLs shall maintain
registration of a certification mark with the U.S. Patent and Trademark
Office, and an NRTL's procedures shall require clients to apply the
NRTL's registered certification mark

[[Page 50783]]

to the certified equipment to signify that the equipment is certified
by an NRTL and complies with the requirements of an appropriate safety
test standard. In addition, the test standard(s), certification
category, or a symbol or code that identifies the test standard(s) to
which the unit is certified shall be shown adjacent to the NRTL's mark.
These markings provide users with evidence that the equipment complies
with applicable safety test standard requirements and is safe for use.
The EPA is not proposing to establish specific requirements or
protocols for laboratories because OSHA already has established such
requirements and performs detailed reviews of equipment certification
entities. OSHA's review of NRTLs includes a thorough evaluation of
application materials, assessments of the organization's programs and
facilities, publication of findings in the Federal Register, response
to public comments, and announcement of a final decision on NRTLs. OSHA
also performs ongoing evaluations of NRTLs and responds to safety
concerns that occur in the field. Because NRTLs must be recognized to
test to a specific safety standard, all of the requirements of that
particular safety standard are adopted by the NRTL, which is similar to
SNAP's current use condition approach for HFC-32, R-452B, R-454A, R-
454B, R-454C, R-457A, R-290, and R-441A that incorporates by reference
a particular safety standard.
By not incorporating by reference a specific edition of a relevant
safety standard in this use condition option, the EPA intends to
increase efficiencies by not having to propose a new rule each time a
safety standard is updated and to leverage OSHA's NRTL Program. The EPA
does not expect this option to pose significant additional burden on
manufacturers or NRTLs because most manufacturers of residential and
light commercial AC and heat pump equipment have their equipment
certified by an NRTL already. Manufacturers that do not already certify
their equipment through an OSHA-recognized NRTL would need to do so
beginning two years after the effective date of the final rule.
The EPA is aware of three entities, UL, Intertek, and CSA Group,
that are currently NRTLs and test and certify equipment to industry
consensus safety standards for equipment in the residential and light
commercial AC and heat pumps end-use. The EPA understands there may be
additional entities now or in the future.
As noted previously, the current SNAP regulations incorporate by
reference UL 60335-2-40, 3rd edition, which is no longer the latest
edition of a standard that is publicly available and applicable to this
end-use. OSHA regulations do not specify specific editions of
standards. Rather, an NRTL recognized for an ANSI-approved test
standard may use either the latest proprietary version or the latest
ANSI version of the standard, regardless of which version appears in
its list of test standards on OSHA's web page for the NRTL. When an
NRTL applies to be recognized to test to a particular standard, they
must submit the specific standard to which they aim to test. If an NRTL
is found to be testing and certifying equipment to a standard they are
not recognized for, OSHA may act.
As discussed earlier in this section, the EPA is proposing to
remove the existing use conditions specific to refrigerant charge size
limits for R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A in
residential and light commercial AC and heat pump applications. Rather
than duplicating charge size restrictions in a separate use condition,
the EPA is proposing to rely on the charge size restrictions inherent
in the process of getting residential and light commercial AC and heat
pump equipment certified by an NRTL to an industry consensus safety
standard that is designed to allow for safe use of flammable
refrigerants.
Under this third-party certification option, all three of the new
refrigerant listings and eight updated refrigerant listings proposed
for this end-use would include the use conditions described in Sections
IV.F.1., IV.F.2., and IV.F.3. There would also be a condition that
equipment be certified by an OSHA-recognized NRTL to a U.S. industry
consensus safety standard that is designed to allow for safe use of
flammable refrigerants in residential and light commercial AC and heat
pump equipment.
The EPA performed an assessment to examine the human health and
environmental risks of each of the proposed new substitutes. These
assessments are available in the docket.\57\ As discussed in Section
IV.E., the EPA also conducted updated analyses for three representative
substitutes for the updated listings to evaluate the health and safety
implications of designing and using AC equipment in accordance with the
latest edition of UL 60335-2-40, which the EPA proposes to view as one
example of a U.S. industry consensus safety standard that could be used
to meet this third-party certification requirement. These analyses
found that use of these proposed refrigerants in accordance with this
standard would not pose greater overall risk to human health and the
environment than other acceptable substitutes for new equipment in this
end-use. These assessments are available in the docket.\58\ Proposed
regulatory text for these new and updated listings under this potential
option can be found in the docket under the title ``Proposed Regulatory
Text for SNAP Rule 27'' in the section ``Proposed revisions to
Appendices R, V, W, and new Appendix Z--Third-Party Certification
Option (co-proposed as an alternative to Section III).''
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\57\ See in section XII., ``References'': ICF, 2025a; ICF,
2025b; and ICF, 2025c.
\58\ See in section XII., ``References'': ICF, 2025e; ICF,
2025f; and ICF, 2025g.
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5. When would the use conditions take effect?
For the newly listed refrigerants in this end-use, the use
conditions would take effect on the effective date of a final rule
based upon this proposal. For the refrigerants for which the EPA is
proposing to update use conditions in this end-use, the EPA is
proposing to allow regulated entities to follow either the existing use
conditions or the proposed updated use conditions from the effective
date of a final rule until two years after the effective date of the
final rule.
If the EPA finalizes the third-party certification option,
equipment manufactured between the effective date of the final rule and
two years after that effective date could follow either the existing
use conditions that include use of either UL 60335-2-40, 3rd edition
\59\ or the updated use conditions that would include certification of
equipment by an OSHA-recognized NRTL. The updated use conditions would
neither apply to nor affect equipment manufactured before the effective
date of the final rule.
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\59\ Or UL 484, 8th edition for R-290 and R-441A.
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G. What additional information is the EPA including in these proposed
listings?

For all proposed listings in this end-use, the EPA is including
recommendations, found in the ``Further Information'' column of the
proposed listings, to protect personnel from the risks of using
flammable refrigerants. Similar to our previous listings of flammable
refrigerants, the EPA is including information on the OSHA requirements
at 29 CFR part 1910, proper ventilation, personal protective equipment
(PPE), fire extinguishers, use of spark-proof tools

[[Page 50784]]

and equipment designed for flammable refrigerants, and training.
If the third-party certification option described in Section
IV.F.4.b. is finalized, the EPA would also include a sentence in the
``Further Information'' column stating that the EPA views UL 60335-2-40
to be an example of an appropriate U.S. industry consensus safety
standard that mitigates risks.
Since this additional information is not part of the regulatory
decision under SNAP, these statements are not binding for use of the
substitute under the SNAP program. While the statements in the
``Further Information'' column are not legally binding under the SNAP
program, the EPA encourages users of substitutes to apply all
statements in the ``Further Information'' column in their use of these
substitutes.

V. Household Refrigerators and Freezers

A. What is the EPA proposing in this action?

The EPA is proposing to list HCR 4141 as acceptable, subject to use
conditions, for use in new household refrigerators and freezers. The
EPA would list HCR 4141 in a table in the new appendix Z of 40 CFR part
82, subpart G.
The EPA is proposing several use conditions for the use of HCR 4141
in the household refrigerators and freezers end-use. SNAP use
conditions are designed to ensure that refrigerants are listed for
specific end-uses and in a way that mitigates risks to human health and
the environment. In summary, the EPA is co-proposing two options for
use conditions to address flammability risks of the refrigerant HCR
4141 in household refrigerators and freezers similar to the two options
discussed in Section IV.F.4. for the residential and light commercial
AC and heat pumps end-use. The key difference between the two options
in the household refrigerators and freezers end-use and the two options
in the residential and light commercial AC and heat pumps end-use is
the industry safety standard that the EPA would incorporate by
reference or would describe as being a relevant industry consensus
safety standard for third-party certification. In the household
refrigerators and freezers end-use the relevant U.S. industry consensus
safety standard that addresses safe use of flammable refrigerant is UL
60335-2-24, ``Household and Similar Electrical Appliances--Safety--Part
2-24: Particular Requirements for Refrigerating Appliances, Ice-Cream
Appliances and Ice-Makers,'' rather than UL 60335-2-40.
Under both options, the EPA proposes the same use conditions that
would restrict the use of the refrigerant HCR 4141 to new equipment
that is specifically designed for that refrigerant and that would
require warning labels and markings on equipment to inform consumers,
technicians, and first responders of potential flammability hazards.
Those common use conditions are described in Section V.E.
The two co-proposed options take two different potential approaches
to proposed use conditions addressing design safety requirements for
household refrigerators and freezers and in particular, charge size.
These options are described in detail in Sections V.E.4.a. and V.E.4.b.
Section V.E.4.a. describes an option in which the EPA would incorporate
by reference UL 60335-2-24, 3rd edition, including testing and charge
sizes. Section V.E.4.b. describes an option in which the EPA would
require household refrigerators and freezers to be certified to a U.S.
industry consensus safety standard such as UL 60335-2-24 by an
organization that OSHA recognizes as an NRTL. The EPA will consider
comments and available information and could finalize either of these
two co-proposals.
The common use conditions are described in Sections V.E.1., V.E.2.,
and V.E.3. The use condition option requiring household refrigerators
and freezers using HCR 4141 to meet a specific edition of UL 60335-2-24
is described in Section V.E.4.a. The option for a use condition
requiring third-party certification of household refrigerators and
freezers using HCR 4141 is described in Section V.E.4.b.
The proposed regulatory text for this listing using the third-party
certification option appears in the docket for this rulemaking under
the title ``Proposed Regulatory Text for SNAP Rule 27'' in the section
``Proposed revisions to Appendices R, V, W, and new Appendix Z--Third-
Party Certification Option (co-proposed as an alternative to Section
III).'' The proposed regulatory text for this listing using the
incorporate by reference option can be found in the docket for this
rulemaking under the title ``Proposed Regulatory Text for SNAP Rule
27'' in the section ``Proposed revisions to Appendices R, V, W, and new
Appendix Z--Incorporate by Reference Option.'' If one of the use
condition options is finalized, the EPA would publish a corresponding
finalized listing for HCR 4141 in new household refrigerators and
freezers in appendix Z of 40 CFR part 82, subpart G.

B. Background on Household Refrigerators and Freezers

Household refrigerators, freezers, and combination refrigerators
and freezers are intended primarily for residential use, although they
may be used outside the home (e.g., workplace kitchen pantries). The
designs and refrigeration capacities of equipment vary widely. This
equipment is composed of three main categories: household freezers only
offer storage space at freezing temperatures, household refrigerators
only offer storage space at non-freezing temperatures, and products
with both a refrigerator and freezer in a single unit which are most
common and are referred to as combination refrigerators and freezers.
Small refrigerated household appliances (e.g., chilled kitchen drawers,
wine coolers, mini-fridges, stand-alone ice makers, home ice cream
makers) are also within this end-use. In addition, refrigerators or
freezers that are designed for consumer, but not commercial or
professional, use and that are merely situated on a moving vehicle
(e.g., personal vehicle, recreational vehicle, or boat for leisure
purposes) are within the scope of the household refrigerators and
freezers end-use for purposes of the SNAP program. These uses are
within the scope of the relevant U.S. industry safety standard, UL
60335-2-24. Throughout this document, we refer to all these uses with
the phrase ``household refrigerators and freezers.'' Refrigerators or
freezers in a commercial kitchen such as onboard a cruise ship or on
aircraft are not household refrigerators or freezers for purposes of
the SNAP program and such equipment is outside the scope of UL 60335-2-
24. Household refrigerators and freezers have all refrigeration
components integrated, and for the smallest types, the refrigeration
circuit is entirely brazed or welded. These systems are charged with
refrigerant at the factory and typically require only an electricity
supply to begin operation.
ASHRAE's Handbook of Refrigeration provides an overview of food
preservation regarding household refrigerators and freezers. Generally,
a storage temperature between 32 and 39 [deg]F (0 to 3.9 [deg]C) is
desirable for preserving fresh food. Humidity and higher or lower
temperatures are more suitable for certain foods and beverages. Wine
chillers, for example, are frequently used for storing wine, and have
slightly higher optimal temperatures from 45 to 65 [deg]F (7.2 to 18.3
[deg]C). Freezers and combination refrigerators and freezers that are
designed to store food for long durations

[[Page 50785]]

have temperatures below 8 [deg]F (-13.3 [deg]C) and are designed to
hold temperatures near 0 to 5 [deg]F (-17.7 to -15 [deg]C). In single-
door refrigerators, the optimum conditions for food preservation are
typically warmer than this because food storage is not intended for
long-term storage.

C. What are the ASHRAE groups for refrigerant flammability and
toxicity?

See Section IV.C. for information on ASHRAE groups for refrigerant
flammability and toxicity.

D. What is HCR 4141 and how does it compare to other refrigerants in
the household refrigerators and freezers end-use?

HCR 4141 is a blend of the saturated HCs R-600a, R-600, and R-290,
all of which are higher flammability refrigerants having an ASHRAE
safety group of A3; the percentage of each component in the blend is
claimed as CBI. See Section IV.D. for environmental information,
flammability information, and toxicity and exposure information on HCR
4141. The redacted submission and supporting documentation for HCR 4141
in household refrigerators and freezers are provided in the docket. The
EPA performed a risk screening assessment to examine the human health
and environmental risks of this substitute which also is available in
the docket.\60\
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\60\ ICF, 2025h. Risk Screen on Substitutes in Household
Refrigerators and Freezers (New Equipment); Substitute: HCR 4141.
---------------------------------------------------------------------------

Comparison to other substitutes in the household refrigerators and
freezers end-use: The specific atmospheric effects values can be found
in the individual risk screen for HCR 4141. The values were determined
consistent with the source information noted in Section III.C. above
(e.g., CAA; the AIM Act; WMO, 2022) as well as using the methodology
for determining values for blends of chemicals (i.e., determined by the
percentage of each component). The EPA compared HCR-4141 to other A3
refrigerants listed as acceptable subject to use conditions for the
same end-use. The MIR of the blend HCR 4141 is expected to be less than
that of R-600a (MIR of 1.23 g O<INF>3</INF>/g isobutane) and greater
than that of R-290 (MIR of 0.49 g O<INF>3</INF>/g propane). The MIR of
HCR 4141 is greater than that of compounds that have been excluded from
the EPA's regulatory definition of VOC \61\ addressing the development
of SIPs to attain and maintain the NAAQS, such as HFC-152a.
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\61\ 40 CFR 51.100(s).
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The EPA's risk screen for HCR 4141 in new household refrigerators
and freezers \62\ found that HCR 4141 can be used without exceeding its
recommended OEL of 1,000 ppm (8-hr TWA); thus, the toxicity risks of
HCR 4141 are comparable to those of other acceptable substitutes in new
household refrigerators and freezers, which also are used without
exceeding their OELs.
---------------------------------------------------------------------------

\62\ ICF, 2025h. Op. cit.
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Although we noted that the flammability of HCR 4141 may be greater
than that of other available substitutes that have ASHRAE 1, 2 or 2L
flammability classifications in the same end-use, we found its
flammability risk to be not significant even under worst-case
assumptions in this end-use when following the proposed use
conditions.\63\ Further, its flammability risk is comparable to that of
other A3 refrigerants that the EPA has previously listed as acceptable
in this end-use. We note that flammability risk can be minimized by use
consistent with industry safety standards such as UL 60335-2-24--which
would be required by the proposed use conditions--as well as
recommendations in the manufacturers' SDS and other safety precautions
common in the refrigeration and air conditioning industry. The proposed
use conditions for household refrigerators and freezers would maintain
low potential risk associated with the flammability of this alternative
so that it would not pose greater overall risk than other acceptable
substitutes in this end-use.
---------------------------------------------------------------------------

\63\ ICF, 2025h. Op. cit.
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E. What use conditions is the EPA proposing in this action for the new
listing for HCR 4141 in new household refrigerators and freezers?

The proposed use conditions described in this section would apply
to new household refrigerators and freezers using HCR 4141. Many of the
proposed use conditions mirror the SNAP program's historical approach
to requirements for flammable refrigerants in this end-use. The
proposed use condition related to use in new equipment only is
consistent with previously listed higher flammability refrigerants in
this end-use. The proposed use conditions related to labels and
markings are very similar to what has previously been required by SNAP
for higher flammability refrigerants in this end-use, with a few
updates made specifically to better align the EPA requirements with
updated industry safety standards. A use condition option that proposes
to incorporate by reference the latest edition of UL 60335-2-24 is
consistent with the EPA's historical practice for listing flammable
refrigerants in this end-use. The other co-proposed option, while
different from the EPA's historical practice of incorporating portions
of or entire industry consensus safety standards by reference, would
address situations where the EPA's regulations require adherence to
editions of industry consensus safety standards that have been updated
and replaced subsequent to the issuance of a final rule. The EPA
proposes the following use conditions:
1. New Equipment Only; Not Intended for Use as a Retrofit Alternative
The EPA is proposing that HCR 4141 may be used only in new
equipment designed specifically and clearly identified for the
refrigerant. In other words, this substitute must not be used as a
conversion or ``retrofit'' \64\ refrigerant for existing equipment
designed for another refrigerant. The EPA has established this same
requirement for other A3 refrigerants in this end-use and in certain
other refrigeration and AC end-uses, such as vending machines, retail
food refrigeration--stand-alone units, and very low temperature
refrigeration. This requirement is intended to ensure that equipment
using a higher flammability refrigerant is specifically designed to
address flammability risks.
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\64\ Sometimes conversion refrigerant substitutes are
inaccurately referred to as ``drop in'' replacements.
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2. Labels
The EPA is proposing to require labeling of household refrigerators
and freezers using HCR 4141. The following markings, or the equivalent,
would need to be provided and be permanent:
a. ``DANGER--Risk of fire or explosion. Flammable refrigerant used.
Do not use mechanical devices to defrost refrigerator. Do not puncture
refrigerant tubing.'' This marking would need to be located on or near
any evaporators that can be contacted by the consumer.
b. ``DANGER--Risk of fire or explosion. Flammable refrigerant used.
To be repaired only by trained service personnel. Use only
manufacturer-authorized service parts. Any repair equipment used must
be designed for flammable refrigerants. Follow all manufacturer repair
instructions. Do not puncture refrigerant tubing.'' This marking would
need to be located near the machine compartment.
c. ``CAUTION \65\--Risk of fire or explosion. Dispose of
refrigerator

[[Page 50786]]

properly in accordance with the applicable federal or local
regulations. Flammable refrigerant used.'' This marking would need to
be located on the exterior of the refrigeration equipment.
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\65\ The word ``CAUTION'' may be substituted with the word
``WARNING.''
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d. ``CAUTION \66\--Risk of fire or explosion due to puncture of
refrigerant tubing; follow handling instructions carefully. Flammable
refrigerant used.'' This marking would need to be located near all
exposed refrigerant tubing.
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\66\ The word ``CAUTION'' may be substituted with the word
``WARNING.''
---------------------------------------------------------------------------

Both the 3rd and 2nd editions of UL 60335-2-24 have required labels
with the above text as a hazard warning on refrigerated equipment that
uses a flammable refrigerant. The 3rd edition of UL 60335-2-24 has
revised two requirements in the 2nd edition concerning warning labels.
The first change was that one marking would no longer be required that
stated, ``CAUTION--Risk of fire or explosion. Flammable refrigerant
used. Consult repair manual/owner's guide before attempting to service
this product. All safety precautions must be followed.'' The EPA also
would not require this marking in the proposed use conditions.
The second change to the labels in the 3rd edition of UL 60335-2-24
is that the height of the letters on the warning labels have changed
from no less than 6.4 mm (\1/4\ inch) to no less than 3.2 mm (\1/8\
inch), with the signal words ``DANGER,'' ``WARNING,'' and ``CAUTION''
being no less than 5.0 mm (0.2 inch). This would be a smaller font size
that would allow for smaller labels that would be more convenient for
manufacturers to apply. The EPA is instead proposing that the label
text size be no less than 6.4 mm (\1/4\ inch) to allow for greater
visibility for technicians, consumers, recyclers, and first responders.
The larger font size is also consistent with the font size that the EPA
has previously required for these labels in other SNAP rules for
refrigeration or AC equipment using flammable refrigerants.
3. Color-Coded Hoses and Piping
The EPA is proposing to require that equipment have distinguishing
red (PMS #185 or RAL 3020) color-coded hoses and piping to indicate use
of a flammable refrigerant. This color would need to be present at all
service ports and other parts of the system where service puncturing or
other actions creating an opening from the refrigerant circuit to the
atmosphere might be expected, would need to extend a minimum of one
inch (25 mm) in both directions from such locations, and would need to
be replaced if removed. The EPA has applied this proposed use condition
in past actions for flammable refrigerants.\67\
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\67\ See 86 FR 24444, May 6, 2021, and 88 FR 26382, April 28,
2023.
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Red markings are a requirement of the 3rd edition of UL 60335-2-24.
The standard allows for an exception if the labels are visible when a
technician attempts to access a process tube. In addition, the 3rd
edition of UL 60335-2-24 calls for red markings but does not specify
any particular shade of red. The EPA's proposal would not allow for
this exception and is specifying particular shades of red, as in
previous rules.
4. Use Condition Options Related to Equipment Certification or Industry
Safety Standard Requirements
The EPA is co-proposing two options for a use condition related to
equipment certification or industry safety standard requirements for
equipment that uses HCR 4141 in household refrigerators and freezers.
Under the first option, the EPA would incorporate by reference a new
edition of the safety standard for this end-use. Under the second
option, the EPA would require household refrigerators and freezers to
be certified by an organization that is recognized as an NRTL to a U.S.
industry consensus safety standard that is designed to allow for safe
use of flammable refrigerants in household refrigerators and freezers.
This is the same proposed approach discussed in Section IV.F.4.a.
For the most recent listings of flammable refrigerants used in
household refrigerators and freezers, the EPA addressed design elements
to reduce flammability risks by incorporating by reference the 2nd
edition of UL 60335-2-24, ``Household and Similar Electrical
Appliances--Safety--Part 2-24: Particular Requirements for
Refrigerating Appliances, Ice-Cream Appliances and Ice-Makers.'' \68\
The EPA is co-proposing an option to incorporate by reference UL 60335-
2-24, 3rd edition (dated July 29, 2022, with revisions through February
29, 2024). As discussed in Section IV.F.4.b., the Agency recognizes
that certain standards, including UL 60335-2-24, are under continuous
maintenance, meaning that they are updated and superseded by newer
editions. This often means that regulations and safety standards are
out of step. Therefore, the EPA is proposing another option to
streamline use conditions and to maintain consistency with the most
current version of the relevant standards. This potential option is
discussed in Section V.E.4.b.
---------------------------------------------------------------------------

\68\ Dated April 28, 2017. See 83 FR 38969; August 8, 2018.
---------------------------------------------------------------------------

Each co-proposal in Sections IV.F.4.a. and IV.F.4.b. would include
certain use conditions in addition to the common use conditions in
Sections V.E.1., V.E.2., and V.E.3. (i.e., for use in new equipment
only, labels, and color-coded hoses and piping). The use conditions for
HCR 4141 would apply to household refrigerators and freezers
manufactured on and after the effective date of the final rule. The use
conditions would be in a new appendix Z of 40 CFR part 82, subpart G.
a. Incorporate by Reference UL 60335-2-24, 3rd Edition Option
In this first co-proposal, the EPA proposes that the refrigerant
HCR 4141 may be used only in equipment that meets all the requirements
in UL 60335-2-24.\69\ The EPA has set a similar requirement for the use
of R-290, R-600a, and R-441A in household refrigerators and
freezers,\70\ where the Agency's regulations require that those
refrigerants be used only in equipment meeting the requirements of the
2nd edition \71\ of UL 60335-2-24, rather than the 3rd edition of that
standard. In this proposed new listing for HCR 4141 in new household
refrigerators and freezers, the EPA would incorporate by reference the
standard UL 60335-2-24, ``Safety Requirements for Household and Similar
Electrical Appliances, Part 2: Particular Requirements for
Refrigerating Appliances, Ice-Cream Appliances and Ice-Makers.'' \72\
This safety standard establishes requirements for the evaluation of
household and similar electrical appliances, and safe use of flammable
refrigerants. The EPA previously incorporated by reference UL 60335-2-
24, 2nd edition for R-290, R-441A, and R-600a in our most recent rule
on flammable refrigerants in household refrigerators and freezers.\73\
This proposal would incorporate by reference the latest edition and
revisions to that safety standard. Where the rule includes requirements
that are different than those of UL 60335-2-24 (e.g., font size), the
EPA is proposing that the appliance would need to meet the requirements
of the rule. UL 60335-2-24 establishes requirements for the evaluation
of household and similar electrical appliances and the safe use of

[[Page 50787]]

A2, A2L, or A3 refrigerants. The charge size limit for each separate
refrigerant circuit (i.e., compressor, condenser, evaporator, and
refrigerant piping) is 150 grams (5.3 ounces), remaining the same in
the 3rd edition as in the 2nd edition.
---------------------------------------------------------------------------

\69\ 3rd edition, July 29, 2022, with revisions through February
29, 2024.
\70\ See 83 FR 38969; August 8, 2018, and appendix R of 40 CFR
part 82, subpart G.
\71\ 2nd edition of UL 60335-2-24 dated April 28, 2017.
\72\ 3rd edition, July 29, 2022, with revisions through February
29, 2024.
\73\ See 83 FR 38969; August 8, 2018.
---------------------------------------------------------------------------

Both the 2nd and 3rd editions require testing of refrigeration
appliances containing flammable refrigerants, including leakage tests,
temperature and scratch tests, and heat testing requirements to address
the hazards due to ignition of leaked refrigerant by potential ignition
sources associated with the appliance. These tests are intended, among
other things, to ensure that any leaks will result in concentrations
well below the LFL, and that potential ignition sources will not be
able to create temperatures high enough to start a fire. Specifically,
the leakage test ensures that refrigerant concentrations do not reach
or exceed 75 percent of the LFL inside any internal or external
electrical component compartments. Appliances that comply with UL
60335-2-24 have passed appropriate ignition or leakage tests as
stipulated in the standard. In addition, UL 60335-2-24, 3rd edition,
includes labels and markings, as discussed in Sections V.E.2. and
V.E.3. UL standard 60335-2-24 was developed using a consensus-based
approach developed in cooperation with parties with an interest in
participating in the development or use of the standard. For example,
UL uses a process where experts with various interests, including
manufacturers, experts in assessing the safety of products, government
agencies, and academia, come together to agree on the safety
requirements for a product, resulting in a standard that reflects a
collective consensus on best practices for safety. While similar
standards exist from other bodies such as the IEC, we are proposing in
this option to use specific UL standards that are most applicable and
used by U.S. manufacturers. The EPA used this approach in previous SNAP
rules concerning lower and higher flammability refrigerants.\74\ UL
standard 60335-2-24 was developed using a consensus-based approach
developed in cooperation with parties with an interest in participating
in the development or use of the standard. For example, UL uses a
process where experts with various interests, including manufacturers,
experts in assessing the safety of products, government agencies, and
academia, come together to agree on the safety requirements for a
product, resulting in a standard that reflects a collective consensus
on best practices for safety. While similar standards exist from other
bodies such as the IEC, we are proposing in this option to rely on
specific UL standards that are most applicable and used by U.S.
manufacturers. The approach of incorporating a UL standard by reference
is the same as that in our previous rules on flammable
refrigerants.\75\
---------------------------------------------------------------------------

\74\ See 76 FR 78832, December 20, 2011; 80 FR 19454, April 10,
2015; 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.
\75\ See 76 FR 78832, December 20, 2011; 80 FR 19454, April 10,
2015; 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.
---------------------------------------------------------------------------

Under this incorporate by reference option, this listing would
include the use conditions described in Sections V.E.1., V.E.2., and
V.E.3. as well as a use condition that the refrigerant may only be used
in equipment that meets all the requirements of UL 60335-2-24, 3rd
edition.
The EPA performed an assessment to examine the human health and
environmental risks of HCR 4141 in household refrigerators and
freezers. This assessment is available in the docket.\76\ The proposed
regulatory text for this new listing under this option can be found in
the docket under the title ``Proposed Regulatory Text for SNAP Rule
27'' in the section ``Proposed revisions to Appendices R, V, W, and new
Appendix Z--Incorporate by Reference Option.''
---------------------------------------------------------------------------

\76\ ICF, 2025h. Risk Screen on Substitutes in Household
Refrigerators and Freezers (New Equipment); Substitute: HCR 4141.
2025.
---------------------------------------------------------------------------

b. Third-Party Certification Option
Under this second co-proposal, the EPA is proposing a use condition
where all household refrigerators and freezers using HCR 4141 must be
certified by an OSHA-recognized NRTL to a U.S. industry consensus
safety standard that is designed to allow for safe use of flammable
refrigerants in household refrigerators and freezers and mitigates
risks such that the listed refrigerant can be used in a manner that
does not pose a greater overall risk to human health and the
environment than other substitutes in this end-use. The industry
consensus safety standard must be designed for use in the United States
and be consistent with best industry safety practices.\77\ For further
detail on requirements of applicable industry consensus safety
standards that the EPA proposes to find necessary to sufficiently
mitigate risks, see Section IV.F.4.b. While the EPA is proposing
reliance on certification by these NRTLs, the EPA is not opening OSHA's
regulations at 29 CFR 1910.7 for comment, including definitions or
requirements, nor is the EPA seeking comment on the OSHA program
itself. For further information on OSHA's NRTL Program, see Section
IV.F.4.b.
---------------------------------------------------------------------------

\77\ e.g., UL 60335-2-24.
---------------------------------------------------------------------------

By not incorporating by reference a specific edition of a relevant
safety standard in this use condition option, the EPA intends to
increase efficiencies by not having to propose a new rule each time a
standard is updated and to leverage OSHA's NRTL Program. The EPA does
not expect this option to pose significant additional burden on
manufacturers or NRTLs because most manufacturers of household
refrigerators and freezers have their equipment certified by an NRTL
already. Manufacturers that do not already certify their equipment
through an OSHA-recognized NRTL would need to do so beginning two years
after the effective date of the final rule.
Under this third-party certification option, the listing would
include the use conditions described in Sections V.E,1., V.E.2., and
V.E.3. as well as a use condition that equipment be certified by an
OSHA-recognized NRTL to a U.S. industry consensus safety standard that
is designed to allow for safe use of flammable refrigerants in
household refrigerators and freezers. The EPA proposes that the use
conditions for HCR 4141 in new household refrigerators and freezers
would apply on the effective date of the final rule.
The EPA performed an assessment to examine the human health and
environmental risks of HCR 4141 in household refrigerators and
freezers. This assessment is available in the docket.\78\ Proposed
regulatory text for the new listing for HCR 4141 in household
refrigerators and freezers under this option can be found in the docket
under the title ``Proposed Regulatory Text for SNAP Rule 27'' in the
section ``Proposed revisions to Appendices R, V, W, and new Appendix
Z--Third-Party Certification Option (co-proposed as an alternative to
Section III).''
---------------------------------------------------------------------------

\78\ ICF, 2025h.
---------------------------------------------------------------------------

F. What additional information is the EPA including in this proposed
listing?

The ``Further Information'' column of the proposed listing for HCR
4141 in household refrigerators and freezers includes applicable OSHA
requirements at 29 CFR part 1910, suggestions on ventilation and PPE,
appropriate type of fire extinguisher (Class B), and suggestions for
technicians. Among the suggestions for technicians are the appropriate
type of tools and equipment to use for servicing, conditions for

[[Page 50788]]

release of refrigerant if it is not recovered, and a recommendation
that only technicians specifically trained in handling of flammable
refrigerants service equipment containing the refrigerant.
The ``Further Information'' column of the listing for HCR 4141
under the third-party certification option would be the same as under
the incorporation by reference of UL 60335-2-24 option.\79\ In
addition, because the EPA would not require use of UL 60335-2-24 in a
use condition under the third-party certification option, the Agency
would include a recommendation to follow the latest edition of UL
60335-2-24 or similar industry safety standard. While the statements in
the ``Further Information'' column are not legally binding under the
SNAP program, the EPA encourages users of HCR 4141 to apply all
statements in the ``Further Information'' column in their use of this
substitute.
---------------------------------------------------------------------------

\79\ See section V.E.4.
---------------------------------------------------------------------------

VI. Water Coolers

A. What is the EPA proposing in this action?

The EPA is proposing to update use conditions for the previously
listed refrigerant R-290 for use in water coolers. The EPA listed R-290
as acceptable, subject to use conditions, in new water coolers in SNAP
Rule 21.\80\ The industry consensus safety standard that was
incorporated by reference at the time of the original listing has since
been updated. The EPA is not proposing to move this listing from
acceptable, subject to use conditions, to any other listing category
(e.g., unacceptable).
---------------------------------------------------------------------------

\80\ See 81 FR 86778; December 1, 2016.
---------------------------------------------------------------------------

The proposed updated use conditions include a requirement that R-
290 be used in new equipment only, specific requirements for warning
labels, and specific requirements for markings. As with some other
listings in this rule, the EPA is co-proposing two options for an
additional use condition related to equipment certification or industry
safety standard requirements for R-290 in water coolers. The EPA
intends to finalize one of these co-proposed options along with an
appropriate transition period to provide manufactures with opportunity
for a smooth transition between the existing use conditions and the
updated use conditions. Throughout this section, the term ``updated use
conditions'' refers to the set of use conditions being proposed that
would apply to new equipment manufactured after the effective date of
the final rule. The updated use conditions would neither apply to nor
affect equipment manufactured before the effective date of the final
rule.
The proposed regulatory text for this listing can be found in the
docket for this rulemaking under the title ``Proposed Regulatory Text
for SNAP Rule 27'' in the section ``Proposed revisions to Appendices R,
V, W, and new Appendix Z--Incorporate by Reference Option'' and in the
section ``Proposed revisions to Appendices R, V, W, and new Appendix
Z--Third-Party Certification Option (co-proposed as an alternative to
Section III).'' If one of the use condition options is finalized, the
EPA would publish a corresponding finalized listing for R-290 in water
coolers in appendix V to 40 CFR part 82, subpart G.

B. Background on Water Coolers

Water coolers are self-contained refrigerated units providing
chilled water for drinking. They may or may not feature detachable
containers of water. These devices are extensively used in homes,
workplaces, public facilities, and warehouses typically employing a
compact refrigeration system to chill water. Many models are self-
contained, incorporating either bottle-fed or point-of-use water
sources.

C. What are the ASHRAE groups for refrigerant flammability and
toxicity?

See Section IV.C. for information on ASHRAE groups for refrigerant
flammability and toxicity.

D. What is R-290 and how does it compare to other refrigerants in the
water coolers end-use?

See Section IV.E. for information about R-290 and its
environmental, flammability, and toxicity and exposure impacts.
Redacted supporting documentation for R-290 in water coolers is
provided in the docket. The EPA performed a risk screening assessment
to examine the human health and environmental risks of R-290 in water
coolers which also is available in the docket.\81\
---------------------------------------------------------------------------

\81\ ICF, 2025i. Risk Screen on Substitutes in Water Coolers
(New Equipment); Substitute: Propane (R-290). 2025.
---------------------------------------------------------------------------

Environmental information: See Section IV.D. for discussion of the
EPA's analysis of potential air quality impacts due to emissions of R-
290 and other HC refrigerants that are VOCs under EPA's regulatory
definition of VOC.\82\ The analysis showed relatively minimal air
quality impacts of R-290 released to the atmosphere from the end-uses
where it is already listed as acceptable, subject to use conditions,
including water coolers. The EPA therefore concluded that R-290 does
not have a greater overall impact on human health and the environment
based on its effects on local air quality than other refrigerants
listed as acceptable in the same end-uses.
---------------------------------------------------------------------------

\82\ 40 CFR 51.100(s).
---------------------------------------------------------------------------

The EPA previously exempted R-290 in water coolers from the venting
prohibition under CAA section 608(c)(2), finding that such venting,
release, or disposal does not pose a threat to the environment.\83\ The
EPA is not proposing to change either of these decisions and is not
reopening them for comment.
---------------------------------------------------------------------------

\83\ See 81 FR 86778; December 1, 2016; 40 CFR
82.154(a)(1)(viii).
---------------------------------------------------------------------------

Flammability information: R-290 exhibits higher flammability than
other alternatives in this end-use and has an ASHRAE flammability
classification of 3.
Toxicity and exposure data: R-290 has an ASHRAE toxicity
classification of A (lower toxicity).
Comparison to other acceptable substitutes in the water coolers
end-use: The atmospheric effects values can be found in the individual
risk screen for R-290. These were determined consistent with the source
information noted in Section III.C. above. Other acceptable substitutes
for the water coolers end-use include R-480A, R-513A, HFC-134a, R-404A,
and R-507A. The atmospheric effects for R-290 are better than or
comparable to other listed substitutes. R-290 has an ODP of 0, which is
lower than or identical to the ODPs of other alternatives in this end-
use.
R-290 is a VOC, unlike the other substitutes listed in this end-
use. However, because of the relatively minimal air quality impacts of
R-290 if it is released to the atmosphere from the end-uses where it is
listed as acceptable, subject to use conditions, even in a worst-case
scenario, the EPA has previously concluded that R-290 does not have a
greater overall impact on human health and the environment based on its
effects on local air quality than other refrigerants listed as
acceptable in the same end-use. When used in this end-use, workplace
and consumer exposure to R-290 is not expected to exceed relevant
exposure limits. Thus, R-290 does not pose significantly greater
toxicity risks than other acceptable refrigerants in this end-use.
The flammability risks of R-290 in this end-use, determined by the
likelihood of exceeding the LFL, are evaluated in the risk screen
previously referenced. Other acceptable substitutes

[[Page 50789]]

in this end-use category, including R-404A and HFC-134a, have an ASHRAE
flammability class of 1. The proposed updated use conditions reduce the
potential risk associated with the flammability of this alternative so
it would not pose greater overall risk than other acceptable
substitutes in this end-use. Updating the use conditions for this
refrigerant would enable it to continue to be available and used safely
in the industry. This proposed revised listing under SNAP would provide
greater flexibility to use R-290, while maintain safe use in this end-
use.
The EPA previously found R-290 acceptable, subject to use
conditions, in new water coolers in SNAP Rule 21.\84\ Those
requirements are codified in appendix V of 40 CFR part 82, subpart G.
The EPA provided information on the environmental and health properties
of R-290 and the various substitutes available at that time for use in
this end-use. The EPA's risk screen for R-290 in water coolers is
available in the docket for that previous rulemaking.\85\
---------------------------------------------------------------------------

\84\ See 81 FR 86778; December 1, 2016.
\85\ EPA-HQ-OAR-2015-0663.
---------------------------------------------------------------------------

The existing use conditions for R-290 in water coolers address safe
use of this higher flammability refrigerant and include incorporation
by reference of Supplement SB to UL 399, 7th edition, a requirement
that the refrigerant only be used in new equipment that is designed
specifically and clearly identified for the refrigerant, a requirement
that the charge size not exceed 60 grams per refrigerant circuit in the
water cooler, and requirements for markings and warning labels on
equipment using the refrigerant to inform consumers and technicians of
potential flammability hazards.
Without appropriate use conditions, the flammability risk posed by
this refrigerant would be higher than nonflammable refrigerants because
individuals may not be aware that their actions could potentially cause
a fire, and because the refrigerant could be used in existing equipment
that has not been designed specifically to minimize flammability risks.
Our assessment and listing decisions in SNAP Rule 21 \86\ found that
with the use conditions, the use of this substitute, including the risk
due to flammability, does not present a greater overall risk in the
end-use than other substitutes that are currently or potentially
available for that same end-use. The EPA has not updated the use
conditions for R-290 in water coolers since 2016.
---------------------------------------------------------------------------

\86\ See 81 FR 86778; December 1, 2016.
---------------------------------------------------------------------------

In the Notice of Proposed Rulemaking for SNAP Rule 21, the EPA
proposed 150 g of R-290 as the charge size limit.\87\ This proposed
charge size was greater than the 60 g charge size limit in the 7th
edition of UL 399. Based upon the EPA's initial risk screen prepared
for that rulemaking, a worst-case release of an entire charge of 150 g
of R-290 in a small room could result in exceeding the LFL. The release
of a charge of 120 g, as well as the 60 g charge limit in the 7th
edition of UL 399, would not result in exceeding the LFL. Based upon
public comment, the EPA revised its risk screen and finalized a 60 g
charge limit to be consistent with the 60 g limit in the 7th edition of
UL 399.
---------------------------------------------------------------------------

\87\ See 81 FR 22810; April 18, 2016.
---------------------------------------------------------------------------

Based on additional risk screening and in response to a request
from a manufacturer of water coolers, the EPA now proposes to find that
the larger charge size of 130 g in the 8th edition of UL 399 with
revisions through February 28, 2024, can be used safely through
proposed, updated use conditions to address flammability risks.

E. What use conditions is the EPA proposing in this action for the
updated listing for R-290 in new water coolers?

The use conditions that currently apply to R-290 in the water
coolers end-use incorporate by reference an industry consensus safety
standard \88\ that has been updated since the listing decision was
finalized. Similar to Section IV.F. for updated use conditions in the
residential and light commercial AC and heat pumps end-use, the EPA is
proposing to update the listing for R-290 in the water coolers end-use
so that the use conditions reflect updated industry safety standards.
---------------------------------------------------------------------------

\88\ UL 399, 7th edition.
---------------------------------------------------------------------------

Many of the proposed use conditions described in this section
mirror existing use conditions. A use condition option described that
proposes to incorporate by reference the latest edition of UL 399 is
consistent with the EPA's historical practice for listing flammable
refrigerants in this end-use. The other co-proposed option, while
different from the EPA's historical practice of incorporating portions
of or entire industry consensus safety standards by reference, would
address situations where the EPA regulations require adherence to
editions of industry consensus safety standards that have been updated
and replaced subsequent to the issuance of a final rule. The EPA
proposes the following use conditions:
1. New Equipment Only; Not Intended for Use as a Retrofit Alternative
The EPA is proposing that R-290 may be used only in new equipment
designed specifically and clearly identified for the refrigerant. In
other words, this refrigerant must not be used as a conversion or
``retrofit'' refrigerant for existing equipment designed for another
refrigerant. This is an existing use condition for R-290 in water
coolers and the EPA is only addressing use of R-290 in new equipment
which can be properly designed for higher flammability refrigerants.
2. Labels
The EPA is proposing to require labeling of water coolers using R-
290. The following statements would need to be attached on labels at
the locations provided and be permanent:
a. On or near any evaporators that the user can contact: ``DANGER--
Risk of Fire or Explosion. Flammable Refrigerant Used. Do Not Puncture
Refrigerant Tubing.''
b. On the inside of the water cooler near the compressor/condenser
compartment: ``DANGER--Risk of Fire or Explosion. Flammable Refrigerant
Used. To Be Repaired Only by Trained Service Personnel. Do Not Puncture
Refrigerant Tubing.''
c. On the inside of the water cooler near the compressor/condenser
compartment: ``CAUTION--Risk of Fire or Explosion. Flammable
Refrigerant Used. Consult Instruction Manual/Repair Manual/Owner's
Guide Before Attempting to Install or Service This Product. All Safety
Precautions Must be Followed.''
d. On the outside of the water cooler: ``CAUTION--Risk of Fire or
Explosion. Dispose of Properly in Accordance With Federal Or Local
Regulations. Flammable Refrigerant Used.''
e. Near all exposed tubing: ``CAUTION--Risk of Fire or Explosion
Due To Puncture Of Refrigerant Tubing; Follow Handling Instructions
Carefully. Flammable Refrigerant Used.''
The proposed text of the labels is verbatim in language to those
required by the section SB6.1.1 through SB6.1.5 of Supplement SB of
both the 7th and 8th editions of UL 399. As required in section SB6.1.1
of both the 7th and 8th editions of UL 399, the minimum height for
lettering must be \1/4\ inch (6.4 mm) for all these labels, making it
easy for technicians, consumers, retail storeowners, first responders,
and those disposing the appliance to view the warning labels. These
requirements are also aligned with previous labeling requirements for
A3 refrigerants in

[[Page 50790]]

SNAP Rule 21.\89\ Under both the use condition options proposed and
discussed in Sections VI.E.4.a. and VI.E.4.b., the proposed listing
would maintain this use condition for labels.
---------------------------------------------------------------------------

\89\ See 81 FR 86778; December 1, 2016.
---------------------------------------------------------------------------

3. Color-Coded Hoses and Piping
An existing use condition for R-290 in water coolers is that they
must have distinguishing red (PMS #185) color-coded pipes, hoses, or
other devices through which the refrigerant passes, to indicate the use
of a flammable refrigerant. This color must be applied at all service
ports and other parts of the system where service puncturing or other
actions creating an opening from the refrigerant circuit to the
atmosphere might be expected and must extend a minimum of one inch (25
mm) in both directions from such locations. If removed, these markings
also shall be replaced. These markings are the same as those required
in section SB6.1.6 of Supplement SB to the 7th and 8th editions of UL
399, although the exact wording of those requirements is slightly
different (e.g., states ``refrigerant tubing or other devices through
which the refrigerant is intended to be serviced''). The EPA proposes
that this same use condition continue to apply. This would be the case
either for the incorporate by reference option described in Section
VI.E.4.a. or for the third-party certification option described in
Section VI.E.4.b.
4. Use Condition Options Related to Equipment Certification or Industry
Safety Standard Requirements
In the initial listing of R-290 as acceptable, subject to use
conditions, for use in water coolers, the EPA set two use conditions
that relate to charge size and risk mitigation: (1) limiting the
maximum charge of R-290 to 60 g in each refrigerant circuit and (2)
requiring that water coolers using R-290 must meet all requirements of
Supplement SB to the 7th edition of UL 399, dated August 22, 2008, with
all revisions through October 18, 2013. Supplement SB to the 7th
edition of UL 399 set a maximum refrigerant charge size of 2 ounces or
60 g for class 3 (higher flammability) refrigerants and other
requirements such as construction requirements, performance testing,
and marking requirements.
The latest revision to the 8th edition of UL 399 issued in February
2024 allows up to 130 g of A3 refrigerants, including R-290, in water
coolers. The Agency's most recent risk screening finds that R-290 may
be used safely in new water coolers in accordance with the 8th edition
of UL 399 and a charge size of up to 130 g of R-290 to mitigate
flammability risks.
These water coolers are factory charged with R-290 by the
manufacturer. The risk of fire is minimal if water coolers meet the
provisions of the 8th edition of UL 399 and have a charge size of R-290
no greater than 130 g. Water coolers containing R-290 should not be
installed in enclosed areas and water coolers containing R-290 that are
installed in lobbies or locations of egress (e.g., hallways) and would
need to have a charge size no greater than three times the LFL, or 114
g of R-290, as stated in standards such as ASHRAE 15 and UL 399. Water
coolers installed in locations with adequate space and/or ventilation
in accordance with the EPA recommendations and requirements, industry
consensus safety standards, and the installation and maintenance
manuals for equipment using R-290, are unlikely to pose flammability
risk and human health risk to end-users, personnel, or the general
population when the proposed use conditions are followed. Thus, the EPA
proposes to find that updating the charge size and being consistent
with the 8th edition of UL 399 to address flammability risks from use
of R-290 in water coolers is appropriate to protect against such risks.
EPA is proposing to update the condition to follow Supplement SB of
the 7th edition of UL 399 and remove the existing, separate use
condition to use a charge size of R-290 of no greater than 60 g.
Supplement SB contains specific safety criteria for water coolers using
flammable refrigerants such as R-290. These requirements, including
testing to meet safety standards, are designed to mitigate risks
associated with flammable refrigerants. EPA proposes to find that the
requirements in the 8th edition of UL 399, including the larger charge
size of 130 g, allow R-290 to be used in a manner that sufficiently
addresses flammability risks.
The EPA is co-proposing two options for a use condition related to
equipment certification or industry safety standard requirements for
the use of R-290 in water coolers. Section VI.E.4.a. describes an
option in which the EPA would incorporate by reference a new edition of
the industry consensus safety standard for this end-use. Section
VI.E.4.b. describes an option in which the EPA would require water
coolers to be certified by an organization that is recognized as an
NRTL to a U.S. industry consensus safety standard that is designed to
allow for safe use of flammable refrigerants and mitigates risks such
that R-290 can be used in a manner that does not pose a greater overall
risk to human health and the environment than other substitutes in this
end-use.
a. Incorporate by Reference UL 399, 8th Edition Option
For background on the SNAP program's recent approach to identifying
use conditions for lower and higher flammability refrigerants, refer to
Section IV.F.4.a. In this first co-proposed option, the EPA proposes
that R-290 only be used in water coolers that meet all the requirements
listed in Supplement SB of UL 399, 8th edition. The EPA is proposing to
incorporate by reference Supplement SB of UL 399, ``Standard for
Safety: Drinking Water Coolers,'' 8th edition, March 30, 2017, with
revisions through February 28, 2024, which establishes requirements for
the evaluation of household and similar electrical appliances, and safe
use of flammable refrigerants. Where the rule requirements are
different than those of UL 399, the EPA is proposing that the appliance
would need to meet the requirements of the rule.
UL 399 establishes requirements for the evaluation of water coolers
and the safe use of refrigerants with a flammability classification of
A2, A2L, or A3. This section summarizes relevant requirements of UL 399
for information only and is not meant to be a complete review of the
standard or how it is applied.
The EPA has evaluated the revisions to the standard published in
the 8th edition and finds that construction and use of water coolers in
accordance with the 8th edition would not pose greater overall risk to
human health and the environment when compared to use in accordance
with the 7th edition. The charge size limit for each separate
refrigerant circuit (i.e., compressor, condenser, evaporator, and
refrigerant piping) is 130 grams (4.6 ounces), which is more than the
60 g limit in the 7th edition.
Both the 7th and 8th editions of UL 399 require testing of water
coolers containing flammable refrigerants, including leakage tests,
temperature and scratch tests, and heat testing requirements to address
the hazards due to ignition of leaked refrigerant by potential ignition

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