Document ID: EPA-HQ-OAR-2021-0347-0001
Agency: epa
Document Type: Proposed Rule
Title: Protection of Stratospheric Ozone: Listing of HFO-1234yf under the Significant New Alternatives Policy Program for Motor Vehicle Air Conditioning in Nonroad Vehicles and Servicing Fittings for Small Refrigerant Cans
Posted Date: 2021-12-06T05:00Z

[Federal Register Volume 86, Number 231 (Monday, December 6, 2021)]
[Proposed Rules]
[Pages 68962-68982]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-25440]

[[Page 68962]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 82

[EPA-HQ-OAR-2021-0347; FRL-8470-01-OAR]
RIN 2060-AV25

Protection of Stratospheric Ozone: Listing of HFO-1234yf Under 
the Significant New Alternatives Policy Program for Motor Vehicle Air 
Conditioning in Nonroad Vehicles and Servicing Fittings for Small 
Refrigerant Cans

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: Pursuant to the EPA's Significant New Alternatives Policy 
program, this action proposes to list the refrigerant 2,3,3,3-
tetrafluoroprop-1-ene, also known as HFO-1234yf or R-1234yf, as 
acceptable, subject to use conditions, in the motor vehicle air 
conditioning end-use for certain types of newly manufactured nonroad 
(also called off-road) vehicles, which includes some vehicles that are 
also considered heavy-duty vehicles. EPA is also proposing to adopt the 
current versions of the industry safety standards SAE J639, SAE J1739, 
and SAE J2844 by incorporating them by reference into the use 
conditions for the proposed listings in nonroad vehicles and previous 
listings for certain onroad vehicles covered in final rules issued 
separately in March 2011 and December 2016. In addition, EPA is 
proposing to require unique servicing fittings for use with small 
refrigerant cans (two pounds or less) of 2,3,3,3-tetrafluoroprop-1-ene 
that are used to service onroad and nonroad vehicles. Finally, EPA is 
proposing to add a reference to the Agency's regulations under the 
Toxic Substances Control Act for 2,3,3,3-tetrafluoroprop-1-ene for the 
proposed listings in nonroad vehicles and previous listings for certain 
onroad vehicles. Aside from the changes proposed in this action, the 
Agency is not reopening for comment other portions of the March 2011 
and December 2016 final rules.

DATES: Comments must be received on or before January 20, 2022. Any 
party requesting a public hearing must notify the contact listed below 
under FOR FURTHER INFORMATION CONTACT by 5 p.m. Eastern Daylight Time 
on December 13, 2021. If a virtual public hearing is held, it will take 
place on or before December 21, 2021 and further information will be 
provided on EPA's Stratospheric Ozone website at www.epa.gov/ozone/snap.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2021-0347, to the Federal eRulemaking Portal: https://www.regulations.gov. Follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or withdrawn. EPA 
may publish any comment received to its public docket. Do not submit 
electronically any information you consider to be Confidential Business 
Information (CBI) 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. 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). For additional submission methods, EPA's 
full public comment policy, information about CBI or multimedia 
submissions, and general guidance on making effective comments, please 
visit https://www.epa.gov/dockets/commenting-epa-dockets. The EPA is 
temporarily suspending its Docket Center and Reading Room for public 
visitors, with limited exceptions, to reduce the risk of transmitting 
COVID-19. Our Docket Center staff will continue to provide remote 
customer service via email, phone, and webform. We encourage the public 
to submit comments via https://www.regulations.gov or email, as there 
may be a delay in processing mail and faxes. Hand deliveries and 
couriers may be received by scheduled appointment only. For further 
information on EPA Docket Center services and the current status, 
please visit us online at https://www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT: Chenise Farquharson, Stratospheric 
Protection Division, Office of Atmospheric Programs (Mail Code 6205 T), 
Environmental Protection Agency, 1200 Pennsylvania Ave. NW, Washington, 
DC 20460; telephone number: 202-564-7768; email address: 
[email protected]. Notices and rulemakings under EPA's 
Significant New Alternatives Policy program are available on EPA's 
Stratospheric Ozone website at www.epa.gov/snap/snap-regulations.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. General Information
    A. Executive Summary and Background
    B. SNAP Program Background
    1. Rulemaking
    2. Listing of Unacceptable/Acceptable Substitutes
    3. Petition Process
    4. 90-Day Notification
    C. Does this action apply to me?
    D. What acronyms and abbreviations are used in the preamble?
II. What is EPA proposing in this action?
    A. Proposed Listing of HFO-1234yf as Acceptable, Subject To Use 
Conditions, for MVAC Systems in Newly Manufactured Nonroad Vehicles
    1. What is the affected end-use?
    2. What are the ASHRAE classifications for refrigerant 
flammability?
    3. How does HFO-1234yf compare to other refrigerants for these 
MVAC applications with respect to SNAP criteria?
    4. What are the proposed use conditions?
    B. Proposed Modifications to Existing Use Conditions for MVAC 
Systems in Other Vehicle Types
    C. Proposed Servicing Fittings for Small Cans of HFO-1234yf
    1. What is the affected end-use?
    2. How does HFO-1234yf compare to other refrigerants for this 
MVAC application with respect to SNAP criteria?
    3. What is the proposed use condition?
    D. Proposed Incorporation by Reference of SAE Standards
    E. When would the listings apply?
    F. What is the relationship between this SNAP rule and other 
federal rules?
    G. On which topics is EPA specifically requesting comment?
III. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and 
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health and Safety Risks
    H. Executive Order 13211: Actions That Significantly Affect 
Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations
IV. References

I. General Information

A. Executive Summary and Background

    In this action, EPA is proposing to list 2,3,3,3-tetrafluoroprop-1-
ene, also known as hydrofluoroolefin (HFO)-1234yf or R-1234yf, 
hereafter referred to as ``HFO-1234yf,'' as acceptable, subject to use 
conditions, as of 30 days after publication of any final rule, for MVAC

[[Page 68963]]

systems \1\ in the following types of newly manufactured nonroad 
vehicles,\2\ including some vehicles that are also considered heavy-
duty (HD) \3\ vehicles:
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    \1\ Under the SNAP program, MVAC systems are those systems that 
provide passenger comfort cooling for light-duty cars and trucks, 
heavy-duty vehicles (large pick-ups, delivery trucks, recreational 
vehicles, and semi-trucks), nonroad vehicles, buses, and rail 
vehicles. See final rules published on March 29, 2011 (76 FR 17488) 
and on December 1, 2016 (81 FR 86778). For informational purposes, 
we note that this includes systems that are also included in the 
definitions that apply under other provisions of EPA's regulations 
under title VI of the CAA. In this regard, we note that EPA's 
subpart F regulations at 40 CFR 82.152 define ``MVAC-like 
appliance'' to mean ``a mechanical vapor compression, open-drive 
compressor appliance with a full charge of 20 pounds or less of 
refrigerant used to cool the driver's or passenger's compartment of 
off-road vehicles or equipment. This includes, but is not limited 
to, the air-conditioning equipment found on agricultural or 
construction vehicles. This definition is not intended to cover 
appliances using R-22 refrigerant.'' By contrast, EPA's subpart F 
regulations at 40 CFR 82.152 define ``Motor vehicle air conditioner 
(MVAC)'' as ``any appliance that is a motor vehicle air conditioner 
as defined in 40 CFR part 82, subpart B.'' The subpart B regulations 
at 40 CFR 82.32 provide that: ``Motor vehicle air conditioners means 
mechanical vapor compression refrigeration equipment used to cool 
the driver's or passenger's compartment of any motor vehicle. This 
definition is not intended to encompass the hermetically sealed 
refrigeration systems used on motor vehicles for refrigerated cargo 
and the air conditioning systems on passenger buses using HCFC-22 
refrigerant.'' Further, the subpart B regulations at 40 CFR 82.32 
provide that: ``Motor vehicle as used in this subpart means any 
vehicle which is self-propelled and designed for transporting 
persons or property on a street or highway, including but not 
limited to passenger cars, light duty vehicles, and heavy duty 
vehicles. This definition does not include a vehicle where final 
assembly of the vehicle has not been completed by the original 
equipment manufacturer.''
    \2\ In the past, EPA has referred to these vehicles as ``off-
road vehicles'' under the SNAP program. In this action, we are 
aligning our terminology with that of other EPA programs and using 
the term ``nonroad vehicle,'' which is defined under CAA section 216 
to mean ``a vehicle that is powered by a nonroad engine and that is 
not a motor vehicle or a vehicle used solely for competition.'' 
EPA's regulations issued under that section of the Act defining a 
nonroad engine are codified at subpart A of 40 CFR part 1068.
    \3\ Heavy-duty vehicles are often subdivided by vehicle weight 
classifications, as defined by the vehicle's gross vehicle weight 
rating (GVWR), which is a measure of the combined curb (empty) 
weight and cargo carrying capacity of the truck. Heavy-duty vehicles 
have GVWRs above 8,500. See https://www.epa.gov/emission-standards-reference-guide/vehicle-weight-classifications-emission-standards-reference-guide.
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     Agricultural tractors with greater than 40 horsepower 
(HP);
     Self-propelled agricultural machinery;
     Compact equipment;
     Construction, forestry, and mining equipment; and
     Commercial utility vehicles.
    EPA has previously listed HFO-1234yf as acceptable, subject to use 
conditions, in new light-duty (LD) passenger cars and trucks (76 FR 
17488; March 29, 2011) and new medium-duty passenger vehicles (MDPV), 
HD pick-up trucks, and complete HD vans (81 FR 86778; December 1, 
2016). The use conditions for those prior listings require that motor 
vehicle air conditioning (MVAC) systems designed to use HFO-1234yf meet 
the requirements of three technical safety standards developed by SAE 
International (SAE) (i.e., SAE J639, SAE J1739, and SAE J2844) and are 
intended to mitigate flammability and toxicity risks. In this action, 
EPA is proposing to require the same use conditions, with certain 
updates discussed below, for MVAC systems designed to use HFO-1234yf in 
certain newly manufactured nonroad vehicles. EPA is proposing to list 
HFO-1234yf as acceptable, subject to use conditions, after its 
evaluation of human health and environmental information on various 
substitutes submitted to the Significant New Alternatives Policy (SNAP) 
program. In proposing to list HFO-1234yf as acceptable, subject to use 
conditions, this action would provide additional flexibility for 
industry stakeholders by expanding the list of acceptable substitutes 
for certain types of nonroad vehicles.
    EPA is also proposing to adopt the current versions of SAE J639, 
SAE J1739, and SAE J2844 by incorporating them by reference into the 
use conditions for the nonroad vehicles addressed in this action. EPA 
also proposes to modify the use conditions for the previous listings of 
HFO-1234yf for MVAC systems in certain vehicles to replace the 
references to older versions of the three SAE standards with references 
to the current versions. The current versions of the three standards 
are SAE J639 (revised November 2020), ``Safety and Design Standards for 
Motor Vehicle Refrigerant Vapor Compression Systems;'' SAE J1739 
(revised January 2021), ``Potential Failure Mode and Effects Analysis 
(FMEA) Including Design FMEA, Supplemental FMEA-MSR, and Process 
FMEA;'' and SAE J2844 (revised January 2013), ``R-1234yf (HFO-1234yf) 
New Refrigerant Purity and Container Requirements for Use in Mobile 
Air-Conditioning Systems.''
    In addition, EPA is proposing to include a use condition for HFO-
1234yf to provide for servicing air conditioning systems in the nonroad 
vehicles addressed in this action, including use of small refrigerant 
cans (two pounds or less). The use condition, which would require 
specific servicing fittings, would apply to the nonroad vehicles for 
which we are newly proposing to list HFO-1234yf as acceptable, subject 
to use conditions, as well as for all types of vehicles for which EPA 
has previously listed HFO-1234yf as acceptable, subject to use 
conditions. For the existing listings, EPA is proposing to revise the 
existing use conditions to require unique servicing fittings for use 
with small cans (two pounds or less).
    Finally, EPA is proposing to include a reference to the Agency's 
Significant New Use Rule (SNUR) for HFO-1234yf under the Toxic 
Substances Control Act (80 FR 37166, June 30, 2015) in Appendix B 
subpart G of part 82, under the `Comments' column, for the listings of 
HFO-1234yf for the nonroad vehicles addressed in this action, as well 
as for all the previous listings of HFO-1234yf as acceptable, subject 
to use conditions, for various vehicle types. The SNUR states that 
commercial users or consumers can only recharge MVAC systems with HFO-
1234yf where the original charging of the system with HFO-1234yf was 
done by the original equipment manufacturer.
    Aside from the proposed updates to refer to the most current 
versions of the SAE standards, the proposed addition of a use condition 
relating to servicing fittings for small cans, and the proposed 
reference to the June 2015 SNUR, the Agency is not reopening for 
comment other portions of the March 29, 2011, and December 1, 2016, 
final rules.
    EPA notes that there are additional requirements that concern the 
sale or offer for sale of refrigerants, including a sales restriction 
under the regulations implementing section 608 of the CAA, which can be 
found at 40 CFR part 82 subpart F. These regulations collectively 
comprise the national recycling and emissions reduction program and may 
be commonly referred to as the stationary refrigeration and air 
conditioning management program. The general sales restriction 
provisions are codified at 82.154(c) and the specifications for self-
sealing valves relevant to an exemption to the sales restriction for 
small cans of MVAC refrigerant are codified at 82.154(c)(2). This 
proposal does not propose to modify the provisions under 40 CFR 82.154, 
including the restriction on the sale of substitute refrigerants and 
requirements for self-sealing valves. The Agency is not proposing and 
is not reopening for comment regulations promulgated under section CAA 
608.

B. SNAP Program Background

    The SNAP program implements section 612 of the Clean Air Act (CAA). 
Several major provisions of section 612 are:

[[Page 68964]]

1. Rulemaking
    Section 612 requires EPA to promulgate rules making it unlawful to 
replace any class I (chlorofluorocarbon (CFC), halon, carbon 
tetrachloride, methyl chloroform, methyl bromide fluorocarbon, and 
chlorobromomethane) or class II (hydrochlorofluorocarbon (HCFC)) ozone-
depleting substances (ODS) with any substitute that the Administrator 
determines may present adverse effects to human health or the 
environment where the Administrator has identified an alternative that 
(1) reduces the overall risk to human health and the environment and 
(2) is currently or potentially available.
2. Listing of Unacceptable/Acceptable Substitutes
    Section 612(c) requires 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.
3. Petition Process
    Section 612(d) grants the right to any person to petition EPA to 
add a substance to, or delete a substance from, the lists published in 
accordance with section 612(c).
4. 90-Day Notification
    Section 612(e) directs 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 a new or existing chemical is introduced into 
interstate commerce for significant new use as a substitute for a class 
I substance.\4\ The producer must also provide the Agency with the 
producer's unpublished health and safety studies on such substitutes.
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    \4\ EPA's SNAP regulations at 82.176 extend this requirement to 
substitutes for class II substances, providing that ``[a]ny producer 
of a new substitute must submit a notice of intent to introduce a 
substitute into interstate commerce 90 days prior to such 
introduction.''
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    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 has identified five types of listing decisions: Acceptable; 
acceptable subject to use conditions; acceptable subject to narrowed 
use limits; unacceptable; and pending (40 CFR 82.180(b)). Use 
conditions and narrowed use limits are both considered ``use 
restrictions,'' as described below. 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 only if certain conditions in the way 
that the substitute is used are met to minimize risks to human health 
and the environment. EPA describes such substitutes as ``acceptable 
subject to use conditions.'' (40 CFR 82.180(b)(2)). 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. EPA describes these substitutes as ``acceptable 
subject to narrowed use limits.'' Under the narrowed use limit, users 
intending to adopt these substitutes ``must ascertain that other 
alternatives are not technically feasible.'' (40 CFR 82.180(b)(3)).
    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, EPA examines 
the 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.
    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, these statements 
are not binding for use of the substitute under the SNAP program. 
However, regulatory requirements so listed are binding as applicable 
under other regulatory programs (e.g., worker protection regulations 
promulgated by the U.S. Occupational Safety and Health Administration 
(OSHA)). The ``further information'' classification does not 
necessarily include all other legal obligations pertaining to the use 
of the substitute. While the items listed are not legally binding under 
the SNAP program, EPA encourages users of substitutes to apply all 
statements in the ``further information'' column in their use of these 
substitutes. In many instances, the information simply refers to sound 
operating practices that have already been identified in existing 
industry and/or building codes or standards. Thus, many of the 
statements, if adopted, would not require the affected user to make 
significant changes in existing operating practices.
    For additional information on the SNAP program, visit the SNAP 
portion of EPA's Ozone Layer Protection website at https://www.epa.gov/snap. Copies of the full lists of acceptable substitutes for ODS in all 
industrial sectors are available at https://www.epa.gov/snap/snap-substitutes-sector. 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 published March 18, 
1994 (59 FR 13044), codified at 40 CFR part 82, subpart G. SNAP 
decisions and the appropriate Federal Register citations found at: 
https://www.epa.gov/snap/snap-regulations. Substitutes listed as 
unacceptable; acceptable, subject to narrowed use limits; or 
acceptable, subject to use conditions, are also listed in the 
appendices to 40 CFR part 82, subpart G.
    In this proposed rule, EPA refers to listings made in a final rule 
issued on December 1, 2016, at 81 FR 86778 (``2016 Rule'') in which the 
Agency listed HFO-1234yf as acceptable, subject to use conditions, in 
new MDPV, HD pick-up trucks, and complete HD vans. The 2016 Rule also 
changed the listings for certain hydrofluorocarbons (HFCs) and blends 
from acceptable to unacceptable in various end-uses in the 
refrigeration and air conditioning, foam blowing, and fire suppression 
sectors. After a challenge to the 2016 Rule, the United States Court of 
Appeals for the District of Columbia Circuit (``the court'') issued a 
partial vacatur of the 2016 Rule ``only to the extent it requires 
manufacturers to replace HFCs that were previously and lawfully 
installed as substitutes for ozone-depleting substances.'' \5\ The 
court's decision on the 2016 Rule did not vacate the listing of HFO-
1234yf for certain types of vehicles, and this proposed rule is not 
EPA's response to the court's decision on the 2016 Rule.
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    \5\ Mexichem Fluor, Inc. v. EPA, No. 17-1024, 760 Fed. Appx. 6, 
9 (D.C. Cir., April 5, 2019).
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C. Does this action apply to me?

    The following list identifies types of regulated entities that may 
be affected by this proposed rule and their respective North American 
Industrial Classification System (NAICS) codes:

 All Other Basic Organic Chemical Manufacturing (NAICS 325199)
 All Other General Merchandise Stores (NAICS 452990)

[[Page 68965]]

 All Other Miscellaneous Chemical Product and Preparation 
Manufacturing (NAICS 325998)
 Automotive Parts and Accessories Stores (NAICS 441310)
 Automotive Repair Shops Not Elsewhere Classified, Including 
Air Conditioning and Radiator Specialty Shops (NAICS 811198)
 Gasoline Stations with Convenience Stores (NAICS 447110)
 General automotive repair shops (NAICS 811111)
 Heavy Duty Truck Manufacturing (NAICS 336120)
 Industrial Gas Manufacturing (NAICS 32512)
 Motor Vehicle Body Manufacturing (NAICS 336211)
 Motor Vehicle Parts Manufacturing (NAICS 3363)
 Other Automotive Repair and Maintenance (NAICS 81119)
 Other Motor Vehicle Parts Manufacturing (NAICS 336390)
 Recyclable Material Merchant Wholesalers (NAICS 423930)
 Refrigeration Equipment and Supplies Merchant Wholesalers 
(NAICS 423740)

    This list is not intended to be exhaustive but provides a guide for 
readers regarding types of entities likely to be regulated by this 
action if it becomes final as proposed. This list includes the types of 
entities that EPA is now aware could potentially be regulated by this 
action. Other types of entities not listed above could also be 
regulated. 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. 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.

C. What acronyms and abbreviations are used in the preamble?

    Below is a list of acronyms and abbreviations used in the preamble 
of this document:

AIHA--American Industrial Hygiene Association
AC--Air Conditioning
ACH--Changes Per Hour
AEM--Association of Equipment Manufacturers
ATEL--Acute Toxicity Exposure Limit
ANSI--American National Standards Institute
ASHRAE--American Society of Heating, Refrigerating and Air-
Conditioning Engineers
ASTM--American Society for Testing and Materials
CAA--Clean Air Act
CAS Reg. No.--Chemical Abstracts Service Registry Identification 
Number
CBI--Confidential Business Information
CGA--Compressed Gas Association
CFC--Chlorofluorocarbon
CFD--Computational Fluid Dynamics
CFR--Code of Federal Regulations
CO2--Carbon Dioxide
CRP--Cooperative Research Project
DIY--Do-It-Yourself
EEAP--Environmental Effects Assessment Panel
E.O.--Executive Order
EPA--United States Environmental Protection Agency
FCL--Flammability Concentration Limit
FMEA--Failure Mode and Effects Analysis
FR--Federal Register
GHG--Greenhouse Gas
GWP--Global Warming Potential
GVWR--Gross Vehicle Weight Rating
HCFC--Hydrochlorofluorocarbon
HD--Heavy-Duty
HD GHG--Heavy-Duty Greenhouse Gas
HF--Hydrogen Fluoride
HFC--Hydrofluorocarbon
HFO--Hydrofluoroolefin
HP--Horsepower
ICF--ICF International, Inc.
IPCC--Intergovernmental Panel on Climate Change
LD--Light-Duty
LD GHG--Light-Duty Greenhouse Gas
LFL--Lower Flammability Limit
MDPV--Medium-Duty Passenger Vehicle
MVAC--Motor Vehicle Air Conditioning
MY--Model Year
NAAQS--National Ambient Air Quality Standards
NAICS--North American Industrial Classification System
NOAEL--No Observed Adverse Effect Level
NRC--National Research Council
OEM--Original Equipment Manufacturer
ODP--Ozone Depletion Potential
ODS--Ozone-depleting Substance
OMB--United States Office of Management and Budget
OSHA--Occupational Safety and Health Administration
PPE--Personal Protective Equipment
ppm--Parts Per Million
PRA--Paperwork Reduction Act
RCL--Reference Concentration Limit
RFA--Regulatory Flexibility Act
SAE--SAE International
SAP--Scientific Assessment Panel
SDS--Safety Data Sheet
SIP--State Implementation Plan
SNAP--Significant New Alternatives Policy
SNUN--Significant New Use Notice
SNUR--Significant New Use Rule
STEL--Short-term Exposure Limit
TFA--Trifluoroacetic Acid
TLV--Threshold Limit Value
TSCA--Toxic Substances Control Act
TWA--Time Weighted Average
UFL--Upper Flammability Limit
UMRA--Unfunded Mandates Reform Act
UNEP--United Nations Environmental Programme
USGCRP--U.S. Global Change Research Program
VOC--Volatile Organic Compounds
WEEL--Workplace Environmental Exposure Limit
WMO--World Meteorological Organization

II. What is EPA proposing in this action?

A. Proposed Listing of HFO-1234yf as Acceptable, Subject to Use 
Conditions, for MVAC Systems in Certain Newly Manufactured Nonroad 
Vehicles

    EPA is proposing to list HFO-1234yf as acceptable, subject to use 
conditions, for MVAC systems in several types of newly manufactured 
nonroad vehicles, specifically: Agricultural tractors greater than 40 
HP; self-propelled agricultural machinery; compact equipment; 
construction, forestry, and mining equipment; and commercial utility 
vehicles. All MVAC refrigerants listed as acceptable are subject to use 
conditions requiring labeling and the use of unique fittings as 
described in Appendix B to subpart G of part 82--Substitutes Subject to 
Use Restrictions and Unacceptable Substitutes. EPA is proposing to list 
HFO-1234yf as acceptable, subject to use conditions, in the five 
nonroad vehicle types. The proposed use conditions would require that 
MVAC systems designed to use HFO-1234yf meet the requirements of SAE 
J639, SAE J1739, and SAE J2844 and would help to ensure that use of 
HFO-1234yf will not have a significantly greater overall impact on 
human health and the environment than other alternatives for use in 
those vehicles. EPA is proposing to update the existing use conditions 
that are currently required for the use of HFO-1234yf in MVAC systems 
in newly manufactured LD vehicles, MDPVs, HD pick-up trucks, and 
complete HD vans and apply them to all the MVAC systems addressed in 
this proposal. The proposed use conditions are detailed below in 
section II.A.4, ``What are the proposed use conditions?''
    While EPA is proposing to list HFO-1234yf as acceptable, subject to 
use conditions, in certain newly manufactured nonroad vehicles, 
including some vehicles that would also be considered HD vehicles, we 
are requesting comment and information on development of HFO-1234yf 
MVAC systems for other types of HD vehicles not covered in this 
proposal, particularly HD on-road trucks (i.e., Class 4-8 trucks 
between 14,001 and 33,000 or greater pounds). EPA intends to consider 
these comments in determining whether to initiate a separate rulemaking 
to list HFO-1234yf in these other vehicle types.
1. What is the affected end-use?
    Under SNAP, MVAC systems cool the passenger compartment of LD 
passenger

[[Page 68966]]

vehicles and trucks, HD vehicles (e.g., large pick-ups, delivery 
trucks, and semi-trucks), off[hyphen]road vehicles, buses, and 
passenger rail vehicles. These systems are typically charged during 
vehicle manufacture, and the main components are connected by flexible 
refrigerant lines. Nonroad vehicles can be grouped into several 
categories (i.e., agriculture, construction, recreation, and many other 
purposes).\6\ The vehicle types addressed in today's proposal include 
certain types of newly manufactured nonroad vehicles, specifically:
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    \6\ EPA, 2021. Basic Information about the Emission Standards 
Reference Guide for On-road and Nonroad Vehicles and Engines. 
Available online at https://www.epa.gov/emission-standards-reference-guide/basic-information-about-emission-standards-reference-guide-road and in the docket for this rulemaking at 
https://nepis.epa.gov/Exe/ZyPDF.cgi/P100K5U2.PDF?Dockey=P100K5U2.PDF.
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     Agricultural tractors greater than 40 HP (including two-
wheel drive (2WD), mechanical front-wheel drive (MFD), four-wheel drive 
(4WD), and track tractors) that are used for a number of agricultural 
applications such as farm work, planting, landscaping, and loading; 
7 8
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    \7\ Wagner, 2021. May 24, 2021, email from John Wagner of the 
Association of Equipment Manufacturers to EPA. Available in the 
docket for this rulemaking.
    \8\ AEM, 2021. Appendix A: Machine Forms as Classified by AEM 
Membership. Available in the docket for this rulemaking.
---------------------------------------------------------------------------

     Self-propelled agricultural machinery (including combines, 
grain and corn harvesters, sprayers, windrowers, and floaters) that are 
primarily used for harvesting, fertilizer, and herbicide operations; 
\9\
---------------------------------------------------------------------------

    \9\ Ibid.
---------------------------------------------------------------------------

     Compact equipment (including mini excavators, turf mowers, 
skid-steer loaders and tractors less than 40 HP) that are primarily 
used for agricultural operations and residential, commercial, and 
agricultural landscaping; \10\
---------------------------------------------------------------------------

    \10\ Ibid.
---------------------------------------------------------------------------

     Construction, forestry, and mining equipment (including 
excavators, bulldozers, wheel loaders, feller bunchers, log skidders, 
road graders, articulated trucks, sub-surface machines, horizontal 
directional drill, trenchers, and tracked crawlers) that are primarily 
used to excavate surface and subsurface materials during construction, 
landscaping, and road maintenance and building; \11\ and
---------------------------------------------------------------------------

    \11\ Ibid.
---------------------------------------------------------------------------

     Commercial utility vehicles that are primarily used for 
ranching, farming, hunting/fishing, construction, landscaping, property 
maintenance, railroad maintenance, forestry, and mining.\12\
---------------------------------------------------------------------------

    \12\ Ibid.
---------------------------------------------------------------------------

    These nonroad vehicles are almost exclusively used and operated by 
professionals (e.g., agricultural owners or skilled employees/
operators) and vary by size, weight, use, and/or horsepower.\13\ For 
example, commercial utility vehicles typically weigh between 1,200 and 
2,400 pounds, while agricultural tractors >40 HP typically weigh 
between 39,000 and 50,000 pounds.14 15 MVAC systems in these 
nonroad vehicles can have charge sizes ranging from 650 grams (23 
ounces) to 3,400 grams (120 ounces) depending on the manufacturer and 
cab size, compared to a range of 390 grams (14 ounces) to 1,600 grams 
(56 ounces) for MVAC systems in light and medium duty passenger 
vehicles, HD pickups, and complete HD vans.\16\ Additionally, unlike 
onroad passenger vehicles, for example, nonroad vehicles are limited to 
non-highway terrain (e.g., fields, construction sites, forests, and 
mines), have more robust components, are operated at low working 
speeds, and there are typically a limited number of vehicles in the 
same location.
---------------------------------------------------------------------------

    \13\ EPA, 2021. Basic Information about the Emission Standards 
Reference Guide for On-road and Nonroad Vehicles and Engines. 
Available online at https://www.epa.gov/emission-standards-reference-guide/basic-information-about-emission-standards-reference-guide-road and in the docket for this rulemaking.
    \14\ Heavy-duty vehicles are often subdivided by vehicle weight 
classifications, as defined by the vehicle's gross vehicle weight 
rating (GVWR), which is a measure of the combined curb (empty) 
weight and cargo carrying capacity of the truck. Heavy-duty vehicles 
have GVWRs above 8,500. See https://www.epa.gov/emission-standards-reference-guide/vehicle-weight-classifications-emission-standards-reference-guide.
    \15\ Wagner, 2021. May 24, 2021, email from John Wagner of the 
Association of Equipment Manufacturers to EPA. Available in the 
docket for this rulemaking.
    \16\ ICF, 2016. Technical Support Document for Acceptability 
Listing of HFO-1234yf for Motor Vehicle Air Conditioning in Limited 
Heavy-Duty Applications. Available in the public docket for this 
rulemaking.
---------------------------------------------------------------------------

2. What are the ASHRAE classifications for refrigerant flammability?
    The American National Standards Institute/American Society of 
Heating, Refrigerating and Air Conditioning Engineers (ANSI/ASHRAE) 
Standard 34-2019 assigns a safety group classification for each 
refrigerant which consists of two to three alphanumeric characters 
(e.g., A2L or B1). The initial capital letter indicates the toxicity 
and the numeral 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 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.
    Refrigerants are also assigned a flammability classification 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).\17\ The flammability classification ``1'' is given to 
refrigerants that, when tested, show no flame propagation. The 
flammability classification ``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 classification ``2L'' 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.), have 
an LFL greater than 0.10 kg/m\3\, and have a maximum burning velocity 
of 10 cm/s or lower when tested at in dry air at 73.4 [deg]F (23.0 
[deg]C) and 14.7 psia (101.3 kPa). The flammability classification 
``3'' is given to refrigerants that, when tested, exhibit flame 
propagation and that 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. 
Using these safety group classifications, ANSI/ASHRAE Standard 34-2019 
categorizes HFO-1234yf in the A2L Safety Group.
---------------------------------------------------------------------------

    \17\ ASHRAE, 2019. ANSI/ASHRAE Standard 34-2019: Designation and 
Safety Classification of Refrigerants.

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[[Page 68967]]

[GRAPHIC] [TIFF OMITTED] TP06DE21.006

3. How does HFO-1234yf compare to other refrigerants for these MVAC 
applications with respect to SNAP criteria?
    When reviewing a substitute under SNAP, EPA compares the risk posed 
by that substitute to the risks posed by other alternatives and 
considers whether that specific substitute under review poses 
significantly more risk than other available or potentially available 
alternatives for the same use. For this action, EPA performed a 
comparative risk analysis, based on our criteria for review, including 
an evaluation of environmental impacts, flammability, and toxicity. 
Redacted submissions that do not include information claimed as CBI by 
the submitter and supporting documentation for HFO-1234yf are provided 
in the docket for this proposed rule (EPA-HQ-OAR-2021-0347 at https://www.regulations.gov). EPA's assessments to examine the health and 
environmental risks of HFO-1234yf in each equipment type are also 
available in the docket for this proposed 
rule.18 19 20 21 22
---------------------------------------------------------------------------

    \18\ ICF, 2021a. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles--Agricultural Tractors Greater than 
40 Horsepower) (New Equipment).
    \19\ ICF, 2021b. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles--Self-Propelled Agricultural 
Machinery) (New Equipment).
    \20\ ICF, 2021c. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles--Compact Equipment) (New Equipment).
    \21\ ICF, 2021d. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles--Construction, Forestry, and Mining 
Equipment) (New Equipment).
    \22\ ICF, 2021e. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles--Commercial Utility Vehicles) (New 
Equipment).
---------------------------------------------------------------------------

    As explained more fully below, to help evaluate environmental, 
flammability, and toxicity risks resulting from the use of HFO-1234yf 
in certain types of newly manufactured nonroad vehicles, EPA considered 
the Agency's analyses 23 24 25 26 27 28 29 30 31 conducted 
in support of the 2011 (76 FR 17488; March 29, 2011) and 2016 (81 FR 
86778; December 1, 2016) listing decisions for HFO-1234yf in MVAC 
systems, including information submitted during the public comment 
period of the proposal for the 2011 final decision (October 19, 2009; 
74 FR 53445), such as the SAE Cooperative Research Project's (CRP) risk 
assessments.32 33 34 35 36 These risk assessments are 
available in the docket for this proposed rule. The refrigerants to 
which HFO-1234yf was compared in the 2011 action for LD vehicles are 
the same refrigerants available for use in the nonroad vehicle types 
included in this proposal. In addition, EPA considered risk assessments 
37 38 39 40 41 conducted by the Association of Equipment 
Manufacturers (AEM), an industry consortium of construction and 
agriculture equipment manufacturers, and found these were consistent 
with the Agency's assessments to examine the health and environmental 
risks of HFO-1234yf in each vehicle type.
---------------------------------------------------------------------------

    \23\ EPA, 2005. Risk Analysis for Alternative Refrigerant in 
Motor Vehicle Air Conditioning.
    \24\ ICF, 2008a. Air Conditioning Refrigerant Charge Size to 
Passenger Compartment Volume Ratio Analysis.
    \25\ ICF, 2008b. Revised Characterization of U.S. Hybrid and 
Small Car Sales (Historical and Predicted) and Hybrid Vehicle 
Accidents.
    \26\ ICF, 2009a. Revised Final Draft Assessment of the Potential 
Impacts of HFO-1234yf and the Associated Production of TFA on 
Aquatic Communities and Local Air Quality.
    \27\ ICF, 2009b. Risk Screen on Substitutes for CFC-12 in Motor 
Vehicle Air Conditioning: Substitute: HFO-1234yf.
    \28\ ICF, 2010a. Summary of HFO-1234yf Emissions Assumptions.
    \29\ ICF, 2010b. Summary of Updates to the Vintaging Model that 
Impacted HFO-1234yf Emissions Estimates.
    \30\ ICF, 2010c. Revised Assessment of the Potential Impacts of 
HFO-1234yf and the Associated Production of TFA on Aquatic 
Communities, Soil and Plants, and Local Air Quality.
    \31\ ICF, 2010d. Sensitivity Analysis CMAQ results on projected 
maximum TFA rainwater concentrations and maximum 8-hr ozone 
concentrations.
    \32\ CRP, 2008. Risk Assessment for Alternative Refrigerants 
HFO-1234yf Phase II. Prepared for SAE International Cooperative 
Research Program 1234 by Gradient Corporation.
    \33\ CRP, 2009. Risk Assessment for Alternative Refrigerants 
HFO-1234yf and R-744 (CO2) Phase III. Prepared for SAE International 
Cooperative Research Program 1234 by Gradient Corporation.
    \34\ DuPont and Honeywell. Guidelines for Use and Handling of 
HFO-1234yf (v8.0).
    \35\ Exponent. 2008. HFO-1234yf Refrigerant Concentration and 
Ignition Tests in Full-Scale Vehicle Passenger Cabin and Engine 
Compartment.
    \36\ CRP, 2013.SAE International Cooperative Research Project 
CRP1234-4 on R-1234yf Safety, Finishes Work and Presents 
Conclusions. Available online at: https://www.sae.org/servlets/pressRoom?OBJECT_TYPE=PressReleases&PAGE=showRelease&RELEASE_ID=2146.

    \37\ AEM, 2019. Risk Assessment for HFO-1234yf in Agricultural 
Tractors >= 40 HP including 2WD, MFD, 4WD and Track Type Equipment.
    \38\ AEM, 2020a. Risk Assessment for HFO-1234yf in Self-
Propelled Agricultural Machinery including Combines, Forage 
Harvesters, Sprayers, and Windrowers.
    \39\ AEM, 2020b. Risk Assessment for HFO-1234yf in Compact 
Equipment (Examples include Tractors <40HP, Turf Equipment, Skid 
Steer, Mini-Excavators and Track Loaders).
    \40\ AEM, 2020c. Risk Assessment for HFO-1234yf in Construction, 
Forestry, and Mining Equipment.
    \41\ AEM, 2020d. Risk Assessment for HFO-1234yf in Commercial 
Utility Vehicles.
---------------------------------------------------------------------------

(a) Environmental Impacts
    The SNAP program considers a number of environmental criteria when 
evaluating substitutes: Ozone depleting potential (ODP); climate 
effects, primarily based on global warming potential (GWP); local air 
quality

[[Page 68968]]

impacts, particularly potential impacts on smog formation from 
emissions of volatile organic compounds (VOC); and ecosystem effects, 
particularly from negative impacts on aquatic life. These and other 
environmental and health risks are discussed below.
    HFO-1234yf is chemical substance identified as 2,3,3,3-
tetrafluoroprop-1-ene (CAS Reg. No. 754-12-1). HFO-1234yf has a GWP of 
four,42 43 which is similar to or lower than the GWP of 
other alternatives for the nonroad vehicles addressed in this proposal. 
For example, its GWP is significantly lower than that of HFC-134a, the 
refrigerant most widely used in these vehicles today, which has a GWP 
of 1,430. As shown in Table 1, two other alternatives, HFC-152a,\44\ 
and CO2 \45\ have GWPs of 124 and 1, respectively.
---------------------------------------------------------------------------

    \42\ Nielsen et al., 2007. Atmospheric chemistry of CF3CF=CH2: 
Kinetics and mechanisms of gas-phase reactions with Cl atoms, OH 
radicals, and O3. Chemical Physics Letters 439, 18-22. Available 
online at: https://www.cogci.dk/network/OJN_174_CF3CF=CH2.pdf.
    \43\ Papadimitriou et al., 2007. CF3CF=CH2 and (Z)-CF3CF=CHF: 
temperature dependent OH rate coefficients and global warming 
potentials. Phys. Chem. Chem. Phys., 2007, Vol. 9, p. 1-13. 
Available online at: https://pubs.rsc.org/en/Content/ArticleLanding/2008/CP/b714382f.
    \44\ HFC-152a is listed as acceptable, subject to use 
conditions, for new vehicles only at 40 CFR part 82 subpart G; final 
rule published June 12, 2008 (73 FR 33304).
    \45\ CO2 is listed as acceptable, subject to use 
conditions, for new vehicles only at 40 CFR part 82 subpart G; final 
rule published June 6, 2012 (77 FR 33315).
---------------------------------------------------------------------------

    Other acceptable refrigerants for the nonroad vehicles addressed in 
today's proposal have GWPs ranging from 933 to 3,337. These include 
several blend refrigerants that are listed as acceptable, subject to 
use conditions, for these nonroad vehicles, including the HFC blends 
SP34E and R-426A (also known as RS-24) and the HCFC blends, R-416A 
(also known as HCFC Blend Beta or FRIGC FR12), R-406A, R-414A (also 
known as HCFC Blend Xi or GHG-X4), R-414B (also known as HCFC Blend 
Omicron), HCFC Blend Delta (also known as Free Zone), Freeze 12, GHG-
X5, and HCFC Blend Lambda (also known as GHG-HP). In a final rule 
issued July 20, 2015, at 80 FR 42870 (``2015 Rule''),\46\ EPA listed 
the use of certain refrigerant blends, including the ones mentioned 
above, as unacceptable in newly manufactured LD vehicles starting in MY 
2017. EPA did not propose or finalize a change of status for use of the 
refrigerant blends in MVACs in nonroad vehicles. The refrigerant blends 
remain acceptable, subject to use conditions, for the nonroad vehicles 
addressed in this proposed rule. Also, although they are listed as 
acceptable, subject to use conditions, EPA is not aware of the use or 
development of HFC-152a, CO2, or any of the refrigerant 
blends above in newly manufactured nonroad vehicles.\47\ Additionally, 
all MVAC refrigerants are subject to use conditions requiring labeling 
and the use of unique fittings, and the two lower-GWP alternatives 
currently approved for use in nonroad vehicles (i.e., HFC-152a and 
CO2) are subject to additional use conditions mitigating 
flammability and toxicity as appropriate to the alternative.
---------------------------------------------------------------------------

    \46\ The 2015 Rule, among other things, changed the listings for 
certain HFCs and blends from acceptable to unacceptable in various 
end-uses in the aerosols, refrigeration and air conditioning, and 
foam blowing sectors. After a challenge to the 2015 Rule, the United 
States Court of Appeals for the District of Columbia Circuit (``the 
court'') issued a partial vacatur of the 2015 Rule ``to the extent 
it requires manufacturers to replace HFCs with a substitute 
substance'' (see Mexichem Fluor, Inc. v. EPA, 866 F.3d 451, 462 
(D.C. Cir. 2017) and remanded the rule to the Agency for further 
proceedings. The court also upheld EPA's listing changes as being 
reasonable and not ``arbitrary and capricious.'' See Mexichem Fluor, 
866 F.3d at 462-63.
    \47\ The CAA and EPA's ODS regulations restrict the permissible 
uses of virgin HCFCs. With respect to refrigerants, virgin HCFC-22, 
HCFC-142b and blends containing HCFC-22 or HCFC-142b may now only be 
used to service existing appliances. Consequently, virgin HCFC-22, 
HCFC-142b and blends containing virgin HCFC-22 or HCFC-142b may no 
longer be used as a refrigerant to manufacture new pre-charged 
appliances or appliance components or to charge new appliances 
assembled onsite.

    Table 1--GWP, ODP, and VOC Status of HFO-1234yf Compared to Other Refrigerants in MVAC Systems of Nonroad
                                                  Vehicles \1\
----------------------------------------------------------------------------------------------------------------
           Refrigerants                  GWP             ODP              VOC status              Proposal
----------------------------------------------------------------------------------------------------------------
HFO-1234yf.......................               4               0  No.....................  Acceptable, subject
                                                                                             to use conditions.
CO2, HFC-152a, HFC-134a..........         1-1,430               0  No.....................  No change.
Other refrigerants, including           933-3,340         0-0.098  Yes \2\................  No change.
 IKON A, R-414B, R-416A, R-426A,
 SP34E.
----------------------------------------------------------------------------------------------------------------
\1\ The table does not include not-in-kind technologies listed as acceptable for the stated end-use.
\2\ One or more constituents of the blend are VOC.

    HFO-1234yf does not deplete the ozone layer. Similarly, HFC-134a, 
HFC-152a, CO2, the HFC blends SP34E, and R-426A do not 
deplete the ozone layer; however, the HCFC blends have ODPs ranging 
from 0.012 to 0.056.
    HFO-1234yf, HFC-134a, HFC-152a, and CO2 are exempt from 
the definition of VOC under CAA regulations (see 40 CFR 51.100(s)) 
addressing the development of state implementation plans (SIPs) to 
attain and maintain the National Ambient Air Quality Standards (NAAQS). 
The HFC blends and some of the HCFC blends have one or more components 
that are VOC.
    Another potential environmental impact of HFO-1234yf is its 
atmospheric decomposition to trifluoroacetic acid (TFA, 
CF3COOH). TFA is a strong acid that may accumulate in soil, 
plants, and aquatic ecosystems over time and may have the potential to 
adversely impact plants, animals, and ecosystems.\48\ Simulations have 
found that the amount of TFA in rainfall produced from a transition of 
all mobile air conditioners in the continental United States to HFO-
1234yf has been estimated to be double or more the values observed in 
the United States in 2009 from all sources, natural and artificial 
(i.e., HFC-134a).\49\ In comparison, the amount of TFA produced from 
HFO-1234yf is expected to be higher than that of other fluorinated 
refrigerants in this end-use.
---------------------------------------------------------------------------

    \48\ Other fluorinated compounds also decompose into TFA, 
including HFC-134a.
    \49\ Luecken et al., 2009. Ozone and TFA impacts in North 
America from degradation of 2, 3, 3, 3-tetrafluoropropene (HFO-
1234yf), a potential greenhouse gas replacement. Environmental 
Science & Technology 2009. Available online at: https://www.researchgate.net/profile/Robert_Waterland/publication/40481734_Ozone_and_TFA_impacts_in_North_America_from_degradation_of_2333-Tetrafluoropropene_(HFO-
1234yf)_a_potential_greenhouse_gas_replacement/links/
00b7d514ca9595bf5e000000.pdf.
---------------------------------------------------------------------------

    In support of the 2011 and 2016 listing decisions for HFO-1234yf in 
certain MVAC systems, EPA analyzed potential TFA concentrations from a 
full transition to HFO-1234yf in all

[[Page 68969]]

refrigeration and stationary AC systems including all MVAC 
applications.50 51 52 53 54 EPA has also considered this 
analysis in developing this proposal. The analysis found a maximum 
projected concentration of TFA in rainwater of approximately 1,700 ng/
L. This maximum projected concentration identified in EPA's analysis, 
1700 ng/L,\55\ was roughly 34 percent higher than that projected in a 
2009 peer reviewed article.\56\ The difference in projected TFA 
concentrations in water is a reflection of EPA's reliance on higher 
emission estimates.\57\ Even when relying on more conservative emission 
estimates, a concentration of 1700 ng/L corresponds to roughly 1/600th 
of the No-Observed-Adverse-Effect-Level (NOAEL) for the most sensitive 
algae species, which is also well below the NOAEL for the most 
sensitive aquatic animal species.\58\
---------------------------------------------------------------------------

    \50\ ICF, 2009a. Revised Final Draft Assessment of the Potential 
Impacts of HFO-1234yf and the Associated Production of TFA on 
Aquatic Communities and Local Air Quality.
    \51\ ICF, 2010a. Summary of HFO-1234yf Emissions Assumptions.
    \52\ ICF, 2010b. Summary of Updates to the Vintaging Model that 
Impacted HFO-1234yf Emissions Estimates.
    \53\ ICF, 2010c. Revised Assessment of the Potential Impacts of 
HFO-1234yf and the Associated Production of TFA on Aquatic 
Communities, Soil and Plants, and Local Air Quality.
    \54\ ICF, 2010d. Sensitivity Analysis CMAQ results on projected 
maximum TFA rainwater concentrations and maximum 8-hr ozone 
concentrations.
    \55\ ICF, 2010d. Sensitivity Analysis CMAQ results on projected 
maximum TFA rainwater concentrations and maximum 8-hr ozone 
concentrations.
    \56\ Luecken et al., 2009. Ozone and TFA impacts in North 
America from degradation of 2,3,3,3-tetrafluoropropene (HFO-1234yf), 
a potential greenhouse gas replacement. Environmental Science & 
Technology 2009. Available online at: https://www.researchgate.net/profile/Robert_Waterland/publication/40481734_Ozone_and_TFA_impacts_in_North_America_from_degradation_of_2333-Tetrafluoropropene_(HFO-
1234yf)_a_potential_greenhouse_gas_replacement/links/
00b7d514ca9595bf5e000000.pdf.
    \57\ ICF, 2010d. Sensitivity Analysis CMAQ results on projected 
maximum TFA rainwater concentrations and maximum 8-hr ozone 
concentrations.
    \58\ ICF, 2009a. Revised Final Draft Assessment of the Potential 
Impacts of HFO-1234yf and the Associated Production of TFA on 
Aquatic Communities and Local Air Quality.
---------------------------------------------------------------------------

    Since the 2011 final rule listing HFO-1234yf as acceptable for LD 
vehicles, additional research on TFA has been conducted. The United 
Nations Environment Programme (UNEP) Ozone Secretariat provided a 
summary of key information pertaining to TFA based on the 2014 
Assessment Reports of the Environmental Effects Assessment Panel (EEAP) 
and the Scientific Assessment Panel (SAP) of the Montreal Protocol. The 
brief states, ``While it is well established that TFA is a ubiquitous 
natural component in rivers, lakes, and other surface water bodies, 
uncertainties remain regarding anthropogenic sources, long-term fate 
and abundances as these are linked to current and future use and 
emissions of HFCs, HCFCs, and HFOs. Based on estimates to 2040, 
increases are predicted to remain relatively low and are therefore not 
expected to be a significant risk to human health or detrimental to the 
environment. Projected future increased loadings of TFA to playas, 
land-locked lakes, and the oceans due to continued use of HCFCs, HFCs, 
and replacement products such as HFOs are still judged to present 
negligible risks for aquatic organisms and humans.'' \59\ This UNEP 
brief also states that TFA and its salts ``do not bioconcentrate in 
aquatic organisms, and do not biomagnify in the food chain. Thus, they 
present negligible risk to organisms higher on the food chain, 
including humans.'' The 2018 Assessment Report of the EEAP reiterated 
that ``[overall], there is no new evidence that contradicts the 
conclusion of our previous Assessments that exposure to current and 
projected concentrations of salts of TFA in surface waters present a 
minimal risk to the health of humans and the environment.'' \60\ EEAP 
also referred to a 2017 review of this topic \61\ which reached a 
similar conclusion.
---------------------------------------------------------------------------

    \59\ UNEP, 2015. Ecological Issues on the Feasibility of 
Managing HFCs: Focus on TFA. Inter-sessional Informal Meeting, 12-13 
June 2015. This document accessible at: https://ozone.unep.org/sites/default/files/2020-06/informal%20brief_ecological%20effects_intersessional_June%202015_final%20%281%29.docx.
    \60\ EEAP, 2019. Environmental Effects and Interactions of 
Stratospheric Ozone Depletion, UV Radiation, and Climate Change. 
2018 Assessment Report. Nairobi: Environmental Effects Assessment 
Panel, United Nations Environment Programme (UNEP) 390 pp. Available 
online at: https://ozone.unep.org/science/assessment/eeap.
    \61\ Norwegian Environment Agency, 2017. Study on Environmental 
and Health Effects of HFO Refrigerants, Norwegian Environment Agency 
Report No. No. M-9172017, Oslo, Norway, p. 349.
---------------------------------------------------------------------------

    A 2014 study by Kazil, et al.\62\ analyzed TFA deposition in the 
United States assuming 100 percent of all MVAC systems use HFO-1234yf. 
The results indicated that rainwater TFA concentrations, while varying 
strongly geographically, will be orders of magnitude lower compared to 
the levels at which toxic effects are observed in aquatic systems. More 
recently, the World Meteorological Organization (WMO) concluded that 
``[t]here is increased confidence that [TFA] produced from degradation 
of HFCs, HCFCs, and HFOs will not harm the environment over the next 
few decades,'' \63\ while also calling for periodic reevaluation of 
this conclusion. EPA likewise finds that the data on TFA are not 
sufficient to propose or establish additional restrictions under SNAP 
at this time. In sum, based on our consideration of these documents, 
the additional information available since our 2011 listing decision 
shows no greater risk than our earlier analysis. We further note that 
the requirements for the safe disposal of appliances and the venting 
prohibition under section 608 of the CAA, codified at 40 CFR 82.155 and 
40 CFR 82.154(a), respectively, and accompanying refrigerant management 
requirements reduce emissions of these refrigerants. EPA intends to 
continue reviewing the research on potential impacts from TFA in the 
future and may consider taking additional action in the future if 
warranted.
---------------------------------------------------------------------------

    \62\ Kazil et al., 2014. Deposition and rainwater concentrations 
of trifluoroacetic acid in the United States from the use of HFO-
1234yf. JGR-Atmospheres, 2014.
    \63\ WMO, 2018. Executive Summary: Scientific Assessment of 
Ozone Depletion: 2018, World Meteorological Organization, Global 
Ozone Research and Monitoring Project--Report No. 58, 67 pp., 
Geneva, Switzerland, 2018.
---------------------------------------------------------------------------

    Taking into consideration the analysis conducted in support of the 
2011 listing decision, which was based on conservative emissions 
assumptions and a transition from HFC-134a to HFO-1234yf for all MVAC 
systems (not limited to LD vehicles), and the research that has been 
conducted since, EPA proposes that the use of HFO-1234yf in the nonroad 
vehicles addressed in this action will not pose a significant risk to 
the environment from atmospheric decomposition to TFA.
    Based on the consideration of all of these environmental impacts, 
EPA proposes that HFO-1234yf does not pose significantly greater risk 
to the environment than the other alternatives for use in newly 
manufactured nonroad vehicles addressed in this action, and it poses 
significantly less risk than several of the alternatives with higher 
GWPs and ODPs.
(b) Flammability
    HFO-1234yf is a flammable refrigerant classified as A2L under 
ASHRAE 34-2013. HFC-134a, CO2, and the refrigerant blends 
SP34E and R-426A (also known as RS-24) and the HCFC blends, R-416A 
(also known as HCFC Blend Beta or FRIGC FR12), R-414A (also known as 
HCFC Blend Xi or GHG-X4), R-414B (also known as HCFC Blend Omicron), 
HCFC Blend Delta (also known as Free Zone), Freeze 12, GHG-X5, and HCFC 
Blend Lambda (also known as GHG-HP) are nonflammable refrigerants, 
while HFC-152a and R-406A are slightly more

[[Page 68970]]

flammable than HFO-1234yf with an ASHRAE classification of A2. HFO-
1234yf is flammable when its concentration in air is in the range of 
6.2 percent and 12.3 percent by volume (62,000 ppm to 123,000 ppm).\64\ 
In the presence of an ignition source (e.g., static electricity, a 
spark resulting from a switch malfunction, or a cigarette), an 
explosion or a fire could occur when the concentration of HFO-1234yf 
exceeds its LFL of 62,000 ppm, posing a significant safety concern for 
workers and consumers if it is not handled carefully. However, HFO-
1234yf is difficult to ignite and, in the event of ignition, the flames 
would propagate slowly.\65\
---------------------------------------------------------------------------

    \64\ Chemours, 2019. HFO-1234yf for Use as a Refrigerant. 
Significant New Alternatives Policy Program Submission to the U.S. 
Environmental Protection Agency.
    \65\ HFO-1234yf has a high minimum ignition energy of 5,000-
10,000 mJ and a low burning velocity of 1.5 cm/s (Koban, 2011).
---------------------------------------------------------------------------

    With regards to flammability risks to workers, EPA's risk screens 
evaluated the potential for a fire from release and ignition in 
workplace situations and work-site operations, such as during equipment 
manufacture, servicing and disposal or recycling of vehicle end-of-life 
for the five nonroad vehicles. EPA considered the characteristics that 
could be different from LD and other HD vehicles, such as differences 
in the engine compartment size, passenger cabins, and operating 
conditions, and how those might impact risks. In order to determine the 
potential flammability risks during servicing or end-use in case of a 
release of refrigerant into the cab, concentrations of HFO-1234yf 
immediately following a 60 percent release of refrigerant over a period 
of one minute into the cab were compared to the LFL and upper 
flammability limit (UFL) for HFO-1234yf reported by ASHRAE Standard 34 
(i.e., 62,000 ppm and 123,000 ppm, respectively). The one-minute time 
duration is most appropriate for determining the risks of flammable 
refrigerants because the potential maximum instantaneous concentration 
can be estimated and compared to the LFL. Two key inputs to the models 
were the cab volume (i.e., the space into which the refrigerant would 
leak) and the refrigerant charge size. Because passenger compartment 
volumes and refrigerant charge sizes can vary widely from model to 
model, the highest ratio of charge size to compartment volume 
identified was used as the input into the models.
    In the event of a leak, SAE Standard J2772 specifies that nonroad 
vehicles be manufactured such that the pressure differential between 
the air conditioning system and the cab allows only up to 60 percent of 
the refrigerant charge to be released into the cab.\66\ Independent 
testing of refrigerant releases from nonroad vehicles, according to SAE 
Standard J2772, found that the amount of refrigerant released following 
a line leak was much lower than 60 percent.
---------------------------------------------------------------------------

    \66\ SAE, 2019. Standard J2772: Measurement of Passenger 
Compartment Refrigerant Concentrations Under System Refrigerant 
Leakage Conditions. SAE International.
---------------------------------------------------------------------------

    To represent a plausible worst-case scenario, EPA's box modeling 
assumed that 60 percent of the charge of the air conditioning systems 
for the five nonroad vehicles is released into the cab of the vehicles 
over a period of one minute. EPA's worst-case scenario box modeling 
resulted in the concentration of HFO-1234yf in the cab exceeding the 
LFL of 62,000 ppm, for the five nonroad vehicles. However, the 
estimated exposures were derived using conservative assumptions and 
represent worst-case scenarios with a low probability of occurrence, as 
the analyses assume a rapid release of refrigerant (i.e., one minute), 
assume the minimum required fresh air intake, and do not consider the 
air recirculation rate for the nonroad vehicles or other variables that 
would potentially reduce the concentration levels in the air to below 
the flammable range for HFO-1234yf. Additionally, flammability concerns 
are further reduced due to the design of MVAC systems for the five 
vehicle types as described above in section II.A.1 and the low 
probability of collisions for these nonroad vehicles. MVAC systems in 
the nonroad vehicles are robust and made to withstand strenuous 
operation, which lowers the potential for line leaks due to wear. 
According to AEM, 67 68 69 70 71 the operator's compartment 
in agricultural tractors greater than 40 HP; self-propelled 
agricultural machinery; compact equipment; and construction, forestry, 
and mining equipment is a completely self-contained unit which provides 
an additional level of safety in a collision event. For commercial 
utility vehicles, which are smaller than the other four nonroad vehicle 
types, AEM noted that the engine compartment is contained in the rear 
of the vehicle, under the cargo bed, with the main components of the 
MVAC system in the front of the cabin with only the compressor and two 
lines near the engine. The potential for collisions is also less likely 
because most of the vehicles are operated by trained professionals, 
typically at low speed, and are only driven on the highway to move from 
one site or nonroad location to another.
---------------------------------------------------------------------------

    \67\ AEM, 2019. Risk Assessment for HFO-1234yf in Agricultural 
Tractors >= 40 HP including 2WD, MFD, 4WD and Track Type Equipment.
    \68\ AEM, 2020a. Risk Assessment for HFO-1234yf in Self-
Propelled Agricultural Machinery including Combines, Forage 
Harvesters, Sprayers, and Windrowers.
    \69\ AEM, 2020b. Risk Assessment for HFO-1234yf in Compact 
Equipment (Examples include Tractors <40HP, Turf Equipment, Skid 
Steer, Mini-Excavators and Track Loaders).
    \70\ AEM, 2020c. Risk Assessment for HFO-1234yf in Construction, 
Forestry, and Mining Equipment.
    \71\ AEM, 2020d. Risk Assessment for HFO-1234yf in Commercial 
Utility Vehicles.
---------------------------------------------------------------------------

    In addition to the plausible worst-case scenario analysis, which 
employs a simple box model, EPA's risk screens reference modeling 
conducted by AEM in the flammability assessments. The AEM consortium 
used two different models in its assessments: (1) A box model to 
examine worst-case scenarios for a wide variety of nonroad vehicles 
addressed in this proposal and (2) a computational fluid dynamics (CFD) 
72 73 74 75 76 77 model to more realistically represent the 
behavior of the leaked refrigerant in an nonroad vehicle.The AEM box 
model modeled the release of 60 percent of the refrigerant charge in 
the vehicles with varying charge and cab sizes and assumed a near-
instantaneous leak of refrigerant over a period of 10 seconds. Six of 
the scenarios modeled in the box model resulted in the concentration of 
HFO-1234yf in the cab being equal to or exceeding the LFL; the 
concentrations from the remaining six scenarios were below the LFL. 
Similar to EPA's box modeling, the estimated exposures were derived 
using conservative assumptions and represent worst-case scenarios with 
a low probability of occurrence, as the analyses assume a rapid release 
of refrigerant, assume the minimum required fresh air intake (i.e., 43 
m\3\/hour), and do not consider the air recirculation rate for the 
nonroad vehicles or other variables that would potentially reduce the 
concentration levels in the air to below the flammable range for HFO-
1234yf.
---------------------------------------------------------------------------

    \72\ AEM, 2019. Risk Assessment for HFO-1234yf in Agricultural 
Tractors >= 40 HP including 2WD, MFD, 4WD and Track Type Equipment.
    \73\ AEM, 2020a. Risk Assessment for HFO-1234yf in Self-
Propelled Agricultural Machinery including Combines, Forage 
Harvesters, Sprayers, and Windrowers.
    \74\ AEM, 2020b. Risk Assessment for HFO-1234yf in Compact 
Equipment (Examples include Tractors <40HP, Turf Equipment, Skid 
Steer, Mini-Excavators and Track Loaders).
    \75\ AEM, 2020c. Risk Assessment for HFO-1234yf in Construction, 
Forestry, and Mining Equipment.
    \76\ AEM, 2020d. Risk Assessment for HFO-1234yf in Commercial 
Utility Vehicles.
    \77\ AEM, 2020e. CFD Leak Modeling-Supplemental Information to 
Compliment AEM Machine Form RAs.

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[[Page 68971]]

    Conversely, the maximum concentration reached in the AEM CFD model, 
which models a realistic leak scenario with the release of 60 percent 
of the refrigerant charge released in the nonroad vehicles for 1000 
seconds of simulation, was significantly below the LFL for HFO-1234yf 
of 62,000 ppm. Construction, forestry, and mining vehicles were modeled 
to represent the five nonroad vehicles as they had the highest ratio of 
refrigerant charge to cabin volume among the five nonroad vehicles. AEM 
found that the maximum concentration of HFO-1234yf reached in the cab 
(i.e., 25,700 ppm) is not likely to exceed the LFL for the five nonroad 
vehicles. The AEM CFD model reflects the real-world behavior of 
refrigerant in the cab given a worst-case leak scenario because it 
takes into account the refrigerant entry and exit points and assumes 
worst-case scenario conditions, including the most likely scenario 
where an operator is likely to ignite a cigarette, the highest charge-
to-cab ratio, minimal fresh air flow, and maximum air velocity and 
refrigerant penetration. Additionally, the CFD modeling demonstrates 
the conservativeness of the worst-case scenario box modeling and how 
unlikely its results are; therefore, the worst-case scenario box models 
may be overstating the true risks associated with the use of HFO-1234yf 
in MVAC systems in the nonroad vehicles compared to real-world 
conditions as presented in the CFD model.
    For these reasons, EPA concludes that the currently available 
assessments on the use of HFO-1234yf in newly manufactured nonroad 
vehicles addressed in this action are sufficiently conservative to 
account for all probable flammability risks from the use of HFO-1234yf. 
Relying on a similar analysis considered in support of the 2011 and 
2016 SNAP listings of HFO-1234yf in certain MVAC systems, verifying 
that more recent information is consistent with that analysis, and 
considering unique factors for the nonroad vehicle types, EPA proposes 
to conclude that the use of HFO-1234yf in the newly manufactured 
nonroad vehicles addressed in this action does not pose significantly 
greater flammability risk than the other alternatives when used in 
accordance with the proposed use conditions described below in section 
II.A.4, which are intended to mitigate flammability risks, and 
recommendations in the safety data sheet (SDS) and EPA's risk screens.
(c) Toxicity
    Potential health effects of exposure to HFO-1234yf include 
drowsiness or dizziness. HFO-1234yf may also irritate the skin or eyes 
or cause frostbite, and at sufficiently high concentrations, HFO-1234yf 
may cause irregular heartbeat. HFO-1234yf could cause asphyxiation if 
air is displaced by vapors in a confined space. These potential health 
effects are common to many refrigerants.
    The American Industrial Hygiene Association (AIHA) has established 
a Workplace Environmental Exposure Level (WEEL) of 500 ppm as an 8-hr 
TWA for HFO-1234yf. HFO-1234yf also has an acute toxicity exposure 
limit (ATEL) of 100,000 ppm and a refrigerant concentration limit (RCL) 
of 16,000 ppm, which are both established by ASHRAE. EPA anticipates 
that users will be able to meet the AIHA WEEL and ASHRAE ATEL and RCL, 
limits intended to reduce the risks of flammability in normally 
occupied, enclosed spaces, and address potential health risks by 
following requirements and recommendations in the manufacturer's SDSs 
and other safety precautions common to the refrigerant industry.
    To evaluate human health and safety impacts, including asphyxiation 
and toxicity risks, from the use of HFO-1234yf in the five types of 
nonroad vehicles, the Agency estimated the potential exposures to HFO-
1234yf in the event of a 60 percent release of refrigerant from the 
vehicles under reasonable worst-case scenarios described in the risk 
screens. In the event of a leak, SAE Standard J2772 specifies that 
nonroad vehicles be manufactured such that the pressure differential 
between the air conditioning system and the cab allows only up to 60 
percent of the refrigerant charge to be released into the cab.\78\ The 
analysis of asphyxiation risks considered whether a worst-case release 
of refrigerant under the cab would result in oxygen concentrations of 
12 percent or less. The analysis found that impacts on oxygen 
concentrations did not present a significant risk of asphyxiation at 
the typical charge sizes, and that a 60 percent leak of refrigerant at 
the maximum charge sizes could result in an oxygen concentration below 
19.5 percent but above 12 percent. The estimated exposures were derived 
using conservative assumptions, however, and conditions resulting in 
oxygen levels under 12 percent \79\ are only predicted to occur with 
charge sizes that are significantly larger than the maximum charge 
sizes provided by the submitter or cab sizes that are unlikely for the 
proposed applications. Additionally, the worst-case scenarios did not 
consider conditions that are likely to occur that would increase oxygen 
levels to which individuals would be exposed, such as fresh air flow 
into the cab.
---------------------------------------------------------------------------

    \78\ SAE, 2019. Standard J2772: Measurement of Passenger 
Compartment Refrigerant Concentrations Under System Refrigerant 
Leakage Conditions. SAE International.
    \79\ Twelve percent oxygen in air (i.e., 120,000 ppm) is the 
NOAEL for hypoxia (ICF, 1997).
---------------------------------------------------------------------------

    To assess the toxicity risks to end-users, 15-minute and 30-minute 
TWA exposures were estimated and compared to the standard toxicity 
limits. The estimated TWA exposures were fairly conservative as the 
analyses assume a rapid release of refrigerant (i.e., one minute and 10 
seconds for EPA's and AEM's box models, respectively), assume the 
minimum required ventilation rate (i.e., 43 m\3\/hour), and do not 
consider the air recirculation rate for the vehicles or other variables 
that would potentially reduce the concentration levels in the air. EPA 
found that the estimated 15-minute and 30-minute TWA exposures for HFO-
1234yf in MVAC systems in the nonroad vehicles are not likely to exceed 
the ATEL for HFO-1234yf of 100,000 ppm in a one-minute release scenario 
under EPA's worst-case scenario modeling assumptions. The end-use 
exposures estimated by AEM across all scenarios were also well below 
the ATEL for HFO-1234yf. Furthermore, these exposure estimates were 
derived using conservative assumptions that do not necessarily reflect 
a real-world leak scenario or the larger cab size where MVAC systems 
using HFO-1234yf would typically be installed.
    Additionally, the estimated TWA exposure for HFO-1234yf determined 
from AEM's CFD modeling, which models a realistic leak scenario for the 
nonroad vehicles, was significantly below the ATEL for HFO-1234yf of 
100,000 ppm. Construction, forestry, and mining vehicles were modeled 
to represent the five nonroad vehicles. As noted above, these vehicles 
are a more conservative and an approximately equivalent proxy for the 
other four nonroad vehicle types because they have the highest ratio of 
refrigerant charge to cabin volume among the five nonroad vehicles. 
Therefore, the toxicity risks from using HFO-1234yf in the five nonroad 
vehicles is not likely to exceed the ATEL for the five nonroad 
vehicles.
    Concerning workplace exposure during charging, servicing, and 
disposal of the nonroad vehicles addressed in this proposal, we expect 
that professional technicians have proper training and certification 
and have the proper equipment and knowledge to minimize their risks due 
to exposure to refrigerant from an MVAC system. Thus,

[[Page 68972]]

worker exposure to HFO-1234yf is expected to be low. The vehicles are 
typically charged by the Original Equipment Manufacturer (OEM). During 
air conditioning system manufacture (i.e., charging at OEM location), 
points of release would be from connection/disconnection of temporary 
lines for charging and recovery equipment, although exposure during 
these activities is expected to be minimal due to the use of left-hand 
threaded fittings on storage cylinders, as specified in SAE Standard 
J2844, intended to help mitigate any releases and restrict the 
possibility of cross-contamination with other 
refrigerants.80 81 82 83 84 Furthermore, equipment 
containing HFO-1234yf is expected to be equipped with unique fittings 
for the low-side and high-side service ports of the MVAC system, 
according to SAE Standard J639, also intended to help mitigate any 
releases and restrict the possibility of cross-contamination with other 
refrigerants.\85\
---------------------------------------------------------------------------

    \80\ ICF, 2021a. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles--Agricultural Tractors Greater than 
40 Horsepower) (New Equipment).
    \81\ ICF, 2021b. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles--Self-Propelled Agricultural 
Machinery) (New Equipment).
    \82\ ICF, 2021c. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles--Compact Equipment) (New Equipment).
    \83\ ICF, 2021d. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles--Construction, Forestry, and Mining 
Equipment) (New Equipment).
    \84\ ICF, 2021e. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles--Commercial Utility Vehicles) (New 
Equipment).
    \85\ Ibid.
---------------------------------------------------------------------------

    Servicing of the vehicles is expected to take place outside (e.g., 
out in the field or other outdoor site) rather than at a typical 
servicing center for LD vehicles, for example; therefore, exposure 
during servicing is expected to be less than during charging the MVAC 
system during manufacture. Therefore, occupational exposure during 
these activities was conservatively modeled based on charging. The 
modeled maximum 15-minute TWA exposures for HFO-1234yf during charging 
were compared to the short-term exposure limit (STEL) of 1,500 ppm. 
EPA's modeling indicated that the short-term (15-minute) worker 
exposure concentrations of HFO-1234yf are not likely to exceed its STEL 
for the typical or maximum charge size in the vehicles during charging 
or servicing. Additionally, these exposure estimates are significantly 
lower than the RCL and ATEL of 16,000 ppm and 100,000 ppm, 
respectively, for HFO-1234yf, which are limits intended to reduce the 
risks of asphyxiation and acute toxicity hazards in normally occupied, 
enclosed spaces according to ASHRAE Standard 34.
    EPA also determined that occupational exposure during disposal of 
the vehicles at the typical charge size is not likely to exceed the 
long-term (8-hour) WEEL for HFO-1234yf (i.e., 500 ppm). However, under 
the disposal release scenarios, the modeling showed that occupational 
exposure during disposal of MVAC systems containing HFO-1234yf at the 
maximum charge size (i.e., 3.4 kilograms (120 ounces)) could 
potentially exceed the 8-hour long-term exposure limit. The estimated 
exposures, however, were well below the RCL of 16,000 ppm for HFO-
1234yf and were derived using conservative assumptions and represent a 
worst-case scenario with a low probability of occurrence. These MVAC 
systems are also typically disposed of by CAA section 608-certified 
personnel using proper industrial hygiene techniques while wearing PPE 
to maximize recovery efficiency and limit releases. EPA concludes that 
the manufacture, use, servicing or disposal of HFO-1234yf MVAC systems 
in the newly manufactured nonroad vehicles addressed in this action 
does not pose greater risk toxicity risk to workers than the other 
alternatives when used in accordance with the proposed use conditions.
    Additionally, EPA's review of potential toxicity risks of HFO-
1234yf to the general population indicated that HFO-1234yf is not 
expected to pose significantly greater toxicity risk than other 
alternatives for the MVAC systems in the newly manufactured nonroad 
vehicles addressed in this action. The general population is defined as 
non-personnel who are subject to exposure of the proposed substitute 
near industrial facilities, including manufacturing or equipment 
production factories, equipment operating locations, or recycling 
centers, rather than personnel at end-use. EPA proposes to conclude 
that the use of HFO-1234yf in the newly manufactured nonroad vehicles 
addressed in this action does not pose significantly greater toxicity 
risk than the other alternatives when used in accordance with the 
proposed use conditions described below in section II.A.4, which are 
intended to mitigate toxicity risks, and recommendations in the SDS and 
EPA's risk screens.
4. What are the proposed use conditions?
    All MVAC refrigerants listed as acceptable are subject to use 
conditions requiring labeling and the use of unique fittings. HFC-152a 
and CO2 are subject to additional use conditions mitigating 
flammability and toxicity as appropriate to the alternative. Neither 
HFC-152a nor CO2 can simply be ``dropped'' into existing 
MVAC systems because they are listed as acceptable only for newly 
manufactured vehicles.
    EPA is proposing to list HFO-1234yf as acceptable, subject to use 
conditions, in MVAC systems in certain newly manufactured nonroad 
vehicles because the use conditions are necessary to ensure that use of 
HFO-1234yf will not have a significantly greater overall impact on 
human health and the environment than other alternatives. EPA is 
proposing to update the existing use conditions that are currently 
required for the use of HFO-1234yf in MVAC systems in newly 
manufactured LD passenger cars and trucks, MDPVs, HD pick-up trucks, 
and complete HD vans and then apply them to all the MVAC systems 
addressed in this proposal. Manufacturing and service personnel or 
consumers may not be familiar with refrigeration or AC equipment 
containing a flammable refrigerant. These use conditions will be 
sufficiently protective to ensure use of HFO-1234yf in these nonroad 
vehicles does not pose significantly greater risk than use of other 
alternatives.
    The first proposed use condition requires that HFO-1234yf may be 
used only in new MVAC systems \86\ which have been designed to address 
concerns unique to flammable refrigerants--i.e., HFO-1234yf may not be 
used as a conversion or ``retrofit'' refrigerant for existing MVACs 
designed for other refrigerants. HFO-1234yf was not submitted under the 
SNAP program for use in retrofitted MVAC systems, and no information 
was provided on how to address hazards if HFO-1234yf were to be used in 
MVAC systems that were not designed for a flammable refrigerant. 
Therefore, EPA is only proposing that HFO-1234yf may be used in new 
MVACs that have been properly designed for its use.
---------------------------------------------------------------------------

    \86\ This is intended to mean a completely new refrigeration 
circuit containing a new compressor, evaporator, condenser, and 
refrigerant tubing.
---------------------------------------------------------------------------

    The second proposed use condition requires that MVAC systems 
designed to use HFO-1234yf in newly manufactured agricultural tractors 
greater than 40 HP; self-propelled agricultural machinery; compact 
equipment; construction, forestry, and mining equipment; and commercial 
utility vehicles must meet the requirements of SAE J639 (revised 
November 2020), ``Safety Standards for Motor Vehicle Refrigerant Vapor 
Compression Systems.'' This standard

[[Page 68973]]

sets safety standards that include unique fittings; a warning label 
indicating the refrigerant's identity and that it is a flammable 
refrigerant; and requirements for engineering design strategies that 
include a high-pressure compressor cutoff switch and pressure relief 
devices. This use condition also requires that for connections with 
refrigerant containers for use in professional servicing, use fittings 
must be consistent with SAE J2844 (revised January 2013), ``R-1234yf 
(HFO-1234yf) New Refrigerant Purity and Container Requirements for Use 
in Mobile Air-Conditioning Systems,'' which specifies quick-connect 
fittings that are different from those for any other refrigerant. The 
low-side service port and connections will have an outside diameter of 
14 mm (0.551 inches), and the high-side service port will have an 
outside diameter of 17 mm (0.669 inches), both accurate to within 2 mm. 
Under SAE J2844 (revised January 2013), containers of HFO-1234yf for 
use in professional servicing of MVAC systems must have a left-handed 
screw valve with a diameter of 0.5 inches and Acme (trapezoidal) thread 
with 16 threads per inch.
    Consistent with the conclusion EPA drew at the time of the Agency's 
listing decision for HFO-1234yf in LD vehicles, EPA believes that the 
safety requirements that are included in SAE J639 sufficiently mitigate 
risks of both hydrogen fluoride (HF) generation and refrigerant 
ignition (March 29, 2011; 76 FR 17488) for the nonroad vehicles 
addressed in this proposed action. HFO-1234yf is mildly flammable (A2L 
classification) and, like other fluorinated refrigerants, can decompose 
to form the toxic compound HF when exposed to flame or to sufficient 
heat. The SAE J639 standard can also address flammability and HF risks 
of HFO-1234yf for the nonroad vehicles. For example, SAE J639 provides 
for a pressure relief device designed to minimize direct impingement of 
the refrigerant and oil on hot surfaces and for design of the 
refrigerant circuit and connections to avoid refrigerant entering the 
passenger cabin. The pressure release device ensures that pressure in 
the system will not reach an unsafe level that might cause an 
uncontrolled leak of refrigerant, such as if the MVAC system is 
overcharged. The pressure release device will reduce the likelihood 
that refrigerant leaks would reach hot surfaces that might lead to 
either ignition or formation of HF. These elements of the refrigerant 
circuit and connections are designed to prevent refrigerant from 
entering the passenger cabin if there is a leak. Keeping refrigerant 
out of the passenger cabin minimizes the possibility that there would 
be sufficient levels of refrigerant to reach flammable concentrations 
or that HF would be formed and transported where passengers might be 
exposed.
    The third proposed use condition requires the manufacturer of MVAC 
systems and vehicles to conduct Failure Mode and Effects Analysis 
(FMEA) as provided in SAE J1739 (revised January 2021), ``Potential 
Failure Mode and Effects Analysis (FMEA) Including Design FMEA, 
Supplemental FMEA-MSR, and Process FMEA,'' and keep records of the FMEA 
on file for three years from the date of creation. SAE J1739 (revised 
January 2021) describes a FMEA as ``a systematic group of activities 
intended to: (a) Recognize and evaluate the potential failure of a 
product/process and the effects and causes of that failure, (b) 
identify actions that could eliminate or reduce the change of the 
potential failure occurring, and (c) document the process.'' Through 
the FMEA, OEMs determine the appropriate protective strategies 
necessary to ensure the safe use of HFO-1234yf across their vehicle 
fleet. It is standard industry practice to perform the FMEA and to keep 
it on file while the vehicle is in production and for several years 
afterwards. As with the previous use condition, this use condition is 
intended to ensure that agricultural tractors greater than 40 HP; self-
propelled agricultural machinery; compact equipment; construction, 
forestry, and mining equipment; and commercial utility vehicles 
manufactured with HFO-1234yf MVACs are specifically designed to 
minimize release of the refrigerant into the passenger cabin or onto 
hot surfaces that might result in ignition or in generation of HF.

B. Proposed Modifications To Use Conditions for MVAC Systems in Other 
Vehicle Types

    For the previous listings of HFO-1234yf in the March 29, 2011 (76 
FR 17488), and December 1, 2016 (81 FR 86778), final rules for MVAC 
systems in certain newly manufactured vehicles, EPA is proposing to 
modify the use conditions to replace the reference to older versions of 
SAE J639, SAE J1739, and SAE J2844.
    First, EPA is proposing to replace the reference to SAE J639 
(revised 2011) in the March 2011 and December 2016 final rules with a 
reference to the 2020 version of the standard, ``Safety and Design 
Standards for Motor Vehicle Refrigerant Vapor Compression Systems.'' 
This is the most recent version of the SAE J639 standard, which was 
updated to include system design and safety- related requirements for 
secondary loop HFC-152a MVAC systems, and to make general improvements 
for clarity.
    Second, EPA is proposing to replace the reference to SAE J1739 
(adopted 2009) in the March 2011 and December 2016 final rules with a 
reference to the 2021 version of the standard, ``Potential Failure Mode 
and Effects Analysis (FMEA) Including Design FMEA, Supplemental FMEA-
MSR, and Process FMEA.'' The 2021 version is the most recent version of 
the SAE J1739 standard; it was revised to emphasize the process of FMEA 
selection, creation, documentation, reporting, and change management.
    Finally, EPA is proposing to replace the reference to SAE J2844 
(revised 2011) in the March 2011 final rule with a reference to the 
2013 version of the standard, ``R-1234yf (HFO-1234yf) New Refrigerant 
Purity and Container Requirements for Use in Mobile Air-Conditioning 
Systems.'' This is the most recent version of the SAE J2844 standard; 
it was updated to add the requirements for certification according to 
SAE J2911, ``Procedure for Certification that Requirements for Mobile 
Air Conditioning System Components, Service Equipment, and Service 
Technician Training Meet SAE J Standards.''

C. Proposed Servicing Fittings for Small Cans of HFO-1234yf

    EPA is proposing to include a use condition for HFO-1234yf to 
provide for servicing air conditioning systems. The proposed use 
condition would require unique servicing fittings for use with small 
cans (two pounds or less) for servicing of MVAC systems containing HFO-
1234yf in the nonroad vehicles addressed in this action, as well as 
servicing of the MVAC systems in the vehicles for which HFO-1234yf has 
already been listed as acceptable, subject to use conditions (i.e., new 
LD passenger cars and trucks and new MDPVs, HD pick-up trucks, and 
complete HD vans). The use condition is discussed below in section 
II.C.3., ``What is the proposed use condition?'' EPA previously listed 
HFO-1234yf as acceptable, subject to use conditions, for large 
containers of HFO-1234yf for professional servicing of MVAC systems (76 
FR 17488, March 29, 2011; 77 FR 17344, March 26, 2012). Redacted 
submissions and supporting documentation for HFO-1234yf in small cans 
are provided in the docket for this proposed rule (EPA-HQ-OAR-2021-
0347) at https://www.regulations.gov. As

[[Page 68974]]

explained more fully below, to help evaluate environmental, 
flammability, and toxicity risks resulting from the use of HFO-1234yf 
in small cans for MVAC servicing, EPA conducted a risk screen which is 
available in the docket for this proposed rule.\87\
---------------------------------------------------------------------------

    \87\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Small Cans). Substitute: HFO-1234yf.
---------------------------------------------------------------------------

    Servicing of MVAC systems containing HFO-1234yf with small 
refrigerant cans is expected to take place in a variety of locations, 
including professional and residential garages with differing sizes and 
ventilation rates. As discussed below in section II.C.3 regarding the 
proposed use condition, the small refrigerant cans would need to be 
equipped with a Standard Compressed Gas Association (CGA) 166 left-hand 
thread outlet connection valve in accordance with SAE Standard 
J2844.\88\ The hose connected to the vehicle would also use the low 
side service port per SAE J639.
---------------------------------------------------------------------------

    \88\ SAE J2844 container valve requirements are for HFO-1234yf 
service cylinders with a volume less than or equal to 23 kilograms.
---------------------------------------------------------------------------

    For additional context, we further note that separate from the 
requirements proposed in this rulemaking, the sale of such small 
refrigerant cans would be subject to the regulatory requirements under 
section 608 of the CAA, codified at 40 CFR 82.154. These regulations 
restrict the sale, distribution, and offer for sale or distribution of 
refrigerants, including non-exempt substitute refrigerants, like HFO-
1234yf, to circumstances where certain requirements are met. Specific 
to the sale of small cans of refrigerant, 40 CFR 82.154(c)(1)(ix) 
states that non-exempt substitute refrigerant for use in an MVAC, e.g., 
HFO-1234yf, may be sold, including to DIYers, if it is in a container 
designed to hold two pounds or less of refrigerant which has a unique 
fitting, and, if manufactured or imported on or after January 1, 2018, 
has a self-sealing valve that complies with the self-sealing valve 
specifications codified at 40 CFR 82.154(c)(2). EPA is not proposing to 
modify the existing CAA section 608 provisions under 40 CFR 82.154, 
including the restriction on sale of substitute refrigerants and 
requirements for self-sealing valves. For additional information, EPA 
directs readers to 82.152, where EPA defines a self-sealing valve as 
``a valve affixed to a container of refrigerant that automatically 
seals when not actively dispensing refrigerant and that meets or 
exceeds established performance criteria as identified in Sec.  
82.154(c)(2).''
1. What is the affected end-use?
    EPA is proposing to list HFO-1234yf as acceptable, subject to a use 
condition, in small cans (two pounds or less) for servicing of MVAC 
systems in the nonroad vehicles addressed in this action, as well as in 
MVAC systems in the vehicles for which HFO-1234yf has already been 
listed as acceptable, subject to use conditions. For the existing 
listings in the March 29, 2011 (76 FR 17488), and December 1, 2016 (81 
FR 86778), final rules, EPA is proposing to revise the use conditions 
to require unique servicing fittings for use with small cans.
2. How does HFO-1234yf compare to other refrigerants for these MVAC 
applications with respect to SNAP criteria?
(a) Environmental Impacts
    HFO-1234yf has a GWP of four,89 90 which is similar to 
or lower than the GWP of the other acceptable alternatives for use in 
small cans (i.e., HFC-134a and CO2). HFO-1234yf, HFC-134a, 
and CO2 do not deplete the ozone layer, and are all exempt 
from the definition of VOC under CAA regulations (see 40 CFR 51.100(s)) 
addressing the development of SIPs to attain and maintain the NAAQS. 
For additional information on the environmental impacts of HFO-1234yf, 
see the discussion above in section II.A.3.a.
---------------------------------------------------------------------------

    \89\ Nielsen et al., 2007. Atmospheric chemistry of CF3CF=CH2: 
Kinetics and mechanisms of gas-phase reactions with Cl atoms, OH 
radicals, and O3. Chemical Physics Letters 439, 18-22. Available 
online at: https://www.cogci.dk/network/OJN_174_CF3CF=CH2.pdf.
    \90\ Papadimitriou et al., 2007. CF3CF=CH2 and (Z)-CF3CF=CHF: 
Temperature dependent OH rate coefficients and global warming 
potentials. Phys. Chem. Chem. Phys., 2007, Vol. 9, p. 1-13. 
Available online at: https://pubs.rsc.org/en/Content/ArticleLanding/2008/CP/b714382f.
---------------------------------------------------------------------------

(b) Flammability
    As discussed above in section II.A.3.b, HFO-1234yf is classified as 
A2L under ASHRAE 34-2013, while HFC-134a and CO2 are 
nonflammable refrigerants. HFO-1234yf is flammable when its 
concentration in air is in the range of 6.2 percent and 12.3 percent by 
volume (62,000 ppm to 123,000 ppm). Due to its flammability, small cans 
of HFO-1234yf for MVAC system servicing could pose a safety concern for 
workers and service personnel or consumers if they are not properly 
handled.
    Servicing of MVAC systems with small refrigerant cans containing 
HFO-1234yf is expected to take place in either a professional garage 
bay or a residential garage. To determine the potential flammability 
risks of a catastrophic release of refrigerant during professional and 
DIY MVAC system servicing using a small refrigerant can, EPA analyzed 
plausible worst-case scenarios to model a catastrophic release of HFO-
1234yf \91\ compared with the LFL of 62,000 ppm for HFO-1234yf.\92\ 
Under these plausible worst-case scenarios, the full charge of the 
refrigerant can is assumed to be emitted into the professional garage 
bay and residential garage with 4.0 and 3.1 air changes per hour 
(ACH),\93\ respectively, over the course of 15 minutes, which 
represents the approximate amount of time required to charge the MVAC 
system.\94\ EPA found that the maximum instantaneous concentrations of 
HFO-1234yf in the lower 0.4 meters of the room did not exceed the LFL 
for HFO-1234yf (i.e., 62,000 ppm) for small refrigerant cans (charge 
size of around 1kg (2 pounds) or less).\95\ EPA also found that the 
maximum instantaneous concentration exceeded 25 percent (15,500 ppm) of 
the LFL for HFO-1234yf for DIY servicing under one of the 
scenarios.\96\ However, the scenario was derived using conservative 
assumptions (e.g., minimum room volume, vertical concentration 
gradient). Furthermore, small refrigerant cans are not likely to be 
used in spaces significantly smaller than those modeled in EPA's 
assessment, which are expected to be large enough to accommodate a 
vehicle and adequate space surrounding the vehicle for the user to 
access the MVAC unit. Finally, HFO-1234yf is difficult to ignite and, 
in the event of ignition, the flames would

[[Page 68975]]

propagate slowly.\97\ Therefore, the risk of fire is minimal if small 
refrigerant cans containing HFO-1234yf meet and are used to service 
vehicles in rooms with volumes in accordance with relevant safety 
standards as described below in section II.C.3.
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    \91\ In order to simulate the vertical concentration gradient of 
refrigerant following release, it is assumed that 95 percent of the 
leaked refrigerant mixes evenly into the lower 0.4 meters (1.3 feet) 
of the room, and the rest of the refrigerant mixes evenly in the 
remaining volume (Kataoka 2000).
    \92\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Small Cans). Substitute: HFO-1234yf.
    \93\ The air exchange rates were derived from the requirements 
in ANSI/ASHRAE Standard 62.1-2019, Table 6.1 (ANSI/ASHRAE 2019c). 
Ventilation requirements (presented as cubic feet per minute in the 
standard) were converted to ACH using the assumed room size in the 
residential garage scenario.
    \94\ Perrin Quarles Associates, Inc. (2007) suggests charging 
for up to 15 minutes to fully empty the contents of the refrigerant 
can is a best practice for DIY servicing of an MVAC system. This 
study also indicates that the transfer procedure used for a small 
refrigerant can (e.g., holding upright, rotation method, and other 
flow control methods) influences the transfer time and resulting 
heel remaining in the can.
    \95\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Small Cans). Substitute: HFO-1234yf.
    \96\ Ibid.
    \97\ HFO-1234yf has a high minimum ignition energy of 5,000-
10,000 mJ and a low burning velocity of 1.5 cm/s (Koban, 2011).
---------------------------------------------------------------------------

    Additionally, EPA considered the submitters' detailed assessments 
of the probability of events that might create a fire and approaches to 
mitigate risks. A CFD modeling was conducted by a submitter to simulate 
a severe refrigerant line leak from a 600-gram MVAC system in a garage 
bay of 84 m\3\ without forced ventilation and found that the flammable 
region of the refrigerant plume under the hood of the vehicle was 
small, ranging from 2 inches to a maximum of 10 inches, which quickly 
dispersed. Similarly, leaks from a small refrigerant can containing 
HFO-1234yf during MVAC servicing are not expected to accumulate under 
the vehicle hood in concentrations above the LFL for HFO-1234yf.
    EPA proposes to conclude that the currently available assessments 
on the use of HFO-1234yf in small cans for professional and DIY 
servicing of MVAC systems are sufficiently conservative to account for 
all probable flammability risks from the use of HFO-1234yf. Therefore, 
the use of HFO-1234yf in small cans does not pose significantly greater 
flammability risk than the other alternatives when used in accordance 
with the proposed use condition described below in section II.C.3, 
which is intended to mitigate flammability risks, and recommendations 
in the SDS and EPA's risk screen.
(c) Toxicity
    For a discussion of the potential health effects of HFO-1234yf, see 
the section II.A.3.c above. In evaluating potential asphyxiation and 
toxicity impacts of HFO-1234yf in small cans on human health, EPA 
considered both occupational risk and risk to the general population. 
EPA investigated the risk of asphyxiation and of exposure to toxic 
levels of HFO-1234yf for plausible worst-case scenarios. According to 
the results of EPA's asphyxiation assessment, the use of HFO-1234yf in 
small refrigerant cans does not present a significant risk of 
asphyxiation.\98\ Conditions resulting in oxygen levels under 12 
percent \99\ would only occur with charge sizes that are significantly 
larger than the maximum charge size proposed for small refrigerant cans 
or room sizes that are unlikely for the proposed application. In 
addition, the charge sizes at which an asphyxiation concern would exist 
are also significantly larger (about 18 times) than the average charge 
size of an MVAC system.\100\
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    \98\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Small Cans). Substitute: HFO-1234yf.
    \99\ Twelve percent oxygen in air (i.e., 120,000 ppm) is the 
NOAEL for hypoxia (ICF 1997).
    \100\ EPA's Vintaging Model (EPA 2020) assumes the refrigerant 
charge size for MVACs to be 0.555-1 kilograms in light-duty vehicles 
and 0.79-1.14 kilograms in light-duty trucks.
---------------------------------------------------------------------------

    To evaluate toxicity risks, EPA estimated 15-minute TWA exposures 
for HFO-1234yf in small cans and compared them to the standard toxicity 
limits. The estimated TWA values were conservative as the analysis did 
not consider opened windows or doors, fans operating, conditioned 
airflow (either heated or cooled), or other variables that would reduce 
the levels to which individuals would be exposed. The modeling results 
showed that the estimated 15-minute TWA exposures are not likely to 
exceed the ATEL (i.e., 100,000 ppm) and are all lower than the RCL 
(i.e., 16,000 ppm) for HFO-1234yf.
    EPA also considered testing and air sampling conducted by a 
submitter to determine potential refrigerant exposure to professional 
servicing technicians or DIY users due to leakage of refrigerant cans 
in a small, closed garage with the condenser fan off and the vehicle 
hood partly open.\101\ The various scenarios investigated included 
releases of 170 grams to 680 grams of refrigerant from both an inverted 
and upright can.\102\ Refrigerant samples were taken under the vehicle 
at 0.15 meters above the floor (representing the potential breathing 
area of a technician present in that space) and in the engine 
compartment. The experimentally derived exposure estimates are also 
significantly lower than the RCL (i.e., 16,000 ppm) and ATEL (i.e., 
100,000 ppm) for HFO-1234yf.
---------------------------------------------------------------------------

    \101\ Honeywell International, Inc. 2012. Refrigerant exposure 
to service personnel or DIYers due to leakage of 12 oz charging cans 
or ``small cans.'' Experiments Conducted at Honeywell's Research 
Laboratory in Buffalo, NY USA. January 2012.
    \102\ The orientation of the can during servicing determines the 
phase (i.e., liquid or gas) of the refrigerant that is being 
transferred into the MVAC system. When the can is upright, the 
refrigerant transfers as a gas and when the can is inverted, the 
refrigerant transfers as a liquid (Perrin Quarles Associates, Inc., 
2007). Refrigerant can instructions often direct users to hold the 
can upright or rotate its position during servicing.
---------------------------------------------------------------------------

    Additionally, EPA assessed the potential exposures to workers 
during disposal (e.g., collection, transportation) of small refrigerant 
cans containing HFO-1234yf.\103\ EPA determined that if proper handling 
and disposal guidelines are followed in accordance with good industrial 
hygiene practices and the SDS for HFO-1234yf, there is no significant 
risk to workers during the disposal of HFO-1234yf from MVAC systems or 
HFO-1234yf small refrigerant cans.
---------------------------------------------------------------------------

    \103\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle 
Air Conditioning (Small Cans). Substitute: HFO-1234yf.
---------------------------------------------------------------------------

    For potential toxicity risks of HFO-1234yf to the general 
population, our analysis indicated that HFO-1234yf is not expected to 
present an unreasonable risk to human health in the general population 
when used as a refrigerant in small cans for MVAC servicing.
    Based upon our analysis, workplace and general population exposure 
to HFO-1234yf in small cans when used according to the proposed use 
condition is not expected to exceed relevant exposure limits. 
Therefore, we propose to conclude that the use of HFO-1234yf in small 
cans does not pose significantly greater toxicity risks than other 
acceptable refrigerants when used in accordance with the proposed use 
condition described below in section II.C.3 which is intended to 
mitigate toxicity risks, and recommendations in the SDS and EPA's risk 
screen.
3. What is the proposed use condition?
    EPA's SNAP program has a longstanding approach of requiring unique 
fittings for use with each refrigerant substitute in MVAC systems. This 
is intended to prevent cross contamination of different refrigerants, 
preserve the purity of recycled refrigerants, and ultimately to avoid 
venting of refrigerant consistent with requirements under CAA section 
608(c), codified at 40 CFR 82.154(a). In the 1996 SNAP rule requiring 
the use of fittings on all refrigerants submitted for use in MVAC 
systems, EPA urged industry to develop mechanisms to ensure that the 
refrigerant venting prohibition under CAA section 608 and the 
implementing regulations at 40 CFR 82.154 are observed (61 FR 54032; 
October 16, 1996). EPA has issued multiple SNAP rules codified in the 
CFR requiring the use of fittings unique to a refrigerant for use on 
``containers of the refrigerant, on can taps, on recovery, recycling, 
and charging equipment, and on all [motor vehicle] air conditioning 
system service ports.'' (See appendices C and D to subpart G of 40 CFR 
part 82).
    EPA is proposing that for connections with small cans (two pounds 
or less) of

[[Page 68976]]

HFO-1234yf use fittings must be consistent with SAE J2844 (revised 
January 2013), which specifies quick-connect fittings that are 
different from those for any other refrigerant. The low-side service 
port and connections will have an outside diameter of 14 mm (0.551 
inches), and the high-side service port will have an outside diameter 
of 17 mm (0.669 inches), both accurate to within 2 mm. Under SAE J2844 
(revised January 2013), small cans of HFO-1234yf (e.g., for use in DIY 
servicing of MVAC systems) must have a left-handed screw valve with a 
diameter of 0.5 inches and Acme (trapezoidal) thread with 16 threads 
per inch.

D. Proposed Incorporation by Reference

    EPA is proposing to adopt the current versions of three technical 
safety standards developed by SAE by incorporating them by reference 
into the use conditions for the nonroad vehicles addressed in this 
action. EPA also proposes to modify the use conditions for the previous 
listings of HFO-1234yf in certain MVAC systems to incorporate by 
reference the most current versions of the three standards. The three 
standards are SAE J639 (revised November 2020), ``Safety and Design 
Standards for Motor Vehicle Refrigerant Vapor Compression Systems;'' 
SAE J1739 (revised January 2021), ``Potential Failure Mode and Effects 
Analysis (FMEA) Including Design FMEA, Supplemental FMEA-MSR, and 
Process FMEA;'' and SAE J2844 (revised January 2013), ``R-1234yf (HFO-
1234yf) New Refrigerant Purity and Container Requirements for Use in 
Mobile Air-Conditioning Systems.'' Section II.A.4 of this preamble 
discusses these standards in greater detail.
    EPA finds, as in past rules, that it is appropriate to reference 
consensus standards that set conditions to reduce risk. As in past 
listings of flammable refrigerants, we find that such standards have 
already gone through a development phase that incorporates the latest 
findings and research. Likewise, such standards have gone through a 
vetting and refinement process that provides the affected parties an 
opportunity to comment. For the U.S. MVAC industry, EPA sees SAE 
standards in general as a pervasively used body of work to address 
risks, and these standards are the most applicable and recognized by 
the U.S. market.
    Incorporation by reference allows federal agencies to comply with 
the requirement to publish rules in the Federal Register and the Code 
of Federal Regulations by referring to material already published 
elsewhere. The legal effect of incorporation by reference is that the 
material is treated as if it were published in the Federal Register and 
Code of Federal Regulations.
    SAE J639, J1739, and J2844 are available for purchase by mail at: 
SAE Customer Service, 400 Commonwealth Drive, Warrendale, PA 15096-
0001; Telephone: 1-877-606-7323 in the U.S. or Canada (other countries 
dial 1-724-776-4970); internet address for SAE J639: https://www.sae.org/standards/content/j639_201112/; internet address for SAE 
J1739: https://www.sae.org/standards/content/j1739_202101/; internet 
address for SAE J2844: https://www.sae.org/standards/content/j2844_201301/. The cost of SAE J639, J1739, and J2844 is $85 each for 
an electronic or hard copy. The cost of obtaining these standards is 
not a significant financial burden for manufacturers of MVAC systems, 
and purchase is not required for those selling, installing, or 
servicing the MVAC systems covered by these standards. Therefore, the 
EPA concludes that SAE J639, J1739, and J2844 are reasonably available.

E. When would the listings apply?

    EPA proposes that all the proposed listings, if finalized, would 
apply 30 days after the date of publication of a final rule. This date, 
the same as the proposed effective date of this regulation, supports 
the safe use of this substitute without undue delay.

F. What is the relationship between this SNAP rule and other federal 
rules?

1. Significant New Use Rule for HFO-1234yf Under the Toxic Substances 
Control Act
    In a Final Rule published on March 29, 2011 (76 FR 17488), EPA 
noted that the listing of HFO-1234yf as acceptable, subject to use 
conditions, in new passenger cars and trucks did not apply to small 
cans. EPA stated that the Agency ``would require additional information 
on consumer risk and a set of unique fittings from the refrigerant 
manufacturer for use with small cans or containers of HFO-1234yf before 
we would be able to issue a revised rule that allows for consumer 
filling, servicing, or maintenance of MVAC systems with HFO-1234yf'' 
\104\ and that use of small cans would need to be consistent with EPA's 
final SNUR for HFO-1234yf under TSCA (October 27, 2010; 75 FR 65987). 
EPA has since revised the SNUR (80 FR 37166, June 30, 2015) to require 
the submission of a significant new use notice (SNUN) for commercial 
use of HFO-1234yf other than in passenger cars and vehicles in which 
the original charging of MVAC systems with HFO-1234yf was done by the 
OEM and use of HFO-1234yf in consumer products other than products used 
to recharge the MVAC systems in passenger cars and vehicles in which 
the original charging of MVAC systems with HFO-1234yf was done by the 
OEM, among other things. Manufacturers of small cans of HFO-1234yf have 
also submitted a unique fitting specifically for use with small can 
taps and small refrigerant cans for EPA's review. Today's proposed 
listing of HFO-1234yf would apply to small cans, weighing two pounds or 
less, for DIY or professional use. Consistent with the revised June 
2015 SNUR for HFO-1234yf, commercial use or use in consumer products to 
recharge MVAC systems with HFO-1234yf in passenger cars and vehicles 
may only occur without submission of a SNUN and review by EPA if the 
OEM originally charged the system with HFO-12324yf.
---------------------------------------------------------------------------

    \104\ EPA, 2011. Protection of Stratospheric Ozone: New 
Substitute in the Motor Vehicle Air Conditioning Sector Under the 
Significant New Alternatives Policy (SNAP) Program; Final Rule. 
March 29, 2011 (76 FR 17488). Available online at: https://www.govinfo.gov/content/pkg/FR-2011-03-29/pdf/2011-6268.pdf.
---------------------------------------------------------------------------

    EPA is proposing to include a reference to the June 30, 2015 SNUR 
(80 FR 37166) in Appendix B subpart G of part 82, under the `Comments' 
column, for the listings of HFO-1234yf for the nonroad vehicles 
addressed in this action. EPA is also proposing to modify the existing 
listings of HFO-1234yf as acceptable, subject to use conditions, for 
various vehicle types, by including the reference to the June 2015 SNUR 
in the Comments column in Appendix B subpart G of part 82.
2. CAA Sections 608 and 609
    Among other things, section 608 of the CAA prohibits individuals 
from knowingly venting or otherwise releasing into the environment any 
refrigerants except those specifically exempted in certain end uses, 
while maintaining, servicing, repairing, or disposing of air 
conditioning or refrigeration equipment. HFO-1234yf is not exempt from 
the venting prohibition in any application; therefore, knowing release 
of HFO-1234yf from MVAC systems in the nonroad vehicles addressed in 
this action, or any other MVAC system, by any person maintaining, 
servicing, repairing, or disposing of such systems is prohibited. MVAC 
end-of-life disposal and recycling specifications are also covered 
under CAA section 608 and EPA's regulations issued under that section 
of the Act, which are codified at subpart F of 40 CFR part 82. In 
addition, as mentioned above in sections I.A and

[[Page 68977]]

II.C, there are additional requirements that concern the sale or offer 
for sale of refrigerants, including a sales restriction under 40 CFR 
subpart F and specifically at 82.154(c)(1) and related specifications 
for self-sealing valves at 82.154(c)(2). This proposal does not propose 
to modify the provisions under 40 CFR 82.154, including the restriction 
on sale of substitute refrigerants and requirements for self-sealing 
valves. The Agency is not proposing to revise, and is not reopening for 
comment, regulations promulgated under section CAA 608 in this action.
    CAA section 609 establishes standards and requirements regarding 
the servicing or repair of MVAC systems.\105\ EPA has issued 
regulations implementing this statutory requirement and those 
regulations are codified at subpart B of 40 CFR part 82. Under section 
609 and its implementing regulations, no person repairing or servicing 
motor vehicles for consideration \106\ may perform any service on an 
MVAC that involves the refrigerant without properly using approved 
refrigerant recovery or recovery and recycling equipment, and no such 
person may perform such service unless such person has been properly 
trained and certified. Refrigerant handling equipment must be certified 
by EPA or an independent organization approved by EPA. The statutory 
and regulatory provisions regarding MVAC servicing apply to all 
refrigerants, including HFO-1234yf. Today's proposal will not have any 
impact on EPA's regulations under sections 608 or 609 of the Clean Air 
Act.
---------------------------------------------------------------------------

    \105\ Under the SNAP program, MVAC systems are those systems 
that provide passenger comfort cooling for light-duty cars and 
trucks, heavy-duty vehicles (large pick-ups, delivery trucks, 
recreational vehicles, and semi-trucks), nonroad vehicles, buses, 
and rail vehicles. See final rules published on March 29, 2011 (76 
FR 17488) and on December 1, 2016 (81 FR 86778). For informational 
purposes, we note that this includes systems that are also included 
in the definitions that apply under other provisions of EPA's 
regulations under title VI of the CAA. In this regard, we note that 
EPA's regulations at 40 CFR 82.152 define ``MVAC-like appliance'' to 
mean ``a mechanical vapor compression, open-drive compressor 
appliance with a full charge of 20 pounds or less of refrigerant 
used to cool the driver's or passenger's compartment of nonroad 
vehicles or equipment. This includes, but is not limited to, the 
air-conditioning equipment found on agricultural or construction 
vehicles. This definition is not intended to cover appliances using 
R-22 refrigerant.'' By contrast, EPA's regulations at 40 CFR 82.152 
define ``Motor vehicle air conditioner (MVAC)'' as ``any appliance 
that is a motor vehicle air conditioner as defined in 40 CFR part 
82, subpart B.'' The subpart B regulations at 40 CFR 82.32 provide 
that: ``Motor vehicle air conditioners means mechanical vapor 
compression refrigeration equipment used to cool the driver's or 
passenger's compartment of any motor vehicle. This definition is not 
intended to encompass the hermetically sealed refrigeration systems 
used on motor vehicles for refrigerated cargo and the air 
conditioning systems on passenger buses using HCFC-22 refrigerant.'' 
Further, the subpart B regulations at 40 CFR 82.32 provide that: 
``Motor vehicle as used in this subpart means any vehicle which is 
self-propelled and designed for transporting persons or property on 
a street or highway, including but not limited to passenger cars, 
light duty vehicles, and heavy duty vehicles. This definition does 
not include a vehicle where final assembly of the vehicle has not 
been completed by the original equipment manufacturer.''
    \106\ Service for consideration means receiving something of 
worth or value to perform service, whether in money, credit, goods, 
or services.
---------------------------------------------------------------------------

3. Would this action listing HFO-1234yf as acceptable, subject to use 
conditions, for certain nonroad vehicles and small cans affect EPA's HD 
greenhouse gas standards?
    The Phase 1 HD Greenhouse Gas (GHG) rule (76 FR 57106; September 
15, 2011) set GHG standards for the HD industry in three discrete 
categories--combination tractors, HD pickups and vans, and vocational 
vehicles. The Phase 1 rule also set separate standards for engines that 
power vocational vehicles and combination tractors--based on the 
relative degree of homogeneity among vehicles within each category. As 
part of the Phase 1 HD GHG standards, EPA finalized a low leakage 
standard of 1.50 percent leakage per year for AC systems installed in 
HD pickup trucks and vans and combination tractors for model years 2014 
and later. On October 25, 2016, EPA finalized Phase 2 HD GHG standards 
that built on the existing Phase 1 HD GHG standards, and also finalized 
GHG standards for certain trailers used in combination with HD tractors 
(81 FR 73478). The nonroad vehicles for which EPA is proposing to list 
HFO-1234yf are not regulated under the Phase 1 or Phase 2 HD GHG 
standards. Additionally, today's proposal, should EPA adopt it, will 
have no direct effect on the HD GHG standards, either for Phase 1 or 
Phase 2.

G. On which topics is EPA specifically requesting comment?

    EPA requests comment on all aspects of this proposal, including 
proposed decisions to list HFO-1234yf as acceptable, subject to use 
conditions, in MVAC systems in certain newly manufactured nonroad 
vehicles and small cans, the proposed incorporation of the latest 
versions of the relevant SAE standards, and the proposed dates when the 
proposed listings would apply if finalized.
    EPA also requests information on development of HFO-1234yf MVAC 
systems for other types of HD or nonroad vehicles, particularly on-road 
trucks (i.e., Class 4-8 trucks between 14,001 and 33,000 or greater 
pounds). EPA will consider these comments in determining whether to 
initiate a separate rulemaking to list HFO-1234yf in other 
applications.

III. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action is not a significant regulatory action and was 
therefore not submitted to the Office of Management and Budget (OMB) 
for review.

B. Paperwork Reduction Act (PRA)

    This action does not impose any new information collection burden 
under the PRA. OMB has previously approved the information collection 
activities contained in the existing regulations and has assigned OMB 
control number 2060-0226. The approved Information Collection Request 
includes five types of respondent reporting and recordkeeping 
activities pursuant to SNAP regulations: Submission of a SNAP petition, 
filing a TSCA/SNAP Addendum, notification for test marketing activity, 
recordkeeping for substitutes acceptable subject to use restrictions, 
and recordkeeping for small volume uses. This rule contains no new 
requirements for reporting or recordkeeping.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. In 
making this determination, EPA concludes that the impact of concern for 
this rule is any significant adverse economic impact on small entities 
and that the agency is certifying that this rule will not have a 
significant economic impact on a substantial number of small entities 
if the rule has no net burden on the small entities subject to the 
rule. Because the use conditions are consistent with industry consensus 
standards, no change in business practice is required to meet the use 
conditions, resulting in no adverse impact compared to the absence of 
this proposed rule. Thus, the rule would not impose new costs on small 
entities if finalized as proposed.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate as described in 
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect 
small governments. The action imposes no

[[Page 68978]]

enforceable duty on any state, local or tribal governments or the 
private sector.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the states, on the relationship between 
the national government and the states, or on the distribution of power 
and responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    This action does not have tribal implications as specified in 
Executive Order 13175. It will not have substantial direct effects on 
tribal governments, on the relationship between the Federal government 
and Indian tribes, or on the distribution of power and responsibilities 
between the Federal government and Indian tribes, as specified in 
Executive Order 13175. Thus, Executive Order 13175 does not apply to 
this action.

G. Executive Order 13045: Protection of Children From Environmental 
Health and Safety Risks

    This action is not subject to Executive Order 13045 because it is 
not economically significant as defined in Executive Order 12866, and 
because EPA does not believe the environmental health or safety risks 
addressed by this action present a disproportionate risk to children. 
This action's health and risk assessments are contained in the 
comparisons of toxicity for HFO-1234yf, as well as in the risk screens 
for HFO-1234yf. The risk screens are in the docket for this rulemaking.

H. Executive Order 13211: Actions That Significantly Affect Energy 
Supply, Distribution, or Use

    This action is not subject to Executive Order 13211, because it is 
not a significant regulatory action under Executive Order 12866.

I. National Technology Transfer and Advancement Act

    This action involves technical standards. EPA proposes to adopt the 
current versions of three technical safety standards developed by SAE 
by incorporating them by reference into the use conditions for the 
nonroad vehicles addressed in this action. EPA also proposes to modify 
the use conditions for the previous listings of HFO-1234yf in MVAC 
systems to incorporate by reference the most current versions of the 
three standards. The use conditions would ensure that HFO-1234yf would 
not present significantly greater risk to human health or the 
environment than other alternatives available for use in MVAC. 
Specifically, the three standards are:
    1. SAE J639: Safety and Design Standards for Motor Vehicle 
Refrigerant Vapor Compression Systems (revised November 2020). This 
document establishes safety standards for HFO-1234yf MVAC systems that 
include unique fittings; a warning label indicating the refrigerant's 
identity and that it is a flammable refrigerant; and requirements for 
engineering design strategies that include a high-pressure compressor 
cutoff switch and pressure relief devices. This standard is available 
at https://www.sae.org/standards/content/j639_201112/.
    2. SAE J1739: Potential Failure Mode and Effects Analysis (FMEA) 
Including Design FMEA, Supplemental FMEA-MSR, and Process FMEA (revised 
January 2021). This standard describes potential FMEA in design and 
potential FMEA in manufacturing and assembly processes. It requires 
manufacturers of MVAC systems and vehicles to conduct a FMEA and 
assists users in the identification and mitigation of risk by providing 
appropriate terms, requirements, ranking charts, and worksheets. This 
standard is available at https://www.sae.org/standards/content/j1739_202101/.
    3. SAE J2844: R-1234yf (HFO-1234yf) New Refrigerant Purity and 
Container Requirements for Use in Mobile Air-Conditioning Systems 
(revised January 2013). This standard sets purity standards and 
describes container requirements, including fittings for refrigerant 
cylinders. For connections with refrigerant containers for use in 
professional servicing, use fittings must be consistent with SAE J2844 
(revised January 2013). For connections with small refrigerant cans for 
consumer or professional use, use fittings must have a diameter of 0.5 
inches, a thread pitch of 16 thread per inch, and a left thread 
direction, consistent with SAE J2844. This standard is available at 
https://www.sae.org/standards/content/j2844_201301/.
    These standards may be purchased by mail at: SAE Customer Service, 
400 Commonwealth Drive, Warrendale, PA 15096-0001; by telephone: 1-877-
606-7323 in the United States or 724-776-4970 outside the United States 
or in Canada. The cost of SAE J639, SAE J1739, and SAE J2844 is $85 
each for an electronic or hardcopy. The cost of obtaining these 
standards is not a significant financial burden for manufacturers of 
MVAC systems and purchase is not required for those selling, 
installing, and servicing the systems. Therefore, EPA concludes that 
the use of SAE J639, SAE J1739, and SAE J2844 are reasonably available.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    A regulatory action may involve potential environmental justice 
concerns if it could: (1) Create new disproportionate impacts on people 
of color, low-income populations, and/or indigenous peoples; (2) 
exacerbate existing disproportionate impacts on people of color, low-
income populations, and/or indigenous peoples; or (3) present 
opportunities to address existing disproportionate impacts on people of 
color, low-income populations, and/or indigenous peoples through the 
action under development.
    EPA believes that this action does not have disproportionately high 
and adverse human health or environmental effects on people of color, 
low-income populations and/or indigenous peoples, as specified in 
Executive Order 12898 (59 FR 7629, February 16, 1994). The proposed 
listings for HFO-1234yf in the vehicle types addressed in this action 
would provide additional lower-GWP alternatives for the MVAC end-use. 
By providing a lower-GWP alternative for this end-use, this proposed 
rule is also anticipated to reduce the use and eventual emissions of 
potent GHGs in this end-use, which could help to reduce the effects of 
climate change, including the public health and welfare effects on 
minority populations, low-income populations and/or indigenous peoples. 
This action's health and environmental risk assessments are contained 
in the comparison of health and environmental risks for HFO-1234yf, as 
well as in the risk screens that are available in the docket for this 
rulemaking. EPA's analysis indicates that other environmental impacts 
and human health impacts of HFO-1234yf are comparable to or less than 
those of other substitutes that are listed as acceptable for the same 
end-use. Based on these considerations, EPA expects that, if this 
proposal becomes final as proposed, the effects on minority 
populations, low-income populations and/or indigenous peoples would not 
be disproportionately high and adverse.

IX. References

    Unless specified otherwise, all documents are available 
electronically through the Federal Docket Management System, Docket 
number EPA-HQ-OAR-2021-0347.

AEM, 2019. Risk Assessment for HFO-1234yf in Agricultural Tractors 
>=40 HP

[[Page 68979]]

including 2WD, MFD, 4WD and Track Type Equipment.
AEM, 2020a. Risk Assessment for HFO-1234yf in Self-Propelled 
Agricultural Machinery including Combines, Forage Harvesters, 
Sprayers, and Windrowers.
AEM, 2020b. Risk Assessment for HFO-1234yf in Compact Equipment 
(Examples include Tractors <40HP, Turf Equipment, Skid Steer, Mini-
Excavators and Track Loaders).
AEM, 2020c. Risk Assessment for HFO-1234yf in Construction, 
Forestry, and Mining Equipment.
AEM, 2020d. Risk Assessment for HFO-1234yf in Commercial Utility 
Vehicles.
AEM, 2020e. CFD Leak Modeling-Supplemental Information to Compliment 
AEM Machine Form RAs.
AEM, 2021. Appendix A: Machine Forms as Classified by AEM 
Membership.
ASHRAE, 2019. ANSI/ASHRAE Standard 34-2019: Designation and Safety 
Classification of Refrigerants.
Chemours, 2019. HFO-1234yf for Use as a Refrigerant. Significant New 
Alternatives Policy Program Submission to the U.S. Environmental 
Protection Agency.
CRP, 2008. Risk Assessment for Alternative Refrigerants HFO-1234yf 
Phase II. Prepared for SAE International Cooperative Research 
Program 1234 by Gradient Corporation.
CRP, 2009. Risk Assessment for Alternative Refrigerants HFO-1234yf 
and R-744 (CO2) Phase III. Prepared for SAE International 
Cooperative Research Program 1234 by Gradient Corporation.
CRP, 2013. SAE International Cooperative Research Project CRP1234-4 
on R-1234yf Safety, Finishes Work and Presents Conclusions. 
Available online at: https://www.sae.org/servlets/pressRoom?OBJECT_TYPE=PressReleases&PAGE=showRelease&RELEASE_ID=2146.

DuPont and Honeywell, 2008. Guidelines for Use and Handling of HFO-
1234yf (v8.0).
EEAP, 2019. Environmental Effects and Interactions of Stratospheric 
Ozone Depletion, UV Radiation, and Climate Change. 2018 Assessment 
Report. Nairobi: Environmental Effects Assessment Panel, United 
Nations Environment Programme (UNEP) 390 pp. Available online at: 
https://ozone.unep.org/science/assessment/eeap.
EPA, 2005. Risk Analysis for Alternative Refrigerant in Motor 
Vehicle Air Conditioning.
EPA, 2011. Protection of Stratospheric Ozone: New Substitute in the 
Motor Vehicle Air Conditioning Sector Under the Significant New 
Alternatives Policy (SNAP) Program; Final Rule. March 29, 2011 (76 
FR 17488). Available online at: https://www.govinfo.gov/content/pkg/FR-2011-03-29/pdf/2011-6268.pdf.
EPA, 2016. Protection of Stratospheric Ozone: Update to the 
Refrigerant Management Requirements Under the Clean Air Act. 
November 18, 2016. 81 FR 82272. Available online at: https://www.regulations.gov/document?D=EPA-HQ-OAR-2015-0453-0125.
EPA, 2021. Basic Information about the Emission Standards Reference 
Guide for On-road and Nonroad Vehicles and Engines. Available online 
at https://www.epa.gov/emission-standards-reference-guide/basic-information-about-emission-standards-reference-guide-road.
Exponent, 2008. HFO-1234yf Refrigerant Concentration and Ignition 
Tests in Full-Scale Vehicle Passenger Cabin and Engine Compartment.
ICF, 1997. Physiological Effects of Alternative Fire Protection 
Agents--Hypoxic Atmospheres Conference. Stephanie Skaggs prepared 
the proceedings of the conference held May 22, 1997 in New London, 
CT.
ICF, 2008a. Air Conditioning Refrigerant Charge Size to Passenger 
Compartment Volume Ratio Analysis.
ICF, 2008b. Revised Characterization of U.S. Hybrid and Small Car 
Sales (Historical and Predicted) and Hybrid Vehicle Accidents.
ICF, 2009a. Revised Final Draft Assessment of the Potential Impacts 
of HFO-1234yf and the Associated Production of TFA on Aquatic 
Communities and Local Air Quality.
ICF, 2009b. Risk Screen on Substitutes for CFC-12 in Motor Vehicle 
Air Conditioning: Substitute: HFO-1234yf.
ICF, 2010a. Summary of HFO-1234yf Emissions Assumptions.
ICF, 2010b. Summary of Updates to the Vintaging Model that Impacted 
HFO-1234yf Emissions Estimates.
ICF, 2010c. Revised Assessment of the Potential Impacts of HFO-
1234yf and the Associated Production of TFA on Aquatic Communities, 
Soil and Plants, and Local Air Quality.
ICF, 2010d. Sensitivity Analysis CMAQ results on projected maximum 
TFA rainwater concentrations and maximum 8-hr ozone concentrations.
ICF, 2016. Technical Support Document for Acceptability Listing of 
HFO-1234yf for Motor Vehicle Air Conditioning in Limited Heavy-Duty 
Applications.
ICF, 2021a. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles Agricultural Tractors Greater than 40 
Horsepower) (New Equipment).
ICF, 2021b. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles Self-Propelled Agricultural 
Machinery) (New Equipment).
ICF, 2021c. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles Compact Equipment) (New Equipment).
ICF, 2021d. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles--Construction, Forestry, and Mining 
Equipment) (New Equipment).
ICF, 2021e. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Nonroad Vehicles Commercial Utility Vehicles) (New 
Equipment).
ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air 
Conditioning (Small Cans). Substitute: HFO-1234yf.
Kazil et al., 2014. Deposition and rainwater concentrations of 
trifluoroacetic acid in the United States from the use of HFO-
1234yf. JGR-Atmospheres, 2014.
Kataoka, O., Yoshizawa, M., & Hirakawa, T., 2000. Allowable Charge 
Limit of Flammable Refrigerants and Ventilation Requirements. Daikin 
Industries. International Refrigeration and Air Conditioning 
Conference. Paper 506. Available online at: https://docs.lib.purdue.edu/iracc/506.
Luecken et al., 2009. Ozone and TFA impacts in North America from 
degradation of 2, 3, 3, 3-tetrafluoropropene (HFO-1234yf), a 
potential greenhouse gas replacement. Environmental Science & 
Technology 2009. Available online at: https://www.researchgate.net/profile/Robert_Waterland/publication/40481734_Ozone_and_TFA_impacts_in_North_America_from_degradation_of_2333-Tetrafluoropropene_(HFO-
1234yf)_a_potential_greenhouse_gas_replacement/links/
00b7d514ca9595bf5e000000.pdf.
Nielsen, et al., 2007. Atmospheric chemistry of CF3CF=CH2: Kinetics 
and mechanisms of gas-phase reactions with Cl atoms, OH radicals, 
and O3. Chemical Physics Letters 439, 18-22. Available online at: 
https://www.cogci.dk/network/OJN_174_CF3CF=CH2.pdf.
Norwegian Environment Agency, 2017. Study on Environmental and 
Health Effects of HFO Refrigerants, Norwegian Environment Agency 
Report No. M-9172017, Oslo, Norway, p. 349.
Papadimitriou, et al., 2007. CF3CF=CH2 and (Z)-CF3CF=CHF: 
Temperature dependent OH rate coefficients and global warming 
potentials. Phys. Chem. Chem. Phys., 2007, Vol. 9, p. 1-13. 
Available online at: https://pubs.rsc.org/en/Content/ArticleLanding/2008/CP/b714382f.
Perrin Quarles Associates, Inc., 2007. Disposable Container Heel 
Testing Study Report. Prepared for United States Environmental 
Protection Agency by Perrin Quarles Associates, Inc. March 21, 2007.
SAE, 2013. Standard J2844: R-1234yf (HFO-1234yf) New Refrigerant 
Purity and Container Requirements for Use in Mobile Air-Conditioning 
Systems. (Revised January 2013).
SAE, 2019. Standard J2772: Measurement of Passenger Compartment 
Refrigerant Concentrations Under System Refrigerant Leakage 
Conditions. SAE International. (Revised September 2019).
SAE, 2020. Standard J639: Safety and Design Standards for Motor 
Vehicle Refrigerant Vapor Compression Systems. (Revised November 
2020).
SAE, 2021. Standard J1739: Potential Failure Mode and Effects 
Analysis (FMEA) Including Design FMEA, Supplemental FMEA-MSR, and 
Process FMEA. (Revised January 2021).

[[Page 68980]]

UNEP, 2015. Ecological Issues on the Feasibility of Managing HFCs: 
Focus on TFA. Inter-sessional Informal Meeting, 12-13 June 2015. 
Available online at: https://ozone.unep.org/sites/default/files/2020-06/informal%20brief_ecological%20effects_intersessional_June%202015_final%20%281%29.docx.
Wagner, J., 2021. Email from John Wagner, Association of Equipment 
Manufacturers to Chenise Farquharson, EPA.
WMO, 2018. Executive Summary: Scientific Assessment of Ozone 
Depletion: 2018, World Meteorological Organization, Global Ozone 
Research and Monitoring Project--Report No. 58, 67 pp., Geneva, 
Switzerland, 2018. Available online at: https://ozone.unep.org/sites/default/files/2019-05/SAP-2018-Assessment-report.pdf.

List of Subjects in 40 CFR Part 82

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Incorporation by reference, Recycling, Reporting 
and recordkeeping requirements, Stratospheric ozone layer, Motor 
vehicle air conditioning.

Michael S. Regan,
Administrator.
    For the reasons set forth in the preamble, EPA proposes to amend 40 
CFR part 82 as follows:

PART 82--PROTECTION OF STRATOSPHERIC OZONE

0
1. The authority citation for part 82 continues to read as follows:

    Authority:  42 U.S.C. 7414, 7601, 7671--7671q.

Subpart G--Significant New Alternatives Policy Program

0
2. Appendix B to subpart G of part 82 is amended by
0
a. Revising the existing four entries for HFO-1234yf in the table 
titled ``Refrigerants--Acceptable Subject to Use Conditions''
0
b. Adding five new entries for HFO-1234yf to the table titled 
``Refrigerants--Acceptable Subject to Use Conditions''.
    The revisions and additions read as follows:

Appendix B to Subpart G of Part 82--Substitutes Subject to Use 
Restrictions and Unacceptable Substitutes

                                                   Refrigerants--Acceptable Subject to Use Conditions
--------------------------------------------------------------------------------------------------------------------------------------------------------
            Application                    Substitute              Decision                     Conditions                           Comments
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
CFC-12 Automobile Motor Vehicle Air  HFO-1234yf as a        Acceptable subject to  As of [30 days after publication of   Additional training for service
 Conditioning (New equipment in       substitute for CFC-    use conditions.        final rule]:.                         technicians recommended.
 passenger cars and light-duty        12.                                          (1) HFO-1234yf MVAC systems must      HFO-1234yf is also known as
 trucks only).                                                                      adhere to all of the safety           2,3,3,3-tetrafluoro-prop-1-ene
                                                                                    requirements of SAE J639,\1\ \4\      (CAS. Reg. No. 754-12-1).
                                                                                    \5\ including requirements for a     Consistent with EPA's
                                                                                    flammable refrigerant warning         Significant New Use Rule for
                                                                                    label, high-pressure compressor       HFO-1234yf under the Toxic
                                                                                    cutoff switch and pressure relief     Substances Control Act,
                                                                                    devices, and unique fittings. For     commercial users or consumers
                                                                                    connections with refrigerant          can only recharge MVAC systems
                                                                                    containers for use in professional    with HFO-1234yf where the
                                                                                    servicing, use fittings must be       original charging of the
                                                                                    consistent with SAE J2844 \3\ \4\     system with HFO-1234yf was
                                                                                    \5\). For connections with small      done by the original equipment
                                                                                    refrigerant cans for consumer or      manufacturer.
                                                                                    professional use, use fittings must  Refrigerant containers of HFO-
                                                                                    have a diameter of 0.5 inches, a      1234yf for use in professional
                                                                                    thread pitch of 16 thread per inch,   servicing are from 5 lbs. (2.3
                                                                                    and a left thread direction,          L) to 50 lbs. (23 L) in size.
                                                                                    consistent with SAE J2844. (2)        Requirements for handling,
                                                                                    Manufacturers must conduct Failure    storage, and transportation of
                                                                                    Mode and Effect Analysis (FMEA) as    compressed gases apply to this
                                                                                    provided in SAE J1739 \2\ \4\ \5\.    refrigerant, such as
                                                                                    Manufacturers must keep the FMEA on   regulations of the
                                                                                    file for at least three years from    Occupational Safety and Health
                                                                                    the date of creation.                 Administration at 29 CFR
                                                                                                                          1910.101 and the Department of
                                                                                                                          Transportation's requirements
                                                                                                                          at 49 CFR 171-179.
                                                                                                                         Requirements for handling,
                                                                                                                          storage, and transportation of
                                                                                                                          compressed gases apply to this
                                                                                                                          refrigerant, such as
                                                                                                                          regulations of the
                                                                                                                          Occupational Safety and Health
                                                                                                                          Administration at 29 CFR
                                                                                                                          1910.101 and the Department of
                                                                                                                          Transportation's requirements
                                                                                                                          at 49 CFR 171-179.
Motor vehicle air conditioning       HFO-1234yf...........  Acceptable subject to  As of [30 days after publication of   Additional training for service
 (newly manufactured medium-duty                             use conditions.        final rule]:.                         technicians recommended.
 passenger vehicles).                                                              (1) HFO-1234yf MVAC systems must      HFO-1234yf is also known as
                                                                                    adhere to all of the safety           2,3,3,3-tetrafluoro-prop-1-ene
                                                                                    requirements of SAE J639,\1\ \4\      (CAS. Reg. No. 754-12-1).
                                                                                    \5\ including requirements for a     Consistent with EPA's
                                                                                    flammable refrigerant warning         Significant New Use Rule for
                                                                                    label, high-pressure compressor       HFO-1234yf under the Toxic
                                                                                    cutoff switch and pressure relief     Substances Control Act,
                                                                                    devices, and unique fittings. For     commercial users or consumers
                                                                                    connections with refrigerant          can only recharge MVAC systems
                                                                                    containers for use in professional    with HFO-1234yf where the
                                                                                    servicing, use fittings must be       original charging of the
                                                                                    consistent with SAE J2844.\3\ \4\     system with HFO-1234yf was
                                                                                    \5\ For connections with small        done by the original equipment
                                                                                    refrigerant cans for consumer or      manufacturer.
                                                                                    professional use, use fittings must
                                                                                    have a diameter of 0.5 inches, a
                                                                                    thread pitch of 16 thread per inch,
                                                                                    and a left thread direction,
                                                                                    consistent with SAE J2844.
                                                                                   (2) Manufacturers must conduct
                                                                                    Failure Mode and Effect Analysis
                                                                                    (FMEA) as provided in SAE J1739.\2\
                                                                                    \4\ \5\ Manufacturers must keep the
                                                                                    FMEA on file for at least three
                                                                                    years from the date of creation.

[[Page 68981]]

 
Motor vehicle air conditioning       HFO-1234yf...........  Acceptable subject to  As of [30 days after publication of   Additional training for service
 (newly manufactured heavy-duty                              use conditions.        final rule]:.                         technicians recommended.
 pickup trucks).                                                                   (1) HFO-1234yf MVAC systems must      HFO-1234yf is also known as
                                                                                    adhere to all of the safety           2,3,3,3-tetrafluoro-prop-1-ene
                                                                                    requirements of SAE J639,\1\ \4\      (CAS No 754-12-1).
                                                                                    \5\ including requirements for a     Consistent with EPA's
                                                                                    flammable refrigerant warning         Significant New Use Rule for
                                                                                    label, high-pressure compressor       HFO-1234yf under the Toxic
                                                                                    cutoff switch and pressure relief     Substances Control Act,
                                                                                    devices, and unique fittings. For     commercial users or consumers
                                                                                    connections with refrigerant          can only recharge MVAC systems
                                                                                    containers for use in professional    with HFO-1234yf where the
                                                                                    servicing, use fittings must be       original charging of the
                                                                                    consistent with SAE J2844.\3\ \4\     system with HFO-1234yf was
                                                                                    \5\ For connections with small        done by the original equipment
                                                                                    refrigerant cans for consumer or      manufacturer.
                                                                                    professional use, use fittings must
                                                                                    have a diameter of 0.5 inches, a
                                                                                    thread pitch of 16 thread per inch,
                                                                                    and a left thread direction,
                                                                                    consistent with SAE J2844.
                                                                                   (2) Manufacturers must conduct
                                                                                    Failure Mode and Effect Analysis
                                                                                    (FMEA) as provided in SAE J1739.\2\
                                                                                    \4\ \5\ Manufacturers must keep the
                                                                                    FMEA on file for at least three
                                                                                    years from the date of creation.
Motor vehicle air conditioning       HFO-1234yf...........  Acceptable subject to  As of [30 days after publication of   Additional training for service
 (newly manufactured complete heavy-                         use conditions.        final rule]:.                         technicians recommended.
 duty vans only).                                                                  (1) HFO-1234yf MVAC systems must      HFO-1234yf is also known as
                                                                                    adhere to all of the safety           2,3,3,3-tetrafluoro-prop-1-ene
                                                                                    requirements of SAE J639,\1\ \4\      (CAS No 754-12-1).
                                                                                    \5\ including requirements for a     HFO-1234yf is acceptable for
                                                                                    flammable refrigerant warning         complete heavy-duty vans.
                                                                                    label, high-pressure compressor       Complete heavy-duty vans are
                                                                                    cutoff switch and pressure relief     not altered by a secondary or
                                                                                    devices, and unique fittings. For     tertiary manufacturer.
                                                                                    connections with refrigerant
                                                                                    containers for use in professional
                                                                                    servicing, use fittings must be
                                                                                    consistent with SAE J2844.\3\ \4\
                                                                                    \5\ For connections with small
                                                                                    refrigerant cans for consumer or
                                                                                    professional use, use fittings must
                                                                                    have a diameter of 0.5 inches, a
                                                                                    thread pitch of 16 thread per inch,
                                                                                    and a left thread direction,
                                                                                    consistent with SAE J2844.
                                                                                   (2) Manufacturers must conduct        Consistent with EPA's
                                                                                    Failure Mode and Effect Analysis      Significant New Use Rule for
                                                                                    (FMEA) as provided in SAE J1739.\2\   HFO-1234yf under the Toxic
                                                                                    \4\ \5\ Manufacturers must keep the   Substances Control Act,
                                                                                    FMEA on file for at least three       commercial users or consumers
                                                                                    years from the date of creation.      can only recharge MVAC systems
                                                                                                                          with HFO-1234yf where the
                                                                                                                          original charging of the
                                                                                                                          system with HFO-1234yf was
                                                                                                                          done by the original equipment
                                                                                                                          manufacturer.
Motor vehicle air conditioning       HFO-1234yf...........  Acceptable subject to  As of [30 days after publication of   Additional training for service
 (newly manufactured nonroad                                 use conditions.        final rule]:.                         technicians recommended.
 agricultural tractors with greater                                                (1) HFO-1234yf MVAC systems must      HFO-1234yf is also known as
 than 40 horsepower).                                                               adhere to all of the safety           2,3,3,3-tetrafluoro-prop-1-ene
                                                                                    requirements of SAE J639,\1\ \4\      (CAS No 754-12-1).
                                                                                    \5\ including requirements for a     Consistent with EPA's
                                                                                    flammable refrigerant warning         Significant New Use Rule for
                                                                                    label, high-pressure compressor       HFO-1234yf under the Toxic
                                                                                    cutoff switch and pressure relief     Substances Control Act,
                                                                                    devices, and unique fittings. For     commercial users or consumers
                                                                                    connections with refrigerant          can only recharge MVAC systems
                                                                                    containers for use in professional    with HFO-1234yf where the
                                                                                    servicing, use fittings must be       original charging of the
                                                                                    consistent with SAE J2844.\3\ \4\     system with HFO-1234yf was
                                                                                    \5\ For connections with small        done by the original equipment
                                                                                    refrigerant cans for consumer or      manufacturer.
                                                                                    professional use, use fittings must
                                                                                    have a diameter of 0.5 inches, a
                                                                                    thread pitch of 16 thread per inch,
                                                                                    and a left thread direction,
                                                                                    consistent with SAE J2844.
                                                                                   (2) Manufacturers must conduct
                                                                                    Failure Mode and Effect Analysis
                                                                                    (FMEA) as provided in SAE J1739.\2\
                                                                                    \4\ \5\ Manufacturers must keep the
                                                                                    FMEA on file for at least three
                                                                                    years from the date of creation.
Motor vehicle air conditioning       HFO-1234yf...........  Acceptable subject to  As of [30 days after publication of   Additional training for service
 (newly manufactured nonroad self-                           use conditions.        final rule]:.                         technicians recommended.
 propelled agricultural machinery).                                                (1) HFO-1234yf MVAC systems must      HFO-1234yf is also known as
                                                                                    adhere to all of the safety           2,3,3,3-tetrafluoro-prop-1-ene
                                                                                    requirements of SAE J639,\1\ \4\      (CAS No 754-12-1).
                                                                                    \5\ including requirements for a     Consistent with EPA's
                                                                                    flammable refrigerant warning         Significant New Use Rule for
                                                                                    label, high-pressure compressor       HFO-1234yf under the Toxic
                                                                                    cutoff switch and pressure relief     Substances Control Act,
                                                                                    devices, and unique fittings. For     commercial users or consumers
                                                                                    connections with refrigerant          can only recharge MVAC systems
                                                                                    containers for use in professional    with HFO-1234yf where the
                                                                                    servicing, use fittings must be       original charging of the
                                                                                    consistent with SAE J2844.\3\ \4\     system with HFO-1234yf was
                                                                                    \5\ For connections with small        done by the original equipment
                                                                                    refrigerant cans for consumer or      manufacturer.
                                                                                    professional use, use fittings must
                                                                                    have a diameter of 0.5 inches, a
                                                                                    thread pitch of 16 thread per inch,
                                                                                    and a left thread direction,
                                                                                    consistent with SAE J2844.
                                                                                   (2) Manufacturers must conduct
                                                                                    Failure Mode and Effect Analysis
                                                                                    (FMEA) as provided in SAE J1739.\2\
                                                                                    \4\ \5\ Manufacturers must keep the
                                                                                    FMEA on file for at least three
                                                                                    years from the date of creation.
Motor vehicle air conditioning       HFO-1234yf...........  Acceptable subject to  As of [30 days after publication of   Additional training for service
 (newly manufactured nonroad                                 use conditions.        final rule]:.                         technicians recommended.
 compact equipment).                                                               (1) HFO-1234yf MVAC systems must      HFO-1234yf is also known as
                                                                                    adhere to all of the safety           2,3,3,3-tetrafluoro-prop-1-ene
                                                                                    requirements of SAE J639,\1\ \4\      (CAS No 754-12-1).
                                                                                    \5\ including requirements for a     Consistent with EPA's
                                                                                    flammable refrigerant warning         Significant New Use Rule for
                                                                                    label, high-pressure compressor       HFO-1234yf under the Toxic
                                                                                    cutoff switch and pressure relief     Substances Control Act (80 FR
                                                                                    devices, and unique fittings. For     37166, June 30, 2015),
                                                                                    connections with refrigerant          commercial users or consumers
                                                                                    containers for use in professional    can only recharge MVAC systems
                                                                                    servicing, use fittings must be       with HFO-1234yf where the
                                                                                    consistent with SAE J2844.\3\ \4\     original charging of the
                                                                                    \5\ For connections with small        system with HFO-1234yf was
                                                                                    refrigerant cans for consumer or      done by the original equipment
                                                                                    professional use, use fittings must   manufacturer.
                                                                                    have a diameter of 0.5 inches, a
                                                                                    thread pitch of 16 thread per inch,
                                                                                    and a left thread direction,
                                                                                    consistent with SAE J2844).

[[Page 68982]]

 
                                                                                   (2) Manufacturers must conduct
                                                                                    Failure Mode and Effect Analysis
                                                                                    (FMEA) as provided in SAE J1739.\2\
                                                                                    \4\ \5\ Manufacturers must keep the
                                                                                    FMEA on file for at least three
                                                                                    years from the date of creation.
Motor vehicle air conditioning       HFO-1234yf...........  Acceptable subject to  As of [30 days after publication of   Additional training for service
 (newly manufactured nonroad                                 use conditions.        final rule]:.                         technicians recommended.
 construction, forestry, and mining                                                (1) HFO-1234yf MVAC systems must      HFO-1234yf is also known as
 equipment).                                                                        adhere to all of the safety           2,3,3,3-tetrafluoro-prop-1-ene
                                                                                    requirements of SAE J639,\1\ \4\      (CAS No 754-12-1).
                                                                                    \5\ including requirements for a     Consistent with EPA's
                                                                                    flammable refrigerant warning         Significant New Use Rule for
                                                                                    label, high-pressure compressor       HFO-1234yf under the Toxic
                                                                                    cutoff switch and pressure relief     Substances Control Act,
                                                                                    devices, and unique fittings. For     commercial users or consumers
                                                                                    connections with refrigerant          can only recharge MVAC systems
                                                                                    containers for use in professional    with HFO-1234yf where the
                                                                                    servicing, use fittings must be       original charging of the
                                                                                    consistent with SAE J2844.\3\ \4\     system with HFO-1234yf was
                                                                                    \5\ For connections with small        done by the original equipment
                                                                                    refrigerant cans for consumer or      manufacturer.
                                                                                    professional use, use fittings must
                                                                                    have a diameter of 0.5 inches, a
                                                                                    thread pitch of 16 thread per inch,
                                                                                    and a left thread direction,
                                                                                    consistent with SAE J2844.
                                                                                   (2) Manufacturers must conduct
                                                                                    Failure Mode and Effect Analysis
                                                                                    (FMEA) as provided in SAE J1739.\2\
                                                                                    \4\ \5\ Manufacturers must keep the
                                                                                    FMEA on file for at least three
                                                                                    years from the date of creation.
Motor vehicle air conditioning       HFO-1234yf...........  Acceptable subject to  As of [30 days after publication of   Additional training for service
 (newly manufactured nonroad                                 use conditions.        final rule]:.                         technicians recommended.
 commercial utility vehicles).                                                     (1) HFO-1234yf MVAC systems must      HFO-1234yf is also known as
                                                                                    adhere to all of the safety           2,3,3,3-tetrafluoro-prop-1-ene
                                                                                    requirements of SAE J639,\1\ \4\      (CAS No 754-12-1).
                                                                                    \5\ including requirements for a     Consistent with EPA's
                                                                                    flammable refrigerant warning         Significant New Use Rule for
                                                                                    label, high-pressure compressor       HFO-1234yf under the Toxic
                                                                                    cutoff switch and pressure relief     Substances Control Act,
                                                                                    devices, and unique fittings. For     commercial users or consumers
                                                                                    connections with refrigerant          can only recharge MVAC systems
                                                                                    containers for use in professional    with HFO-1234yf where the
                                                                                    servicing, use fittings must be       original charging of the
                                                                                    consistent with SAE J2844.\3\ \4\     system with HFO-1234yf was
                                                                                    \5\ For connections with small        done by the original equipment
                                                                                    refrigerant cans for consumer or      manufacturer.
                                                                                    professional use, use fittings must
                                                                                    have a diameter of 0.5 inches, a
                                                                                    thread pitch of 16 thread per inch,
                                                                                    and a left thread direction,
                                                                                    consistent with SAE J2844.
                                                                                   (2) Manufacturers must conduct
                                                                                    Failure Mode and Effect Analysis
                                                                                    (FMEA) as provided in SAE J1739.\2\
                                                                                    \4\ \5\ Manufacturers must keep the
                                                                                    FMEA on file for at least three
                                                                                    years from the date of creation.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ SAE, J639, Safety and Design Standards for Motor Vehicle Refrigerant Vapor Compression Systems, Revised November 9, 2020.
\2\ SAE, J1739, Potential Failure Mode and Effects Analysis (FMEA) Including Design FMEA, Supplemental FMEA-MSR, and Process FMEA, Revised January 13,
  2021.
\3\ SAE, J2844, R-1234yf (HFO-1234yf) New Refrigerant Purity and Container Requirements for Use in Mobile Air-Conditioning Systems, Revised January 4,
  2013.
\4\ You may purchase the material from SAE by mail: SAE Customer Service, 400 Commonwealth Drive, Warrendale, PA 15096-0001; by telephone: 1-877-606-
  7323 in the United States or 724-776-4970 outside the United States or in Canada; or web: https://www.sae.org/standards.
\5\ The Director of the Federal Register approves this incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. All approved
  material is available for inspection at U.S. EPA's Air and Radiation Docket; EPA West Building, Room 3334, 1301 Constitution Ave. NW, Washington, DC
  202-566-1742 and is available from SAE International (SAE), 400 Commonwealth Drive, Warrendale, PA 15096-0001, 1-877-606-7323, https://www.sae.org/standards standards. They are also available for inspection at the National Archives and Records Administration (NARA). For information on the availability of
  this material at NARA, email [email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html.

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[FR Doc. 2021-25440 Filed 12-3-21; 8:45 am]
BILLING CODE 6560-50-P