RefrigerantASHRAE R-143a

R143a PT Chart

Q: What is R-143a used for?

Exclusively as a blend component in HFC formulations — R-404A (52% R-143a) for low-temperature commercial refrigeration, R-507A (50%) as alternative R-502 replacement. R-143a provides capacity in these blends; flammability is suppressed by R-125 (also a major component).

Q: What's R-143a's GWP?

4,470 — the highest among mainstream HFC blend components. The long atmospheric lifetime (~52 years) drives the very high GWP. R-143a is the primary contributor to R-404A's GWP of 3,922 — without R-143a, R-404A would have much lower GWP.

Q: Is R-143a flammable?

Yes — ASHRAE class A2L (lower flammability). The flammability is part of why R-143a is never used standalone — combining A2L classification with very high GWP gives R-143a the worst of both characteristics for standalone refrigerant use.

Q: Why is R-143a used in blends if its GWP is so high?

For capacity at low-temperature operating conditions. R-143a's vapor pressure profile is well-suited to low-temperature commercial refrigeration applications (walk-in freezers, frozen food cases). R-404A's design used 52% R-143a content specifically to match R-502's low-temperature capacity in the same equipment. Modern low-GWP blends achieve low-temperature capacity through different chemistry (R-32 plus R-1234yf and similar) without R-143a's very high GWP.

Q: Can R-143a be used as a refrigerant by itself?

Technically yes, but practically never. The A2L flammability would require A2L-rated equipment; the very high GWP (4,470) is among the worst regulatory positions of any HFC. No commercial application uses R-143a standalone.

Q: What lubricant does R-143a use?

Standalone R-143a (rare/nonexistent in practice) would use POE.

Q: Is R-143a being phased out?

Indirectly through the phase-down of R-404A and R-507A. As these blends face AIM Act and EU F-Gas restrictions, R-143a production volumes decrease. Modern low-GWP blends use little or no R-143a.

Updated October 19, 2026

R-143a

A2L Lower toxicity, lower flammabilityHFC (pure) AIM Act HFC

Illustration of a refrigerant cylinder painted light green gray (RAL 7044), the color AHRI Guideline N-2017 calls for on all new refrigerant containers from 2020^{[4], section 4.8}. Label: R-143a, safety class A2L, GWP 4,470. Red band on the shoulder: AHRI Guideline N-2017 calls for one on containers of flammable refrigerants^{[4], section 4.7}.

CH3CF3

Pure HFC (1,1,1-trifluoroethane, CH₃CF₃) — A2L lower flammability, GWP 4,470. Almost exclusively used as a blend component in R-404A (52%) and R-507A (50%); not used as standalone refrigerant due to flammability and very high GWP.

R-143a saturation pressure is 88.3 PSIG at 40°F, 150.4 PSIG at 70°F, and 237.2 PSIG at 100°F. These are the gauge readings on a static, fully-saturated system; a running system's high side sits well above them. The full table below runs from −40°F to 150°F in 1°F steps.

Not yet checked against an independent source.

Saturation @ 70°F

150.4 PSIG

GWP (100-yr)

4,470 AIM Act exchange value (IPCC AR4)

Boiling point

−53.0°F

Sourced facts

ASHRAE safety class: A2L^[1]
Chemical formula: CH₃CF₃^[1]
GWP (100-yr): 4,470
ODP: 0^[1]
Normal boiling point: −53.0°F (−47.2°C)^[2]
Use as standalone: Almost never^[1]
Component in R-404A: 52%^[1]
Component in R-507A: 50%^[1]

R-143a PT calculator Superheat

R-143a PT chart — printable saturation table

Looking for the R-143a PT chart PDF for shop reference? The complete pressure-temperature saturation table is below: every 1° increment from −40°F to 150°F (or to the refrigerant's critical temperature). Use the Print / Save as PDF button in the table header to download a clean, table-only PDF (the rest of the page is hidden from the print output).

R-143a PT Chart — Pressure-Temperature Saturation Table

Computed with CoolProp 7.2.0 in 1°F steps · hvacptcharts.com

R-143a · 1° increments · °F / PSIG

Tinted rows: 32°F H₂O freeze

R-143a pressure-temperature saturation table in Fahrenheit and PSIG
Temp (°F)	Pressure (PSIG)
−40°F	5.8
−39°F	6.3
−38°F	6.8
−37°F	7.3
−36°F	7.9
−35°F	8.4
−34°F	9.0
−33°F	9.5
−32°F	10.1
−31°F	10.7
−30°F	11.3
−29°F	11.9
−28°F	12.5
−27°F	13.1
−26°F	13.8
−25°F	14.4
−24°F	15.1
−23°F	15.8
−22°F	16.5
−21°F	17.2
−20°F	17.9
−19°F	18.6
−18°F	19.3
−17°F	20.1
−16°F	20.9
−15°F	21.6
−14°F	22.4
−13°F	23.2
−12°F	24.0
−11°F	24.9
−10°F	25.7
−9°F	26.6
−8°F	27.4
−7°F	28.3
−6°F	29.2
−5°F	30.1
−4°F	31.0
−3°F	32.0
−2°F	32.9
−1°F	33.9
0°F	34.9
1°F	35.9
2°F	36.9
3°F	37.9
4°F	39.0
5°F	40.0
6°F	41.1
7°F	42.2
8°F	43.3
9°F	44.4
10°F	45.6
11°F	46.7
12°F	47.9
13°F	49.1
14°F	50.3
15°F	51.5
16°F	52.8
17°F	54.0
18°F	55.3
19°F	56.6
20°F	57.9
21°F	59.3
22°F	60.6
23°F	62.0
24°F	63.4
25°F	64.8
26°F	66.2
27°F	67.7
28°F	69.1
29°F	70.6
30°F	72.1
31°F	73.6
32°F H₂O freeze	75.2
33°F	76.7
34°F	78.3
35°F	79.9
36°F	81.6
37°F	83.2
38°F	84.9
39°F	86.6
40°F	88.3
41°F	90.0
42°F	91.8
43°F	93.5
44°F	95.3
45°F	97.2
46°F	99.0
47°F	100.9
48°F	102.8
49°F	104.7
50°F	106.6
51°F	108.6
52°F	110.5
53°F	112.5
54°F	114.6
55°F	116.6
56°F	118.7
57°F	120.8
58°F	122.9
59°F	125.1
60°F	127.3
61°F	129.5
62°F	131.7
63°F	133.9
64°F	136.2
65°F	138.5
66°F	140.9
67°F	143.2
68°F	145.6
69°F	148.0
70°F	150.4
71°F	152.9
72°F	155.4
73°F	157.9
74°F	160.5
75°F	163.0
76°F	165.6
77°F	168.3
78°F	170.9
79°F	173.6
80°F	176.3
81°F	179.1
82°F	181.9
83°F	184.7
84°F	187.5
85°F	190.4
86°F	193.3
87°F	196.2
88°F	199.2
89°F	202.2
90°F	205.2
91°F	208.2
92°F	211.3
93°F	214.4
94°F	217.6
95°F	220.8
96°F	224.0
97°F	227.2
98°F	230.5
99°F	233.8
100°F	237.2
101°F	240.6
102°F	244.0
103°F	247.4
104°F	250.9
105°F	254.4
106°F	258.0
107°F	261.6
108°F	265.2
109°F	268.9
110°F	272.6
111°F	276.3
112°F	280.1
113°F	283.9
114°F	287.8
115°F	291.7
116°F	295.6
117°F	299.5
118°F	303.5
119°F	307.6
120°F	311.7
121°F	315.8
122°F	320.0
123°F	324.2
124°F	328.4
125°F	332.7
126°F	337.0
127°F	341.4
128°F	345.8
129°F	350.2
130°F	354.7
131°F	359.3
132°F	363.9
133°F	368.5
134°F	373.2
135°F	377.9
136°F	382.7
137°F	387.5
138°F	392.3
139°F	397.2
140°F	402.2
141°F	407.2
142°F	412.3
143°F	417.4
144°F	422.5
145°F	427.7
146°F	433.0
147°F	438.3
148°F	443.7
149°F	449.1
150°F	454.6

R-143a pressure-temperature saturation table in Celsius and kPa
Temp (°C)	Pressure (kPa)
−40°C	40
−39°C	46
−38°C	53
−37°C	59
−36°C	66
−35°C	74
−34°C	81
−33°C	89
−32°C	97
−31°C	105
−30°C	114
−29°C	122
−28°C	131
−27°C	141
−26°C	150
−25°C	160
−24°C	170
−23°C	181
−22°C	192
−21°C	203
−20°C	214
−19°C	226
−18°C	238
−17°C	250
−16°C	263
−15°C	276
−14°C	289
−13°C	303
−12°C	317
−11°C	332
−10°C	347
−9°C	362
−8°C	378
−7°C	394
−6°C	410
−5°C	427
−4°C	445
−3°C	462
−2°C	481
−1°C	499
0°C H₂O freeze	518
1°C	538
2°C	558
3°C	578
4°C	599
5°C	621
6°C	642
7°C	665
8°C	688
9°C	711
10°C	735
11°C	759
12°C	784
13°C	810
14°C	836
15°C	862
16°C	890
17°C	917
18°C	946
19°C	974
20°C	1,004
21°C	1,034
22°C	1,065
23°C	1,096
24°C	1,128
25°C	1,160
26°C	1,193
27°C	1,227
28°C	1,262
29°C	1,297
30°C	1,333
31°C	1,369
32°C	1,406
33°C	1,444
34°C	1,483
35°C	1,522
36°C	1,562
37°C	1,603
38°C	1,645
39°C	1,687
40°C	1,730
41°C	1,774
42°C	1,819
43°C	1,864
44°C	1,910
45°C	1,958
46°C	2,006
47°C	2,054
48°C	2,104
49°C	2,155
50°C	2,206
51°C	2,258
52°C	2,312
53°C	2,366
54°C	2,421
55°C	2,477
56°C	2,534
57°C	2,592
58°C	2,652
59°C	2,712
60°C	2,773
61°C	2,835
62°C	2,899
63°C	2,964
64°C	3,029
65°C	3,096
66°C	3,165

CoolProp 7.2.0 · PSIG/kPa = gauge · PSIA = PSIG + 14.6959 · kPa(abs) = kPa(gauge) + 101.325

Full saturation values at 1° increments. Toggle between °F / PSIG and °C / kPa. Use Print / Save as PDF for laminated shop reference, or download the CSV / JSON below for use in other tools. R-143a PT chart data: CoolProp 7.2.0 (published Helmholtz equations of state / mixture models — see the source citations above).

A2L

Lower toxicity, lower flammability

Lower toxicity. Flame propagates in air at 60°C, but with a low burning velocity (≤ 10 cm/s) and a heat of combustion < 19,000 kJ/kg. ASHRAE safety group A2L: lower toxicity and lower flammability. R-32, R-454B, R-1234yf, R-1234ze(E), R-452B, R-454C, R-455A, R-516A are A2L.

Flammability: Low (burning velocity ≤ 10 cm/s)
Toxicity: Lower (OEL ≥ 400 ppm)

Classification per ANSI/ASHRAE Standard 34-2022^{[1], safety group definitions and refrigerant safety classifications}. See full reference.

Saturation pressure-temperature curve

Pressure

Temperature

Highlight at°F

Quick lookup — R-143a

Temp:°F

150.4PSIG(1,037 kPa)

Range: −40 to 150°F Open full PT calculator →

Common service temperatures

32°F

75PSIG

Freezing

45°F

97PSIG

Heat-pump heat

70°F

150PSIG

Standard

75°F

163PSIG

Test ref

80°F

176PSIG

Warm

95°F

221PSIG

Summer peak

Saturation values from CoolProp 7.2.0^[2]. Operating pressure on a running system differs — see the operating-pressure references for in-use values.

At a glance

Chemistry

CH3CF3

1,1,1-Trifluoroethane

Lubricant compatibility

POEMO

Used almost exclusively as a blend component (R-404A, R-507A). A2L mild flammability; high GWP.

Common applications

Blend component in R-404A, R-507A, R-427A
Standalone use is rare

Properties

Boiling point (1 atm)
−53.0°F (−47.2°C)
Critical point
162.9°F (72.7°C) at 531 PSIG
Molar mass
84.04 g/mol
ODP
0
GWP (100-yr)
4,470 AIM Act exchange value (IPCC AR4) IPCC: AR4 4,470 · AR5 4,800 · AR6 5,810
Atmospheric lifetime
51 years
New-equipment status (US)
Restricted in 41 new-equipment categories — US new-equipment rules (40 CFR 84.54).

What is R-143a?

R-143a is 1,1,1-trifluoroethane (CH₃CF₃) — a pure HFC with A2L safety classification and the highest GWP (4,470) among mainstream HFC blend components^[1]^[3]. R-143a is essentially never used as a standalone refrigerant — its A2L flammability and very high GWP make alternatives preferable for nearly all direct refrigeration applications.

R-143a's commercial role is exclusively as a blend component. The major HFC blends using R-143a: R-404A (52% R-143a — largest mass fraction), R-507A (50%), R-428A, R-427A, R-434A. In these blends R-143a provides volumetric refrigeration capacity at low-temperature operating conditions; the flammability is suppressed by R-125 in A1 blends.

Where R-143a is used

Component in R-404A (52% mass) — primary low-temperature commercial refrigeration blend
Component in R-507A (50%) — alternative R-502 replacement
Component in R-427A — R-22 retrofit blend
Component in R-434A — alternative R-22 retrofit
Standalone use is essentially non-existent in commercial HVAC

Regulatory & phase-down status

R-143a faces phase-down pressure indirectly through the phase-down of HFC blends containing R-143a. R-404A (52% R-143a) and R-507A (50%) are aggressively phased down under AIM Act and EU F-Gas Regulation^[3]. As these blends are restricted for new equipment, R-143a production volumes decrease.

Modern low-GWP blends (R-454C, R-455A, R-448A, R-449A) contain little or no R-143a. The structural trajectory is away from R-143a use in commercial HVAC blend formulations.

Service notes

R-143a is essentially never encountered as a standalone refrigerant in field service. Service technicians work with R-143a as a component in HFC blends (primarily R-404A and R-507A); the blend behavior dominates service considerations.

POE oil compatible. Standard HFC service procedures apply when encountered in blend form.

Operating cycle

Phase-down timeline

R-143a is a regulated substance under the AIM Act. Its GWP under 40 CFR 84.64 is 4,470, at or above the limit in 41 of the categories 40 CFR 84.54 restricts (listed under “All 84.54 categories restricting R-143a”).

From January 1, 2025 — new retail food refrigeration — stand-alone units: manufacture / import restricted (GWP ≥ 150)^{[3], §84.54(a)(4)}.
From January 1, 2028 — new retail food refrigeration — stand-alone units: sale and distribution restricted (GWP ≥ 150)^{[3], §84.54(b)}.

HFC production & consumption allowances step down to 30% of baseline in 2029–2033, 20% of baseline in 2034–2035, and 15% of baseline in 2036 and later (42 U.S.C. 7675(e)(2)(C)).

Full 40 CFR 84.54 new-equipment rules for R-143a →

US new-equipment rules (40 CFR 84.54)

R-143a is a regulated substance under the AIM Act. Under 40 CFR 84.64(a) its GWP is 4,470, the AIM Act exchange value. That value is compared against each 40 CFR 84.54 subsector limit below.

Effective	Equipment subsector	Limit	Restriction	¶
January 1, 2025	Retail food refrigeration — stand-alone units	GWP ≥ 150	Manufacture / import	(a)(4)
January 1, 2028	Retail food refrigeration — stand-alone units	GWP ≥ 150	Sale / distribution	(b)

All 84.54 categories restricting R-143a (41)^[3]

Refrigeration, air conditioning & heat pumps (34)
January 1, 2025	Self-contained residential & light-commercial AC and heat pump products	GWP ≥ 700	(a)(1)
January 1, 2025	Chillers for comfort cooling	GWP ≥ 700	(a)(10)(i)
January 1, 2025	Chillers for ice rinks	GWP ≥ 700	(a)(10)(ii)
January 1, 2025	Residential dehumidifiers	GWP ≥ 700	(a)(2)
January 1, 2025	Household refrigerators and freezers	GWP ≥ 150	(a)(3)
January 1, 2025	Retail food refrigeration — stand-alone units	GWP ≥ 150	(a)(4)
January 1, 2025	Vending machines	GWP ≥ 150	(a)(5)
January 1, 2025	Residential & light-commercial AC and heat pump systems (except VRF)	GWP ≥ 700	(c)(1)
January 1, 2025	Chillers for comfort cooling	GWP ≥ 700	(c)(3)
January 1, 2025	Ice rinks	GWP ≥ 700	(c)(4)
January 1, 2026	Chillers for industrial process refrigeration, fluid exiting the chiller warmer than −22°F (−30°C)	GWP ≥ 700	(a)(10)(iii)
January 1, 2026	Industrial process refrigeration products (non-chiller), charge 200 lb or greater, refrigerant entering the evaporator warmer than −22°F (−30°C)	GWP ≥ 150	(a)(12)(i)
January 1, 2026	Industrial process refrigeration products (non-chiller), charge less than 200 lb, refrigerant entering the evaporator warmer than −22°F (−30°C)	GWP ≥ 300	(a)(12)(ii)
January 1, 2026	Ice makers — batch type up to 1,000 lb of ice per 24 h and continuous type up to 1,200 lb per 24 h	GWP ≥ 150	(a)(8)(i)
January 1, 2026	Industrial process refrigeration systems (non-chiller), charge 200 lb or greater, evaporator inlet warmer than −22°F (−30°C), not the high-temperature side of a cascade	GWP ≥ 150	(c)(10)(i)
January 1, 2026	Industrial process refrigeration systems (non-chiller), charge less than 200 lb, evaporator inlet warmer than −22°F (−30°C)	GWP ≥ 300	(c)(10)(ii)
January 1, 2026	Industrial process refrigeration — high-temperature side of cascade systems, evaporator inlet warmer than −22°F (−30°C)	GWP ≥ 300	(c)(10)(iii)
January 1, 2026	Variable refrigerant flow (VRF) residential & light-commercial AC and heat pump systems	GWP ≥ 700	(c)(2)
January 1, 2026	Chillers for industrial process refrigeration, fluid exiting the chiller warmer than −22°F (−30°C)	GWP ≥ 700	(c)(5)(i)
July 27, 2026	Refrigerated transport — intermodal containers with a box temperature of −31°F (−35°C) or higher	GWP ≥ 700	(a)(6)
July 27, 2026	Retail food refrigeration — remote condensing units	GWP ≥ 1,400	(c)(11)(i)
July 27, 2026	Refrigerated transport — intermodal containers with a box temperature of −31°F (−35°C) or higher	GWP ≥ 700	(c)(7)
July 27, 2026	Cold storage warehouse systems	GWP ≥ 700	(c)(9)(i)
January 1, 2027	Self-contained products in data center, information technology equipment facility, and computer room cooling	GWP ≥ 700	(a)(11)
January 1, 2027	Refrigerated food processing and dispensing products outside the scope of UL 621, charge 500 g or less	GWP ≥ 150	(a)(9)(i)
January 1, 2027	Supermarket systems	GWP ≥ 1,400	(c)(12)(i)
January 1, 2027	Data center, information technology equipment facility, and computer room cooling systems	GWP ≥ 700	(c)(13)
January 1, 2028	Chillers for industrial process refrigeration, fluid exiting the chiller from −58°F to −22°F (−50°C to −30°C)	GWP ≥ 700	(a)(10)(iv)
January 1, 2028	Industrial process refrigeration products (non-chiller), refrigerant entering the evaporator from −58°F to −22°F (−50°C to −30°C)	GWP ≥ 700	(a)(12)(iii)
January 1, 2028	Industrial process refrigeration systems (non-chiller), evaporator inlet from −58°F to −22°F (−50°C to −30°C)	GWP ≥ 700	(c)(10)(iv)
January 1, 2028	Chillers for industrial process refrigeration, fluid exiting the chiller from −58°F to −22°F (−50°C to −30°C)	GWP ≥ 700	(c)(6)(i)
January 1, 2032	Retail food refrigeration — remote condensing units	GWP ≥ 150 (200 lb or greater, not the cascade high side); GWP ≥ 300 (less than 200 lb); GWP ≥ 300 (cascade high side)	(c)(11)(ii)
January 1, 2032	Supermarket systems	GWP ≥ 150 (200 lb or greater, not the cascade high side); GWP ≥ 300 (less than 200 lb); GWP ≥ 300 (cascade high side)	(c)(12)(ii)
January 1, 2032	Cold storage warehouse systems	GWP ≥ 150 (200 lb or greater, not the cascade high side); GWP ≥ 300 (less than 200 lb); GWP ≥ 300 (cascade high side)	(c)(9)(ii)
Motor vehicle air conditioning (3)
October 24, 2024	Motor vehicle air-conditioning in Model Year 2025 and later light-duty passenger cars and trucks (gross vehicle weight rating under 8,500 lb)	GWP ≥ 150	(a)(13)(i)
Model Year 2028	Motor vehicle air-conditioning in medium-duty passenger vehicles, heavy-duty pickup trucks and complete heavy-duty vans whose air-conditioning will not be modified by upfitters	GWP ≥ 150	(a)(13)(ii)
January 1, 2028	Motor vehicle air-conditioning in certain nonroad vehicles (agricultural tractors over 40 horsepower; self-propelled agricultural machinery; compact equipment; construction, forestry and mining equipment; and commercial utility vehicles)	GWP ≥ 150	(a)(13)(iii)
Foam blowing agents (2)
January 1, 2025	Foam products: rigid polyurethane appliance foam, commercial refrigeration foam, laminated boardstock, marine flotation foam, sandwich panels, slabstock; flexible polyurethane; integral skin polyurethane; polystyrene (extruded boardstock, billet, extruded sheet); phenolic insulation board and bunstock; polyisocyanurate laminated boardstock; polyolefin; rigid polyurethane spray foam	GWP ≥ 150	(a)(14)
January 1, 2026	Foam products in the (a)(14) formulations for use in space and military applications	GWP ≥ 150	(a)(15)
Aerosol propellants / solvents (2)
January 1, 2025	Aerosol products	GWP ≥ 150	(a)(16)(i)
January 1, 2028	Aerosol products (all, except defense sprays as defined in 84.3)	GWP ≥ 150	(a)(16)(ii)

Servicing. 40 CFR 84.54 restricts new manufacture/import, later sale/distribution, and installation. "Installation" is defined in 84.54(e); repairing or servicing existing R-143a equipment is not an installation unless it meets 84.54(e), so existing systems can keep being serviced. From January 1, 2029, servicing or repairing R-143a equipment in supermarket systems, refrigerated transport or automatic commercial ice makers must be done with reclaimed refrigerant^[5].

EU (retail-food / cold-storage)

Under Regulation (EU) No 517/2014, since replaced by (EU) 2024/573, applying from March 11, 2024 (compared against the AR4 headline GWP), R-143a's GWP is at or above the limit in:

Art. 13(3): from January 1, 2020, F-gases with GWP ≥ 2,500 may not be used to service or maintain refrigeration equipment with a charge of 40 t CO₂e or more — except military equipment, equipment cooling products below −50 °C, and, until January 1, 2030, reclaimed or recycled gas.
Annex III row 11: Refrigerators and freezers for commercial use (hermetically sealed equipment) — GWP ≥ 2,500, from January 1, 2020.
Annex III row 12: Stationary refrigeration equipment — GWP ≥ 2,500, from January 1, 2020 (except equipment designed to cool products below −50°C).
Annex III row 11: Refrigerators and freezers for commercial use (hermetically sealed equipment) — GWP ≥ 150, from January 1, 2022.
Annex III row 13: Multipack centralised refrigeration systems for commercial use with a rated capacity of 40 kW or more — GWP ≥ 150, from January 1, 2022 (the primary refrigerant circuit of a cascade system may use GWP below 1,500).

Regulation (EU) No 517/2014.

Source: 40 CFR 84.54, current through 91 FR 31329 (May 26, 2026). Installation defined at 40 CFR 84.54(e).

Global warming potential, in context

Reading the R-143a PT chart

R-143a's PT chart is a single saturation curve. The pressure envelope is high. The vapor pressure profile is similar to R-125 and contributes to R-404A's and R-507A's pressure characteristics.

R-143a is rarely encountered as a standalone refrigerant in field service, so its standalone PT chart is primarily a reference for understanding blend behavior.

Frequently asked

›What is R-143a used for?

Exclusively as a blend component in HFC formulations — R-404A (52% R-143a) for low-temperature commercial refrigeration, R-507A (50%) as alternative R-502 replacement^[1]. R-143a provides capacity in these blends; flammability is suppressed by R-125 (also a major component).

›What's R-143a's GWP?

4,470 — the highest among mainstream HFC blend components^[3]. The long atmospheric lifetime (~52 years) drives the very high GWP. R-143a is the primary contributor to R-404A's GWP of 3,922 — without R-143a, R-404A would have much lower GWP.

›Is R-143a flammable?

Yes — ASHRAE class A2L (lower flammability)^[1]. The flammability is part of why R-143a is never used standalone — combining A2L classification with very high GWP gives R-143a the worst of both characteristics for standalone refrigerant use.

›Why is R-143a used in blends if its GWP is so high?

For capacity at low-temperature operating conditions. R-143a's vapor pressure profile is well-suited to low-temperature commercial refrigeration applications (walk-in freezers, frozen food cases). R-404A's design used 52% R-143a content specifically to match R-502's low-temperature capacity in the same equipment.

Modern low-GWP blends achieve low-temperature capacity through different chemistry (R-32 plus R-1234yf and similar) without R-143a's very high GWP.

›Can R-143a be used as a refrigerant by itself?