RefrigerantASHRAE R-1234ze(E)

R1234ze PT Chart

Q: What is R-1234ze used for?

Centrifugal chillers in commercial cooling applications, and as a component in lower-GWP HFC/HFO blends (R-454B, R-450A, R-515A, R-515B). Honeywell markets the standalone refrigerant as Solstice ze.

Q: What's the difference between R-1234yf and R-1234ze?

Both are pure HFOs with very low GWP — GWP 1 for both on the US EPA basis (40 CFR 84.64), and below 1 (R-1234yf) to about 1 (R-1234ze) under strict IPCC AR5/AR6. R-1234yf (2,3,3,3-tetrafluoropropene) is used in mobile AC with pressure envelope similar to R-134a. R-1234ze (1,3,3,3-tetrafluoropropene, E-isomer) is used in chillers with lower pressure envelope better matched to centrifugal compressor designs. Isomer differences in molecular structure produce different pressure profiles despite similar chemical compositions.

Q: Is R-1234ze flammable?

Yes — ASHRAE class A2L (lower flammability with low burning velocity). A2L equipment design requirements apply per UL 60335-2-40 — A2L-listed equipment, A2L-rated leak detection in some installations, ignition-source isolation in the refrigerant circuit.

Q: What's the GWP of R-1234ze?

The headline figure is 1 on the US EPA basis (40 CFR 84.64(b) Table 1); IPCC AR5 lists below 1. R-1234ze's ~16-day atmospheric lifetime is far below the integration window IPCC's later assessments use for a precise figure, so the underlying climate impact is essentially negligible. R-1234ze sits in the same lowest-impact tier as R-1234yf, R-290 propane, and R-744 CO₂.

Q: What is Solstice ze?

Honeywell's trade name for R-1234ze. Honeywell is the primary commercial manufacturer of standalone R-1234ze; the refrigerant is also used as a component in Chemours and other manufacturer blends.

Q: Can R-1234ze replace R-134a in chillers?

For new chiller equipment: yes — R-1234ze is used for very-low-GWP new installations. For retrofit of existing R-134a chillers: not directly — R-1234ze has a substantially lower pressure envelope that requires compressor redesign.

Updated October 19, 2026

R-1234ze

A2L Lower toxicity, lower flammabilityHFO (pure)

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^{[7], section 4.8}. Label: R-1234ze, safety class A2L, GWP 1. Red band on the shoulder: AHRI Guideline N-2017 calls for one on containers of flammable refrigerants^{[7], section 4.7}.

CHF=CHCF3

Pure HFO (E-isomer of 1,3,3,3-tetrafluoropropene, CHF=CHCF₃) — chiller and heat pump refrigerant. GWP 1 (US EPA basis, 40 CFR 84.64); strict IPCC AR5/AR6 ≈ 1. A2L safety class. Honeywell Solstice ze. Lower pressure envelope than R-134a; well-suited to centrifugal chiller designs.

R-1234ze saturation pressure is 22.2 PSIG at 40°F, 49.5 PSIG at 70°F, and 89.9 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

49.5 PSIG

GWP (100-yr)

1 US EPA value, 40 CFR 84.64(b)

Boiling point

−2.2°F

Sourced facts

ASHRAE safety class: A2L^[1]
Chemical formula: CHF=CHCF₃ (E)^[1]
GWP (100-yr): 1
ODP: 0^[1]
Normal boiling point: −2.2°F (−19.0°C)^[3]
Lubricant: POE / PVE
Trade name: Solstice ze^[6]

R-1234ze PT calculator Superheat

R-1234ze PT chart — printable saturation table

Looking for the R-1234ze 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-1234ze PT Chart — Pressure-Temperature Saturation Table

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

R-1234ze · 1° increments · °F / PSIG

Tinted rows: NBP atmospheric crossover · 32°F H₂O freeze

R-1234ze pressure-temperature saturation table in Fahrenheit and PSIG
Temp (°F)	Pressure (PSIG)
−40°F	19.1 in. Hg vac.
−39°F	18.7 in. Hg vac.
−38°F	18.4 in. Hg vac.
−37°F	18.1 in. Hg vac.
−36°F	17.7 in. Hg vac.
−35°F	17.4 in. Hg vac.
−34°F	17.0 in. Hg vac.
−33°F	16.6 in. Hg vac.
−32°F	16.2 in. Hg vac.
−31°F	15.8 in. Hg vac.
−30°F	15.4 in. Hg vac.
−29°F	15.0 in. Hg vac.
−28°F	14.6 in. Hg vac.
−27°F	14.2 in. Hg vac.
−26°F	13.7 in. Hg vac.
−25°F	13.3 in. Hg vac.
−24°F	12.8 in. Hg vac.
−23°F	12.4 in. Hg vac.
−22°F	11.9 in. Hg vac.
−21°F	11.4 in. Hg vac.
−20°F	10.9 in. Hg vac.
−19°F	10.4 in. Hg vac.
−18°F	9.9 in. Hg vac.
−17°F	9.3 in. Hg vac.
−16°F	8.8 in. Hg vac.
−15°F	8.2 in. Hg vac.
−14°F	7.7 in. Hg vac.
−13°F	7.1 in. Hg vac.
−12°F	6.5 in. Hg vac.
−11°F	5.9 in. Hg vac.
−10°F	5.3 in. Hg vac.
−9°F	4.6 in. Hg vac.
−8°F	4.0 in. Hg vac.
−7°F	3.4 in. Hg vac.
−6°F	2.7 in. Hg vac.
−5°F	2.0 in. Hg vac.
−4°F	1.3 in. Hg vac.
−3°F	0.6 in. Hg vac.
−2°F NBP (atmospheric)	0.1
−1°F	0.4
0°F	0.8
1°F	1.2
2°F	1.5
3°F	1.9
4°F	2.3
5°F	2.7
6°F	3.1
7°F	3.5
8°F	4.0
9°F	4.4
10°F	4.8
11°F	5.3
12°F	5.8
13°F	6.2
14°F	6.7
15°F	7.2
16°F	7.7
17°F	8.2
18°F	8.7
19°F	9.2
20°F	9.7
21°F	10.2
22°F	10.8
23°F	11.3
24°F	11.9
25°F	12.5
26°F	13.0
27°F	13.6
28°F	14.2
29°F	14.8
30°F	15.4
31°F	16.1
32°F H₂O freeze	16.7
33°F	17.4
34°F	18.0
35°F	18.7
36°F	19.4
37°F	20.1
38°F	20.8
39°F	21.5
40°F	22.2
41°F	22.9
42°F	23.7
43°F	24.4
44°F	25.2
45°F	26.0
46°F	26.8
47°F	27.6
48°F	28.4
49°F	29.2
50°F	30.0
51°F	30.9
52°F	31.7
53°F	32.6
54°F	33.5
55°F	34.4
56°F	35.3
57°F	36.2
58°F	37.2
59°F	38.1
60°F	39.1
61°F	40.1
62°F	41.1
63°F	42.1
64°F	43.1
65°F	44.1
66°F	45.2
67°F	46.2
68°F	47.3
69°F	48.4
70°F	49.5
71°F	50.6
72°F	51.7
73°F	52.9
74°F	54.0
75°F	55.2
76°F	56.4
77°F	57.6
78°F	58.8
79°F	60.1
80°F	61.3
81°F	62.6
82°F	63.9
83°F	65.2
84°F	66.5
85°F	67.8
86°F	69.2
87°F	70.6
88°F	71.9
89°F	73.3
90°F	74.8
91°F	76.2
92°F	77.6
93°F	79.1
94°F	80.6
95°F	82.1
96°F	83.6
97°F	85.2
98°F	86.7
99°F	88.3
100°F	89.9
101°F	91.5
102°F	93.1
103°F	94.8
104°F	96.5
105°F	98.2
106°F	99.9
107°F	101.6
108°F	103.3
109°F	105.1
110°F	106.9
111°F	108.7
112°F	110.5
113°F	112.4
114°F	114.2
115°F	116.1
116°F	118.0
117°F	120.0
118°F	121.9
119°F	123.9
120°F	125.9
121°F	127.9
122°F	129.9
123°F	132.0
124°F	134.1
125°F	136.2
126°F	138.3
127°F	140.4
128°F	142.6
129°F	144.8
130°F	147.0
131°F	149.3
132°F	151.5
133°F	153.8
134°F	156.1
135°F	158.4
136°F	160.8
137°F	163.2
138°F	165.6
139°F	168.0
140°F	170.5
141°F	172.9
142°F	175.4
143°F	178.0
144°F	180.5
145°F	183.1
146°F	185.7
147°F	188.3
148°F	191.0
149°F	193.6
150°F	196.3

R-1234ze pressure-temperature saturation table in Celsius and kPa
Temp (°C)	Pressure (kPa)
−40°C	−65
−39°C	−63
−38°C	−60
−37°C	−58
−36°C	−56
−35°C	−54
−34°C	−51
−33°C	−49
−32°C	−46
−31°C	−43
−30°C	−40
−29°C	−37
−28°C	−34
−27°C	−31
−26°C	−27
−25°C	−24
−24°C	−20
−23°C	−17
−22°C	−13
−21°C	−9
−20°C	−4
−19°C NBP (atmospheric)	0
−18°C	4
−17°C	9
−16°C	14
−15°C	19
−14°C	24
−13°C	29
−12°C	35
−11°C	40
−10°C	46
−9°C	52
−8°C	58
−7°C	65
−6°C	71
−5°C	78
−4°C	85
−3°C	92
−2°C	100
−1°C	107
0°C H₂O freeze	115
1°C	123
2°C	132
3°C	140
4°C	149
5°C	158
6°C	167
7°C	177
8°C	187
9°C	197
10°C	207
11°C	218
12°C	229
13°C	240
14°C	251
15°C	263
16°C	275
17°C	287
18°C	300
19°C	313
20°C	326
21°C	340
22°C	353
23°C	368
24°C	382
25°C	397
26°C	412
27°C	428
28°C	444
29°C	460
30°C	477
31°C	494
32°C	511
33°C	529
34°C	547
35°C	566
36°C	585
37°C	604
38°C	624
39°C	644
40°C	665
41°C	686
42°C	708
43°C	730
44°C	752
45°C	775
46°C	798
47°C	822
48°C	846
49°C	871
50°C	896
51°C	922
52°C	948
53°C	974
54°C	1,001
55°C	1,029
56°C	1,057
57°C	1,086
58°C	1,115
59°C	1,145
60°C	1,175
61°C	1,206
62°C	1,237
63°C	1,269
64°C	1,302
65°C	1,335
66°C	1,369

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-1234ze 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-1234ze

Temp:°F

49.5PSIG(341 kPa)

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

Common service temperatures

32°F

17PSIG

Freezing

45°F

26PSIG

Heat-pump heat

70°F

49PSIG

Standard

75°F

55PSIG

Test ref

80°F

61PSIG

Warm

95°F

82PSIG

Summer peak

Saturation values from CoolProp 7.2.0^[3]. Operating pressure on a running system differs — see the operating-pressure references for in-use values.

At a glance

Chemistry

CHF=CHCF3

1,3,3,3-Tetrafluoropropene (the E isomer is the default unless Z specified)

Lubricant compatibility

POEPVEMO

Long-term low-GWP replacement for R-134a in chillers, heat pumps, and commercial refrigeration.

Trade names

Solstice ze — Honeywell
Opteon 1100 — Chemours (some references)

Common applications

Centrifugal chillers (low-pressure / large-tonnage)
Heat pumps (commercial)
Foam blowing agent
Aerosol propellant

Properties

Boiling point (1 atm)
−2.2°F (−19.0°C)
Critical point
228.9°F (109.4°C) at 512 PSIG
Molar mass
114.04 g/mol
ODP
0
GWP (100-yr)
1 US EPA value, 40 CFR 84.64(b) IPCC: AR4 not assessed · AR5 <1 · AR6 1.37
Atmospheric lifetime
0.045 years
New-equipment status (US)
Not an AIM Act regulated substance; 40 CFR 84.54 GWP limits don't apply.

What is R-1234ze?

R-1234ze is pure 1,3,3,3-tetrafluoropropene in the E (trans) isomer configuration — a single-molecule HFO with very low GWP and a pressure envelope well-suited to centrifugal chiller compressor designs^[1].

The defining characteristic vs R-134a is the lower operating pressure. The lower pressure makes R-1234ze a better match for centrifugal chiller impeller designs operating at moderate pressure ratios.

Where R-1234ze is used

Centrifugal chillers — new equipment installations
High-temperature heat pumps — industrial process heating
Component in R-454B, R-450A, R-515A, R-515B blends
Aerosol propellant in some specialty applications
Foam blowing agent in polyurethane insulation

Regulatory & phase-down status

R-1234ze faces no phase-down pressure — under any reasonable GWP basis (1 on the US EPA basis per 40 CFR 84.64, ≈1 per AR5/AR6) the value sits below every regulatory threshold^[4].

Service notes

POE or PVE (polyvinyl ether) oil required depending on equipment OEM. Mineral oil is not compatible. The A2L safety class requires A2L-listed equipment and A2L-rated leak detection in some installations^[5].

R-1234ze operating pressures are lower than R-134a across the chiller operating range — standard 500 PSI manifold gauges have ample margin. Pure single-component refrigerant; no glide handling needed.

Operating cycle

Phase-down timeline

R-1234ze is not an AIM Act regulated substance (not one of the 18 HFCs in 42 U.S.C. 7675(c), and not a blend containing one). The 40 CFR 84.54 GWP limits don't apply.

Global warming potential, in context

Medium-pressure centrifugal & screw chillers

Retrofit and replacement paths

R-1234ze replaces

R-134a A1 · GWP 1,430

Reading the R-1234ze PT chart

R-1234ze's PT chart is a single saturation curve — R-1234ze is pure single-component HFO with no temperature glide^[1]. Service measurement uses standard single-curve procedures: superheat = suction line temp − saturation temp; subcooling = saturation temp − liquid line temp.

The pressure envelope is substantially lower than R-134a. This is the engineering reason R-1234ze is well-suited to centrifugal chiller designs but not to R-134a retrofit (the pressure delta is too large for direct refrigerant swap).

R-1234ze vs R-134a: saturation pressure

Saturation pressure (PSIG, gauge) for R-1234ze vs R-134a. Each column shows the percent difference from R-1234ze. Source: CoolProp 7.2.0 dataset.
Temp	R-1234ze	R-134a
0°F	0.8	6.5
40°F	22.2	35.0(+58%)
70°F	49.5	71.1(+44%)
100°F	89.9	124.2(+38%)

Frequently asked

›What is R-1234ze used for?

Centrifugal chillers in commercial cooling applications, and as a component in lower-GWP HFC/HFO blends (R-454B, R-450A, R-515A, R-515B). Honeywell markets the standalone refrigerant as Solstice ze^[6].

›What's the difference between R-1234yf and R-1234ze?

Both are pure HFOs with very low GWP — GWP 1 for both on the US EPA basis (40 CFR 84.64), and below 1 (R-1234yf) to about 1 (R-1234ze) under strict IPCC AR5/AR6. R-1234yf (2,3,3,3-tetrafluoropropene) is used in mobile AC with pressure envelope similar to R-134a. R-1234ze (1,3,3,3-tetrafluoropropene, E-isomer) is used in chillers with lower pressure envelope better matched to centrifugal compressor designs.

Isomer differences in molecular structure produce different pressure profiles despite similar chemical compositions.

›Is R-1234ze flammable?

Yes — ASHRAE class A2L (lower flammability with low burning velocity). A2L equipment design requirements apply per UL 60335-2-40 — A2L-listed equipment, A2L-rated leak detection in some installations, ignition-source isolation in the refrigerant circuit^[5].

›What's the GWP of R-1234ze?

The headline figure is 1 on the US EPA basis (40 CFR 84.64(b) Table 1); IPCC AR5 lists below 1^[2]. R-1234ze's ~16-day atmospheric lifetime is far below the integration window IPCC's later assessments use for a precise figure, so the underlying climate impact is essentially negligible. R-1234ze sits in the same lowest-impact tier as R-1234yf, R-290 propane, and R-744 CO₂.

›What is Solstice ze?

Honeywell's trade name for R-1234ze^[6]. Honeywell is the primary commercial manufacturer of standalone R-1234ze; the refrigerant is also used as a component in Chemours and other manufacturer blends.

›Can R-1234ze replace R-134a in chillers?