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R-22 PT Chart: Pressure-Temperature Table and Lookup

Last reviewed October 2026

R-22 PT Chart

Quick Answer

At 40 °F, R-22 is at 68.6 psig at sea level. Set your elevation in the lookup if you are well above sea level.

R-22 pressure and temperature

Elevation

Saturation temperature°F

68.6psig

R-22 at 40 °F, sea level

Gauge pressure assumes sea-level air (14.7 psia). Set your elevation if you are well above sea level: a gauge reads against the air around it.

R-22 pressure-temperature chart · GreenCalculus · greencalculus.com/data/r-22-pt-chart/

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Gauge pressure at sea level, -40 to 150 °F. Below 0 psig the reading is a vacuum, in inches of mercury.

Temp (°F)	Pressure (psig)
-40	0.6
-39	1.0
-38	1.4
-37	1.8
-36	2.2
-35	2.6
-34	3.1
-33	3.5
-32	4.0
-31	4.5
-30	4.9
-29	5.4
-28	5.9
-27	6.4
-26	6.9
-25	7.4
-24	8.0
-23	8.5
-22	9.1
-21	9.6
-20	10.2
-19	10.8
-18	11.4
-17	12.0
-16	12.6
-15	13.2
-14	13.9
-13	14.5
-12	15.2
-11	15.9
-10	16.5
-9	17.2
-8	17.9
-7	18.7
-6	19.4
-5	20.1
-4	20.9
-3	21.7
-2	22.4
-1	23.2
0	24.0
1	24.9
2	25.7
3	26.5
4	27.4
5	28.3
6	29.2
7	30.1
8	31.0
9	31.9
10	32.8
11	33.8
12	34.8
13	35.8
14	36.8
15	37.8
16	38.8
17	39.9
18	40.9
19	42.0
20	43.1
21	44.2
22	45.3
23	46.5
24	47.6
25	48.8
26	50.0
27	51.2
28	52.4
29	53.7
30	55.0
31	56.2
32	57.5
33	58.8
34	60.2
35	61.5
36	62.9
37	64.3
38	65.7
39	67.1
40	68.6
41	70.0
42	71.5
43	73.0
44	74.5
45	76.1
46	77.6
47	79.2
48	80.8
49	82.4
50	84.1
51	85.7
52	87.4
53	89.1
54	90.8
55	92.6
56	94.4
57	96.1
58	98.0
59	99.8
60	101.6
61	103.5
62	105.4
63	107.3
64	109.3
65	111.2
66	113.2
67	115.3
68	117.3
69	119.4
70	121.4
71	123.5
72	125.7
73	127.8
74	130.0
75	132.2
76	134.5
77	136.7
78	139.0
79	141.3
80	143.6
81	146.0
82	148.4
83	150.8
84	153.2
85	155.7
86	158.2
87	160.7
88	163.2
89	165.8
90	168.4
91	171.0
92	173.7
93	176.4
94	179.1
95	181.8
96	184.6
97	187.4
98	190.2
99	193.0
100	195.9
101	198.8
102	201.8
103	204.7
104	207.7
105	210.8
106	213.8
107	216.9
108	220.0
109	223.2
110	226.4
111	229.6
112	232.8
113	236.1
114	239.4
115	242.8
116	246.1
117	249.5
118	253.0
119	256.4
120	260.0
121	263.5
122	267.1
123	270.7
124	274.3
125	278.0
126	281.7
127	285.4
128	289.2
129	293.0
130	296.9
131	300.8
132	304.7
133	308.6
134	312.6
135	316.7
136	320.7
137	324.8
138	329.0
139	333.2
140	337.4
141	341.6
142	345.9
143	350.3
144	354.6
145	359.0
146	363.5
147	368.0
148	372.5
149	377.1
150	381.7

R-22 is the refrigerant in older US air-conditioners and heat pumps. This chart gives its saturation pressure at every whole degree from -40 to 150 °F, computed from the reference equation of state and checked against NIST and two manufacturer charts.

Checked

We compared every value with 4 published tables from NIST, Arkema and Daikin. They agree with this chart to within 0.08 psi at every temperature both cover. How we checked

How to read an R-22 PT chart

A pressure-temperature (PT) chart gives the pressure at which a refrigerant boils or condenses at each temperature: its saturation pressure. Where liquid and vapor are both present, as in an evaporator, a condenser or a cylinder, the pressure and the temperature are tied together, so a gauge reading tells you the temperature the refrigerant is boiling or condensing at.

The pressures are gauge pressure (psig) at sea level. Below 0 psig the refrigerant is under vacuum, and the chart shows inches of mercury instead. Switch the units above to °C, kPa or bar, and type any temperature or pressure into the lookup for a value between the rows.

Superheat and subcooling: a worked example

The lookup above does both calculations. Here is what it does, with example readings. They show the method only; they are not target pressures for any system.

Worked example

Superheat. The suction gauge reads 69 psig and the suction line is at 52 °F. On the saturation line, 69 psig is a saturation temperature of 40.3 °F. Superheat is 52 − 40.3 = 11.7 °F.

Subcooling. The liquid line gauge reads 196 psig and the liquid line is at 90 °F. On the saturation line, 196 psig is 100.0 °F. Subcooling is 100.0 − 90 = 10.0 °F.

Whether a superheat or subcooling figure is right for a system depends on that system. Compare with the manufacturer’s charging instructions.

How far off a reading can be

Superheat and subcooling are differences of a few degrees, so a small error in the pressure shows up in the answer. This table works out, from the R-22 chart itself, how far each common mistake moves the result.

Mistake	Superheat suction at 40 °F	Subcooling liquid at 100 °F
The gauge reads 1 psi off	off by 0.7 °F (0.4 °C)	off by 0.3 °F (0.2 °C)
At 5,000 ft, using a sea-level chart	reads high by 1.7 °F (1.0 °C)	reads low by 0.9 °F (0.5 °C)

Worked out from this chart. For R-22, 1 °F is about 1.5 psi at a 40 °F suction and 2.9 psi at a 100 °F liquid line. At 5,000 ft a gauge reads 2.5 psi lower than at sea level for the same refrigerant pressure. R-22 is a single compound, so it has one column and no column mix-up.

Gauge pressure and elevation

A gauge reads the difference between the refrigerant’s pressure and the air around it. Air pressure falls with height, so at the same temperature a gauge reads higher up a mountain than at sea level. At 40 °F, R-22 reads 68.6 psig at sea level and 71.0 psig at 5,000 ft, where standard air pressure is 12.23 psia.

Enter your elevation in the lookup and the whole chart, CSV and printout switch to it. The tool uses the standard atmosphere, which is what Arkema’s 5,000 ft chart uses; our values match that chart to within 0.08 psi. Weather moves air pressure too, by much less.

About R-22

**GreenCalculus** MasterBrain data version 2026.284 · 1 factor from IPCC AR6 · key refrigerants.r_22 · each resolves at verify.greencalculus.com/‹key› with its source cell.
Type	HCFC, single compound
Composition	Single compound, chlorodifluoromethane (CHClF₂)
ASHRAE 34 safety class	A1: lower toxicity, no flame propagation
GWP-100 (IPCC AR6)	1960

Boiling point at 1 atm: -41.5 °F (-40.8 °C)
Critical temperature: 205.1 °F (96.2 °C)
Critical pressure: 723.7 psia (4,990 kPa)

Boiling point and critical point are computed from the same equation of state as the chart. GWP is from our refrigerant GWP dataset; the refrigerant leakage calculator turns a leak into CO₂e.

R-22 is an ozone-depleting HCFC. Under the Clean Air Act phaseout, the US has allowed no production or import of HCFC-22 since 2020; EPA notes that some uses continue, such as servicing existing refrigeration and air-conditioning equipment (US EPA).

How we checked these numbers

Every value is computed with CoolProp 8.0.0 from the reference equation of state for R-22 (Kamei, Beyerlein and Jacobsen (1995), International Journal of Thermophysics 16(5)), as absolute pressure, then converted to gauge. Before publishing, we compared it with every independent table we could find:

Published table	Largest gap	Points compared	Range
NIST Chemistry WebBook, saturation properties (SRD 69)	0.00 psi at 147 °F	190	-40 to 150 °F
Arkema, Forane refrigerant pressure-temperature chart, PPC/SDC 05-2025 (NIST REFPROP 10)	0.05 psi at 65 °F	39	-40 to 150 °F
Daikin Comfort Technologies, A1 vs. A2L Pressure Temperature Chart, USA, PM-A2LPTC-USA 04-24 (values from Weitron)	0.05 psi at 6 °F	80	-38 to 150 °F
Arkema, Forane pressure-temperature chart, high elevation (5,000 ft) (NIST REFPROP 9) (at 5,000 ft)	0.08 psi at -20 °F	39	-40 to 150 °F

Gauge pressure at 5,000 ft: our absolute pressure less standard-atmosphere air pressure there (12.23 psia).

Checked 28 Oct 2026. A chart printed to one decimal place rounds by up to 0.05 psi.

The °C table is computed at whole degrees Celsius, not converted from the °F rows, and the two agree to within 0.01 psi.

Questions about the R-22 PT chart

What is the pressure of R-22 at 40 °F?

At sea level, R-22 is at 68.6 psig at 40 °F. At 5,000 ft the same refrigerant reads 71.0 psig, because the gauge reads against thinner air.

What should my R-22 pressure be?

The chart gives the saturation pressure at each temperature, not an operating target. Running pressures depend on the system, the load, the airflow and the charge. Compare with the manufacturer’s charging instructions, and use the chart to turn a gauge reading into a saturation temperature for superheat or subcooling.

What does R-22 read when the system is off?

When a system has been off long enough to even out, any part holding both liquid and vapor sits at the saturation pressure for its temperature. At 70 °F that is 121.4 psig for R-22 at sea level. It shows refrigerant is present, not how much.

Does elevation change the R-22 reading?

Yes. A gauge reads against the air around it, and air pressure falls with height. At 5,000 ft the standard atmosphere is 12.23 psia instead of 14.70, so every gauge reading is about 2.5 psi higher than at sea level for the same refrigerant temperature. Set your elevation in the lookup to correct the whole chart.

Can you still buy R-22?

The US has allowed no production or import of HCFC-22 (R-22) since 2020 under the Clean Air Act phaseout. EPA notes that some uses continue, such as servicing existing equipment, so the R-22 still in circulation is refrigerant already made.

Other refrigerants

Pressures are gauge at sea level; for blends, liquid (bubble) / vapor (dew). Safety classes are ASHRAE 34.

Version history

1.1.1 (29 October 2026): sources moved into a compact card at the end of the page, so they no longer break up the reading.
1.1 (28 October 2026): new section on how far off a reading can be, worked out for this refrigerant, and a note on how closely the published charts agree.
1.0.1 (28 October 2026): other refrigerants shown as cards, with each gas’s use, pressure at 40 °F, type and safety class.
1.0 (28 October 2026): first published.

Provenance

MasterBrain v2026.284

The factor this page used

Read from MasterBrain when this page was built. Each row names the published document and the cell the number came from, so you can check it against the original.

refrigerants.r_221,960kg CO₂e per kg leakedIPCC AR6 IPCC AR6 WGI Ch 7 Table 7.SM.7 (HCFC-22 GWP-100)AR6-100 · retrieved 17 May 2026

See every source and its licence

Cite this page

APA

GreenCalculus. (2026). R-22 PT Chart: Pressure-Temperature Table and Lookup. MasterBrain data edition v2026.284 (6 Nov 2026). https://greencalculus.com/data/r-22-pt-chart/

BibTeX

@misc{greencalculus_r_22_pt_chart_2026,
  author       = {{GreenCalculus}},
  title        = {R-22 PT Chart: Pressure-Temperature Table and Lookup},
  year         = {2026},
  organization = {GreenCalculus},
  publisher    = {Numbers Publishing Pte. Ltd.},
  note         = {MasterBrain data edition v2026.284 (6 Nov 2026)},
  url          = {https://greencalculus.com/data/r-22-pt-chart/}
}

Drawn from 21,133 factors across 294 source documents · edition v2026.284, updated 6 Nov 2026 · every source and its licence

R-22 PT Chart

How to read an R-22 PT chart

Superheat and subcooling: a worked example

How far off a reading can be

Gauge pressure and elevation

About R-22

How we checked these numbers

Questions about the R-22 PT chart

Other refrigerants

Version history

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