N°001Free field tool

Refrigerant P-T Chart & Calculator

A free ammonia P-T chart and pressure-temperature calculator built for field technicians. Look up R-717 pressure-temperature relationships in PSIG and °F — then do the same for transcritical CO2 (R-744), legacy R-404A, and low-GWP R-454B. It works both directions: temperature to saturation pressure, and gauge pressure back to saturation temperature, interpolated between table points exactly like the RefriTech Pro app does offline.

Free — no signupPSIG / °F4 refrigerantsSame tables as the app

N°002Two-way lookup

Calculate

Refrigerant

Temperature (°F)

Valid range: -60°F to 120°F

Saturation pressure — R-717

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N°003Quick reference

Charts

Full saturation pressure-temperature charts for all four refrigerants — temperatures in °F, pressures in psig (values below 0 psig indicate a vacuum). Ammonia-first, from ASHRAE/IIAR-style saturation data: the exact tables bundled offline in the RefriTech Pro app.

R-717 — Ammonia (NH3)

The industrial baseline. Saturation data from -60°F to 120°F, including the -28°F atmospheric boiling point at 0 psig. Values below 0 psig are a vacuum.

Saturation pressure-temperature chart for R-717, temperature in degrees Fahrenheit, pressure in psig
Temp (°F)	Pressure (psig)
-60	-9.2
-55	-8.2
-50	-7.0
-45	-5.7
-40	-4.3
-35	-2.6
-30	-0.8
-28	0.0
-25	1.3
-20	3.6
-15	6.2
-10	9.0
-5	12.2
0	15.7
5	19.6
10	23.8
15	28.4
20	33.5
25	39.0
30	45.0
35	51.6
40	58.6
45	66.3
50	74.5
55	83.4
60	92.9
65	103.1
70	114.1
75	125.8
80	138.3
85	151.7
90	165.9
95	181.1
100	197.2
105	214.3
110	232.3
115	251.5
120	271.7

R-744 — Carbon Dioxide (CO2)

Transcritical and cascade systems run very high pressures. Data covers -60°F to 85°F as R-744 approaches its critical point at 87.8°F.

Saturation pressure-temperature chart for R-744, temperature in degrees Fahrenheit, pressure in psig
Temp (°F)	Pressure (psig)
-60	68.5
-55	80.4
-50	93.6
-45	108.2
-40	124.3
-35	141.9
-30	161.2
-25	182.3
-20	205.2
-15	230.1
-10	257.1
-5	286.3
0	317.8
5	351.9
10	388.6
15	428.2
20	470.8
25	516.6
30	565.8
35	618.8
40	675.8
45	737.3
50	803.5
55	875.0
60	952.3
65	996.0
70	1017.0
75	1035.0
80	1050.0
85	1060.0

R-404A — HFC Blend

Legacy HFC blend (R-125/143a/134a) being phased down under the Kigali Amendment. Saturation data from -60°F to 120°F.

Saturation pressure-temperature chart for R-404A, temperature in degrees Fahrenheit, pressure in psig
Temp (°F)	Pressure (psig)
-60	-4.6
-55	-2.0
-50	1.0
-45	4.3
-40	8.0
-35	12.2
-30	16.8
-25	21.9
-20	27.6
-15	33.9
-10	40.8
-5	48.4
0	56.7
5	65.8
10	75.7
15	86.5
20	98.2
25	110.8
30	124.5
35	139.2
40	155.0
45	172.0
50	190.2
55	209.7
60	230.5
65	252.8
70	276.6
75	302.0
80	329.0
85	357.8
90	388.5
95	421.0
100	456.0
105	493.0
110	532.0
115	574.0
120	618.0

R-454B — Opteon XL41

Low-GWP HFO replacement for R-404A. Mildly flammable (A2L) — verify component compatibility. Saturation data from -60°F to 120°F.

Saturation pressure-temperature chart for R-454B, temperature in degrees Fahrenheit, pressure in psig
Temp (°F)	Pressure (psig)
-60	-6.8
-55	-4.2
-50	-1.3
-45	1.9
-40	5.5
-35	9.5
-30	13.9
-25	18.9
-20	24.3
-15	30.3
-10	37.0
-5	44.2
0	52.2
5	60.8
10	70.2
15	80.4
20	91.4
25	103.4
30	116.2
35	130.0
40	144.8
45	160.6
50	177.6
55	195.8
60	215.2
65	236.0
70	258.2
75	281.8
80	307.0
85	333.8
90	362.4
95	392.8
100	425.2
105	459.6
110	496.2
115	535.0
120	576.2

N°004P-T in the field

How

Superheat

Convert suction pressure to saturation temperature, then subtract it from the measured suction-line temperature. The difference is superheat — proof the evaporator is feeding correctly.

Subcooling

Convert liquid-line pressure to saturation temperature and subtract the measured liquid-line temperature. Healthy subcooling means the condenser and liquid feed are doing their jobs.

Charging & gauge checks

Set head-pressure targets, sanity-check transducers against a calibrated gauge, and confirm relief and defrost setpoints from the same saturation data — no laminated card required.

N°005Take it into the engine room

Offline

This calculator ships offline in the RefriTech Pro app — beside 16 diagnostic systems, 280 symptoms, and 1,791 probability-ranked causes.

Superheat and subcooling calculators, multi-equipment checklists, PDF service reports, and relief-valve tracking — built ammonia-first for industrial refrigeration, and built to keep working in a freezer with zero bars.

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