Refrigerant pressure-temperature chart
Pick a refrigerant, then type a temperature or a gauge pressure: the tool gives the saturation point and the full chart, corrected for your elevation. Covers the refrigerants you meet on residential and light-commercial jobs.
Saturation pressure at a glance (psig, sea level)
| Refrigerant | 20 °F | 40 °F | 45 °F | 100 °F | 105 °F | 120 °F |
|---|---|---|---|---|---|---|
| R-410A | 78.4 | 118.4 | 130.1 | 318.5 | 341.9 | 419.4 |
| R-454B | 70.3 | 107.0 | 117.8 | 300.8 | 322.8 | 395.7 |
| R-32 | 80.0 | 121.0 | 133.0 | 325.7 | 349.6 | 429.3 |
| R-22 | 43.1 | 68.6 | 76.1 | 195.9 | 210.8 | 260.0 |
| R-134a | 18.4 | 35.0 | 40.1 | 124.2 | 135.0 | 171.2 |
For blends (R-410A, R-454B) the low temperatures show the vapor (dew) value and the high temperatures the liquid (bubble) value, the ones you would use for superheat and subcooling. Each refrigerant's page has the full chart.
How to read a PT chart
A pressure-temperature chart gives the saturation temperature: the temperature at which the refrigerant boils or condenses at a given pressure. Inside the evaporator and condenser, where liquid and vapor are both present, pressure and temperature are locked together, so one gauge reading tells you the other.
- Find your pressure on the chart (or type it into the tool) and read the saturation temperature next to it.
- Superheat = suction line temperature − saturation temperature at suction pressure. Use the superheat calculator.
- Subcooling = saturation temperature at liquid line pressure − liquid line temperature. Use the subcooling calculator.
- Gauges read psig, pressure above the air around you. Charts are built for sea level (14.696 psi). At 5,000 ft your gauge reads about 2.5 psi high against the chart; enter your elevation in the tool and it corrects for it.
Working on refrigerant circuits?
Opening the refrigerant circuit on stationary equipment using the refrigerants on this page requires EPA Section 608 certification, and suppliers can only sell you most refrigerants if you have it. See how to get EPA 608 certified or take the free EPA 608 practice tests.
Where the numbers come from
R-22, R-32 and R-134a: NIST Chemistry WebBook. R-410A: Arkema Forane 410A tables (NIST REFPROP 9.0). R-454B: Chemours Opteon XL41 tables (NIST REFPROP 10). Converted to gauge pressure at sea level. The equipment manufacturer's charging chart and data plate govern.
FAQ
What is a PT chart used for?
To convert a gauge pressure into the refrigerant's saturation temperature, or the other way round. That saturation temperature is what you subtract from or compare with line temperatures to get superheat and subcooling.
Why are there two pressure columns for some refrigerants?
Blends like R-454B have temperature glide: at the same pressure the liquid starts boiling a little colder than the vapor finishes condensing. Use the vapor (dew) column for superheat and the liquid (bubble) column for subcooling.
Why don't my gauges match the chart?
Check elevation first: gauges read relative to local air pressure, so at altitude they read high against a sea-level chart. Then check that the refrigerant is what the data plate says, and that air or non-condensables aren't in the system.
Is this tool free?
Yes. No account, no email, no download. It runs in your browser and works on your phone at the unit.