R-22 PT Chart: Saturation Pressure from −40°F to 150°F

Put in the pressure from your gauge, or walk it up and down with the buttons and the slider, and the lookup returns the temperature at which R-22 saturates. There's no glide on R-22, so the same saturation temperature is used for superheat and for subcooling. Choose Temperature under I have a to read the chart from the other side; a temperature that lands between two rows shows the rows on either side. If you'd like Celsius and kilopascals too, tick Also show °C and kPa. Every degree from −40°F to 150°F is listed in the chart below the lookup.

Worked example: R-22 at 75°F and at 70 psig

Show the math

At the default of 75°F there's nothing to work out, since the table has a 75°F row. R-22's saturation pressure there is 132.22 psig.

The default pressure, 70 psig, needs one small step. The 40°F row reads 68.56 psig and the 41°F row reads 70.02 psig. Seventy is 1.44 psi past the first of those, out of 1.46 psi between them, so it's about 0.99 of the way to 41°F. The exact figure is 40.99°F, and rounded to a tenth the tool reports 41.0°F.

R-22 has one saturation curve, because it's a single-component refrigerant. The bubble and dew pressures in CoolProp's data are identical on every row, so the table needs just one pressure column. Its lowest row is still above atmospheric: at −40°F R-22 reads 0.57 psig, so unlike R-134a this chart has no vacuum cells.

R-22 and Section 608 leak repair

The federal leak-repair requirements under Section 608 sit in 40 CFR 82.157. Paragraph (a) sets their reach: "As of April 10, 2020, this section applies only to appliances with a full charge of 50 or more pounds of any class I or class II refrigerant or blend containing a class I or class II refrigerant." The same paragraph goes on to say that "the requirements of this section do not apply to appliances containing solely substitute refrigerants."

R-22 is HCFC-22, an ozone-depleting refrigerant rather than a substitute: Appendix B to Subpart A of Part 82 lists it as a class II controlled substance, with an ozone depletion potential of 0.055. So an appliance holding 50 pounds or more of it is still covered by 82.157. An R-22 appliance below 50 pounds is outside that section.

For covered appliances, the section sets leak-rate limits by type of equipment: 10 percent for comfort cooling and other appliances it doesn't list separately, 20 percent for commercial refrigeration and 30 percent for industrial process refrigeration. Once refrigerant is added to an appliance leaking faster than its limit, the owner or operator generally has 30 days to find and repair the leaks, or 120 days where an industrial process shutdown is needed. The rule's text covers the exceptions and records.

Equipment that runs only on HFCs isn't under 82.157. EPA handles HFC leaks through a separate 2024 rule, the Emissions Reduction and Reclamation rule at 40 CFR Part 84, subpart C. That rule reaches appliances holding 15 pounds or more of a refrigerant containing an HFC, or a substitute for an HFC with a GWP above 53. Compliance runs from January 1, 2026, and the rule excludes residential and light commercial air conditioning and heat pumps.

If you are studying for Section 608 certification, both leak-repair rules come up again in the Type II practice test.

Using the chart for superheat and subcooling

R-22's single curve means a suction pressure and a liquid pressure are converted with identical data. The superheat and subcooling calculator covers R-22 and does both subtractions for you. It gives no target: the equipment manufacturer's charging instructions supply those.

How this chart was made

Every row is a saturation point that CoolProp 8.0.0 computed at a whole degree. The chart shows gauge pressure, meaning CoolProp's absolute figure less 14.696 psi for a standard sea-level atmosphere.

The rows were then compared with Hudson Technologies' R-22 distributor chart at seven temperatures spread from −40°F to 150°F. At every one of those points the two charts sit within 1% of each other as a share of absolute pressure, and the widest gap was 0.44 psi, at 70°F. The methodology page describes how the charts are checked.

When a pressure lands between rows, the lookup interpolates on a straight line and rounds to 0.1°F. It doesn't guess beyond the first or last row.