# Refrigerant PT Charts (Pressure-Temperature)

A refrigerant PT chart lists the pressure at which a refrigerant boils or condenses at each temperature. Techs use it to turn gauge pressures into saturation temperatures for superheat and subcooling. Pure refrigerants like R-32 and R-22 have one column; blends like R-454B have bubble (liquid) and dew (vapor) columns. Each refrigerant needs its own chart.

## Key takeaways

- At 100°F the four refrigerants rank R-32 > R-410A > R-454B > R-22 by pressure. Using the wrong chart gives a believable but wrong answer.
- Dew (vapor) column for superheat, bubble (liquid) column for subcooling. On pure refrigerants they're the same number.
- Charts are in psig at sea level. At 5,000 ft the atmosphere is about 12.2 psia, so your gauge reads about 2.5 psi high against the chart.
- A PT chart gives saturation conditions, not a target charge. The equipment manufacturer's charging chart decides that.
- Every table here is computed with CoolProp 8.0.0 and tested against published Daikin and Arkema charts.

## PT charts for each refrigerant

**Four common HVAC refrigerants side by side (pressures in psig at sea level, from our CoolProp tables)**

| Refrigerant | Type | ASHRAE class | GWP (EPA SNAP) | 40°F (dew) | 100°F (bubble) | Glide | U.S. status (Oct 2026) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| [R-410A](https://www.brix.so/reference/refrigerant-pt-chart/r-410a) | Blend, R-32/R-125 50/50 (near-azeotropic) | A1 | 2,090 | 118.4 | 318.5 | 0.2°F | HFC phasedown; new systems only from pre-2025 components |
| [R-454B](https://www.brix.so/reference/refrigerant-pt-chart/r-454b) | Blend, R-32/R-1234yf 68.9/31.1 (zeotropic) | A2L | 470 | 107.5 | 303.3 | 2.7°F | Acceptable with use conditions for new AC/heat pumps |
| [R-32](https://www.brix.so/reference/refrigerant-pt-chart/r-32) | Pure (single component) | A2L | 675 | 121.0 | 325.7 | 0 | Acceptable with use conditions for new AC/heat pumps |
| [R-22](https://www.brix.so/reference/refrigerant-pt-chart/r-22) | Pure HCFC (single component) | A1 | Ozone-depleting HCFC | 68.6 | 195.9 | 0 | Production and import ended Jan 1, 2020; service with reclaimed |

_GWP values from [EPA SNAP's residential AC and heat pump listing](https://www.epa.gov/snap/substitutes-residential-and-light-commercial-air-conditioning-and-heat-pumps). R-22 is a class II ozone-depleting substance regulated under the HCFC phaseout ([EPA](https://www.epa.gov/ods-phaseout/phaseout-class-ii-ozone-depleting-substances)) rather than listed as a substitute. Glide is at a typical suction pressure. R-410A status: see [our post on the 2026 deadline change](https://www.brix.so/news/epa-r-410a-installation-deadline-change)._

### Open a chart

- [R-410A PT chart](https://www.brix.so/reference/refrigerant-pt-chart/r-410a): Near-azeotropic blend, both columns, 2026 phasedown status.
- [R-454B PT chart](https://www.brix.so/reference/refrigerant-pt-chart/r-454b): A2L blend with about 2.5–2.7°F glide.
- [R-32 PT chart](https://www.brix.so/reference/refrigerant-pt-chart/r-32): Pure A2L refrigerant, one column.
- [R-22 PT chart](https://www.brix.so/reference/refrigerant-pt-chart/r-22): Legacy HCFC, production ended 2020.

## How do you read a refrigerant PT chart?

Pick the chart for the refrigerant on the nameplate, then go from what you know to what you need. If you have a gauge pressure, find it in the pressure column and read the saturation temperature on that row. If you have a temperature, find its row and read the pressure. Between rows, interpolate, or use the [refrigerant PT calculator](https://www.brix.so/tools/refrigerant-pt-calculator), which does it for you.

1. **Confirm the refrigerant.** Read the nameplate. R-410A, R-32 and R-454B equipment can look alike, and their charts are not interchangeable.
2. **Choose the column.** On a blend, use dew (vapor) for anything on the suction side and bubble (liquid) for the liquid line. On R-32 or R-22 there's one column.
3. **Convert the pressure.** Read the saturation temperature at your gauge pressure. Correct for altitude first if you're well above sea level.
4. **Compare with the pipe.** Suction line temperature minus the dew point is superheat. Bubble point minus liquid line temperature is subcooling.
5. **Judge against the target.** The target comes from the unit's charging chart or installation instructions, not from the PT chart.

## Bubble point, dew point and glide

A single-component refrigerant boils at one temperature for each pressure. A blend of refrigerants with different boiling points doesn't: it starts boiling at the bubble point and finishes at the dew point, a little warmer. That spread is temperature glide. R-454B has about 2.7°F of it at typical suction pressure, enough to throw superheat off by that much if you read the wrong column. R-410A has about 0.2°F, which is why older R-410A charts printed a single column.

## Do PT charts change with altitude?

The physics doesn't change, but your gauge does. PT charts are printed in psig relative to a sea-level atmosphere of 14.696 psia. A gauge zeroed at altitude reads relative to thinner air, so for the same saturation temperature it shows a higher number. Using [NASA's standard-atmosphere model](https://www.grc.nasa.gov/www/k-12/airplane/atmos.html), the air is about 12.2 psia at 5,000 ft and 10.9 psia at 8,000 ft.

> **Altitude correction, worked (illustrative reading)**
>
> An R-410A suction gauge reads 118 psig. At sea level that's a dew point of 39.8°F.
>
> At 5,000 ft, subtract the 2.5 psi difference first: 118 − 2.5 = 115.5 psig on the chart, a dew point of **38.7°F**.
>
> Skipping the correction overstates saturation temperature by 1.1°F, so superheat comes out about a degree low. Near sea level it doesn't matter; in Denver it starts to.

## What a PT chart can't tell you

- **Whether the charge is right.** Pressure alone moves with indoor load and outdoor temperature. You need the line temperature too, and the manufacturer's target.
- **Which refrigerant is in the system.** A system topped off with the wrong refrigerant, or a mix, won't follow any chart. Recover it and recharge with the nameplate refrigerant.
- **Normal operating pressures.** A chart gives saturation pressure at a temperature. What a healthy system runs at depends on its design, airflow and conditions.
- **Whether it's safe to retrofit.** That's an EPA listing and manufacturer question, covered on the [R-22 page](https://www.brix.so/reference/refrigerant-pt-chart/r-22).

> **Verify against the manufacturer's installation instructions**
>
> These charts are references for saturation pressure. Charging targets for a specific unit come from its installation instructions and charging chart, which take precedence over any generic table.

## How we build and check these charts

We don't copy manufacturer charts. Each table is computed from published equations of state with [CoolProp](https://coolprop.org) 8.0.0, the open-source property library, from −40°F to 150°F in 5°F steps, and stored with the library version and date. Blends are modeled at their ASHRAE 34 compositions. An automated test suite then checks 20 temperatures per refrigerant against the [Daikin A1 vs. A2L chart](https://www.chadwellsupply.com/globalassets/articles-pk/a2l/a2lptc-usa_04-24.pdf), plus the [Arkema R-454B chart](https://forane.arkema.com/files/live/sites/shared_arkema/files/downloads/fluorochemicals/Forane%20Ref%20PT%20Regular%20Chart%20EN) and the [Arkema wall chart](https://forane.arkema.com/files/live/sites/fluorogases_forane_arkema/files/downloads/literature/general-forane-literature/forane-wall-chart-americas.pdf). R-22, R-32 and R-410A agree within 0.1 psi. R-454B agrees with Daikin within 1.4 psi and with Arkema within 1.5%, a smaller spread than the up-to-3-psi gap between those two manufacturers' own R-454B charts.

### Tools that use these tables

- [Refrigerant PT calculator](https://www.brix.so/tools/refrigerant-pt-calculator): Pressure ↔ temperature with an altitude correction.
- [Superheat calculator](https://www.brix.so/tools/superheat-calculator): Suction pressure and line temperature to superheat.
- [Subcooling calculator](https://www.brix.so/tools/subcooling-calculator): Liquid pressure and line temperature to subcooling.
- [Superheat and subcooling lesson](https://www.brix.so/academy/hvac/refrigeration/superheat-subcooling): The method, with worked examples.

## Frequently asked questions

### What is a PT chart used for in HVAC?

It converts between pressure and saturation temperature for a specific refrigerant. Techs use it to find the evaporator and condenser saturation temperatures from gauge readings, which they need to calculate superheat and subcooling and judge the charge.

### Why do some PT charts have two columns?

Blends like R-454B and R-410A boil over a small temperature range, so each temperature has a bubble (liquid) pressure and a dew (vapor) pressure. Use dew for superheat and bubble for subcooling. Single-component refrigerants like R-32 and R-22 need only one column.

### Which refrigerant has the highest pressure?

Of these four, at 100°F: R-32, then R-410A, then R-454B, then R-22. R-32 is 325.7 psig and R-22 is 195.9 psig at that temperature. Tools and gauges must be rated for the refrigerant you're working on.

### Can I use an R-410A chart for R-454B?

No. R-454B runs lower pressure than R-410A, 107.5 vs 118.4 psig dew at 40°F, and it has more glide. Using the R-410A chart on an R-454B system misreads saturation temperature by several degrees.

### Are PT charts in psig or psia?

Field PT charts, including these, are in psig: gauge pressure relative to a sea-level atmosphere of 14.696 psia. Add 14.696 for absolute pressure. At altitude, subtract the difference between 14.696 and local air pressure from your gauge reading before using the chart.

### Why don't two PT charts match exactly?

Different charts use different property models and rounding, especially for blends. For R-22, R-32 and R-410A published charts agree within a tenth of a psi; for R-454B, Daikin's and Arkema's charts differ by up to about 3 psi near 100°F. When they disagree, follow the equipment manufacturer.

## Related

- [R-410A PT Chart (Pressure-Temperature)](https://www.brix.so/reference/refrigerant-pt-chart/r-410a)
- [R-454B PT Chart (Pressure-Temperature)](https://www.brix.so/reference/refrigerant-pt-chart/r-454b)
- [R-32 PT Chart (Pressure-Temperature)](https://www.brix.so/reference/refrigerant-pt-chart/r-32)
- [R-22 PT Chart (Pressure-Temperature)](https://www.brix.so/reference/refrigerant-pt-chart/r-22)
- [Refrigerant PT Calculator (Pressure ↔ Temperature)](https://www.brix.so/tools/refrigerant-pt-calculator)
- [Superheat Calculator](https://www.brix.so/tools/superheat-calculator)
- [Subcooling Calculator](https://www.brix.so/tools/subcooling-calculator)
- [Superheat and Subcooling, Explained with Worked Examples](https://www.brix.so/academy/hvac/refrigeration/superheat-subcooling)
- [EPA Removes the January 1, 2026 R-410A Installation Deadline: What Contractors Need to Know](https://www.brix.so/news/epa-r-410a-installation-deadline-change)
- [HVAC Software That Answers the Phone, Books the Tech and Keeps the Books](https://www.brix.so/for/hvac)

## Sources

- [CoolProp 8.0.0: thermophysical property library (HEOS backend), used to compute every table](https://coolprop.org/coolprop/HighLevelAPI.html) (checked 2026-10-24)
- [Daikin Comfort Technologies: A1 vs. A2L Pressure Temperature Chart, USA (PM-A2LPTC-USA_04-24)](https://www.chadwellsupply.com/globalassets/articles-pk/a2l/a2lptc-usa_04-24.pdf) (checked 2026-10-24)
- [Arkema Forane: Pressure Temperature Chart, R-454B (PPC/SDC 05-2025)](https://forane.arkema.com/files/live/sites/shared_arkema/files/downloads/fluorochemicals/Forane%20Ref%20PT%20Regular%20Chart%20EN) (checked 2026-10-24)
- [Arkema Forane: refrigerant pressure-temperature wall chart, Americas (2019, NIST REFPROP 9.0)](https://forane.arkema.com/files/live/sites/fluorogases_forane_arkema/files/downloads/literature/general-forane-literature/forane-wall-chart-americas.pdf) (checked 2026-10-24)
- [U.S. EPA SNAP: Substitutes in residential and light commercial AC and heat pumps (GWP values)](https://www.epa.gov/snap/substitutes-residential-and-light-commercial-air-conditioning-and-heat-pumps) (checked 2026-10-24)
- [U.S. EPA: Phaseout of Class II Ozone-Depleting Substances (HCFC-22)](https://www.epa.gov/ods-phaseout/phaseout-class-ii-ozone-depleting-substances) (checked 2026-10-24)
- [NASA Glenn Research Center: Earth Atmosphere Model (troposphere pressure curve fit)](https://www.grc.nasa.gov/www/k-12/airplane/atmos.html) (checked 2026-10-24)

Last verified against [CoolProp 8.0.0, cross-checked against the Daikin A1 vs. A2L PT chart (04-24) and Arkema Forane charts (2019, 05-2025)](https://www.chadwellsupply.com/globalassets/articles-pk/a2l/a2lptc-usa_04-24.pdf) on 2026-10-24.

Talk to BRIX: call or text (518) 588-1122, email eeharris2004@gmail.com, or book a 15-minute call at https://cal.com/ethanharris/15min.

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Written by BRIX Editorial Team. Last updated 2026-10-24.
Canonical: https://www.brix.so/reference/refrigerant-pt-chart