Refrigerant PT Comparison Tool
Pick 2-4 refrigerants from the dataset; the tool overlays their saturation curves on one chart. Glide visible for zeotropic blends. Useful for retrofit feasibility, new-equipment specification, and commercial low-GWP transition planning.
Updated October 26, 2026
| Temp (°F) | R-22 | R-410A | R-32 | R-454B |
|---|---|---|---|---|
| −20 | 10.2 | 26.3 | 26.8 | 24.3 / 22.6 |
| 0 | 24.0 | 48.4 | 49.3 | 45.3 / 42.7 |
| 20 | 43.1 | 78.7 | 80.0 | 73.9 / 70.3 |
| 40 | 68.6 | 118.8 | 121.0 | 112.0 / 107.0 |
| 45 | 76.1 | 130.6 | 133.0 | 123.1 / 117.8 |
| 95 | 181.8 | 296.4 | 302.9 | 279.9 / 270.4 |
| 100 | 195.9 | 318.5 | 325.7 | 300.8 / 290.9 |
| 110 | 226.4 | 366.4 | 374.9 | 345.9 / 335.2 |
| 120 | 260.0 | 419.4 | 429.3 | 395.7 / 384.3 |
Solid line = bubble curve, dashed line = dew curve (zeotropic blends only). Charts of refrigerants with very different pressure ranges (e.g. R-744 vs anything else) compress the lower-pressure curves on the linear axis.
What the PT comparison chart actually shows
Each curve on the overlay chart represents one refrigerant's saturation pressure plotted against saturation temperature. At any temperature on the x-axis, you can read off the pressure at which that refrigerant's liquid and vapor coexist in equilibrium. Comparing two curves at the same temperature shows the pressure delta between the refrigerants.
For pure refrigerants and azeotropes (single saturation temperature per pressure), each is a single solid curve. For zeotropic blends, two curves: the bubble line (solid) where the first vapor forms when heating the liquid, and the dew line (dashed) where the last liquid disappears when condensing the vapor. The vertical distance between bubble and dew at any pressure is the glide.
Common comparison presets — what each one reveals
| Use case | Refrigerants to overlay | What to look for |
|---|---|---|
| Residential AC phase-down | R-22 · R-410A · R-32 · R-454B | Pressure envelope trajectory across HCFC → HFC → A2L |
| R-22 retrofit candidates | R-22 · R-407C · R-422D | Which retrofit matches R-22 envelope; dew vs bubble for zeotropes |
| Commercial LT low-GWP | R-404A · R-449A · R-454C | AIM Act compliance path; capacity match at low-temp evap |
| Mobile AC transition | R-134a · R-1234yf | SAE J639 / EU MAC Directive compatibility |
| Chiller refrigerants | R-134a · R-513A · R-1234ze(E) | Centrifugal chiller R-134a replacement options |
| High vs low pressure | R-744 · R-410A · R-22 · R-134a | CO₂ trans-critical envelope vs traditional HFC range |
Reading the chart for retrofit feasibility
A successful refrigerant retrofit requires the candidate's pressure envelope to fall within the equipment's design pressure ratings across the full operating range. The PT overlay reveals this at a glance.
What PT comparison alone does NOT tell you
The pressure-envelope match shown by the PT overlay is necessary but not sufficient for retrofit decisions. Other factors that the chart does not show must be evaluated separately:
- Lubricant compatibility. R-22 systems use mineral oil; HFC replacements (R-407C, R-410A) require POE. HFC blends with a small hydrocarbon component (R-422D, R-438A) include it specifically to retain mineral-oil compatibility. The PT chart cannot show this.
- Safety classification. A1 (non-flammable, low-toxicity) vs A2L (lower flammability) vs A3 (flammable) vs B (toxic) shift charge limits, refrigerant detection where the standard requires it, and installation procedures. R-32 / R-454B are A2L; R-410A is A1. Same pressure envelope, different safety regime.
- GWP. On the IPCC AR4 basis the dataset carries R-22 at 1,810, R-407C at 1,774 and R-410A at 2,088 (AR4) — retrofitting R-22 to R-407C gives almost no climate benefit. R-454C sits at 146 (AR5; its HFO constituent has no AR4 value), a substantial reduction. The PT chart shows pressure, not climate impact.
- Capacity. Pressure envelope match does not guarantee capacity match — equipment sizing matters.
- Component pressure ratings. Beyond the refrigerant pressure envelope, the system's line set, valves, accumulator, receiver, and compressor have their own pressure ratings. Equipment originally certified for R-22 cannot be retrofitted to R-410A or R-744 without re-rating.
When to use this calculator vs the others
- PT Comparison Tool (this page) — quick visual envelope check across 2-4 refrigerants. Best for preliminary retrofit screening, new-equipment specification, and education.
- Retrofit Compatibility — structured pair-comparison covering pressure, lubricant, safety class, glide, GWP, application fit. Use after PT screening to evaluate full feasibility.
- PT Calculator — single-refrigerant lookup, either direction. Use for specific point calculations after deciding on a refrigerant.
- Refrigerant Comparison Guide — long-form sourced reference for all common HVAC refrigerant comparisons.
- Per-refrigerant detail pages — every refrigerant in the dataset has its own page with full PT chart, properties, lubricant, safety classification, and replacement options.
Primary sources
- CoolProp 7.2.0 (Bell, Wronski, Quoilin, Lemort 2014, doi:10.1021/ie4033999) — REFPROP-compatible Helmholtz EOS for all saturation pressures.
- CoolProp 8.0.0 — same Helmholtz EOS engine, newer release, for lower-GWP fluids CoolProp 7.2.0 did not yet ship (R-450A, R-515A, R-515B, R-1224yd(Z), and the pure HFO R-1336mzz(Z)).
- ASHRAE Standard 34-2022 — refrigerant designation, safety classification, composition.
- Manufacturer technical datasheets— Chemours and Honeywell PT charts for the two R-404A retrofit blends CoolProp does not model (R-438A, R-448A), and Chemours’ Opteon XP30 charts for R-514A.
- AIM Act (40 CFR Part 84) — phase-down schedule for high-GWP refrigerants driving retrofit and new-equipment decisions.
- SAE J639 / J2912 — mobile AC service procedures for R-134a and R-1234yf.
- EU F-Gas Regulation (517/2014, 2024/573) — European phase-down driving similar refrigerant transitions globally.
How to read your results
- Bubble curve (solid line)
- Each solid line is one refrigerant's saturated-liquid pressure at the temperature on the x-axis. Read it at your evaporator and condenser saturation temperatures to see the pressure that refrigerant runs, and use the bubble curve as the reference for subcooling.
- Dew curve (dashed line)
- Drawn only for zeotropic blends, the dashed line is the saturated-vapor pressure where the last liquid flashes to vapor. Use it as the reference for superheat on blends; pure refrigerants and azeotropes show no dashed line because their bubble and dew curves coincide.
- Temperature glide (gap between a blend's two curves)
- The separation between a blend's solid and dashed lines is its temperature glide, the spread across the phase change at a given pressure. A wide gap (R-407C, R-454C) means saturation temperature is not a single value, so TXV sensing, superheat, and subcooling must reference the correct curve; a negligible gap means the blend behaves like a pure refrigerant.
- Pressure delta between refrigerants (vertical distance between curves)
- The vertical gap between any two curves at the same temperature is the pressure difference between those refrigerants at that operating point. A small delta (roughly within 20%) signals a comparable operating envelope suited to retrofit; a large delta means different component pressure ratings, charge, and possibly equipment redesign.
- Color-coded series legend
- The legend maps each color to a selected refrigerant and flags zeotropic blends as bubble / dew so you know which series carry a second dashed curve. Use it to keep series straight where curves cross or bunch together.
- Temperature and pressure axes (unit toggles)
- The x-axis is saturation temperature and the y-axis is saturation gauge pressure, switchable between °F/PSIG and °C/kPa. Overlaying refrigerants with very different envelopes (e.g. R-744 vs an HFC) makes the linear y-axis compress the low-pressure curves toward zero — the values stay correct, but split those into separate comparisons for readability.
How to use this calculator
- Tool starts with R-22, R-410A, R-32, and R-454B — the residential AC phase-down trajectory.
- Swap any refrigerant from the dropdowns. Add up to 4 series, or remove down to 2.
- Toggle units between °F/°C and PSIG/kPa.
- Read curves at your operating points: 40°F evap / 110°F cond for residential AC; −20°F evap / 95°F cond for LT walk-in; 45°F evap / 110°F cond for chiller.
- For zeotropic blends, both bubble (solid) and dew (dashed) curves are shown — the gap is the glide.
Common errors
- Comparing across vastly different pressure envelopes (R-744 + R-1234ze) on one chart — readability suffers. Split into separate comparisons.
- Ignoring glide on zeotropic blends — the wide gap matters for service measurement and capacity calculations.
- Treating curve crossover as significant — at one specific temperature curves can coincide; the broader envelope shape matters more.
- Using PT overlay alone for retrofit decisions — lubricant compatibility, safety class, and GWP need separate evaluation.
Underlying math
Formula
Each plotted curve = saturation pressure at given temperature for that refrigerant. For pure refrigerants and azeotropes: P_sat = f(T) single curve. For zeotropic blends: P_bubble = f(T) solid, P_dew = f(T) dashed.
Source
Saturation pressures from CoolProp (REFPROP-compatible Helmholtz EOS): CoolProp 7.2.0 (Bell, Wronski, Quoilin, Lemort 2014, doi:10.1021/ie4033999) for most fluids and CoolProp 8.0.0 for newer low-GWP fluids (R-450A, R-515A/B, R-1224yd(Z), R-1336mzz(Z)). R-514A comes from Chemours' Opteon XP30 charts, and the two R-404A retrofit blends CoolProp does not model — R-438A and R-448A — from named manufacturer PT charts (Chemours, Honeywell).
Worked example
R-410A vs R-32 vs R-454B at 95°F (typical residential design ambient): R-410A: 296 PSIG R-32: 303 PSIG (+2% vs R-410A) R-454B: 280 PSIG bubble / 270 PSIG dew (−5% vs R-410A) At 40°F (evaporator): R-410A: 119 PSIG R-32: 121 PSIG R-454B: 112 PSIG / 107 PSIG Interpretation: R-32 runs slightly higher pressure than R-410A; R-454B slightly lower. All three within standard 500 PSI service equipment ratings.
Related tools
PT Calculator
Single-refrigerant lookup, either direction.
Retrofit Compatibility
Structured pair comparison: lubricants, safety, pressure, glide, GWP.
R-410A detail page
Full reference + GWP + retrofit guidance.
R-454B detail page
Leading R-410A replacement (A2L).
Full Comparison Guide
Long-form sourced guide to all common HVAC refrigerant comparisons.
Frequently asked
›What does this tool show?
Pick 2-4 refrigerants and the tool overlays their saturation pressure-temperature curves on one set of axes. The result makes pressure-envelope comparisons across the operating range immediate — R-454B vs R-410A across residential AC, R-22 vs R-407C for retrofit, R-32 vs R-410A for new-equipment specification.
›Why are some curves dashed?
Solid lines are the bubble (saturated liquid) curve at the temperature given. Dashed lines are the dew (saturated vapor) curve. For pure refrigerants and azeotropes (R-22, R-32, R-134a, R-507A) the two coincide so only the solid line is drawn. For zeotropic blends (R-407C, R-454C, R-455A, R-448A, R-449A) both are shown and the vertical gap at any temperature is the temperature glide at that pressure.
›Why does my comparison look squished when I mix high- and low-pressure refrigerants?
If you include refrigerants with very different operating envelopes — R-744 (CO₂, 800+ PSIG at 70°F) with R-1234ze (~50 PSIG at 70°F) — the linear y-axis compresses lower-pressure curves toward zero. The relationship is still correct but visual readability suffers. For wildly different envelopes, do two separate comparisons (high-pressure family, low-pressure family) for cleaner reading.
›How do I compare two refrigerants for retrofit feasibility?
Retrofit feasibility depends on more than the PT curve: lubricant compatibility, component pressure rating, safety class change, capacity match, and glide all matter. The PT overlay shows whether system pressures will be comparable across the operating range (look at the curves at 40°F evaporator and 110°F condenser for residential AC; −20°F evap and 95°F cond for LT walk-in). For a structured pair comparison, use the Retrofit Compatibility Calculator.
›What are the typical use cases for PT comparison?
Five primary uses: (1) retrofit feasibility — R-22 vs candidate replacement (R-407C, R-422D); (2) new-equipment specification — R-32 vs R-410A vs R-454B for residential AC; (3) commercial transition — R-404A vs R-448A vs R-449A vs R-454C for low-GWP commercial refrigeration; (4) mobile AC — R-134a vs R-1234yf compatibility; (5) phase-down trajectory visualization — showing pressure envelope evolution across a refrigerant family over decades.
›Does the chart account for service temperature ranges?
The chart spans −40°F to 130°F by default — covering the residential AC service range. For commercial refrigeration use the lower end (−40°F to 30°F evap, 80°F to 130°F condenser). For chillers focus on the 30°F-130°F band. For mobile AC focus on the 30°F-150°F band. The chart includes the full envelope but interpretive focus depends on application.
›What's the relationship between PT curve slope and operating efficiency?
Steep PT curves (high dP/dT) mean small temperature changes produce large pressure swings. R-32 is steeper than R-410A; R-744 (CO₂) is steeper than R-32 in its sub-critical regime. Steep curves require pressure-rated components and tighter charge control but offer higher volumetric capacity per unit displacement. Flatter PT curves (R-134a, R-1234yf) are forgiving but lower capacity.