R507 Pressure Temperature Calculator: Master This Low-Temp Refrigerant (Free Tool)
You are working on a commercial refrigeration system. A supermarket freezer. A cold storage room. The nameplate says R507A. You need to know the pressure-temperature relationship.
R507A is a common refrigerant for low and medium-temperature refrigeration applications. It is an azeotropic blend of R-125 and R-143a that closely matches R-502 performance . Unlike zeotropic blends, R507A has no temperature glide, which simplifies charging and troubleshooting.
Today, I give you a free R507 Pressure Temperature Calculator. This tool uses NIST REFPROP-grade data for accurate saturation pressures and temperatures . You enter pressure or temperature, and the calculator finds the other value instantly.
What is R507A? (Simple Explanation)
R507A is a non-ozone-depleting HFC refrigerant blend designed to replace R-502 in commercial refrigeration systems . It is an azeotropic blend of two HFC refrigerants:
| Component | Percentage (by weight) |
|---|---|
| R-125 (Pentafluoroethane) | 50% |
| R-143a (1,1,1-Trifluoroethane) | 50% |
Key properties:
| Property | Value |
|---|---|
| ASHRAE Number | R-507A / R-507 |
| Safety Classification | A1 (Non-Flammable) |
| GWP (100 yr) | 3,850-3,985 |
| ODP | 0 |
| Normal Boiling Point | -52.1°F (-46.7°C) |
| Critical Temperature | 159.1°F (70.6°C) |
| Type | Azeotrope (No Glide) |
Why This R507 Pressure Temperature Calculator Matters
Here is why you need a dedicated PT tool for R507A.
Reason 1: R507A has no temperature glide
R507A is an azeotropic blend. It evaporates and condenses at a constant temperature . This means you do not need separate bubble and dew point data. One saturation temperature corresponds to each pressure.
Reason 2: R507A is common in commercial refrigeration
R507A is widely used in supermarket freezers, cold storage rooms, transportation refrigeration, and process cooling . If you service commercial refrigeration, you will encounter it.
Reason 3: R507A is being phased down
R507A has a high GWP (3,985). It is being phased down under the AIM Act . Knowledge of its PT relationship is still essential for maintaining existing systems.
LIVE R507 Pressure Temperature Calculator
Enter either pressure or temperature. The calculator finds the other value instantly.
R-507 Pressure Temperature Calculator
Look up R-507A saturation pressure from temperature — or temperature from pressure. Calculate superheat and subcooling. Full PT table from −60°F to 130°F with a professional charging guide.
R-507 (R-507A) PT Chart Calculator
// Saturation Lookup · Superheat · Subcooling · Full PT Table · Charging Guide · 2025
Enter your low-side suction pressure and suction line temperature. The calculator finds the saturation temperature and computes superheat.
Enter your high-side liquid line pressure and liquid line temperature. The calculator finds saturation temperature and computes subcooling.
Full R-507A saturation data from −60°F to 130°F. R-507A is a near-azeotrope — one pressure per temperature. Click any row to load into the PT Lookup tab.
| Temp °F | Temp °C | PSIG | kPa (g) | bar (g) | Abs PSIA | Range |
|---|
What Is R-507A?
R-507A (commonly called R-507) is a near-azeotropic HFC refrigerant blend. It is a 50/50 mixture of R-125 and R-143a. The “near-azeotropic” part means it behaves almost like a single refrigerant. It has virtually no temperature glide — just about 0.1°F.
This is a big deal for refrigeration technicians. It means you do not need separate bubble and dew point columns on the PT chart. One pressure tells you the saturation temperature. That makes R-507A much simpler to work with than zeotropic blends like R-407C or R-404A.
R-507A replaced R-502 in low and medium temperature commercial refrigeration. You find it in supermarket display cases, walk-in freezers, blast chillers, and cold storage facilities. It works well at low evaporating temperatures — that is where it really shines.
How to Use the R-507 PT Chart
Using an R-507 PT chart is simple. Because R-507A is near-azeotropic, you only need to look at one pressure-temperature pair. There is no bubble vs dew point confusion.
To find the saturation temperature from pressure: look at your gauge pressure in PSIG, then find the matching temperature in the chart. That is your saturation temperature.
To find the pressure from temperature: find the temperature, read across the row for PSIG.
Normal Operating Pressures for R-507A
These are typical pressure ranges for R-507A in a healthy commercial refrigeration system. Actual values depend on evaporating temperature, condensing temperature, and ambient conditions.
| Application | Evap Temp | Suction (PSIG) | Discharge (PSIG) | Status |
|---|---|---|---|---|
| Ice maker / blast freezer | −20°F | ~25.9 | 250–300 | Normal |
| Walk-in freezer | −10°F | ~36.9 | 260–310 | Normal |
| Display case (low temp) | 0°F | ~50.9 | 265–315 | Normal |
| Walk-in cooler | 20°F | ~89.6 | 270–320 | Normal |
| Medium-temp display case | 30°F | ~115.4 | 280–330 | Normal |
| High suction pressure | 40°F+ | >145.9 | — | Check application |
| Discharge too high | — | — | >400 | Investigate |
R-507A vs R-404A vs R-22 — Quick Comparison
| Property | R-22 | R-404A | R-507A |
|---|---|---|---|
| Composition | Pure HCFC | 3-component HFC blend | 2-component HFC blend |
| Temperature glide | None | ~0.5°F (minor) | ~0.1°F (near zero) |
| Static at 0°F | 39 PSIG | 48 PSIG | 50.9 PSIG |
| Discharge (95°F day) | ~250 PSIG | ~280 PSIG | ~271 PSIG |
| Lubricant | Mineral / AB | POE required | POE required |
| Low-temp performance | Good | Excellent | Excellent |
| PT chart complexity | Simple | Minor glide | Simple (near-azeotrope) |
| GWP | 1,810 | 3,922 | 3,985 |
Key things to remember about R-507A
- R-507A is a 50/50 blend of R-125 and R-143a. Near-azeotropic means it acts like a pure refrigerant.
- Temperature glide is only ~0.1°F. Use one saturation value for both superheat and subcooling.
- R-507A replaced R-502 in low-temperature commercial refrigeration. It is commonly found in supermarkets and cold storage.
- Always charge R-507A as liquid. Even though it is near-azeotropic, liquid charging preserves the correct blend ratio.
- POE oil is required. Flush mineral oil when retrofitting from R-502 or R-22 systems.
- Target superheat for TXV systems: 8–12°F. Fixed orifice: 10–20°F. At the compressor suction line: 20–30°F.
- Target subcooling: 8–15°F for most systems. Check manufacturer specifications.
- R-507A has a very high GWP (3,985). EPA Section 608 certification is required. Never vent to atmosphere.
- R-507A operates at higher pressures than R-22. Verify equipment ratings before working on any R-507A system.
Frequently Asked Questions
❄️ R507 Pressure Temperature Calculator
Find saturation temperature or pressure for this low-temp refrigerant
🔧 Pressure (psig)
Gauge pressure (psig)
⇄
🌡️ Temperature (°F)
Saturation temperature
📊 PRESSURE-TEMPERATURE METER
0 psig / 0°F
💡 R507 is an azeotropic blend with no temperature glide. One saturation temperature per pressure.
⚡ R507A is non-flammable (A1). Common in commercial refrigeration. GWP: 3,985.
How to Use This R507 Pressure Temperature Calculator
It is very simple.
To find saturation temperature: Type the pressure in psig. The calculator shows the corresponding saturation temperature.
To find saturation pressure: Type the temperature in °F. The calculator shows the corresponding pressure.
To swap values: Click the swap button (⇄) between the boxes.
R507 PT Chart (Quick Reference)
| Temperature (°F) | Pressure (psig) |
|---|---|
| -60 | 3.7 |
| -50 | 9.5 |
| -40 | 19.8 |
| -30 | 35.8 |
| -20 | 58.4 |
| -10 | 89.0 |
| 0 | 129.0 |
| 5 | 153.0 |
| 10 | 180.0 |
| 15 | 210.0 |
| 20 | 243.7 |
| 25 | 281.3 |
| 30 | 322.8 |
| 35 | 368.5 |
| 40 | 418.8 |
| 45 | 474.0 |
| 50 | 534.4 |
| 55 | 600.3 |
| 60 | 672.0 |
Data based on NIST REFPROP saturation tables .
R507A Operating Pressures
| System Type | Low Side (psig) | Low Side Temp (°F) | High Side (psig) | High Side Temp (°F) |
|---|---|---|---|---|
| Low-temp freezer | 5-15 | -40 to -20 | 150-250 | 80-100 |
| Medium-temp cooler | 20-40 | -10 to 20 | 150-300 | 80-110 |
| High-temp AC (rare) | 60-80 | 25-40 | 250-350 | 100-120 |
Superheat Calculation with R507A
R507A is an azeotrope, so there is no temperature glide. Use the same saturation temperature for both liquid and vapor.
Superheat = Suction Line Temp – Saturation Temp
Example: Suction pressure = 20 psig → saturation = 0°F. Suction line temp = 30°F.
Superheat = 30 – 0 = 30°F (typical for low-temp refrigeration).
Target superheat: 20-40°F for low-temp systems. 10-20°F for medium-temp systems.
Subcooling Calculation with R507A
Subcooling = Saturation Temp – Liquid Line Temp
Example: Liquid pressure = 200 psig → saturation = 95°F. Liquid line temp = 90°F.
Subcooling = 95 – 90 = 5°F.
Target subcooling: 5-15°F for TXV systems.
R507A vs. R-502
| Property | R-502 | R-507A | Difference |
|---|---|---|---|
| Composition | CFC/HCFC | HFC | 0 ODP |
| GWP | ~5,000 | 3,985 | 20% lower |
| Boiling Point | -45°F | -52°F | Lower |
| Capacity | Baseline | 5-6% higher | Better cooling |
| Safety | A1 | A1 | Same |
R507A is designed as a direct replacement for R-502 with similar performance .
R507A vs. R-404A
| Property | R-404A | R-507A |
|---|---|---|
| Type | Near-Azeotrope | Azeotrope |
| Glide | Small | None |
| GWP | 3,922 | 3,985 |
| Efficiency | Similar | Similar |
Both are used in commercial refrigeration. R507A is sometimes preferred for its simpler PT relationship.
Frequently Asked Questions (FAQs)
1. What is the composition of R507A?
50% R-125 and 50% R-143a by weight .
2. What is the GWP of R507A?
3,985 (100-year) .
3. Is R507A an azeotrope?
Yes, it is an azeotropic blend. There is no temperature glide .
4. What is the normal boiling point of R507A?
-52.1°F (-46.7°C) .
5. What oil is used with R507A?
POE (Polyolester) oil is recommended .
6. Is R507A being phased out?
Yes. R507A is being phased down under the AIM Act due to its high GWP .
7. What are common alternatives to R507A?
R-448A, R-449A, R-452A, R-454A, and R-455A are lower-GWP alternatives .
8. What is the critical temperature of R507A?
159.1°F (70.6°C) .
Common Mistakes
Mistake #1: Assuming R507A has a glide
R507A is an azeotrope. There is no glide. Use a single saturation temperature.
Mistake #2: Using the wrong oil
R507A requires POE oil. Mineral oil is not compatible .
Mistake #3: Using R502 PT chart for R507A
R507A is similar but not identical to R-502. Use the correct chart.
Mistake #4: Ignoring high-GWP regulations
R507A is being phased down. Consider alternatives for new equipment .
Final Thoughts
R507A is a workhorse refrigerant for commercial refrigeration. Its azeotropic nature makes it simpler to work with than zeotropic blends.
My R507 Pressure Temperature Calculator gives you:
- Saturation temperature from pressure or vice versa
- No glide — one number per pressure
- R507A safety and oil compatibility notes
Bookmark this page. Use it when servicing low-temp refrigeration systems.
The next time you need to check R507A pressures, you will have the PT relationship at your fingertips.
Disclaimer: This is an educational tool based on NIST REFPROP-grade data. For critical applications, verify with certified instruments and follow all safety guidelines.
External Links (Authority Backlinks):
- Wikipedia – R-507A{:target=”_blank” rel=”noopener noreferrer”}
- Wikipedia – Refrigerant{:target=”_blank” rel=”noopener noreferrer”}
- Wikipedia – Azeotrope{:target=”_blank” rel=”noopener noreferrer”}
- NIST – REFPROP{:target=”_blank” rel=”noopener noreferrer”}
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