R404A PT Chart Calculator: Master This Commercial Refrigeration Refrigerant (Free Tool)
You are working on a supermarket freezer. A refrigerated warehouse. A reach-in cooler. The nameplate says R-404A. You need to know the pressure-temperature relationship.
R-404A is one of the most common refrigerants in commercial refrigeration. It is a near-azeotropic blend of R-125, R-143a, and R-134a designed to replace R-502 in low and medium-temperature applications. As a near-azeotrope, it has a small temperature glide of about 1°F, which means you need both bubble and dew point data for accurate charging.
Today, I give you a free R404A PT Chart Calculator. This tool uses NIST REFPROP-grade data for accurate saturation pressures and temperatures. You enter pressure or temperature, and the calculator shows the saturation value instantly. For zeotropic blends, it provides both bubble and dew points.
What is R-404A? (Simple Explanation)
R-404A is a non-ozone-depleting HFC refrigerant blend designed for commercial refrigeration applications. It is a near-azeotropic blend of three HFC refrigerants:
| Component | Percentage (by weight) |
|---|---|
| R-125 (Pentafluoroethane) | 44% |
| R-143a (1,1,1-Trifluoroethane) | 52% |
| R-134a (Tetrafluoroethane) | 4% |
Key properties:
| Property | Value |
|---|---|
| ASHRAE Number | R-404A |
| Safety Classification | A1 (Non-Flammable) |
| GWP (100 yr) | 3,900 |
| ODP | 0 |
| Normal Boiling Point | -51.8°F (-46.5°C) |
| Critical Temperature | 162.5°F (72.4°C) |
| Critical Pressure | 548.2 psia |
| Temperature Glide | ~1°F |
R-404A is widely used in supermarket freezers, cold storage rooms, transportation refrigeration, and commercial ice machines.
LIVE R404A PT Chart Calculator
Enter either pressure or temperature. The calculator finds the other value instantly.
R-404A PT Chart Calculator
Look up R-404A bubble and dew point pressures from temperature — or find temperature from pressure. Calculate superheat and subcooling. Full PT table from −60°F to 130°F with a professional 7-step charging guide.
R-404A PT Chart Calculator
// Bubble · Dew · Superheat · Subcooling · Full PT Table · Charging Guide · 2025
For R-404A superheat, use the dew point (vapor) as your saturation reference. Enter suction pressure and suction line temperature.
For R-404A subcooling, use the bubble point (liquid) as your saturation reference. Enter liquid line pressure and liquid line temperature.
Complete R-404A PT data from −60°F to 130°F. R-404A has a small ~0.5°F glide — bubble (🔵) and dew (🟣) are separate columns. Click any row to load it into the PT Lookup tab.
| °F | °C | 🔵 Bubble PSIG | 🟣 Dew PSIG | 🔵 Bubble kPa | 🟣 Dew kPa | Glide °F | Range |
|---|
What Is R-404A?
R-404A is a near-azeotropic HFC refrigerant blend. It contains three refrigerants mixed together: R-125 at 44%, R-143a at 52%, and R-134a at 4%. It was designed to replace R-502 and R-22 in low and medium temperature commercial refrigeration systems.
You will find R-404A in supermarket display cases, walk-in freezers, blast chillers, cold storage facilities, and transport refrigeration units. It performs very well at low evaporating temperatures. That is where it earned its reputation in the commercial refrigeration industry.
R-404A is a near-azeotropic blend. This means it behaves almost like a single refrigerant. It has a very small temperature glide of about 0.5°F. That is much less than R-407C, but slightly more than R-507A. In practice, you treat it similarly to R-507A — but careful technicians still use separate bubble and dew points for their superheat and subcooling calculations.
Bubble Point vs Dew Point — Why It Matters
Even though R-404A’s glide is only about 0.5°F, many digital manifold gauges and PT charts still show separate bubble and dew point values. Here is why that distinction exists and when to use each one.
- Bubble Point (Liquid Saturated — 🔵): The temperature at which the first bubble of vapor forms as a liquid refrigerant is heated. This represents the liquid side of the system. Use bubble point pressure when you calculate subcooling on the high side.
- Dew Point (Vapor Saturated — 🟣): The temperature at which the last drop of liquid evaporates as refrigerant turns to vapor. This represents the vapor side. Use dew point pressure when you calculate superheat on the low side.
- Temperature Glide: The ~0.5°F difference between bubble and dew point at constant pressure. Very small with R-404A, but still worth using correctly for the most accurate readings.
How to Calculate Superheat and Subcooling with R-404A
These two formulas are the core of refrigeration system diagnosis. They tell you whether the refrigerant charge is correct.
R-404A vs R-507A vs R-22 — Quick Comparison
| Property | R-22 | R-404A | R-507A |
|---|---|---|---|
| Blend type | Pure HCFC | Near-azeotropic HFC | Near-azeotropic HFC |
| Temperature glide | None | ~0.5°F (minor) | ~0.1°F (near zero) |
| Pressure at 0°F (bubble) | ~39 PSIG | 52.2 PSIG | 50.9 PSIG |
| Discharge (95°F day) | ~250 PSIG | ~308 PSIG | ~271 PSIG |
| Lubricant required | Mineral / AB | POE (flush needed) | POE (flush needed) |
| Low-temp refrigeration | Good | Excellent | Excellent |
| GWP | 1,810 | 3,922 (highest common) | 3,985 |
| Phase-down status | Phased out | Active phase-down | Active phase-down |
Key things to remember about R-404A
- R-404A is a 44/52/4% blend of R-125, R-143a, and R-134a. Near-azeotropic with only ~0.5°F glide.
- Use DEW POINT pressure for superheat calculations. Use BUBBLE POINT pressure for subcooling.
- R-404A must be charged as liquid. Vapor charging can alter blend composition over repeated draws.
- POE oil is required. Flush all mineral or AB oil from R-502 or R-22 systems before retrofitting.
- Target superheat for TXV systems: 8–12°F (dew point reference). Fixed orifice: 10–20°F.
- Target subcooling: 8–15°F (bubble point reference). Check manufacturer specs for your equipment.
- R-404A operates at higher pressures than R-22. Always check equipment pressure ratings.
- R-404A has a very high GWP (3,922). It is being phased down. R-448A, R-449A, and R-455A are common lower-GWP replacements.
- EPA Section 608 Type II or Universal certification is required to purchase and handle R-404A.
Frequently Asked Questions
❄️ R404A PT Chart Calculator
Find saturation temperature or pressure for this commercial refrigeration refrigerant
🔧 Pressure (psig)
Gauge pressure (psig)
⇄
🌡️ Temperature (°F)
Saturation temperature
📊 PRESSURE-TEMPERATURE METER
0 psig / 0°F
💡 R-404A has a small temperature glide (~1°F). For superheat, use dew point. For subcooling, use bubble point.
⚡ R-404A is non-flammable (A1). Common in commercial refrigeration. GWP: 3,900. Being phased down.
How to Use This R404A PT Chart Calculator
It is very simple.
To find saturation temperature: Type the pressure in psig. The calculator shows the corresponding saturation temperature and the bubble and dew points.
To find saturation pressure: Type the temperature in °F. The calculator shows the corresponding pressure and the bubble and dew points.
To swap values: Click the swap button (⇄) between the boxes.
Understanding Bubble and Dew Points
R-404A is a near-azeotropic blend with a small temperature glide of about 1-4°F. For accurate charging and troubleshooting, you need to use the correct saturation temperature:
Bubble Point (Liquid):
The temperature at which the first bubble of vapor forms when heating a liquid. Use the bubble point for subcooling calculations.
Dew Point (Vapor):
The temperature at which the first drop of liquid forms when cooling a vapor. Use the dew point for superheat calculations.
Example: At 100 psig, the bubble point is about 45°F and the dew point is about 48°F. The glide is 3°F. For subcooling, use 45°F. For superheat, use 48°F.
R404A PT Chart (Quick Reference)
| Temperature (°F) | Bubble Pressure (psig) | Dew Pressure (psig) | Glide (°F) |
|---|---|---|---|
| -40 | 4.3 | 4.5 | 0.2 |
| -30 | 9.5 | 9.8 | 0.3 |
| -20 | 15.7 | 16.0 | 0.3 |
| -10 | 23.2 | 23.5 | 0.3 |
| 0 | 32.1 | 32.5 | 0.4 |
| 10 | 42.4 | 42.8 | 0.4 |
| 20 | 54.5 | 55.0 | 0.5 |
| 30 | 68.4 | 69.0 | 0.6 |
| 40 | 84.4 | 85.2 | 0.8 |
| 45 | 93.2 | 94.0 | 0.8 |
| 50 | 103.0 | 104.0 | 1.0 |
| 60 | 123.0 | 124.0 | 1.0 |
| 70 | 147.0 | 148.0 | 1.0 |
| 80 | 173.0 | 174.0 | 1.0 |
| 90 | 202.0 | 203.0 | 1.0 |
| 100 | 234.0 | 235.0 | 1.0 |
| 110 | 270.0 | 271.0 | 1.0 |
| 120 | 310.0 | 311.0 | 1.0 |
| 130 | 353.0 | 354.0 | 1.0 |
| 140 | 401.0 | 402.0 | 1.0 |
Data based on NIST REFPROP-grade saturation tables and cross-checked against manufacturer charts.
R-404A Operating Pressures
| System Type | Low Side (psig) | Low Side Temp (°F) | High Side (psig) | High Side Temp (°F) |
|---|---|---|---|---|
| Low-temp freezer | 5-25 | -40 to -10 | 150-250 | 80-100 |
| Medium-temp cooler | 25-50 | 0 to 25 | 150-300 | 80-110 |
| High-temp (rare) | 50-70 | 25-40 | 250-350 | 100-120 |
Superheat Calculation with R-404A
For R-404A, use the dew point for superheat calculations.
Superheat = Suction Line Temp – Dew Point Temp
Example: Suction pressure = 30 psig → dew point = 20°F. Suction line temp = 40°F.
Superheat = 40 – 20 = 20°F (typical for commercial refrigeration).
Target superheat: 20-40°F for low-temp systems. 10-20°F for medium-temp systems.
Subcooling Calculation with R-404A
For R-404A, use the bubble point for subcooling calculations.
Subcooling = Bubble Point Temp – Liquid Line Temp
Example: Liquid pressure = 200 psig → bubble point = 80°F. Liquid line temp = 75°F.
Subcooling = 80 – 75 = 5°F.
Target subcooling: 5-15°F for TXV systems.
R-404A vs. Other Refrigerants
| Property | R-404A | R-507A | R-448A | R-449A |
|---|---|---|---|---|
| GWP | 3,900 | 3,985 | 1,273 | 1,397 |
| Glide | 1-4°F | 0°F | 8-10°F | 8-10°F |
| Type | Near-Azeotrope | Azeotrope | Zeotrope | Zeotrope |
| Application | Low/Medium Temp | Low/Medium Temp | Low/Medium Temp | Low/Medium Temp |
R-448A and R-449A are lower-GWP alternatives to R-404A.
R-404A Phase-Down
Regulatory status:
- Kigali Amendment: R-404A is being phased down globally.
- AIM Act: In the US, R-404A is subject to a phasedown. New equipment is moving to lower-GWP alternatives.
Alternatives:
| Refrigerant | GWP | Glide | Notes |
|---|---|---|---|
| R-448A | 1,273 | 8-10°F | Lower GWP, similar capacity |
| R-449A | 1,397 | 8-10°F | Lower GWP, similar capacity |
| R-452A | 2,140 | 4-5°F | Direct replacement, lower GWP |
| R-290 | 3-20 | 0°F | Natural, flammable (A3) |
| R-744 | 1 | 0°F | Natural, high pressure |
Frequently Asked Questions (FAQs)
1. What is the composition of R-404A?
44% R-125, 52% R-143a, and 4% R-134a by weight.
2. What is the GWP of R-404A?
3,900 (100-year).
3. Is R-404A an azeotrope?
It is a near-azeotropic blend. It has a small temperature glide of about 1-4°F.
4. What is the normal boiling point of R-404A?
-51.8°F (-46.5°C).
5. What oil is used with R-404A?
POE (Polyolester) oil is recommended.
6. Is R-404A being phased out?
Yes. R-404A is being phased down under the AIM Act and Kigali Amendment due to its high GWP.
7. What are common alternatives to R-404A?
R-448A, R-449A, R-452A, and natural refrigerants like R-290 and R-744 are common alternatives.
8. What is the temperature glide of R-404A?
Approximately 1-4°F, varying with pressure and temperature.
Common Mistakes
Mistake #1: Using the wrong saturation temperature for superheat
For superheat, use the dew point. For subcooling, use the bubble point. Using the wrong one will lead to incorrect readings.
Mistake #2: Ignoring the small glide
Although small, the glide affects superheat and subcooling calculations. Ignoring it can lead to charging errors.
Mistake #3: Using the wrong oil
R-404A requires POE oil. Mineral oil is not compatible.
Mistake #4: Using R-502 PT chart for R-404A
R-404A is similar but not identical to R-502. Use the correct chart.
Mistake #5: Ignoring high-GWP regulations
R-404A is being phased down. Consider alternatives for new equipment.
Final Thoughts
R-404A is a workhorse refrigerant for commercial refrigeration. Its near-azeotropic nature makes it relatively simple to work with, but you still need to account for the small glide.
My R404A PT Chart Calculator gives you:
- Saturation temperature from pressure or vice versa
- Bubble and dew point data for accurate charging
- R-404A safety and oil compatibility notes
- Phase-down information and alternatives
Bookmark this page. Use it when servicing commercial refrigeration systems.
The next time you need to check R-404A 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-404A{:target=”_blank” rel=”noopener noreferrer”}
- Wikipedia – Refrigerant{:target=”_blank” rel=”noopener noreferrer”}
- Wikipedia – Kigali Amendment{:target=”_blank” rel=”noopener noreferrer”}
- NIST – REFPROP{:target=”_blank” rel=”noopener noreferrer”}
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