R-32 Pressure Temperature Chart
Complete Guide to R-32 Pressure Temperature Chart (PT Chart) – HVAC Technician Guide
1. Introduction to R-32 Refrigerant
R-32 is a next-generation HFC refrigerant widely used in modern air conditioners. It is becoming increasingly popular in India due to:
- Higher energy efficiency
- Lower environmental impact
- Better cooling performance
Applications:
- Split AC
- Inverter AC
- Heat pumps
Many brands like Daikin and Panasonic use R-32 in their AC systems.
2. What is a Pressure Temperature (PT) Chart?
A Pressure Temperature Chart (PT Chart) shows the relationship between:
- Pressure (PSI or Bar)
- Saturation Temperature
Why it is important:
- Converts pressure into temperature
- Helps in system diagnosis
- Used for superheat and subcooling calculation
3. Why R-32 PT Chart is Important
Using the PT chart helps technicians:
- Identify correct operating pressure
- Detect system faults
- Ensure proper refrigerant charge
- Improve system efficiency
4. Properties of R-32 Refrigerant
| Property | Value |
|---|---|
| Type | HFC |
| ODP | 0 |
| GWP | ~675 |
| Glide | None |
| Flammability | A2L |
| Efficiency | High |
5. R-32 Pressure Temperature Chart (°F vs PSI)
R-32 PT Chart (°F / PSIG)
| Temp (°F) | Pressure (PSIG) |
|---|---|
| -40 | 6 |
| -30 | 11 |
| -20 | 18 |
| -10 | 26 |
| 0 | 36 |
| 10 | 48 |
| 20 | 62 |
| 30 | 78 |
| 40 | 96 |
| 50 | 117 |
| 60 | 140 |
| 70 | 166 |
| 80 | 195 |
| 90 | 226 |
| 100 | 260 |
| 110 | 297 |
| 120 | 337 |
| 130 | 379 |
| 140 | 424 |
6. R-32 Pressure Temperature Chart (°C vs PSI)
R-32 PT Chart (°C / PSIG)
| Temp (°C) | Pressure (PSIG) |
|---|---|
| -40 | 6 |
| -35 | 8 |
| -30 | 11 |
| -25 | 14 |
| -20 | 18 |
| -15 | 22 |
| -10 | 26 |
| -5 | 31 |
| 0 | 36 |
| 5 | 42 |
| 10 | 48 |
| 15 | 55 |
| 20 | 62 |
| 25 | 70 |
| 30 | 78 |
| 35 | 87 |
| 40 | 96 |
| 45 | 106 |
| 50 | 117 |
| 55 | 128 |
| 60 | 140 |
| 65 | 153 |
| 70 | 166 |
7. How to Read an R-32 PT Chart
Steps:
- Measure pressure using gauge
- Find pressure in PT chart
- Convert to temperature
- Compare with actual pipe temperature
8. Superheat and Subcooling with R-32
Superheat Formula
Subcooling Formula
Typical Values:
- Superheat: 5–10°C
- Subcooling: 8–12°C
9. Charging Guidelines for R-32
Important:
- Charge in liquid form
- Use proper manifold gauges
- Avoid mixing refrigerants
10. R-32 vs R-410A Pressure Comparison
| Temp (°C) | R-32 | R-410A |
|---|---|---|
| 25 | 70 PSI | 118 PSI |
| 40 | 96 PSI | 170 PSI |
| 60 | 140 PSI | 260 PSI |
R-32 operates at lower pressure than R-410A.
11. Troubleshooting Using PT Chart
Low Pressure:
- Refrigerant leak
- Undercharge
- Evaporator issue
High Pressure:
- Overcharge
- Dirty condenser
- Poor airflow
12. Safety and Handling
- R-32 is mildly flammable (A2L)
- Avoid sparks
- Use proper tools
13. Advantages and Disadvantages
Advantages:
- High efficiency
- Lower GWP
- Better cooling
Disadvantages:
- Flammable
- Requires trained technician
14. Common Mistakes
- Overcharging
- Wrong PT chart
- Ignoring superheat
15. Top 10 FAQs – R-32 Pressure Temperature Chart
Q1. What is R-32 refrigerant used for?
R-32 is widely used in split air conditioners and heat pump systems due to its high efficiency and lower environmental impact.
Q2. What is the normal pressure of R-32 refrigerant?
R-32 pressure depends on temperature. For example, at 25°C, the pressure is around 70 PSIG.
Q3. Is R-32 better than R-410A?
Yes, R-32 is more energy efficient, has lower global warming potential, and requires less refrigerant charge.
Q4. Is R-32 refrigerant safe to use?
R-32 is mildly flammable (A2L), but it is safe when handled by trained technicians using proper tools.
Q5. How do you read an R-32 PT chart?
You measure the system pressure, locate it on the PT chart, and convert it to saturation temperature for analysis.
Q6. What is the superheat range for R-32 systems?
Typical superheat for R-32 systems ranges between 5°C to 10°C depending on system design.
Q7. What is the subcooling range for R-32?
Subcooling is typically maintained between 8°C to 12°C for optimal system performance.
Q8. Can R-32 replace R-410A refrigerant?
R-32 can replace R-410A in specially designed systems, but it is not a direct drop-in replacement.
Q9. Why is my R-32 AC pressure low?
Low pressure may be caused by refrigerant leakage, undercharging, or evaporator airflow issues.
Q10. Why is R-32 considered eco-friendly?
R-32 has a lower Global Warming Potential (GWP ~675) compared to R-410A, making it more environmentally friendly.
16. Conclusion
R-32 is the future refrigerant for residential AC systems. Understanding its pressure-temperature relationship is essential for:
- Proper charging
- Efficient operation
- Troubleshooting
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