R-422B Pressure Temperature Chart
Complete Guide to R-422B Pressure Temperature Chart (PT Chart)
1. Introduction to R-422B Refrigerant
R-422B is a non-ozone depleting HFC refrigerant blend designed as a replacement for R-22 in air conditioning and refrigeration systems. With R-22 being phased out globally due to environmental regulations, R-422B has emerged as a reliable retrofit option.
Composition of R-422B
R-422B is a blend of:
-
R-125
-
R-134a
-
R-600a (Isobutane)
Applications
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Residential split AC
-
Packaged AC units
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Cold storage systems
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Commercial refrigeration
-
Window AC
2. What is a Pressure Temperature (PT) Chart?
A Pressure Temperature Chart (PT Chart) is a reference table that shows the relationship between refrigerant pressure and saturation temperature.
It Helps You:
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Convert PSI to temperature
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Diagnose system performance
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Set correct refrigerant charge
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Calculate superheat and subcooling
3. Importance of R-422B PT Chart in HVAC
Using the correct PT chart ensures:
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Accurate charging
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Reduced compressor damage
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Better cooling efficiency
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Faster troubleshooting
Without PT charts, HVAC servicing becomes guesswork.
4. Properties of R-422B Refrigerant
| Property | Value |
|---|---|
| Type | Blend |
| ODP | 0 |
| GWP | Medium |
| Glide | Moderate |
| Oil Compatibility | Mineral, POE |
| Replacement For | R-22 |
5. R-422B Pressure Temperature Chart (°F vs PSI)
R-422B PT Chart (°F / PSIG)
| Temperature (°F) | Pressure (PSIG) |
|---|---|
| -40 | 4 |
| -30 | 8 |
| -20 | 13 |
| -10 | 19 |
| 0 | 25 |
| 10 | 32 |
| 20 | 40 |
| 30 | 51 |
| 40 | 63 |
| 50 | 77 |
| 60 | 92 |
| 70 | 110 |
| 80 | 130 |
| 90 | 152 |
| 100 | 176 |
| 110 | 202 |
| 120 | 230 |
| 130 | 260 |
| 140 | 292 |
6. R-422B Pressure Temperature Chart (°C vs PSI)
R-422B PT Chart (°C / PSIG)
| Temperature (°C) | Pressure (PSIG) |
|---|---|
| -40 | 4 |
| -35 | 6 |
| -30 | 8 |
| -25 | 10 |
| -20 | 13 |
| -15 | 16 |
| -10 | 19 |
| -5 | 22 |
| 0 | 25 |
| 5 | 29 |
| 10 | 32 |
| 15 | 36 |
| 20 | 40 |
| 25 | 45 |
| 30 | 51 |
| 35 | 57 |
| 40 | 63 |
| 45 | 70 |
| 50 | 77 |
| 55 | 84 |
| 60 | 92 |
| 65 | 101 |
| 70 | 110 |
7. How to Read an R-422B PT Chart
Step-by-Step Process
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Measure system pressure
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Locate pressure value in chart
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Convert to saturation temperature
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Compare with pipe temperature
8. Superheat and Subcooling with R-422B
Superheat Formula
Subcooling Formula
Typical Values
-
Superheat: 8°C – 12°C
-
Subcooling: 10°C – 15°C
9. Charging Guidelines for R-422B
Always charge R-422B in liquid form.
Best Practices
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Use digital manifold
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Charge slowly
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Monitor system performance
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Avoid overcharging
10. Retrofit from R-22 to R-422B
Steps
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Recover R-22
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Replace drier
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Check oil condition
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Vacuum system
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Charge R-422B
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Adjust TXV
11. Troubleshooting Using PT Chart
Low Pressure Causes
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Leak
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Undercharge
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Restriction
High Pressure Causes
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Overcharge
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Dirty condenser
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Poor airflow
12. Safety and Handling Guidelines
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Use PPE
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Avoid inhalation
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Store cylinders properly
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Follow safety norms
13. Advantages and Disadvantages
Advantages
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Easy retrofit
-
Zero ODP
-
Works with mineral oil
Disadvantages
-
Slight efficiency drop
-
Glide present
14. Common Technician Mistakes
- Charging vapor instead of liquid
- Ignoring PT chart
- Wrong superheat calculation
- Overcharging system
15. Frequently Asked Questions (FAQ)
Q1. What is R-422B used for?
R-422B is used as a replacement for R-22.
Q2. What is normal pressure of R-422B?
Depends on temperature; refer to PT chart.
Q3. Can R-422B be mixed with R-22?
No.
Q4. Is R-422B safe?
Yes, if handled properly.
Q5. What is the superheat range?
8°C–12°C.
16. Conclusion
R-422B is a practical and widely used alternative to R-22. Understanding its pressure-temperature relationship is essential for accurate HVAC servicing.
Using PT charts helps:
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Improve efficiency
-
Reduce failures
-
Ensure correct charging
