R-450A Pressure Temperature Chart
Complete Guide to R-450A Pressure Temperature Chart (PT Chart)
1. Introduction to R-450A Refrigerant
R-450A (marketed as Solstice® N13) is a low-GWP HFO blend refrigerant developed as a replacement for R-134a in commercial refrigeration and air conditioning systems.
It is widely used in:
-
Medium-temperature refrigeration
-
Supermarket refrigeration systems
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Chillers
-
Transport refrigeration
Composition of R-450A
R-450A is a blend of:
-
R-134a
-
R-1234ze(E)
2. What is a Pressure Temperature (PT) Chart?
A Pressure Temperature Chart (PT Chart) shows the relationship between:
-
Pressure (PSI)
-
Saturation temperature
Why It’s Important:
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Converts pressure to temperature
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Helps calculate superheat and subcooling
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Ensures correct refrigerant charge
-
Helps in troubleshooting
3. Why R-450A PT Chart is Important
R-450A is a zeotropic blend, so PT charts are essential.
Benefits:
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Accurate charging
-
Better system efficiency
-
Prevents compressor damage
-
Improves diagnostics
4. Properties of R-450A Refrigerant
| Property | Value |
|---|---|
| Type | HFO Blend |
| ODP | 0 |
| GWP | Very Low |
| Glide | Low (~1°C) |
| Replacement For | R-134a |
| Oil Compatibility | POE |
5. R-450A Pressure Temperature Chart (°F vs PSI)
R-450A PT Chart (°F / PSIG)
| Temperature (°F) | Pressure (PSIG) |
|---|---|
| -40 | 2 |
| -30 | 4 |
| -20 | 7 |
| -10 | 11 |
| 0 | 16 |
| 10 | 22 |
| 20 | 30 |
| 30 | 39 |
| 40 | 50 |
| 50 | 62 |
| 60 | 76 |
| 70 | 91 |
| 80 | 108 |
| 90 | 126 |
| 100 | 147 |
| 110 | 169 |
| 120 | 193 |
| 130 | 219 |
| 140 | 247 |
6. R-450A Pressure Temperature Chart (°C vs PSI)
R-450A PT Chart (°C / PSIG)
| Temperature (°C) | Pressure (PSIG) |
|---|---|
| -40 | 2 |
| -35 | 3 |
| -30 | 4 |
| -25 | 6 |
| -20 | 7 |
| -15 | 9 |
| -10 | 11 |
| -5 | 13 |
| 0 | 16 |
| 5 | 19 |
| 10 | 22 |
| 15 | 26 |
| 20 | 30 |
| 25 | 34 |
| 30 | 39 |
| 35 | 44 |
| 40 | 50 |
| 45 | 56 |
| 50 | 62 |
| 55 | 69 |
| 60 | 76 |
| 65 | 83 |
| 70 | 91 |
7. Temperature Glide in R-450A
R-450A has very low temperature glide (~1°C).
Meaning:
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Almost behaves like pure refrigerant
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Minimal difference between dew & bubble
Still:
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Use dew point for superheat
-
Use bubble point for subcooling
8. How to Read an R-450A PT Chart
Steps:
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Measure pressure
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Find value in chart
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Convert to temperature
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Compare with actual pipe temperature
9. Superheat and Subcooling with R-450A
Superheat Formula
Subcooling Formula
Typical Values:
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Superheat: 6°C – 10°C
-
Subcooling: 8°C – 12°C
10. Charging Guidelines for R-450A
Always charge in liquid form.
Best Practices:
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Use digital gauges
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Charge slowly
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Monitor system performance
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Avoid overcharging
11. Retrofit from R-134a to R-450A
Steps:
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Recover R-134a
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Replace filter drier
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Check POE oil
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Evacuate system
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Charge R-450A
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Adjust system
12. Troubleshooting Using PT Chart
Low Pressure:
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Leak
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Undercharge
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Evaporator issue
High Pressure:
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Overcharge
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Dirty condenser
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Airflow issue
13. 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 manufacturer guidelines
14. Advantages and Disadvantages
Advantages:
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Very low GWP
-
Energy efficient
-
Easy replacement for R-134a
Disadvantages:
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Slight glide
-
Requires POE oil
15. Common HVAC Technician Mistakes
- Ignoring PT chart
- Charging vapor
- Incorrect superheat
- Overcharging
16. Frequently Asked Questions (FAQ)
Q1. What is R-450A used for?
Medium-temperature refrigeration.
Q2. What is normal pressure?
Depends on temperature.
Q3. Can R-450A replace R-134a?
Yes.
Q4. Is R-450A safe?
Yes.
Q5. What is glide?
Small temperature difference.
17. Conclusion
R-450A is a modern low-GWP refrigerant used as a replacement for R-134a. Understanding its pressure-temperature relationship is essential for accurate HVAC servicing.
Using PT charts properly ensures:
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Accurate charging
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Better efficiency
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Reduced failures
