11.9 - Selected Pressure-Temperature Reference Data

Module: Standalone Reference Appendices and Instructor Resources
Purpose: Provide the verified pressure-temperature data needed to solve the numerical P-T examples and practice questions already included in this course, while also giving a compact teaching reference for pure refrigerants and zeotropic blends
Data verification date: August 14, 2026
Primary numerical source: Arkema Forane® Refrigerants Pressure Temperature Chart, current online chart accessed August 14, 2026
Cross-check source: Arkema Forane® Refrigerants Quick Reference Guide pressure-temperature chart
Underlying property-data note: The current Arkema chart states that its data were generated using NIST REFPROP Version 10.0
Scope note: This is a selected course reference, not a full technician P-T chart. The broader technician-use tables planned for common refrigerants belong in 11.18 - Common Refrigerant Pressure-Temperature Tables.md.

How to Use This Reference

A refrigerant pressure-temperature table links:

SATURATION TEMPERATURE
↔
SATURATION PRESSURE

Before using any value, identify:

1. REFRIGERANT
2. TEMPERATURE UNIT
3. PRESSURE UNIT
4. PRESSURE REFERENCE
5. PURE / AZEOTROPIC / ZEOTROPIC BEHAVIOR
6. BUBBLE OR DEW VALUE, IF A BLEND

The most important rules are:

R-134a DATA
≠
R-22 DATA
≠
R-410A DATA
≠
R-407C DATA

and:

SUPERHEAT
→ SATURATED-VAPOR / DEW REFERENCE

SUBCOOLING
→ SATURATED-LIQUID / BUBBLE REFERENCE

1. Pressure Reference Used in This File

Unless a table explicitly says otherwise, pressures in this file are:

psig

meaning:

pounds per square inch gauge

Gauge pressure uses local atmospheric pressure as its zero reference.

At approximately standard atmospheric conditions:

$$P_{\text{abs}}\approx P_{\text{gauge}}+14.7\text{psi}$$

Therefore:

35.0 psig
≈
49.7 psia

under the standard-atmosphere approximation.

Do not compare a psig table directly with a psia regulatory threshold without converting the pressure reference correctly.

See:

11.2 - Acronyms Symbols Units and Conversions.md

for the detailed gauge/absolute-pressure discussion.

2. What Data the Existing Course Actually Requires

A review of the completed Modules 1-10 shows that the existing numerical P-T lookup questions use a supplied R-134a table.

The course-controlled values used in Module 4 are:

25°F
→ 22.1 psig

40°F
→ 35.0 psig

50°F
→ 45.4 psig

These values are reproduced in Section 3 below and are sufficient to solve the current Module 4 numerical P-T lookup questions without any external chart.

Other course examples involving bubble point, dew point, superheat, and subcooling generally provide the required saturation temperature directly because those examples are testing:

WHICH SATURATION REFERENCE?

rather than memorization of refrigerant property data.

This file also includes small selected R-22, R-410A, and R-407C tables to reinforce the major P-T concepts already taught.

3. R-134a Selected Pressure-Temperature Data

3.1 Refrigerant Identification

R-134a
→ HFC
→ single-component refrigerant

For the technician-level P-T calculations in this course, R-134a has one saturation pressure at each saturation temperature.

Data Definition

• Temperature: °F.
• Pressure: psig.
• Phase reference: Saturation pressure.
• Primary source: Current Arkema Forane P-T chart.
• Cross-check: Arkema Forane Quick Reference Guide.
• Use: Course P-T lookup, static cylinder comparison, and simple superheat/subcooling teaching.

3.2 Selected R-134a Table

Course-Required Values

The three values directly used by the existing Module 4 P-T lookup questions are:

No interpolation is required for the existing numerical questions.

4. R-134a Absolute-Pressure Interpretation

For teaching purposes only, the following approximate values use:

standard atmosphere
≈ 14.7 psia

and:

$$P_{\text{abs}}\approx P_{\text{gauge}}+14.7$$

Example

At 40°F:

$$P_{\text{abs}}\approx 35.0+14.7$$

$$P_{\text{abs}}\approx 49.7\text{psia}$$

The psia values in this section are teaching conversions using the standard-atmosphere approximation.

Actual local atmospheric pressure varies with elevation and weather.

5. R-22 Selected Comparison Data

5.1 Why R-22 Is Included

R-22 is a major legacy EPA 608 refrigerant and is repeatedly used throughout this course as a high-pressure Type II example.

This small table is included to demonstrate:

SAME TEMPERATURE
+
DIFFERENT REFRIGERANT
→ DIFFERENT SATURATION PRESSURE

Data Definition

• Temperature: °F.
• Pressure: psig.
• Phase reference: Saturation pressure.
• Primary source: Current Arkema Forane P-T chart.
• Cross-check: Arkema Forane Quick Reference Guide.

5.2 Selected R-22 Table

6. R-410A Selected Comparison Data

6.1 Why R-410A Is Included

R-410A is repeatedly used in the course as a high-pressure Type II refrigerant example and as a comparison with R-22.

R-410A is a blend with very small temperature glide. The selected field chart used here presents one practical R-410A pressure column.

For exact detailed phase-boundary work, use current manufacturer property data/software appropriate to the specific calculation.

Data Definition

• Temperature: °F.
• Pressure: psig.
• Chart presentation: Single practical R-410A pressure column.
• Primary source: Current Arkema Forane P-T chart.
• Cross-check: Arkema Forane Quick Reference Guide.

6.2 Selected R-410A Table

7. R-22, R-134a, and R-410A Compared

At the same saturation temperature, different refrigerants have different saturation pressures.

Teaching Point

At 40°F:

R-134a
→ 35.0 psig

R-22
→ 68.6 psig

R-410A
→ 118.8 psig

Therefore:

Pressure alone cannot identify an unknown refrigerant unless temperature, equilibrium condition, and refrigerant purity/identity are also considered.

A static P-T comparison is a screening tool, not a complete refrigerant-identification method.

8. R-407C Bubble and Dew Reference

8.1 Why R-407C Needs Two Values

R-407C is a zeotropic blend.

A zeotropic blend has separate:

SATURATED-LIQUID / BUBBLE

and:

SATURATED-VAPOR / DEW

relationships.

The Arkema field chart expresses this as separate:

• Liquid pressure.
• Vapor pressure.

at each listed saturation temperature.

Terminology Mapping

LIQUID PRESSURE COLUMN
→ BUBBLE-LINE PRESSURE

VAPOR PRESSURE COLUMN
→ DEW-LINE PRESSURE

8.2 Selected R-407C Table

Data Definition

• Temperature: °F.
• Pressure: psig.
• Liquid pressure: bubble-line saturation pressure at the listed temperature.
• Vapor pressure: dew-line saturation pressure at the listed temperature.
• Primary source: Current Arkema Forane P-T chart.
• Cross-check: Arkema Forane Quick Reference Guide.

Important Interpretation

At 40°F:

R-407C saturated liquid / bubble pressure
→ 80.2 psig

while:

R-407C saturated vapor / dew pressure
→ 63.2 psig

The difference is not an error.

It reflects the blend’s phase behavior.

9. How to Use Bubble and Dew Data Correctly

For a zeotropic blend:

SUPERHEAT
→ USE DEW / SATURATED-VAPOR REFERENCE

SUBCOOLING
→ USE BUBBLE / SATURATED-LIQUID REFERENCE

9.1 Superheat Logic

At the measured suction pressure:

MEASURED SUCTION PRESSURE
→ FIND DEW-POINT SATURATION TEMPERATURE
→ COMPARE WITH ACTUAL VAPOR-LINE TEMPERATURE

Then:

$$\text{Superheat}=T_{\text{measured vapor}}-T_{\text{dew}}$$

9.2 Subcooling Logic

At the measured liquid pressure:

MEASURED LIQUID PRESSURE
→ FIND BUBBLE-POINT SATURATION TEMPERATURE
→ COMPARE WITH ACTUAL LIQUID-LINE TEMPERATURE

Then:

$$\text{Subcooling}=T_{\text{bubble}}-T_{\text{measured liquid}}$$

9.3 Do Not Average Automatically

Do not automatically use:

(Tbubble + Tdew) / 2

for technician superheat or subcooling calculations.

For the calculations emphasized in this course:

SUPERHEAT → DEW
SUBCOOLING → BUBBLE

unless the specific manufacturer procedure states otherwise.

10. Temperature-Indexed Versus Pressure-Indexed Blend Tables

A P-T reference can be organized in either direction.

10.1 Temperature-Indexed Table

The selected R-407C table in this appendix is:

KNOWN TEMPERATURE
→ READ BUBBLE PRESSURE / DEW PRESSURE

Example:

40°F
→ bubble pressure 80.2 psig
→ dew pressure 63.2 psig

10.2 Pressure-Indexed Table

A technician electronic P-T tool may instead provide:

KNOWN PRESSURE
→ READ BUBBLE TEMPERATURE / DEW TEMPERATURE

This format is especially convenient for:

• Superheat.
• Subcooling.

Both formats describe the same saturation boundaries.

The direction of lookup changes, not the physics.

11. Static Cylinder P-T Screening

A P-T comparison can be useful when a cylinder contains both liquid and vapor and has stabilized near thermal equilibrium.

Use:

IDENTIFY REFRIGERANT
→ ALLOW TEMPERATURE TO STABILIZE
→ MEASURE REFRIGERANT / CYLINDER TEMPERATURE
→ MEASURE PRESSURE
→ COMPARE WITH VERIFIED P-T DATA

A significant mismatch can suggest the need to investigate:

• Noncondensables.
• Wrong refrigerant.
• Mixed refrigerant.
• Measurement error.
• Incomplete thermal stabilization.

A mismatch does not prove one specific cause.

12. Operating-System Pressure Is Not Automatically a Static P-T Test

In a running refrigeration system:

• Vapor can be superheated.
• Liquid can be subcooled.
• Pressure drops occur through piping/components.
• Compressor operation creates pressure differences.
• Heat transfer changes local refrigerant condition.

Therefore:

OPERATING PRESSURE
≠
AUTOMATIC STATIC SATURATION CHECK

P-T data remains essential because it converts operating pressure into the relevant saturation temperature used for:

• Evaporating saturation temperature.
• Condensing saturation temperature.
• Superheat.
• Subcooling.

13. Interpolation

For the existing course numerical questions:

NO INTERPOLATION IS REQUIRED

because the required values are listed directly.

For field work or a future problem where the desired value falls between two table entries:

• Prefer current manufacturer software/app or a verified detailed table.
• Interpolate only when the required accuracy and procedure permit it.
• Do not invent a P-T value from memory.
• Do not extrapolate beyond the valid data range.

The broader Section 11.18 technician tables should minimize the need for manual interpolation by using practical temperature increments.

14. Rounding and Precision

The values in these selected tables are reproduced to the precision shown by the source chart, generally:

0.1 psig

Do not create false precision by adding unnecessary decimal places.

For example:

R-134a at 40°F
→ 35.0 psig

should not be rewritten as:

35.00000 psig

unless a higher-precision source and calculation actually justify that precision.

15. Data Verification Record

15.1 Primary Source Check

The selected numerical values in Sections 3, 5, 6, and 8 were checked against the current online:

Arkema Forane® Refrigerants
Pressure Temperature Chart

The chart:

• Identifies pressure as PSIG.
• Identifies saturation temperature as °F.
• Provides separate liquid/vapor pressure columns for R-407C.
• Includes R-22, R-134a, and R-410A.
• States that its data were generated using NIST REFPROP Version 10.0.

15.2 Cross-Check

The selected values were also compared with Arkema’s separate:

Forane® Refrigerants Quick Reference Guide

The overlapping selected R-22, R-134a, R-407C, and R-410A values agree with the values used in this appendix.

15.3 Existing Course Consistency Check

The current Module 4 answer file already source-controls these R-134a values:

25°F → 22.1 psig
40°F → 35.0 psig
50°F → 45.4 psig

This appendix preserves those exact values so the course does not create a conflicting P-T reference.

16. Copyright and Reuse Note

This appendix does not reproduce a complete manufacturer P-T chart.

Instead, it provides:

• A small number of factual numerical values selected for course use.
• A new table organization created for this project.
• Source identification and verification notes.
• Explanations developed specifically for this course.

For complete field P-T data, use:

• The refrigerant manufacturer’s current P-T chart/app.
• Verified refrigerant property software.
• The planned 11.18 - Common Refrigerant Pressure-Temperature Tables.md.

17. Course Question Coverage Audit

Standalone-Course Requirement

The current numerical P-T questions in Modules 1-10 can be completed without obtaining an outside P-T chart.

18. Common Mistakes and Confusing Points

Mistake 1 - Using the Wrong Refrigerant Table

At 40°F:

R-134a = 35.0 psig
R-22 = 68.6 psig
R-410A = 118.8 psig

The values are not interchangeable.

Mistake 2 - Comparing psig With psia Directly

A regulatory classification may use:

psia

while a field P-T chart uses:

psig

Convert the pressure reference correctly before comparing values.

Mistake 3 - Treating R-407C Bubble and Dew Values as Duplicate Data

They are two different saturation boundaries.

BUBBLE
→ saturated liquid

DEW
→ saturated vapor

Mistake 4 - Using Bubble for Superheat

Superheat concerns vapor.

Use:

DEW

for a zeotropic blend.

Mistake 5 - Using Dew for Subcooling

Subcooling concerns liquid.

Use:

BUBBLE

for a zeotropic blend.

Mistake 6 - Assuming Pressure Alone Identifies Refrigerant

Pressure depends on temperature and condition.

Unknown or contaminated refrigerant should be identified with proper procedures and equipment.

Mistake 7 - Applying a Static Cylinder Comparison Immediately After Recovery

Recovery can heat the cylinder and refrigerant.

Allow stabilization before using a static P-T comparison.

Mistake 8 - Treating Saturation Temperature as Actual Line Temperature

For superheated vapor:

Tactual > Tsaturation

For subcooled liquid:

Tactual < Tsaturation

Mistake 9 - Memorizing P-T Numbers Instead of Using a Table

The course tests the ability to:

READ
INTERPRET
APPLY

P-T data.

It does not require memorizing hundreds of refrigerant property values.

19. EPA 608 Exam Focus

Students should be able to:

• State what a P-T chart relates.
• Identify the refrigerant before using P-T data.
• Distinguish psig from psia.
• Read saturation temperature from a supplied pressure.
• Read saturation pressure from a supplied temperature.
• Explain why a static cylinder must stabilize before P-T screening.
• Recognize that pressure alone does not conclusively identify refrigerant.
• Select dew for zeotropic-blend superheat.
• Select bubble for zeotropic-blend subcooling.
• Recognize that different refrigerants have different pressures at the same temperature.
• Avoid automatically averaging bubble and dew values.

Required Current Course Lookup

R-134a
25°F → 22.1 psig
40°F → 35.0 psig
50°F → 45.4 psig

20. Fast Reference

Pure / Single-Saturation Course Reference

Zeotropic-Blend Reference

21. Cross-Reference Guide

References

Primary Numerical Reference

1. Arkema, Forane® Refrigerants Pressure Temperature Chart, current online chart accessed August 14, 2026.
   https://forane.arkema.com/files/live/sites/shared_arkema/files/downloads/fluorochemicals/Forane%20Ref%20PT%20Regular%20Chart%20EN

Cross-Check Reference

2. Arkema, Forane® Refrigerants Quick Reference Guide, pressure-temperature chart, accessed August 14, 2026.
   https://forane.arkema.com/files/live/sites/fluorogases_forane_arkema/files/downloads/literature/forane-quick-reference-guide.pdf

Independent Property-Data Context

3. National Institute of Standards and Technology, Thermophysical Properties of Fluid Systems, NIST Chemistry WebBook, accessed August 14, 2026.
   https://webbook.nist.gov/chemistry/fluid/

4. National Institute of Standards and Technology, NIST REFPROP: Reference Fluid Thermodynamic and Transport Properties Database, Version 10.0, identified by the current Arkema P-T chart as the source used to generate its property data.

Blend Interpretation Reference

5. The Chemours Company, Temperature Glide in Freon™ MP, HP, and 407C Refrigerant Blends, accessed August 14, 2026. The technical bulletin distinguishes saturated-liquid/bubble and saturated-vapor/dew temperatures and explains use of saturated-vapor temperature for superheat and saturated-liquid temperature for subcooling.

Course Cross-References

6. 3.3 - Temperature Glide Bubble Point and Dew Point

7. 4.6 - Gauge Pressure Absolute Pressure and Vacuum

8. 4.7 - Pressure-Temperature Relationships

9. 4.8 - Superheat and Subcooling

10. 4.10 - Practice Questions

11. 4.11 - Answers and Explanations