2. 6
Introduction to Refrigerants

3. Objectives
Recognize the effect of halogenated refrigerants on the ozone layer.
Summarize Environmental Protection Agency regulations governing refrigerants.
Differentiate between CFC, HCFC, HFC, and blended refrigerants.
Identify refrigerants according to their series number and cylinder color code.

4. Objectives
Interpret pressure-temperature curves, pressure-enthalpy tables, and pressure-enthalpy diagrams.
Summarize the properties and common applications of different refrigerants.
Identify which types of refrigerants are compatible with which lubricants.

5. Ozone Layer Ozone filters ultraviolet radiation
Protects humans, plants, and animals
Maintains stable temperatures
Ozone depletion may have harmful effects
Increase in skin cancer and eye damage
Climate change

6. Refrigerants and the Ozone Layer
Montreal Protocol
Banned production of chlorofluorocarbons (CFCs)
Resulted in development of new refrigerants

7. Clean Air Act (CAA) Federal law Results of Clean Air Act
Guidelines, restrictions, and penalties for releasing refrigerants into the atmosphere
Fines up to $37,500 per day for failure to comply
Results of Clean Air Act
Training and certification required to handle refrigerants
Prevention of significant purposeful releases of refrigerants into atmosphere
Exceptions allow HVACR technicians to do their job

8. Methods to Measure Impact
Ozone depletion potential (ODP)
Compares refrigerant to R-11
Numeric value assigned to each refrigerant
Scale 0 to 1
Value of R-11 = 1
Global warming potential (GWP)
Ratio of substance’s warming effect to that of carbon dioxide
Higher GWP = higher risk of environmental damage

9. ODP and GDP of Refrigerants

10. CFC Refrigerants First halogen-based refrigerants
Composed of chlorine, fluorine, and carbon
Chlorine atoms break apart ozone molecules
Major cause of ozone depletion
No longer manufactured
May still be found in equipment produced before 1995

11. HCFC Refrigerants Composed of hydrogen, chlorine, fluorine, and carbon
Partially halogenated
Have less impact on ozone layer than fully halogenated CFCs
High GWP
EPA requires phase-out by 2030

12. HFC Refrigerants Composed of hydrogen, fluorine, and carbon
Partially halogenated
No chlorine atoms
ODP = 0, but high GWP
Being replaced by lower GWP alternatives
Carbon dioxide
Hydrocarbons
Hydrofluoroolefins (HFOs)

13. Refrigerant Classifications

14. Refrigerant Blends Mixture of two or more refrigerants Classifications
Azeotropes
Zeotropes
Near-azeotropes
Never attempt to make a zeotropic or azeotropic blend

15. Azeotropic Refrigerant Blends
Respond to changes in pressure and temperature like a single refrigerant
Maintain consistent properties
Most contain a phased-out refrigerant
Often called “azeotropes”

16. Zeotropic Refrigerant Blends
Individual refrigerants in a blend respond differently to conditions
Operate under a range of boiling and condensing points
Separation (fractionation) of individual refrigerants
Individual temperature glides
Can change phase and temperature simultaneously
Near-azeotropic refrigerant blends
Similar to zeotropic blends
Narrower range of boiling and condensing points

17. Identifying Refrigerants
First digit indicates refrigerant series
Significance of remaining digits depends on refrigerant’s classification

18. Refrigerant Numbering System
000, 100, 200, 300 series
400, 500, 600, 1000 series
Third number from right indicates series
Next two numbers are assigned sequentially
700 series
Next two numbers are molecular weight

19. Refrigerant Cylinder Color Code
Helps prevent accidental mixing
Not a requirement for all manufacturers
Always read label
Identify refrigerant by ASHRAE number

20. Refrigerant Toxicity and Flammability
Class A refrigerants not known to be toxic at or below 400 ppm
Class B refrigerants known to be toxic at or below 400 ppm
Flammability Ratings
1: No flammability
2: Low flammability
2L: Low flammability and slow burn velocity
3: High flammability

21. Toxicity and Flammability Ratings
Adapted from ANSI/ASHRAE Standard 34–2010

22. Refrigerant Safety Classifications

23. Pressure-Temperature Curve
Shows relationship between refrigerant’s temperature and pressure
Used to determine if unit is operating at correct temperature or pressure
Other methods to determine temperature
Pressure-Temperature charts
Approximation using tubing (skin) temperature

24. Pressure-Temperature Curve

25. Pressure-Enthalpy Table
Lists actual operating temperatures and pressures
Shows volume of 1 lb vapor and density of liquid refrigerant at given temperature
Shows enthalpy (heat content)
Vapor heat content  liquid heat content = latent heat

26. Pressure-Enthalpy Table

27. Pressure-Enthalpy Diagram
Visual graph of thermodynamic properties
Same information contained in pressure-enthalpy table
Used to help understand how each component functions in refrigeration cycle
Shows temperature glide for zeotropic blends

28. Simplified Pressure-Enthalpy Diagram

29. Pressure-Enthalpy Diagram (R-134a)

30. Coefficient of Performance
Ratio of refrigeration effect to heat of compression
Higher coefficient means better efficiency
Used to determine which refrigerant will be most effective in specific system

31. Refrigerant Applications
Based on pressure, temperature, and heat properties of refrigerant
Items to be considered
Boiling point of refrigerant
Latent heat of refrigerant
Operating temperatures
Operating pressures
Equipment size

32. Phaseout of Refrigerants
CFCs
Phaseout completed in 1996
May still be purchased from stockpile by EPA-certified technicians
HCFCs
Phaseout to be completed in 2020 in US
Illegal in new equipment since 2010
Complete phaseout by 2030

33. Commonly Used New Refrigerants
Automotive air conditioning
Transport refrigeration
R-404A
Medium- and low-temperature refrigeration
R-410A
Air conditioning

34. R-717 Ammonia Chemical compound of nitrogen and hydrogen
Low boiling point
Temperatures below zero without pressures below atmospheric
Large refrigerating effect with smaller machinery
Hazards
Flammable at 150,000 to 270,000 ppm
Strong effect on respiratory system

35. Safety When working with ammonia Wear tight-fitting respirator
Stand to one side when operating ammonia valve
Use sulfur candle or spray vapor to detect leaks
Follow all training and safety protocols

36. Cryogenic Fluids Often called freezants
Used in food processing plants to rapidly freeze food
Rapid freezing reduces ice crystals
Results in less damage to food during freezing
Must be kept in insulated-vacuum containers
Expendable

37. Safety When handling cryogenic fluids Never allow fluid to touch skin
Protect entire body with suitable clothing, helmets, and gloves

38. Expendable Refrigerants
Expendable refrigeration system
Releases refrigerant to atmosphere after one use
Uses expendable refrigerant
Refrigerant is not collected for reuse
Other names
Chemical refrigeration system
Open-cycle refrigeration system

39. Refrigeration Lubricants
Lubricant charged into refrigeration system with refrigerant
Lubricates contact between moving parts
Must be able to travel freely through all parts of the system
Characteristics of refrigeration lubricants
Low wax content
High thermal and chemical stability
Low pour point
Low viscosity

40. Wax Content Wax separation Floc test
Precipitates out of lubricant at low temperatures
Can plug control orifices and clog system
Floc test
Determines how easily wax separates
Floc point: Highest temperature at which precipitate appears

41. Stability and Flash Point
Thermal stability
Ability to remain stable in high heat areas
Chemical stability
Ability to not react chemically with refrigerants or other substances
Flash point
Temperature at which vapors from lubricant surface ignite

42. Viscosity Measure of liquid’s resistance to flow
Changes with temperature
Higher temperature reduces viscosity
Lower temperature increases viscosity
Pour point
Lowest temperature at which a lubricant will flow

43. Types of Refrigeration Lubricant
Categories
Mineral oils
Polyol ester
Alkylbenzene
Polyalkylene glycol
Type of lubricant should match type of refrigerant

44. Types of Refrigeration Lubricant

45. Handling Refrigeration Lubricants
Keep lubricants in sealed containers
Transfer lubricants in chemically cleaned containers and lines
Do not expose to air and moisture
Buy small sealed containers
Reseal container after withdrawing lubricant
Unused lubricant may pick up moisture or dirt

46. Adding Lubricant to a System
Ensure correct amount of lubricant
Too little shortens component life
Too much reduces refrigerant-pumping capacity
Follow manufacturer’s recommendations
Make sure lubricant is compatible with refrigerant
Add lubricant only if there are signs of leakage

47. Contaminated Lubricant
Lubricant should be translucent
Evidence of impurities
Discoloration
Odor
Metal shavings and chips
Replace contaminated lubricant
Replace driers and filters