R134 REFRIGERANT BASIC INFORMATION AND TUTORIALS


The blended refrigerant R-134a is a long-term HFC alternative with similar properties to R-12. It has become the new industry-standard refrigerant for automotive air-conditioning and refrigerator/freezer appliances.

R-134a refrigerating performance will suffer at lower temperatures (below -10 degrees F). Some traditional
R-12 applications have used alternatives other than 134a for lower temperatures.
R-134a requires polyolester (POE) lubricants. Traditional mineral oils and alkyl benzenes do not mix with HFC refrigerants, and their use with 134a may cause operation problems or compressor failures.

In addition, automotive A/C systems may use polyalkaline glycols (PAGs), which are typically not seen in stationary equipment. Both POEs and PAGs will absorb moisture and hold onto it to a much greater extent than traditional lubricants.

The moisture will promote reactions in the lubricant as well as the usual problems associated with water corrosion and acid formation. The best way to dry a wet HFC system is to rely on the filter dryer. Deep vacuum will remove “free” water but not the water that has absorbed into the lubricant.

Appliances, both commercial and self-contained refrigeration, centrifugal chillers, and automotive air conditioning utilize R-134a. Retrofitting equipment with a substitute for R-12 is sometimes difficult; there are a number of considerations to be examined before undertaking the task:

1. For centrifugal compressors it is recommended that the manufacturer’s engineering staff become involved in the project—special parts or procedures may be required. This will ensure proper capacity and reliable operation after the retrofit.

2. Most older direct expansion systems can be retrofitted to R-401A, R-409A, R-414B, or R-416A (R 500 to R-401B or R-409A), so long as there are no components that will cause fractionation within the system to occur.

3. Filter driers should be changed at the time of conversion.

4. The system should be properly labeled with refrigerant and lubricant type.


R-12 Medium/High Temperature Refrigeration  (OF evap)
1. See Recommendation Table (this can be found on the National Refrigerants Web site—click on Technical Manual) for blends that work better in high ambient-heat conditions.

2. Review the properties of the new refrigerant you will use and compare them to R-12. Prepare for any adjustments to system components based on pressure difference or temperature glide.

3. Filter dryers should be changed at the time of conversion.

4. The system should be properly labeled with refrigerant and lubricant type. R-12 Low Temperature Refrigeration (20F evap)

1. See Recommendation Table for blends that have better low-temperature capacity.

2. Review the properties of the new refrigerant you will use and compare them to R-12. Prepare for any adjustments to system components based on pressure difference or temperature glide.

3. Filter dryers should be changed at the time of conversion.

4. The system should be properly labeled with refrigerant and lubricant type. Another blended refrigerant that can be used to substitute for R-12 is 401A . It is a blend of R-22, 152a, and 124. The pressure and system capacity match R-12 when the blend is running an average evaporator temperature of 10 to 20 degrees F. Applications for this refrigerant are as a direct expansion refrigerate for R-12 in air-conditioning systems and in R-500 systems.

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