Medium Temperature Retrofit from R12 to R134a

Application Bulletin 120

Application Bulletin Number: Release EN: Date: Revision EN: Date:

120 A25607 12/17/93 Z27301 10/2/15

Subject: Medium Temperature Retrofit from R12 to R134a These are general guidelines only and in no way should they replace, contradict or otherwise take precedence over any local, state or federal law or regulation pertaining to the replacement, reclamation, and recycling of refrigerants. Bristol Compressors does not recommend the changeover of CFC refrigerants to HCFCs or HFCs in systems that are operating properly and have no leaks.

EVAPORATOR TEMPERATURE (°F) -15

C O N D E N S E R T E M P E R A T U R E (°F)

-10

-5

0

10

15

20

30

80

90

APPROVED WINDOW OF OPERATION 100

110

120

130

Figure 1

New Medium Temperature R134a Compressors are identified by the number 4 in the second digit of the model number (example: M4NB262EBAB). The compressors with the 4 in the model number are factory oil charged with Polyolester lubricant. Other medium temperature R12 "B" series (example: M1NB262EBAB) compressors can be used with R134a after draining the mineral oil and charging with Polyolester lubricant as described in paragraph 6.3.2. Bristol's lubricants approved for use with R134a are Polyolester Mobil 22A, ICI 32S and Castrol SW32. The use of any other lubricant may void the compressor warranty. The amount of oil charge for each model is listed in the compressor specification.

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Application Bulletin 120 Page 2

SYSTEM DESIGN 1.0

Refrigerant Metering Devices The performance of each system is very dependent on the proper operation of each metering device. Devices such as solenoid valves, capillary tubes, fixed orifice valves, and expansion valves can perform differently if they are not correctly adjusted or properly sized. For example, the port size of a valve may not be correct for the new refrigerant density. Each valve and metering device manufacturer should be consulted along with the system's manufacturer to ensure all components will work properly in the presence of the new refrigerant and lubricant.

2.0

Filters/Driers The proper selection of a system's filter drier is very important. Some filter driers may not be suitable for the new refrigerant and lubricant. Therefore, the original equipment manufacturer should be contacted for the proper filter drier selection with each new refrigerant and lubricant. It is important to replace the filter drier any time the refrigerant or lubricant in a system is changed. Specifically, Bristol Compressors requires a new suction line filter drier be installed during any compressor replacement. Maintaining good system performance, reliability and cleanliness is closely linked to proper filter drier operation.

3.0

Controls The proper operation of many types of refrigeration equipment requires that the control systems function correctly. The control system could be pressure controls, temperature controls, timing devices, or sophisticated electronic controls. Changing the refrigerant and oil in a system could adversely affect these control systems. Each equipment manufacturer should be consulted to ensure each control system will operate correctly in the presence of a new refrigerant/lubricant combination. Changes most likely will have to be made for continued good equipment performance. These changes could involve adjusting temperature or pressure set points to new values or replacing the control system with a newly designed unit.

4.0

Explanation of R134a vs. R12 Condenser and Evaporator Temperature/Pressure Graphs The graphs on pressure versus temperature are included as a general information guideline. The specific saturated property tables supplied by the chemical manufacturer should be used when conducting system retrofits. The graphs are intended to represent the pressures that R134a delivers versus R12 at the equivalent saturated evaporator and condenser temperatures.

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Application Bulletin 120 Page 3

Saturated Properties of R134a and R12 - Pressure vs. Temperature Graph

Pressure (psia)

Condenser Temperature vs. Pressure

215 210 205 200 195 190 185 180 175 170 165 160 155 150 145 140 135 130 125 120 115 110 105 100

R134A R12

80

90

100 110 Condenser Temperature (°F)

120

130

Figure 2

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Application Bulletin 120 Page 4

Pressure (psia)

Evaporator Temperature vs. Pressure

70 68 66 64 62 60 58 56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10

R134A R12

-20

-10

0

10 20 Evaporator Temperature (°F)

30

40

Figure 3

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50

TABLE 1 Pressure-Temperature Chart Pressure

R134a Saturation

(psig)

Temperature (°F)

15*

-40

10*

-30

5*

-21

0

-15

5

-3

10

7

15

15

20

22

30

35

35

40

40

45

45

50

50

54

55

58

60

62

65

66

70

69

75

73

80

76

85

79

90

82

95

85

100

88

110

93

120

98

130

103

140

107

150

111

165

118

180

123

195

129

210

134

225

139

240

143

255

148

270

152

285

156

300

160

*Inches of Hg. vacuum Revision Z27301

Application Bulletin 120 Page 6

5.0

Maximum Continuous Current (MCC) Data Extensive testing of many compressors with the new refrigerant versus the existing refrigerant have been tested at maximum continuous current (MCC) conditions. The MCC values of the compressors do not change from published R12 values with R134a refrigerant .

6.0

Retrofit Process Retrofit of an existing R12 system with R134a can be accomplished using service practices and equipment commonly used by trained mechanics or service contractors in the field . 6.1

The key steps involved in the retrofit are: - Find the reason for the R12 system/compressor failure and correct - Recover R12 charge from system - Replace filter drier with new filter drier compatible with R134a - Install new compressor and evacuate - Charge system with R134a - Start system and adjust charge and/or controls to achieve desired operation - Label system "Charged with R134a Refrigerant"

6.2

Equipment and supplies needed for retrofit: (Refer to refrigerant manufacturer guidelines) - Safety equipment (gloves, glasses) - Refrigeration manifold gauges - Thermocouples - Vacuum pump - Leak detection equipment - Scale - Recovery unit - Recovery cylinder - Replacement refrigerant - Replacement/approved drier

6.3

Retrofit Procedure: Summarized below is a discussion of the recommended procedures for retrofitting an R12 system to R134a: 6.3.1

Remove R12 Charge. R12 should be removed from the system and collected in a recovery cylinder using a recovery device capable of pulling 10-20 in. Hg vacuum. If the correct R12 charge size for the system is not known, weigh the amount of refrigerant removed, as the initial quantity of R134a charged in the system will be determined from this figure.

6.3.2

Drain/Charge System Lubricant. If mineral oil is the existing lubricant in the system, it will have to be drained. This may require removing the compressor from the system, particularly with small hermetic compressors which have no oil drain. In this case, the lubricant can be drained from the suction line of the compressor. In most small systems, 90-95% of the lubricant can be removed from the compressor in this manner. Larger systems may require drainage from additional points in the system, particularly low spots around the evaporator, to remove the majority of the lubricant. In systems with an oil separator, any lubricant present in the separator should also be drained. In all cases, measure the volume of lubricant removed from the system. Compare to the compressor/system specifications to ensure that the majority of lubricant has been removed. Polyolester lubricant is recommended for use with R134a. In order to achieve equivalent miscibility to R12/mineral oil, the residual mineral oil should be about 5% by weight or less of the total lubricant used in the system. In larger systems, the amount of residual mineral oil can be achieved by using a flushing technique. Up to three lubricant flushes may be required. Flush after 24 to 48 hours of operation. Polyolester oils are very hygroscopic (ability to absorb moisture). This moisture is difficult to remove even with heat and vacuum. Extra care must be taken to prevent moisture from getting into the compressor and system. Do not leave compressor or system open to atmosphere for longer than 15 minutes maximum.

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6.3.3

Install Compressor. Use normal service practices.

6.3.4

Replace Filter Drier. Replace with approved R134a filter drier.

6.3.5

Reconnect System and Evacuate. Use normal service practices. To remove air and other non-condensables in the system, evacuate the system to 200 microns.

6.3.6

Leak Check System. Use normal service practices. If a leak detector is used consult the leak detector manufacturer for unit's sensitivity to R134a. Re-evacuate system following leak check if necessary.

6.3.7

Charge System with R134a. R134a can be charged to the system from either the vapor or liquid phase of the cylinder (the same as R12). The refrigerant system will require less weight of R134a than R12. The optimum charge will vary depending on the operating conditions, size of the evaporator and condenser, size of the receiver (if present), and the length of pipe or tubing runs in the system. For most systems, the optimum charge will be 90% by weight of the original equipment manufacturer R12 charge. It is recommended that the system be initially charged with about 90% by weight of the correct R12 charge. Liquid refrigerant should never enter the suction side of the compressor as this can damage the compressor. If removing liquid from the cylinder and charging to the suction of the compressor, a throttling valve can be used to ensure that the liquid is converted to vapor prior to entering the system.

7.0

6.3.8

Start Up System and Adjust Charge. Start up the system and let conditions stabilize. If the system is undercharged, add additional R134a in small amounts until the system conditions reach the desired levels. Refer to the R134a Pressure-Temperature chart (Table 1). In general, the suction pressure for R134a will run from 1 psia to 3 psia lower than the suction pressure for R12. R134a will have higher discharge pressures and lower discharge temperatures when compared to R12 operation. A typical increase in discharge pressure would be 15 to 25 psia; a typical decrease in discharge temperature would be from 0 to 10°F.

6.3.9

Label Components and System. After retrofitting the system with R134a, label the system components to identify the type of refrigerant R134a) and lubricant in the system, so that the proper refrigerant and lubricant will be used to service the equipment in the future.

Summary With the phase-out of CFCs, existing refrigeration equipment will need to be replaced with new equipment or retrofitted with alternative refrigerants. Using the procedures described above, existing R12 refrigeration systems can be retrofitted for use with R134a, allowing them to continue in service for the remainder of their useful life. Attached is a Retrofit Checklist (Appendix 1) for R134a to assist you in the retrofit process and a System Data Sheet (Appendix 2) to record the system operating conditions for your records.

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Appendix 1 Checklist for R134a Retrofit 1. Consult the original equipment manufacturer of the system components for their recommendation on the following: - Plastics compatibility - Elastomers compatibility - Lubricant (viscosity, manufacturer, additives) - Retrofit procedure to sustain warranty 2. Remove R12 charge from system (need 10-20 in. Hg vacuum to remove charge). Use recovery cylinder --Do not vent to atmosphere-3. Replace filter drier with new drier approved for use with R134a. - Loose fill driers: use XH7 or XH9 desiccant or equivalent - Solid core driers: check with drier manufacturer for recommendation 4. Reconnect system and evacuate with vacuum pump. (Evacuate to 200 microns.) 5. Leak check system. (Re-evacuate system following leak check.) 6. Charge system with R134a. - Initially charge 90% by weight of original equipment manufacturer specified R12 charge. - Amount of refrigerant charged: _________ 7. Start up equipment and adjust charge until desired operating conditions are achieved. - If low in charge, add in increments of 2 - 3% of original R12 charge. - Amount of refrigerant charged: __________ 8. Total refrigerant charged (add 6 and 7): __________ 9. Label components and system for type of refrigerant (R134a) and lubricant (polyolester oil). 10. Conversion is complete!!

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Release EN Number A25607

Release Date 12/17/93

Revisions C24201

9/15/95

Z27301

10/2/15

Revision Z27301

D12109

5/10/96

Application Bulletin 120 Page 11