High Temperature Retrofit from
R22 to R407C
Application Bulletin 124
Application Bulletin
Number:
Release EN:
Date:
Revision EN:
Date:
124
C18811
10/20/95
Z27301
10/2/15
Subject: High Temperature Retrofit from R22 to R407C
These are only general guidelines and in no way should they replace, contradict or otherwise take precedence
over any local, state or federal law or regulation pertaining to the recovery, reclamation, and recycling of refrigerants.
With the phase-out of HCFC’s, existing air conditioning/heat pump equipment will need to be replaced with new
equipment or retrofitted with new components (including the compressor) that are approved for use with the new
refrigerant and their lubricants. Using the procedures described below, existing R22 systems can be retrofitted for
use with R407C, allowing them to continue in service for the remainder of their useful life. Bristol Compressors
does not recommend the changeover of HCFC refrigerants to HFC’s in systems that are operating and have no
leaks.
R407C is a zeotropic blend of refrigerants of the following composition:
R32
R125
R134a
23%
25%
52%
New High Temperature R407C Compressors are identified by the number 7 in the second digit of the model
number (example: H75B28QABC). These compressors are factory oil charged with Polyolester (POE) lubricant
and employ an improved lubrication system which are required for the new refrigerant .
For Bristol’s approved lubricant type and required oil charge amounts for use with R407C, refer to the individual
compressor model specification sheet. This information can be found on Bristol’s website
www.bristolcompressors.com. The use of any other lubricant may void the compressor warranty.
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 R407C refrigerant and Polyolester lubricant. Therefore, the original equipment manufacturer should
be contacted for the proper filter drier selection. 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
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Application Bulletin 124
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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 air conditioning/heat pump equipment requires that the control systems function correctly. The control system could be pressure controls, temperature controls, timing devices, or sophisticated electronic controls. Changing to R407C refrigerant and polyol ester lubricant in a system could adversely affect these control systems. Each equipment manufacturer should be consulted to
ensure each control system will operate correctly with the R407C refrigerant/polyol ester 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 R407C vs. R22 Condenser and Evaporator Temperature/Pressure Graphs
Pressure versus temperature charts and graphs are included on pages 4 through 8 as a general information
guideline. More detailed specific saturated property tables can be obtained from the chemical manufacturer
and should be used when conducting system retrofits. The graphs are intended to represent the pressures
that R407C delivers versus R22 at the equivalent saturated evaporator and condenser temperatures.
4.1
Explanation of refrigerant glide inherent to R407C
4.1.1 R407C has refrigerant “glide”. Glide is due to the different boiling and condensing temperatures of the three components that make up R407C. This means there is not a one to one
relationship between pressure and temperature as with R22. The saturated vapor and saturated liquid values are approximately 10°F apart for a given pressure, whereas with R22 they are
one and the same.
4.1.2 The temperature glide of this refrigerant should not cause any problems as long as you keep
in mind the following points about the relationship between pressures and temperatures of the
evaporator and condenser.
a)
When specifying the evaporating and condensing temperatures use the mean (or
average of dew and bubble point) temperatures.
b)
When setting evaporator superheat, calculate it from the saturated vapor (or dew point)
temperature.
c)
When setting subcooling, calculate it from the saturated liquid (or bubble point) temperature.
4.1.3 Specific examples: (Some interpolation between values may be required)
4.1.3.1
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Set conditions to run a 45°F evaporator, 130°F condenser with 20°F superheat and
15° liquid subcooling.
a)
Find the 45°F mean temperature from Table 1. The pressure corresponding
to this mean temperature is your suction pressure = 94.4 psia.
b)
Calculate the return gas temperature using the dew point temperature at this
pressure. Example: 50.59°F + 20°F superheat = 70.59°F return gas temperature.
c)
Find 130°F mean temperature from Table 1. The pressure corresponding to
this mean temperature is your discharge pressure = 339.4 psia.
d)
Calculate the liquid temperature using the bubble point temperature at this
pressure. Example: 126°F - 15°F subcool = 111°F liquid temperature.
Application Bulletin 124
Page 3
4.1.3.2
Determine the amount of superheat on a system that measures a suction pressure
of 68 psig at the bulb, and the temperature at the bulb reads 52°F.
a)
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Convert 68 psig to psia = 68 + 14.7 (atmospheric pressure) = 82.7 psia. Look
up the dew point temperature from Table 1 at 82.7 psia. This value is 43.3°F.
Your superheat is 52°F - 43.3°F = 8.7°F
Application Bulletin 124
Page 4
R407C PRESSURE/TEMPERATURE TABLE
Saturated Liquid and Saturated Vapor Properties
PSIA
PRESSURE
PSIG
DEW POINT
°F
MEAN TEMP
°F
BUBBLE POINT
°F
10
-4.7
-47.90
-54.48
-61.06
11
-3.7
-44.64
-51.18
-57.72
12
-2.7
-44.59
-49.61
-54.62
13
-1.7
-38.75
-45.24
-51.72
14
-0.7
-36.07
-42.53
-48.99
15
0.3
-33.53
-39.97
-46.40
16
1.3
-31.13
-37.54
-43.95
17
2.3
-28.84
-35.23
-41.62
18
3.3
-26.65
-33.03
-39.40
19
4.3
-24.56
-30.91
-37.26
20
5.3
-22.55
-28.89
-35.22
21
6.3
-20.62
-26.94
-33.25
22
7.3
-18.76
-25.06
-31.35
23
8.3
-16.96
-23.25
-29.53
24
9.3
-15.23
-21.50
-27.76
25
10.3
-13.55
-19.80
-26.05
26
11.3
-11.92
-18.16
-24.39
27
12.3
-10.34
-16.56
-22.78
28
13.3
-8.0
-15.01
-21.21
29
14.3
-7.31
-13.50
-19.69
30
15.3
-5.85
-12.03
-18.21
31
16.3
-4.44
-10.60
-16.76
32
17.3
-3.05
-9.20
-15.35
33
18.3
-1.70
-7.84
-13.98
34
19.3
-0.38
-6.51
-12.64
35
20.3
0.90
-5.21
-11.32
36
21.3
2.16
-3.94
-10.04
37
22.3
3.40
-2.69
-8.78
38
23.3
4.61
-1.47
-7.55
39
24.3
5.79
-0.28
-6.34
40
25.3
6.95
0.90
-5.16
45
30.3
12.44
6.44
0.43
50
35.3
17.47
11.52
5.57
TABLE 1
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Page 5
R407C PRESSURE/TEMPERATURE TABLE (Page 2)
PSIA
PRESSURE
PSIG
DEW POINT
°F
MEAN TEMP
°F
BUBBLE POINT
°F
55
40.3
22.14
16.23
10.32
60
45.3
26.48
20.62
14.76
65
50.3
30.56
24.74
18.92
70
55.3
34.40
28.63
22.85
75
60.3
38.04
32.31
26.57
80
65.3
41.50
35.80
30.10
85
70.3
44.79
39.13
33.47
90
75.3
47.94
42.32
36.69
95
80.3
50.96
45.37
39.78
100
85.3
53.85
48.30
42.75
105
90.3
56.64
51.13
45.61
110
95.3
59.33
53.85
48.37
115
100.3
61.93
56.49
51.04
120
105.3
64.44
59.03
53.62
125
110.3
66.87
61.50
56.12
130
115.3
69.23
63.89
58.54
135
120.3
71.52
66.21
60.90
140
125.3
73.74
68.47
63.19
145
130.3
75.91
70.67
65.42
150
135.3
78.02
72.81
67.59
155
140.3
80.07
74.89
69.71
160
145.3
82.08
76.93
71.78
170
155.3
85.95
80.87
75.78
180
165.3
89.64
84.62
79.60
190
175.3
93.19
88.23
83.27
200
185.3
96.59
91.70
86.80
210
195.3
99.86
95.03
90.20
220
205.3
103.01
98.25
93.48
230
215.3
106.05
101.35
96.65
240
225.3
109.00
104.36
99.71
250
235.3
111.84
107.27
102.69
260
245.3
114.60
110.09
105.58
270
255.3
117.28
112.83
108.38
280
265.3
119.88
115.50
111.11
290
275.3
122.41
118.09
113.77
TABLE 1
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R407C PRESSURE/TEMPERATURE TABLE (Page 3)
PRESSURE
PSIA
PSIG
DEW POINT
°F
MEAN TEMP
°F
BUBBLE POINT
°F
300
285.3
124.88
120.62
116.36
310
295.3
127.27
123.08
118.89
320
305.3
129.61
125.49
121.36
330
315.3
131.89
127.83
123.77
340
325.3
134.12
130.13
126.13
350
335.3
136.29
132.37
128.44
360
345.3
138.41
134.56
130.70
380
365.3
142.52
138.81
135.09
390
375.3
144.51
140.87
137.22
400
385.3
146.46
142.89
139.31
410
395.3
148.37
144.87
141.37
420
405.3
150.24
146.81
143.38
430
415.3
152.08
148.73
145.37
TABLE 1
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Application Bulletin 124
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Saturated Properties
HP81 vs. R502 - Pressure vs. Temperature Graph
Condenser Temperature vs. Pressure
370
360
350
HP81
340
R502
330
320
310
Pressure (psia)
300
290
280
270
260
250
240
230
220
210
200
190
180
170
160
150
80
90
100
110
120
130
Condenser Temperature (°F)
Figure 2
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Pressure (psia)
Evaporator Temperature vs. Pressure
86
84
82
80
78
76
74
72
70
68
66
64
62
60
58
56
54
52
50
48
46
44
42
40
38
36
34
HP81
R502
-10
0
10
Evaporator Temperature (°F)
20
30
Figure 3
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TABLE 1
Pressure-Temperature Chart
Saturated Vapor Temperature °F
Pressure (psig)
(1)
HP81
(1)
Saturated Vapor Temperature °F
R502
Pressure (psig)
HP81(1)
R502
0
-49
-50
46
14
15
2
-44
-45
48
16
16
4
-39
-40
50
17
18
6
-35
-36
52
19
20
8
-32
-32
54
20
21
10
-28
-29
56
22
23
12
-25
-25
58
23
24
14
-22
-22
60
25
26
16
-19
-19
62
26
28
18
-16
-16
64
28
29
20
-13
-13
66
29
30
22
-11
-11
68
31
32
24
-8
-8
70
32
33
26
-6
-6
72
33
34
28
-4
-3
74
34
36
30
-1
-1
76
36
37
32
1
1
78
37
38
34
3
3
80
38
40
36
5
5
85
41
43
38
7
7
90
44
46
40
8
9
95
47
49
42
10
11
100
50
51
44
12
13
105
52
54
Saturated Vapor Temperature (Dew Point)--The temperature (at a given pressure) at which the last drop
of liquid HP81 has boiled. It is also the temperature (at a given pressure) where condensation begins.
Above this temperature (at the same pressure), the refrigerant is superheated vapor.
NOTE: For HP81 the mean evaporator temperature where a change of state occurs is approximately 1°F below
the saturated vapor temperature. For example, at a saturated vapor temperature of 11°F, the mean evaporator temperature is approximately 10°F.
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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 does change with a new refrigerant
due to the different load the new refrigerant places on the compressor. HP81 refrigerant, for example, increases the heat load on the compressor causing the thermal protector to trip (open) sooner. Therefore,
the MCC for HP81 is typically lower than R502.
6.0
Retrofit Process
Overview: Retrofit of an existing R502 system with HP81 can be accomplished using service practices and
service 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 502 system/compressor failure and correct
- Recover R502 charge from system
- Replace filter drier with new filter drier compatible with HP81
- Install new compressor
- Reconnect system and evacuate
- Charge system with HP81
- Start up system and adjust charge and/or controls to achieve desired operation
- Label system "Charged with HP81 Refrigerant"
6.2
Equipment and supplies needed for retrofit: (Refer to refrigerant manufacturer guidelines)
- Safety equipment
- Refrigeration manifold gauges
- Thermocouples
- Vacuum pump
- Leak detection equipment
- Scale
- Recovery unit
- Recovery cylinder
- Replacement refrigerant
- Replacement/approved filter drier
6.3
Remove R502 Charge: R502 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 recommended R502
charge for the system is not known, weigh the amount of refrigerant removed, as the initial quantity
of HP81 to be charged into the system will be determined from this figure.
6.4
Replace Filter Drier: It is recommended to replace the filter drier following system maintenance.
Consult the filter drier manufacturer for their recommended filter drier to use with HP81. Currently,
ALCO's ADK and Sporlan's Catch-All solid core driers are acceptable with HP81. Others may also
be acceptable; again, consult the manufacturer.
6.5
Reconnect System and Evacuate: Use normal service practices. To remove air or other noncondensables in the system, it is recommended that the system be evacuated to 200 microns.
6.6
Leak Check System: Use normal service practices. Evacuate system following leak check with
any gas.
6.7
Charge System with HP81: HP81 is a near-azeotropic mixture; therefore, the vapor composition in
the cylinder is different from the liquid composition. To ensure that the proper refrigerant composition is charged in the system, it is important that liquid only be removed from the charging cylinder.
Cylinders of HP81 are equipped with dip tubes, allowing liquid to be removed from the cylinder
when the cylinder is in the upright position. The proper position is indicated by arrows on the cylinder and cylinder box. Once removed from the cylinder, HP81 can be charged to the system as vapor as long as all of the refrigerant removed from the cylinder is transferred to the system.
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Due to the liquid density difference of HP81 versus R502, the refrigeration system will require less
weight of HP81 than R502. The optimum charge will vary depending on the operating conditions,
size of the evaporator and condenser, size of receiver (if present), and length of pipe or tubing runs
in the system. For most systems, the optimum charge will be 90-95% by weight of the original
R502 charge. It is recommended that the system be initially charged with about 90% by weight of
the original R502 charge.
Add the initial charge to the liquid line of the system with the compressor not running. When the
system and cylinder pressures are equal, load the remainder of the refrigerant into the suction line
of the system. In this step, the compressor will be running. Some compressors may be damaged if
liquid refrigerant enters the suction side of the compressor. Since liquid must be removed from the
charging cylinder, it is important to charge the refrigerant slowly into the suction line to allow it to
vaporize before it enters the system. A throttling valve may be used to cause the refrigerant to vaporize.
7.0
6.8
Start up System and Adjust Charge: Start up the system and let conditions stabilize. If the system
is undercharged, add additional HP81 in small amounts (still removing liquid from the charging cylinder) until the system conditions reach the desired levels. HP81 is more sensitive to charge size
than R502. Therefore, system performance will change more quickly if the system is not optimally
charged with HP81 and it is important not to overcharge the system (refer to Installation and Service Instructions).
6.9
Label Components and System: After retrofitting the system with HP81, label the system components to identify the type of refrigerant (HP81) and lubricant (3GS Mineral Oil) in the system so that
the proper refrigerant and lubricant will be used to service the equipment in the future. Identification
labels are available from DuPont.
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 R502 refrigeration systems can be retrofitted for use with HP81, allowing them to continue in service for the remainder of
their useful life.
Attached is a Retrofit Checklist (Appendix 1) for HP81 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 HP81 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 R502 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 HP81.
- 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 HP81.
- Initially charge 90% by weight of original equipment manufacturer specified
R502 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 R502 charge.
- Amount of refrigerant charged: __________
8. Total refrigerant charged (add 6 and 7): __________
9. Label components and system for type of refrigerant (HP81) and lubricant (3GS
Mineral Oil).
10. Conversion is complete!!
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Release EN Number A23707
Release Date 11/5/93
Revisions
C24201
Revision Z27301
9/15/95
Z27301
10/2/15
Application Bulletin 124
Page 15