RS-51 (R470B) Retrofit Guidelines
RETROFIT PROCEDURE TO REPLACE R404A OR R507
Replacing R404A or R507 with RS-51 essentially will follow the procedure specified by the equipment manufacturer for a refrigerant change. Since RS-51 is zeotropic it is very important that liquid, not vapor, refrigerant be added to the system.
1
Ensure the right equipment is available, eg recovery unit and cylinders, container for recovered lubricant, vacuum pump, weighing scales, replacement drier etc.
2
Before removing the R404A or R507A, operate the unit under standard operating conditions and record the pressures, temperatures, and any other relevant measurable data to establish unit performance. Typically, the appropriate standard conditions for setting up the unit will have already been specified by the equipment supplier.
3
Recover and weigh the R404A or R507A from the unit. The weight should be within the range specified by equipment manufacturer.
4
Replace the filter/drier and evacuate the system.
5
As in the case of R404A and R507, RS-51 should be used with a polyol ester lubricant.
6
Operate the unit under conditions similar to those used in Step 2, closely watching the liquid line sight glass, the compressor oil level sight glass and the suction superheat.
7
Operate the unit under conditions similar to those used in Step 2, closely watching the liquid line sight glass, the compressor oil level sight glass and the suction superheat.
8
RS-51 has a lower liquid flow rate than R404A and R507, so that it may be necessary to close the expansion device relative to its setting for R404A or R507.
9
The evaporator superheat should be checked and changed as necessary by adjusting the TX valve.
10
Existing TXV’s should be replaced with an R-134a valve of similar capacity to the existing R-404A or R-507A valve or modified by replacing the power element with an R-134a power element of similar temperature range as the existing power element. If the system has an electronic expansive device, select the parameters applicable to R134a.
Note:If liquid is observed in the suction line sight glass or the suction superheat is lower than required, close the TX valve further. If the equipment manufacturer recommends charging R404A or R507 by evaporator superheat or liquid sub-cooling, use the same amount of superheat or sub-cooling for RS-51.
11
If a liquid line sight-glass is fitted, charge to a full glass gradually adding more liquid RS-51 until only liquid is passing through the expansion valve. Do not overcharge the system.
12
If more refrigerant is added, re-adjust the expansion device superheat setting as required.
13
Check system thoroughly for leaks.
14
Remove all R404A or R507A labels and clearly label system RS-51.
Warning:Â It is highly recommended that the thermostatic expansion valve be checked and adjusted to compensate for small differences in the pressure temperature relationship of the replacement refrigerant when compared to the original refrigerant. Failure to check and adjust the valve could allow liquid refrigerant to enter the compressor and damage bearings and other compressor components.
RS-51 (R470B) Pressure/Temperature Comparison Values shown: “PSIG” *Denotes “HG” (Mercury)
| TEMPERATURE | RS-51 LIQUID BUBBLE PT. | RS-51 VAPOR DEW PT. | R404A Bold = Bubble Point | R507A | |
|---|---|---|---|---|---|
| °F | °C | PSIG | PSIG | PSIG | PSIG |
| -50 | -45.6 | 15.2 | *15.4 | *0.1 | 1.0 |
| -48 | -44.4 | 16.5 | *14.7 | 0.7 | 1.7 |
| -46 | -43.3 | 18.0 | *13.6 | 1.6 | 2.6 |
| -44 | -42.2 | 19.4 | *12.6 | 2.4 | 3.5 |
| -42 | -41.1 | 20.9 | *11.6 | 3.3 | 4.4 |
| -40 | -40.0 | 22.5 | *10.6 | 4.3 | 5.4 |
| -38 | -38.9 | 24.1 | *9.4 | 5.3 | 6.4 |
| -36 | -37.8 | 25.7 | *8.1 | 6.3 | 7.5 |
| -34 | -36.7 | 27.5 | *6.9 | 7.4 | 8.6 |
| -32 | -35.6 | 29.2 | *5.5 | 8.5 | 9.8 |
| -30 | -34.4 | 31.0 | *4.1 | 9.6 | 11 |
| -28 | -33.3 | 32.9 | *2.6 | 10.8 | 12.2 |
| -26 | -32.2 | 34.8 | *1.2 | 12.0 | 13.5 |
| -24 | -31.1 | 36.8 | 0.2 | 13.3 | 14.8 |
| -22 | -30.0 | 38.9 | 1.0 | 14.6 | 16.2 |
| -20 | -28.9 | 41.0 | 1.9 | 16.0 | 17.6 |
| -18 | -27.8 | 43.1 | 2.8 | 17.4 | 19.1 |
| -16 | -26.7 | 45.4 | 3.7 | 18.9 | 20.6 |
| -14 | -25.6 | 47.6 | 4.7 | 20.4 | 22.2 |
| -12 | -24.4 | 50.0 | 5.7 | 22.0 | 23.8 |
| -10 | -23.3 | 52.4 | 6.7 | 23.6 | 25.5 |
| -8 | -22.2 | 54.9 | 7.8 | 25.3 | 27.3 |
| -6 | -21.1 | 57.4 | 8.9 | 27.0 | 29.1 |
| -4 | -20.0 | 60.0 | 10.1 | 28.8 | 30.9 |
| -2 | -18.9 | 62.7 | 11.3 | 30.7 | 32.8 |
| 0 | -17.8 | 65.5 | 12.5 | 32.6 | 34.8 |
| 2 | -16.7 | 68.3 | 13.9 | 34.6 | 36.9 |
| 4 | -15.6 | 71.2 | 15.2 | 36.6 | 39 |
| 6 | -14.4 | 74.1 | 16.6 | 38.7 | 41.1 |
| 8 | -13.3 | 77.1 | 18.1 | 40.9 | 43.4 |
| 10 | -12.2 | 80.3 | 19.6 | 43.1 | 45.7 |
| 12 | -11.1 | 83.4 | 21.2 | 45.4 | 48.1 |
| 14 | -10.0 | 86.7 | 22.8 | 47.8 | 50.5 |
| 16 | -8.9 | 90.0 | 24.5 | 50.2 | 53 |
| 18 | -7.8 | 93.4 | 26.2 | 52.7 | 55.6 |
| 20 | -6.7 | 96.9 | 28.0 | 55.3 | 58.3 |
| 22 | -5.6 | 100.5 | 29.8 | 57.9 | 61 |
| 24 | -4.4 | 104.1 | 31.8 | 60.7 | 63.8 |
| 26 | -3.3 | 107.9 | 33.7 | 63.5 | 66.7 |
| 28 | -2.2 | 111.7 | 35.8 | 66.3 | 69.7 |
| 30 | -1.1 | 115.6 | 37.9 | 69.3 | 72.7 |
| 32 | 0.0 | 119.5 | 40.1 | 72.3 | 75.9 |
| 34 | 1.1 | 123.6 | 42.3 | 75.5 | 79.1 |
| 36 | 2.2 | 127.7 | 44.6 | 78.7 | 82.4 |
| 38 | 3.3 | 132.0 | 47.0 | 82.0 | 85.8 |
| 40 | 4.4 | 136.3 | 49.5 | 85.3 | 89.2 |
| 42 | 5.6 | 140.7 | 52.1 | 88.8 | 92.8 |
| 44 | 6.7 | 145.2 | 54.7 | 92.4 | 96.5 |
| 46 | 7.8 | 149.8 | 57.4 | 96.0 | 100.2 |
| 48 | 8.9 | 154.5 | 60.2 | 99.8 | 104.1 |
| 50 | 10.0 | 159.2 | 63.0 | 103.6 | 108 |
| 52 | 11.1 | 164.1 | 66.0 | 107.5 | 112 |
| 54 | 12.2 | 169.1 | 69.0 | 111.5 | 116.2 |
| 56 | 13.3 | 174.1 | 72.1 | 115.7 | 120.4 |
| 58 | 14.4 | 179.3 | 75.3 | 119.9 | 124.8 |
| 60 | 15.6 | 184.5 | 78.6 | 124.2 | 129.2 |
| 62 | 16.7 | 189.8 | 82.0 | 128.6 | 133.7 |
| 64 | 17.8 | 195.3 | 85.5 | 133.2 | 138.4 |
| 66 | 18.9 | 200.8 | 89.1 | 137.8 | 143.1 |
| 68 | 20.0 | 206.4 | 92.8 | 142.5 | 148 |
| 70 | 21.1 | 212.2 | 96.5 | 147.4 | 153 |
| 72 | 22.2 | 218.0 | 100.4 | 152.4 | 158.1 |
| 74 | 23.3 | 223.9 | 104.4 | 157.4 | 163.3 |
| 76 | 24.4 | 230.0 | 108.5 | 162.6 | 168.6 |
| 78 | 25.6 | 236.1 | 112.7 | 167.9 | 174.1 |
| 80 | 26.7 | 242.4 | 117.0 | 173.4 | 179.6 |
| 82 | 27.8 | 248.7 | 121.4 | 178.9 | 185.3 |
| 84 | 28.9 | 255.1 | 126.0 | 184.6 | 191.1 |
| 86 | 30.0 | 261.7 | 130.6 | 190.4 | 197.1 |
| 88 | 31.1 | 268.4 | 135.4 | 196.3 | 203.1 |
| 90 | 32.2 | 275.1 | 140.3 | 202.4 | 209.3 |
| 92 | 33.3 | 282.0 | 145.3 | 208.5 | 215.6 |
| 94 | 34.4 | 289.0 | 150.4 | 214.8 | 222.1 |
| 96 | 35.6 | 296.1 | 155.7 | 221.3 | 228.7 |
| 98 | 36.7 | 303.3 | 161.1 | 227.9 | 235.4 |
| 100 | 37.8 | 310.6 | 166.7 | 234.6 | 242.3 |
| 102 | 38.9 | 318.0 | 172.3 | 241.4 | 249.3 |
| 104 | 40.0 | 325.6 | 178.1 | 248.4 | 256.5 |
| 106 | 41.1 | 333.2 | 184.1 | 255.6 | 263.8 |
| 108 | 42.2 | 340.9 | 190.1 | 262.9 | 271.2 |
| 110 | 43.3 | 348.8 | 196.4 | 270.3 | 278.8 |
| 112 | 44.4 | 356.8 | 202.8 | 277.9 | 286.6 |
| 114 | 45.6 | 364.9 | 209.3 | 285.6 | 294.5 |
| 116 | 46.7 | 373.1 | 216.0 | 293.5 | 302.6 |
| 118 | 47.8 | 381.4 | 222.8 | 301.6 | 310.8 |
| 120 | 48.9 | 389.8 | 229.8 | 309.8 | 319.2 |
| 122 | 50.0 | 398.3 | 237.0 | 318.2 | 327.8 |
| 124 | 51.1 | 407.0 | 244.3 | 326.7 | 336.5 |
| 126 | 52.2 | 415.7 | 251.8 | 335.4 | 345.4 |
| 128 | 53.3 | 424.6 | 259.5 | 344.3 | 354.5 |
| 130 | 54.4 | 433.6 | 267.4 | 353.4 | 363.8 |
| 132 | 55.6 | 442.7 | 275.4 | 362.7 | 373.2 |
| 134 | 56.7 | 451.9 | 283.6 | 372.1 | 382.9 |
| 136 | 57.8 | 461.2 | 292.1 | 381.7 | 392.7 |
| 138 | 58.9 | 470.6 | 300.7 | 391.6 | 402.7 |
| 140 | 60.0 | 480.2 | 309.5 | 401.6 | 413 |
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