Checking the R-23 Refrigerant Charge
The R-23 refrigerant charge should be checked with the container empty, the unit OFF and all refrigeration system components above -5 °C (23 °F). The R-134a compressor must not have been operated within the past 30 minutes and there must not be frost on the plate-type R-134a / R-23 heat exchanger tubing.
Observe both the suction and discharge pressures. With the unit OFF, the suction and discharge readings should be equal. The R-23 refrigerant pressure in a fully charged system with the unit OFF will vary with the ambient temperature:
| Ambient Temperature | R-23 System Pressure |
|---|---|
| 0 °C (32 °F) | 1600 kPa, 16 bar, 232 psig |
| 20 °C (68 °F) | 1700 kPa, 17 bar, 247 psig |
| 38 °C (100 °F) | 1800 kPa, 18 bar, 261 psig |
R-23 Refrigeration System Receiver Tank
| 1. | The
bottom sight glass ball will rarely float on a fully charged system
during normal operation.
Note Use the lower sight glass to check or add refrigerant
only on a operating unit that is unable to maintain a -55 C to -65
C (-62 F to -94 F) low temperature.
|
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Correct Refrigerant Charge: If the R-23 system pressure stabilizes between 1500 and 2000 kPa, 15 and 20 bar, 220 and 290 psig, the unit will be fully functional. The R-23 refrigerant charge requires no adjustment.
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Low Refrigerant Charge: If the R-23 system pressure stabilizes between 1000 and 1500 kPa, 10 and 15 bar, 145 and 220 psig, the unit cooling capacity will be reduced but the unit should be able to maintain a -55 C to -70 C (-62 F to -94 F) load temperature. Additional R-23 should be added if possible, but do NOT add by operating the unit.
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Over Charge of Refrigerant: If the R-23 system pressure stabilizes above 2000 kPa, 20 bar, 290 psig, the R-23 system is overcharged and may cause the compressor to stop on high pressure cutout when started to precool a warm container. Remove refrigerant until the system pressure stabilizes at 2000 kPa, 20 bar, 290 psig or below.