10-2014 gForce User Manual ● 35
340 to 415 PSIG (2344 to 2861 kPa)
104 to 121 PSIG (717 to 834 kPa)
6 to 12°F (3.33 to 6.67°C) Differential
8 to 10°F (4.44 to 5.55°C) Differential
Depending on ambient conditions
Measure the superheat at the compressor suction line at least 6 inches (152 mm) away
from the compressor.
Note:
Charging to a full liquid line sight glass should never be the sole
means of determining the correct refrigerant charge. Other parameters
such as superheat, suction pressure, head pressure, sub-cooling and
ambient temperature are also important. A system charged to a clear sight
glass is often overcharged.
5.3.1.2 Variable Capacity Compressor
NOTE:
Prior to refrigerant charging, a system vacuum and moisture
removal procedure must have been carried out. Refer to Section 2.10 Leak
Testing and Section 2.11 Evacuation prior to charging the system.
After field refrigerant piping is properly evacuated connect the refrigerant drum to the
high side and charge with liquid. Make sure all hoses are properly purged. Systems
with R-410A require approximately 3.0 lbs. per nominal ton. The compressor power
must be off and prevented from starting inadvertently/automatically. From a vacuum,
slowly open the service valve to feed liquid refrigerant into the high side of the system
until the pressure equalizes. At this point there will be approximately 70-80% of the
total charge in the system. It is likely that more refrigerant will be required to complete
the charging procedure.
WARNING:
Before starting a compressor, the crankcase heater should be
energized for a minimum of 12 hours to reduce the possibility of liquid
slugging on start-up. Failure to energize the crankcase heater could result
in compressor damage. If the system is charged from a vacuum, the
preheating of the compressor is not necessary.
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