Liebert Extreme Density Chiller XDC - Manual (Page 29)

Piping and Filling with Refrigerant: R-134a and R-407c Circuits
23
For Air Cooled Lee-Temp / Flood Back Head Pressure Control Units Only
NOTE
Proper safety equipment and proper refrigeration tools are required. Check unit nameplate for
correct refrigerant type before topping off or recharging a system.
NOTE
Refrigerant R-407c is a blend of three components and must be introduced and charged from
the cylinder only as a liquid.
Refrigerant R-407c uses a POE (polyolester) lubricant. Do not open the compressor unit piping
to the atmosphere for more than 15 minutes. The compressors contain POE oil that is very
hygroscopic; it quickly absorbs water from the atmosphere. The longer the compressor piping is
open to the atmosphere, the harder it will be to fully evacuate. If left open too long, the POE oil
may need to be replaced before achieving the required vacuum level.
POE oils also have a property that makes them act as a solvent in a refrigeration system.
Maintaining system cleanliness is extremely important because the oil will tend to bring any
foreign matter back to the compressor. Refer to the ASHRAE refrigeration handbook for
general good-practice refrigeration piping.