Vertiv Liebert CRV - 6.2 Piping Guidelines for Liebert MC Condensers

6.2 Piping Guidelines for Liebert MC Condensers
The following operations must be carried out by an experienced refrigeration technician.
NOTICE
Risk of oil contamination with water. Can cause equipment damage.
Liebert systems require the use of POE (polyolester) oil. POE oil absorbs water at a much
faster rate when exposed to air than previously used oils. Because water is the enemy of a
reliable refrigeration system, extreme care must be used when opening systems during
installation or service. If water is absorbed into the POE oil, it will not be easily removed and will
not be removed through the normal evacuation process. If the oil is too wet, it may require an oil
change. 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.
1. When installing the refrigerant piping, note the following:
Brazing:
• All joints must be brazed.
• Avoid butt brazes by using couplings or swaging one of the pipes with a swaging tool.
• Ensure that all brazed joints are leak-free.
• Flow dry nitrogen through the pipes during brazing.
Always use large-radius curves (bending radius at least equal to pipe diameter). Bend the
pipes as follows:
• soft copper: bend by hand or use bending device;
• hard copper: use preformed curves.
• To minimize oxidation, avoid overheating the pipes when brazing.
2. Connect the pipes to the condenser:
• Condensers with butt-brazed pipe connections: Cut the pipe, enlarge it, and braze it to
the pipeline.
• Respect the direction of refrigerant flow. (See labels on refrigerant.)
3. Wash out the pipelines as follows:
a. Plug up the free ends of the pipes.
b. Connect a helium or nitrogen cylinder, fitted with a reducer (maximum pressure 10 bar),
to the 1/4”SAE Schrader valve of the condenser.
c. Pressurize the pipes with helium or nitrogen.
d. Unplug the pipes instantaneously.
e. Repeat steps a through d several times.
This operation is especially important when hard copper piping is used.
4. Open all the shut-off valves on the room unit.
5. Discharge the room unit pressurized with helium (at 1bar) by opening the charge valves so
that all the branches of the circuit are discharged (for example, on the receiver, on the low-
pressure side, and on the compressor delivery).
6. Cut the spun-closed ends off the hot-gas and liquid-line connections on the Liebert CRV.
Vertiv | Liebert CRV Installer/User Guide | 36