4.3 Liebert XDC Interconnection With Liebert XD Cooling Module
All piping must be ASTM (American Society for Testing and Materials) Type ACR copper pipe.
The Liebert XDC may be connected to Liebert XD cooling modules with either Liebert’s XD prefabricated
piping assembly or with rigid, off-the-shelf piping. In either setup, piping for the Liebert XD system is
arranged in a manner similar to piping for a chilled water system. Liebert XD cooling modules are
connected in parallel between main return and supply pipes going to and from the Liebert XDP/Liebert
XDC. Figure 4.1 below represents a typical configuration. For piping details, refer to Liebert’s XD System
Design Manual, SL-16655. The guidelines provided for pipe size must be strictly followed. Failure to size
the main lines and connection lines adequately may result in reduced cooling capacity. The critical
aspects of pipe sizing are related to refrigerant volume and pressure drop. Both must be minimized.
Figure 4.1 Liebert XD system diagram
4.4 Piping Installation Method
The assembly and connection means used for piping in the Liebert XD system are similar to those used
for conventional refrigeration systems. All piping should be installed with high-temperature brazed joints.
Soft soldering is not recommended.
During brazing, the lines must be filled with flowing dry nitrogen to prevent excessive oxidation and scale
formation inside the piping. Prevailing good refrigeration practices must be employed for piping supports,
leak testing, dehydration and charging. Failure to use good system practices may result in damage to the
system. Refer to the ASHRAE refrigeration handbook for general good-practice refrigeration piping.
Insulate all piping lines to prevent condensation in applications where the dew point approaches the
R-134a refrigerant temperature.
Vertiv recommends venting the pressure relief valves for both the R-134a and R-407C sides outside the
conditioned space where it is open to the atmosphere. The R-134a side relief valve is inside the Liebert
XDC unit at the top of the receiver. The R-407C water/glycol-cooled side relief valves are located at each
condenser beneath the Liebert XDC unit in the floor stand. The R-407C air-cooled relief valves are
located outside within the air-cooled system.
Vertiv | Liebert® XDC™ User Manual | 38
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