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3.3 Liebert XDP Interconnection with Liebert XD Cooling Modules
All piping must be ASTM (American Society for Testing and Materials) Type ACR copper pipe.
The Liebert XDP 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 19 represents a typical configuration. For piping details, refer to
Liebert’s XD System Design Manual, SL-16655, available at Liebert’s Web site: www.liebert.com. 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. Each must be minimized.
Figure 19 Liebert XD system diagram
3.4 Piping Installation Methods
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.
Emerson recommends venting the pressure relief valve for the R-134a outside the conditioned space
where it is open to the atmosphere. The R-134a side relief valve is inside the Liebert XDP unit at the
top of the receiver.
3.4.1 Piping Installation—R-134a Pumped Circuit
Emerson recommends venting the relief pressure valve of the Liebert XDP (located at the top of the
receiver) outside of the conditioned space where it is open to the atmosphere.
Liebert XD
Cooling
Module
Liebert XD
Cooling
Module
Liebert XD
Cooling
Module
Liebert XD
Cooling
Module
Liebert XD
Cooling
Module
Liebert XDP
SLOPE—The main supply and return lines to and
from the Liebert XDP must be sloped downward
toward the Liebert XDP at a rate of 1-2" per 20 feet
(25.4-51mm per 6m) of pipe run.
All supply and return
mains must be level
with or above the
top of all Liebert XD
modules