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Piping and Filling with Refrigerant: R-134a and R-407c Circuits
17
Figure 19 Liebert XD system diagram
2.4 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.
Liebert highly recommends venting the pressure relief valves for both the R-134a and R-407c sides out-
side the conditioned space where it is open to the atmosphere. The R-134a side relief valve is inside the
XDC unit at the top of the receiver. The R-407c water/glycol cooled side relief valves are located at each
condenser beneath the XDC unit in the floor stand. The R-407c air cooled relief valves are located outside
within the air cooled system.
2.4.1 Piping Installation—R-134a Pumped Circuit
Liebert highly recommends venting the relief pressure of the Liebert XDC (located at the top of the
receiver) outside of the conditioned space where it is open to the atmosphere.
Piping Mains
All refrigeration piping mains connected to the Liebert XD cooling module, both supply and return,
should be installed with a downward pitch toward the Liebert XDC of 1-2" for every 20 feet (25.4-51mm
per 6m) of pipe run.
Liebert XD
Cooling
Modules
Liebert XD
Cooling
Modules
Liebert XD
Cooling
Modules
Liebert XD
Cooling
Modules
Liebert XD
Cooling
Modules
Liebert XDP/
Liebert XDC
SLOPE—The main supply and return lines to and from the Liebert XDC must be sloped downward
toward the Liebert XDC at a rate of 1-2" for every 20 feet (25.4-51mm per 6m) of pipe run.
Horizontal connector lines should also be sloped downward from the cooling modules toward the
main supply and return lines.
All supply and return
mains must be level
with or above the top
of all Liebert
XD modules