Vertiv Liebert XD Series, System Design Manual

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Replaceable front panels on the Liebert XDH may be customized to match the appearance of various
computer manufacturer’s equipment, allowing the Liebert XDH to blend in with adjacent server
equipment and enclosures. Unidirectional and bidirectional diffusers are available to direct cooling air for
more efficient cooling, depending on the Liebert XDH’s positioning in a row or at the end of a row. Chilled
R-134a refrigerant is provided to the Liebert XDH by a Liebert XDP or by a Liebert XDC. The Liebert XDH
has dual refrigeration circuits, one in the upper half of the module and the other in the lower half. This
permits increasing and decreasing cooling levels in response to server room conditions. The dual
refrigeration circuits permits interlaced connection of two Liebert XD refrigerant sources to enhance
system reliability. The Liebert XDH may be installed in a Liebert XD piping system that includes other
Liebert XD cooling modules.
Controls on the front of the Liebert XDH permit independent operation of the two banks of fans. Dual
power connections ensure continued fan operation if one of two electrical sources fails. Optional smart
modules allow remote shutdown, fan failure alarms, condensate detection and switching fan per bank On
and Off. This saves energy by permitting the module to run with two fans per bank and switching on the
middle when the temperature requires all fans for cooling.
The Liebert XDH is available for hard-piped configurations and with flexible metal pipes with
quick-connect couplings (one-shot or removable) at each end for easy connection to the header system.
The Liebert XDH and Liebert XD Flex Pipes are also available for shipment with a pre-charge of R134a.
This option requires the use of the one-shot flexible pipes.
Figure 1.5 Liebert XDH—horizontal cooling module in hot aisle-cold aisle arrangement
1.6 Liebert XDO—Overhead Cooling Module
The Liebert XDO is an overhead cooling system designed for installation above heat-dissipating
equipment. A fan draws hot air exhausted from the equipment through two cooling coils and discharges
cool air back down to the equipment (see Figure 1.6 on the next page).
Vertiv | Liebert® Xtreme Density™ System Design Manual | 11