Technical Specifications

System Description
5
1.5 Liebert XDH—Horizontal Cooling Module
The Liebert XDH is designed for placement within a row of computer cabinets in the data center in a
hot-aisle-cold-aisle arrangement to maximize the Liebert XDH’s cooling. The Liebert XDH, available
in a half-rack-width module (12" [305mm]), is intended for use with a Liebert XD pumped refrigerant
cooling system, supplied by either a Liebert XDP or Liebert XDC. The module takes in hot air through
the rear from the hot aisle, cools the air by air-to-fluid heat exchangers and discharges the air
through the front of the module into the cold aisle in a diffuse pattern. The cooling air is then drawn
into the enclosures to cool the equipment.
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 5 Liebert XDH—horizontal cooling module in hot aisle-cold aisle arrangement