Completely sealed from room air, high density server racks inside the Liebert XDK-W utilize closed air circulation for cooling. The server heat load is dissipated into the process cold water system through an air-to-waterheat exchanger in the bottom of the rack. Redundant high-performance fans drive closed loop air circulation in the racks interior, while servers are supplied with cold air at the front of the rack.The Liebert XDK-W is a part of the Liebert XD high heat-density cooling product family. Key to the performance and space efficiency of Liebert XDK-W is the Liebert Pumping Unit, XDP-W. The unit houses the isolating heat exchanger between the Liebert XDK-W water circuit and the building chilled water, as well as the control valve, pumps and system controls. It controls the fluid temperature to always be above the actual room dewpoint to prevent condensation on the piping and the coils.